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Shifting gears in iRacing
Share an easy link: edracing.com/gear
• Shift point & layout information from further down.
• iRacing staff (Dave K) discusses asymmetry further down.
• Please help keep this page updated - contact.
• Szymon O's recommended shifting techniques:
if you have seen an update or related information please link me to it
• Skip Barber (iRacing) downshift: Throttle lift, no clutch (with appropriate lift no blip required although many do).
• Star Mazda (iRacing) downshift discussion thread (2014): some say blip not necessary.
• Kia auto clutch discussion thread (2013).
• Downshift throttle blip: I generally blip from habit, I've never analysed the pros and cons, nor do I remember which cars I do it in.
- Robert B advised 2015s3:
• All of the GT3s reportedly use sequential with ignition cut and auto blip.
•
The Aston reportedly uses the same gearbox (same ratios too) as the Corvette: sequential with ignition cut but with manual blip
• Correct gear and pedal layout
• iRacing optimal gear shift points
- iRacing's shift points shown on G27 LEDs are not always optimal.
- I use M-Spec usb shift light & app (user defined shift points).
- I also recommend & use iSpeed to display various stats - other links in my apps section.
• Updated 2016s4
Thanks again to Rob Bryson for his recent updates.
Source: (iRacing member) Robert B via message
Boxes below are resizable
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Keep scrolling for more cars and different tables.
As
noted by Rob:
"Have had a lot of fun with these new cars, here are 3 more tables:
Le Mans Historic presents a peculiar case where knowledge of a car's maximum power rpm will be valuable.
I'm normally a little cautious when releasing tables for cars with variable ratios,
for fear that drivers will assume there is one optimal strategy encompassing all gear sets,
but it's still informative for those who take a closer look".
• Audi 90 GTO
Audi 90 GTO (added 20 Sept 2016)
Parameters:
- 320 ms reaction on manual lift with tone only
- 200 ms reaction on manual lift with lights
- 800 ms illumination time
- 80 ms rev limit allowance
- 99.6% respected rev limit
Rev Limit RPM: 7700
Estimated Max Power RPM: 7700
Setup: baseline, 24.0l fuel (s4 2016)
Notes: Just shift as late as possible with any gear set! Power is
monotonically increasing.
Ratio Ideal Adj_Target Tone_No-L Tone_L Light_Interval
1 7700 7473 6571 6922 [4585,6922]
2 7700 7586 7159 7328 [6174,7328]
3 7700 7655 7464 7535 [7028,7535]
4 7700 7669 7582 7614 [7391,7614]
5 -- -- off off off
• Nissan GTP ZX-T
Nissan GTP ZX-T (added 20 Sept 2016)
Parameters:
- 320 ms reaction on manual lift with tone only
- 200 ms reaction on manual lift with lights
- 800 ms illumination time
- 80 ms rev limit allowance
Rev Limit RPM: 7350 soft
Estimated Max Power RPM: 6500
Setup: low_downforce, 45.5kg fuel (s4 2016)
Notes: 1st gear is traction limited, thus its ideal shift rpm defers to
the rev limit rpm. Cockpit shift light comes on at 7300;
generally speaking, resist the urge to use it. Revs are allowed
to rise above 7350 but torque drops off sharply at this point.
Le Mans Historic drivers should look for 6500-6600rpm down
Mulsanne when choosing a 5th ratio-- not found with this setup!
Ratio Ideal Adj_Target Tone_No-L Tone_L Light_Interval
1 7350 7237 6752 6941 [5661,6941]
2 7200 7200 6829 6968 [6040,6968]
3 7180 7180 7020 7054 [6444,7054]
4 7030 7030 6929 6963 [6685,6963]
5 -- -- off off off
• Ford Mustang FR500S
Ford Mustang FR500S (added 20 Sept 2016)
Parameters:
- 320 ms reaction on manual lift with tone only
- 200 ms reaction on manual lift with lights
- 800 ms illumination time
- 80 ms rev limit allowance
Rev Limit RPM: 7000
Estimated Max Power RPM: 5750
Setup: baseline (s4 2016)
Notes: Top speed reached in 5th gear. Pretty solid matching between the
penultimate cockpit shift light state (4 of 5 illuminated, 6200 rpm)
and the optimal strategy, pretty viable to use it.
Ratio Ideal Adj_Target Tone_No-L Tone_L Light_Interval
1 6850 6850 6485 6645 [5416,6645]
2 6400 6400 6213 6281 [5763,6281]
3 6310 6310 6224 6256 [6015,6256]
4 6230 6230 6209 6217 [6117,6217]
5 -- -- off off off
6 -- -- off off off
• Updated 2016s3
Update after the update to add Cadillac CTS-V, Pontiac Solstice, Ruf RT 12R C-Spec, SCCA Spec Racer Ford (SRF), Skip Barber Formula 2000.
Note, the Skip info has been added with the previous Skip info much further down the page.
Source: with thanks to (iRacing member) Robert B via message
Boxes below are resizable
Chrome and Firefox: click & drag bottom right corner
Scrolling on iPad: I slide my fingers in the box
Keep scrolling for more cars and different tables.
As noted by Rob: the next few (data) is of more limited use than the tables (further down) for cars with fixed ratios due to variation between setups, but someone out there might still be able to glean useful information. Even those looking to use drastically different gear sets may use this info to get a better picture of engine performance.
The general solution for cars with custom ratios is to run an acceleration simulation with the desired gear set, but in order to do this easily, one needs a high quality engine torque curve and aero map. For now, Rob just runs these one at a time as needed.
• SCCA Spec Racer Ford (SRF)
SCCA Spec Racer Ford (added 7 Aug 2016)
Parameters:
- 320 ms reaction on manual lift with tone only
- 200 ms reaction on manual lift with lights
- 800 ms illumination time
- 80 ms rev limit allowance
Rev Limit RPM: 6500
Estimated Max Power RPM: 5200
Setup: baseline (s3-2016)
Notes: Pity the driver still revving this one to the limiter... the
penalty for doing so is pretty massive: 3rd and 4th produce less
than half the forward acceleration as the next gear when at 6500!
Ratio Ideal Adj_Target Tone_No-L Tone_L Light_Interval
1 6200 6200 5624 5867 [3802,5867]
2 5780 5780 5571 5651 [5048,5651]
3 5670 5670 5582 5613 [5371,5613]
4 5590 5590 5559 5571 [5488,5571]
5 -- -- off off off
• Ruf RT 12R C-Spec
Ruf RT 12R C-Spec (added 7 Aug 2016)
Parameters:
- 280 ms reaction on auto lift with tone only
- 180 ms reaction on auto lift with lights
- 800 ms illumination time
- 80 ms rev limit proximity allowance
- 99.6% respected rev limit
Rev Limit RPM: 8500
Estimated Max Power RPM: 7500
Setup: baseline, 45.0l fuel (s3-2016)
Notes: Baseline setup uses the short final drive; the tall option is just
3.8% taller, close enough to share instrument timing with short.
Ratio Ideal Adj_Target Tone_No-L Tone_L Light_Interval
1 8500 8264 7499 7784 [5374,7784]
2 8500 8389 8039 8167 [7070,8167]
3 8360 8360 8146 8217 [7605,8217]
4 8500 8464 8343 8384 [8021,8384]
5 8500 8466 8410 8426 [8273,8426]
6 -- -- off off off
• Pontiac Solstice
Pontiac Solstice (added 7 Aug 2016)
Parameters:
- 320 ms reaction on manual lift with tone only
- 200 ms reaction on manual lift with lights
- 800 ms illumination time
- 80 ms rev limit allowance
- 99.6% respected rev limit
Rev Limit RPM: 7200
Estimated Max Power RPM: 7000
Setup: baseline, 28.3l fuel (s3-2016)
Notes: Top speed is reached in 4th gear. Hilariously wide ratio spacing
for track use.
Ratio Ideal Adj_Target Tone_No-L Tone_L Light_Interval
1 7200 7038 6444 6670 [4975,6670]
2 7200 7131 6911 7002 [6411,7002]
3 7200 7171 7094 7121 [6925,7121]
4 -- -- off off off
5 -- -- off off off
• Cadillac CTS-V Racecar
Cadillac CTS-V Racecar (added 7 Aug 2016)
Parameters:
- 280 ms reaction on auto lift with tone only
- 180 ms reaction on auto lift with lights
- 800 ms illumination time
- 80 ms rev limit proximity allowance
Rev Limit RPM: 7900
Estimated Max Power RPM: 6200
Setup: baseline, 45.0l fuel (s3-2016)
Notes: This car produced very noisy data, making it difficult to measure
in high gears, however the torque curve is very flexible, meaning
deviations from the optimal strategy are hardly felt.
Ratio Ideal Adj_Target Tone_No-L Tone_L Light_Interval
1 7380 7380 6843 7062 [5204,7062]
2 7080 7080 6767 6883 [5881,6883]
3 6950 6950 6785 6848 [6318,6848]
4 6950 6950 6860 6885 [6591,6885]
5 6950 6950 6905 6917 [6763,6917]
6 -- -- off off off
• Dallara DW12 - Road Course
Dallara DW12 - Road Course (added 4 July 2016)
Parameters:
- 280 ms reaction on auto lift with tone only
- 180 ms reaction on auto lift with lights
- 800 ms illumination time
- 80 ms rev limit proximity allowance
- 99.6% respected rev limit
Rev Limit RPM: 12010
Estimated Max Power RPM: 11500
Setup: medium_downforce, 36.1l fuel, custom gear ratios (s3-2016)
Notes: Important: While the optimal shift points for this car are always
going to be up at the limiter regardless of gear set, the timing
behind this data is based on the following gear set: 1st_14/34,
2nd_16/32, 3rd_17/30, 4th_19/30, 5th_19/27, 6th_19/25, Final_17/59.
Choice of 6th gear ratio is free. Road course aero, road course
engine performance.
Ratio Ideal Adj_Target Tone_No-L Tone_L Light_Interval
1 12010 11806 11105 11350 [9146,11350]
2 12010 11896 11479 11731 [10313,11731]
3 12010 11925 11665 11760 [10924,11760]
4 12010 11960 11816 11870 [11405,11870]
5 12010 11961 11922 11930 [11785,11930]
6 -- -- off off off
• HPD ARX-01c
HPD ARX-01c (added 4 July 2016)
Parameters:
- 280 ms reaction on auto lift with tone only
- 180 ms reaction on auto lift with lights
- 800 ms illumination time
- 80 ms rev limit proximity allowance
Rev Limit RPM: 9800 (soft)
Estimated Max Power RPM: 8900
Setup: medium_downforce, 30.0kg fuel, custom gear ratios (s3-2016)
Notes: Important: this data is valid only for the following gear set:
1st_2.571, 2nd_2.000, 3rd_1.667, 4th_1.474, 5th_1.348, 6th_1.261,
Final_3.575. Large differences between optimal and instrumentation.
Note that choice of final drive ratio does not affect ideal shift
points, but does affect timing.
Ratio Ideal Adj_Target Tone_No-L Tone_L Light_Interval
1 9800 9673 9173 9357 [7699,9357]
2 9740 9733 9476 9572 [8724,9572]
3 9520 9520 9370 9425 [8944,9425]
4 9310 9310 9214 9251 [8951,9251]
5 9180 9180 9120 9141 [8960,9141]
6 -- -- off off off
• Aston Martin DBR9
Aston Martin DBR9 (added 4 July 2016)
Parameters:
- 280 ms reaction on auto lift with tone only
- 180 ms reaction on auto lift with lights
- 800 ms illumination time
- 80 ms rev limit proximity allowance
Rev Limit RPM: 7600
Estimated Max Power RPM: 6700
Setup: baseline, 45.0l fuel, custom gear ratios (s3-2016)
Notes: Important: this data is valid only for the following gear set:
Drop_1.389, Final_2.167, 1st_2.857, 2nd_2.188, 3rd_1.789,
4th_1.524, 5th_1.318, 6th_1.190. Large differences between optimal
and instrumentation. Note that choice of final drive ratio and/or
drop ratio does not affect ideal shift points, but does affect
timing.
Ratio Ideal Adj_Target Tone_No-L Tone_L Light_Interval
1 7510 7442 6970 7172 [5440,7172]
2 7390 7390 7070 7184 [6146,7184]
3 7250 7250 7058 7130 [6508,7130]
4 7210 7210 7104 7146 [6794,7146]
5 7070 7070 7016 7038 [6863,7038]
6 -- -- off off off
• Chevrolet Corvette C6.R
Chevrolet Corvette C6.R (added 4 July 2016)
Parameters:
- 280 ms reaction on auto lift with tone only
- 180 ms reaction on auto lift with lights
- 800 ms illumination time
- 80 ms rev limit proximity allowance
Rev Limit RPM: 6200
Estimated Max Power RPM: 5400
Setup: baseline, 45.0l fuel, custom gear ratios (s3-2016)
Notes: Important: this data is valid only for the following gear set:
Drop_1.095, Final_2.167, 1st_2.857, 2nd_2.188, 3rd_1.789, 4th_1.524,
5th_1.318, 6th_1.190. Note that choice of final drive ratio and/or
drop ratio does not affect ideal shift points, but does affect timing.
Ratio Ideal Adj_Target Tone_No-L Tone_L Light_Interval
1 6070 6070 5671 5813 [4555,5813]
2 5910 5910 5659 5752 [4957,5752]
3 5810 5810 5661 5716 [5245,5716]
4 5810 5810 5727 5755 [5499,5755]
5 5660 5660 5617 5632 [5494,5632]
6 -- -- off off off
• Global Mazda MX5
Global Mazda MX-5 Cup
Parameters:
- 320 ms reaction on manual lift with tone only
- 200 ms reaction on manual lift with lights
- 800 ms illumination time
- 80 ms rev limit allowance
Rev Limit RPM: 6850
Estimated Max Power RPM: 6200
Setup: baseline (s3 2016)
Notes: Top speed reached in 5th gear
Ratio Ideal Adj_Target Tone_No-L Tone_L Light_Interval
1 6850 6662 5930 6200 [3907,6200]
2 6850 6783 6533 6628 [5901,6628]
3 6600 6600 6493 6534 [6247,6534]
4 6570 6570 6527 6545 [6438,6545]
5 -- -- off off off
6 -- -- off off off
• Forumla Renault 2.0
Formula Renault 2.0
Parameters:
- 280 ms reaction on auto lift with tone only
- 180 ms reaction on auto lift with lights
- 800 ms illumination time
- 80 ms rev limit proximity allowance
- 99.6% respected rev limit
Rev Limit RPM: 7550
Estimated Max Power RPM: 7550
Setup: baseline (s3 2016)
Notes: --
Ratio Ideal Adj_Target Tone_No-L Tone_L Light_Interval
1 7550 7389 6819 7024 [5314,7024]
2 7550 7461 7139 7259 [6277,7259]
3 7550 7489 7307 7366 [6759,7366]
4 7550 7517 7404 7449 [7101,7449]
5 7550 7519 7459 7479 [7305,7479]
6 7550 7519 7490 7502 [7419,7502]
7 -- -- off off off
• Holden Commodore VF V8SC
Holden Commodore VF V8
Parameters:
- 280 ms reaction on auto lift with tone only
- 180 ms reaction on auto lift with lights
- 800 ms illumination time
- 80 ms rev limit proximity allowance
- 99.6% respected rev limit
Rev Limit RPM: 7500
Estimated Max Power RPM: 7400
Setup: baseline (s3 2016)
Notes: --
Ratio Ideal Adj_Target Tone_No-L Tone_L Light_Interval
1 7500 7385 6842 7052 [5323,7052]
2 7500 7416 7109 7226 [6285,7226]
3 7500 7448 7259 7331 [6784,7331]
4 7500 7466 7363 7402 [7071,7402]
5 7500 7470 7423 7432 [7284,7432]
6 -- -- off off off
• Updated 2016s3
Source: Robert B's GT3 Optimum Shift Points thread
• Top - for use with a shift tone with no accompanying shift lights
• Bottom - for use with per-ratio programmable shift lights with or without an accompanying tone
• Note, I reworded "illuminate" to "light"
• For a tone try an app like Sound Shift ( apps section).
Audi R8 LMS
1st: 7260
2nd: 7536
3rd: 7514
4th: 7482
5th: 7532
Audi R8 LMS
1st: light from 5551 to 7467, tone 7467
2nd: light from 6622 to 7657, tone 7657
3rd: light from 6973 to 7585, tone 7585
4th: light from 7175 to 7528, tone 7528
5th: light from 7378 to 7553, tone 7553
|
BMW Z4 GT3
1st: 8172
2nd: 8551
3rd: 8757
4th: 8792
5th: 8841
BMW Z4 GT3
1st: light from 6363 to 8405, tone 8405
2nd: light from 7584 to 8675, tone 8675
3rd: light from 8230 to 8816, tone 8816
4th: light from 8507 to 8828, tone 8828
5th: light from 8714 to 8855, tone 8855
|
Ford GT GT3
1st: 7153
2nd: 7336
3rd: 7323
4th: 7313
5th: 7318
Ford GT GT3
1st: light from 6183 to 7283, tone 7283
2nd: light from 6795 to 7413, tone 7413
3rd: light from 6978 to 7369, tone 7369
4th: light from 7105 to 7341, tone 7341
5th: light from 7210 to 7332, tone 7332
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McLaren MP4-12C GT3
1st: 6769
2nd: 6836
3rd: 6770
4th: 6732
5th: 6702
McLaren MP4-12C GT3
1st: light from 5566 to 6916, tone 6916
2nd: light from 6169 to 6923, tone 6923
3rd: light from 6397 to 6817, tone 6817
4th: light from 6522 to 6761, tone 6761
5th: light from 6596 to 6717, tone 6717
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Mercedes-Benz AMG GT3
Short Gear Stack
1st: 6762
2nd: 6831
3rd: 6473
4th: 6434
5th: 6437
Mercedes-Benz AMG GT3
Short Gear Stack
1st: light from 5223 to 6951, tone 6951
2nd: light from 6093 to 6926, tone 6926
3rd: light from 6062 to 6527, tone 6527
4th: light from 6178 to 6469, tone 6469
5th: light from 6300 to 6458, tone 6458
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Mercedes-Benz AMG GT3
Standard Gear Stack
1st: 6762
2nd: 6831
3rd: 6631
4th: 6490
5th: 6440
Mercedes-Benz AMG GT3
Standard Gear Stack
1st: light from 5223 to 6951, tone 6951
2nd: light from 6093 to 6926, tone 6926
3rd: light from 6250 to 6683, tone 6683
4th: light from 6276 to 6519, tone 6519
5th: light from 6332 to 6455, tone 6455
|
Ruf RT 12R Track
1st: 8012
2nd: 8115
3rd: 8186
4th: 8738
5th: 8786
Ruf RT 12R Track
1st: light from 5983 to 8261, tone 8261
2nd: light from 6923 to 8275, tone 8275
3rd: light from 7484 to 8279, tone 8279
4th: light from 8407 to 8782, tone 8782
5th: light from 8643 to 8807, tone 8807
|
Rob emphasizes there is a difference between optimal shift
and when instrumentation should give the cues.
We don't react at the same speed to a beep or light - adjust RPM points to suit your reaction time.
Testing methodology and data collection.
To determine the optimal shift points in an intuitive manner and without
access to the engine torque LUTs for each car, I did telemetry runs on
the back straight at Talladega to form a graph for each car of
longitudinal acceleration as a function of speed and gear. The optimal
shift points are those intersections resulting in a frontier of greatest
area covered, or put another way, those granting the least area lost
relative to a constant power contour.
Planning and execution.
Inadequate instrumentation has long been a pet peeve of mine in sim
racing. One of the most frustrating things for me to watch is an
extremely talented driver shifting at all the wrong times due to a lack
of information and/or a poor execution strategy. It is nice to know and
understand what the optimal shift points are for each gear, but it takes
a little bit more to make it happen on track and make real gains.
With the raw numbers out in the open from the telemetry runs, our
goal is to nail as many full-throttle shifts as close as possible to
those points over the course of a lap or race distance using as little
concentration as possible. This calls for effective cockpit aids to give
the driver precisely the information he or she needs as clearly as
possible so they can focus on all the other parts of driving. For a long
time now this has been done with shift lights and/or tones.
It is in my opinion that shift lights and tones are tools of timing —
that they exist to tell the driver when to shift, and not anything
else. The important distinction here is that I don't see shift lights
and tones as ancillary tachometers, that the RPM itself is only
secondary to the issue of timing. As such, a slick and streamlined
light/tone system is programmed off of time domain offsets, not
frequency (RPM).
Long story short, we want to set the tone RPMs at a specific time
interval before each shift point arises in a full throttle acceleration
trace, and likewise with the shift light illumination intervals. Careful
analysis of top level motorsport shows that this is and has been done
for a long time. It's very easy to spot from F1 onboards, particularly
when compared to rudimentary implementations in the sims and sim
hardware we're used to seeing.
I believe that when done correctly, the result is that a driver will
put more shifts closer to the optimum with less thought needed,
granting him or her more focus for the driving itself.
Results.
Rev Limit (RPM): maximum rpm allowed by the engine
Estimated Max Power (RPM): estimate from telemetry for the rpm at which the engine produces maximum power
Ideal Shift Point: optimal rpm at which a shift should be performed in perfect conditions
Adjusted
Target Shift Point: a shift point lower than the ideal allowing for
varying reaction time and small engine rpm fluctuations to avoid hitting
the rev limit
Rev Limit Offset Time (s): minimum time buffer
between an adjusted target shift point and a rev limit as a reaction
time allowance before hitting the limiter
Tone Reaction Time (s): desired time between the tone sounding and the target shift point occurring under full throttle
Shift Light Illumination Interval (s): desired time between the first and last states of the shift light illumination pattern
I use the rev limit offset time to set adjusted target shift points when they are close or coincident with the rev limit RPM.
For the following tables, these values were used:
Reaction Time (tone, no shift lights): 280 ms
Reaction Time (with shift lights): 180 ms
Shift Light Illumination Interval: 800 ms
Rev Limit Offset Time: 80 ms
• Audi R8 LMS
Audi R8 LMS
Parameters:
- 280 ms reaction on auto lift with tone only
- 180 ms reaction on auto lift with lights
- 800 ms illumination time
- 80 ms rev limit proximity allowance
Rev Limit RPM: 8000
Estimated Max Power RPM: 7000
Setup: baseline, standard final drive, 60.0l fuel (s3 2016)
Notes: --
Ratio Ideal Adj_Target Tone_No-L Tone_L Light_Interval
1 8000 7838 7260 7467 [5551,7467]
2 7860 7860 7536 7657 [6622,7657]
3 7710 7710 7514 7585 [6973,7585]
4 7600 7600 7482 7528 [7175,7528]
5 7590 7590 7532 7553 [7378,7553]
6 -- -- off off off
• BMW Z4 GT3
BMW Z4 GT3
Parameters:
- 280 ms reaction on auto lift with tone only
- 180 ms reaction on auto lift with lights
- 800 ms illumination time
- 80 ms rev limit proximity allowance
Rev Limit RPM: 9000
Estimated Max Power RPM: 8300
Setup: baseline, standard final drive, 58.0l fuel (s3 2016)
Notes: --
Ratio Ideal Adj_Target Tone_No-L Tone_L Light_Interval
1 9000 8807 8172 8405 [6363,8405]
2 9000 8900 8551 8675 [7584,8675]
3 9000 8943 8757 8816 [8230,8816]
4 8900 8900 8792 8828 [8507,8828]
5 8900 8900 8841 8855 [8714,8855]
6 -- -- off off off
• Ford GT GT3
Ford GT GT3
Parameters:
- 280 ms reaction on auto lift with tone only
- 180 ms reaction on auto lift with lights
- 800 ms illumination time
- 80 ms rev limit proximity allowance
Rev Limit RPM: 7600
Estimated Max Power RPM: 6800
Setup: baseline, standard final drive, 58.0l fuel (s3 2016)
Notes: --
Ratio Ideal Adj_Target Tone_No-L Tone_L Light_Interval
1 7600 7494 7153 7283 [6183,7283]
2 7550 7537 7336 7413 [6795,7413]
3 7450 7450 7323 7369 [6978,7369]
4 7390 7390 7313 7341 [7105,7341]
5 7360 7360 7318 7332 [7210,7332]
6 -- -- off off off
• McLaren MP4-12C GT3
McLaren MP4-12C GT3
Parameters:
- 280 ms reaction on auto lift with tone only
- 180 ms reaction on auto lift with lights
- 800 ms illumination time
- 80 ms rev limit proximity allowance
Rev Limit RPM: 7820
Estimated Max Power RPM: 6400
Setup: baseline, tall final drive, 65.0l fuel (s3 2016)
Notes: Large differences between optimal and instrumentation. Recommend
using the tall final drive ratio on most tracks.
Ratio Ideal Adj_Target Tone_No-L Tone_L Light_Interval
1 7170 7170 6769 6916 [5566,6916]
2 7070 7070 6836 6923 [6169,6923]
3 6900 6900 6770 6817 [6397,6817]
4 6810 6810 6732 6761 [6522,6761]
5 6740 6740 6702 6717 [6596,6717]
6 -- -- off off off
• Mercedes-Benz AMG GT3 - Short Gear Stack
Mercedes-Benz AMG GT3 - Short Gear Stack
Parameters:
- 280 ms reaction on auto lift with tone only
- 180 ms reaction on auto lift with lights
- 800 ms illumination time
- 80 ms rev limit proximity allowance
Rev Limit RPM: 7500
Estimated Max Power RPM: 6200
Setup: baseline, short gear stack, 60.0l fuel (s3 2016)
Notes: Short and standard gear stacks have different individual ratios
and thus different ideal shift points, as opposed to a swap in
final drive. Large differences between optimal and instrumentation.
Recommend using the standard gear stack at most tracks.
Ratio Ideal Adj_Target Tone_No-L Tone_L Light_Interval
1 7270 7270 6762 6951 [5223,6951]
2 7090 7090 6831 6926 [6093,6926]
3 6620 6620 6473 6527 [6062,6527]
4 6530 6530 6434 6469 [6178,6469]
5 6490 6490 6437 6458 [6300,6458]
6 -- -- off off off
• Mercedes-Benz AMG GT3 - Standard Gear Stack
Mercedes-Benz AMG GT3 - Standard Gear Stack
Parameters:
- 280 ms reaction on auto lift with tone only
- 180 ms reaction on auto lift with lights
- 800 ms illumination time
- 80 ms rev limit proximity allowance
Rev Limit RPM: 7500
Estimated Max Power RPM: 6200
Setup: baseline, standard gear stack, 60.0l fuel (s3 2016)
Notes: Short and standard gear stacks have different individual ratios
and thus different ideal shift points, as opposed to a swap in
final drive. Large differences between optimal and instrumentation.
Recommend using the standard gear stack at most tracks.
Ratio Ideal Adj_Target Tone_No-L Tone_L Light_Interval
1 7270 7270 6762 6951 [5223,6951]
2 7090 7090 6831 6926 [6093,6926]
3 6770 6770 6631 6683 [6250,6683]
4 6570 6570 6490 6519 [6276,6519]
5 6480 6480 6440 6455 [6332,6455]
6 -- -- off off off
• Ruf RT 12R Track
Ruf RT 12R Track
Parameters:
- 280 ms reaction on auto lift with tone only
- 180 ms reaction on auto lift with lights
- 800 ms illumination time
- 80 ms rev limit proximity allowance
Rev Limit RPM: 9400
Estimated Max Power RPM: 7100
Setup: baseline, 65.0l fuel (s3 2016)
Notes: No ratio adjustments on this car. The bias toward higher revs in
gears 4 through 6 is due to a downward inflection in the engine's
power curve which can be avoided when the rpm drops become small.
Ratio Ideal Adj_Target Tone_No-L Tone_L Light_Interval
1 8700 8700 8012 8261 [5983,8261]
2 8540 8540 8115 8275 [6923,8275]
3 8440 8440 8186 8279 [7484,8279]
4 8860 8860 8738 8782 [8407,8782]
5 8840 8840 8786 8807 [8643,8807]
6 -- -- off off off
• Rob's FAQ:
What about changes to the final drive?
The final drive ratio acts only as a torque multiplier for the entire drivetrain, and so it doesn't affect the spacing of individual ratios. Because the spacing doesn't change, the shift points remain the same. The timing, however, changes subtly, but not enough to matter much given the limitations within GT3.
So.. wouldn't mass, fuel load, and total drag level also affect timing since they affect the acceleration curve?
Yes, in theory these values are only correct for one particular vehicle condition, but the differences are fairly small.
Why is there a difference in specified reaction time between using only a tone and using a shift light pattern?
With only a tone, we react to a single audio cue whereas with shift lights, we have earlier warning and can act sooner after the final state is reached. It's important to note that the values used are based on average reactions, not those achievable with full concentration.
What if my dashboard software doesn't support ratio-specific shift light RPM intervals?
If your software lacks this feature, request it from the developer! While I don't own a license to it nor endorse it, Z1 is the only program I'm aware of that has the ability to do this.
What makes for a good shift light pattern?
There is some subjectivity to this, but in my opinion a good pattern is one which is easily legible from your peripheral vision. You want to not only see the pattern, but recognize its shape as it unfolds.
The best-known pattern is probably McLaren's PCU-6 style green-red-blue horizontal LED array. Originally consisting of three large, discrete states in easily-distinguishable primary colors, this pattern is easily followed out of the corner of your eye.
An example pattern:
1 G G
2 G G B B
3 G G B B R R
4 Y Y Y Y Y Y Y Y
• From 2016s2
• McLaren MP4-30
Update: MP4-30 Quick User Guide [ pdf attached to thread ] For me: filed.
iRacing's McLaren MP4-30 added 2016s1 - release notes:
"- New car added! The McLaren MP4-30 Formula 1 racecar features a few cutting edge systems that help set it apart from the pack, including the Drag Reduction System (DRS) to enable boosts of speed on straights, the Energy Recovery System (ERS) to re-charge the vehicle's batteries, and the Motor Generator Unit (MGU) to provide even more power for overtaking. Jump in the cockpit and get ready to experience a truly modern racing machine."
- McLaren MP4-30 forum section.
- Noted from Shift RPMs thread:
- It's been suggested to change gears at the blue lights.
- "The auto shift aid shifts at 12250 if that helps, that is a bit after the last light flips on" (David T).
- "Sound Shift" users:
Member (Bert V) posted how to add the MP4-30:
In version 4.0 add mclarenmp430,McLaren-Honda MP430,8,12000 in file vehicles.ini
As explained by Bert:
mclarenmp430 is the iRacing name
McLaren-Honda MP430 is what he named it
8 is number of gears
12000 RPM's is standard shift point
* App links in my apps section.
- Member Robert B posted:
Post was edited 5 time(s). Last update was at 12/12/2015 1:16 p.m
Let me know if edited again please.
Box below is resizable in Chrome and Firefox (click & drag bottom right corner).
Scrolling on iPad: I slide my fingers in the box.
Sorry it took so long, but the site finally works after Tuesday!
First, the shift light table as programmed into the car, for all fixed MGU-K deployment modes:
1st: 11440 - 12400
2nd: 11440 - 12400
3rd: 11260 - 12160
4th: 10950 - 11850
5th: 11000 - 11450
6th: 10700 - 11200
7th: 10700 - 11300
8th: 10700 - 11300
Rev Limit: ~12850 soft
We see a nice regression in both target shift point, due to the fuel flow restriction above 10500, as well as in RPM spanning width, as the change in RPM drops as we rise through the gearbox.
ATLAS analysis is difficult in traction-limited gears, but I can confirm that for ratios 4 through 7, the upper bound (blue illumination) represents the target shift point almost identically. I would put money on the same holding true for all blue RPMs, and critically this is the case both with and without fixed MGU-K deployment, suggesting a flat amount of torque added over the usable rev range.
I find the default shift lights to be highly usable, and am currently running a ShiftTone setup corresponding to all the final state (blue) RPMs, as follows. I believe this is a healthy baseline and is certainly better than the facepalm-inducing YouTube videos I've watched of drivers shifting up over 12000 for all gears due to a poorly-programmed external solution.
1st: 12400
2nd: 12400
3rd: 12160
4th: 11850
5th: 11450
6th: 11200
7th: 11300
Driving off a light pattern means drivers can react far quicker to the final state vs. a tone alone, but in an ideal world I would both account for said reaction time as well as equalize the pattern illumination time for all gears.
tl;dr is that Mr. Hudec is right—McLaren know what they're doing and if you feel the urge to let it rev out past blue, resist it!
- Notes from Rob's GT3 thread. (2016s2)
Rob emphasizes there is a difference between optimal shift
and when instrumentation should give the cues.
We don't react at the same speed to a beep or light - adjust RPM points to suit your reaction time.
- Results.
Rev Limit (RPM): maximum rpm allowed by the engine
Estimated Max Power (RPM): estimate from telemetry for the rpm at which the engine produces maximum power
Ideal Shift Point: optimal rpm at which a shift should be performed in perfect conditions
Adjusted Target Shift Point: a shift point lower than the ideal allowing for varying reaction time and small engine rpm fluctuations to avoid hitting the rev limit
Rev Limit Offset Time (s): minimum time buffer between an adjusted target shift point and a rev limit as a reaction time allowance before hitting the limiter
Tone Reaction Time (s): desired time between the tone sounding and the target shift point occurring under full throttle
Shift Light Illumination Interval (s): desired time between the first and last states of the shift light illumination pattern
I use the rev limit offset time to set adjusted target shift points when they are close or coincident with the rev limit RPM.
For the following tables, these values were used:
Reaction Time (tone, no shift lights): 280 ms
Reaction Time (with shift lights): 180 ms
Shift Light Illumination Interval: 800 ms
Rev Limit Offset Time: 80 ms
• Reaction time
- I suggest trying an online tool to test your reaction time Eg: http://www.humanbenchmark.com/tests/reactiontime
Apparently I'm a slow old fart, averaging 500 ms. Based on the result, I'll lower my own RPM points slightly.
The points below are Robert's suggestions.
• Skip Barber RPM shift points
Shot by Strop Ten, unknowingly captured my WIP signage
2016s3 iRacing's Skip Barber. Source: (iRacing member) Robert B via message. Skip Barber Formula 2000 (added 7 Aug 2016)
Parameters:
- 320 ms reaction on manual lift with tone only
- 200 ms reaction on manual lift with lights
- 800 ms illumination time
- 80 ms rev limit allowance
Rev Limit RPM: 6400
Estimated Max Power RPM: 5600
Setup: baseline, 11.7l fuel (s3-2016)
Notes: --
Ratio Ideal Adj_Target Tone_No-L Tone_L Light_Interval
1 6190 6190 5949 6043 [5387,6043]
2 6140 6140 5983 6047 [5634,6047]
3 6240 6240 6151 6184 [5946,6184]
4 6270 6270 6237 6248 [6156,6248]
5 -- -- off off off
2015s3 iRacing's Skip Barber. Post by Robert B:
Skip Barber Formula 2000
Parameters: t_reaction = 330 ms
t_illumination = 660 ms
t_limiterbuffer = 70 ms
limiter_ceiling_percent = 0.996
rpm_range_percent = 0.25
Setup: baseline, 11.7L (s3-2015)
Rev Limit RPM: 6400
Estimated Max Power RPM: 5500
Ratio Optimal Shift RPM Adj Target RPM Tone RPM Illumination Interval
1 6200 6200 5956 5422-5956
2 6150 6150 5993 5663-5993
3 6210 6210 6123 5930-6123
4 6260 6260 6222 6154-6222
5 -- -- (off) (off)
As explained by Robert in post, the above is based on telemetry analysis in ATLAS. Screenshot.
2014s3 PL posted
Fanaleds set for
1st: 5700
2nd: 5900
3rd: 6000
4th: 6200
5th: 6200
|
2013 post
N-1: 6300
1-2: 6050
3-4: 6000
4-5: 6250
|
2012 post
N-1: 6350 64/102 (mph/kph)
1-2: 6200 76/122
3-4: 6300 92/147
4-5: 6350 113/118
|
Note: The 2013 post is sourced from Second Shift (written 2010)
(This was the original link http://www.iracing.com/iracingnews/iracing-news/second-shift)
The transmission has reportedly changed since the article was written
To run your own tests, see Optimum Revs thread
• Spec Racer Ford (SRF)
See new SRF information further up page ^^^
My LED shift light set at 5650 RPM for a 5600 - 5700 change
I was changing much higher, lower is definitely better for me.
Eg. 2013s4 my best lap at Phillip Island 1.51.4 (WR at time 1.50.9)
Read the pinned topics in Spec forum section.
RPMs originally from Zen and the art of the Spec Racer Ford thread (7/2012)
Reportedly still valid 12/2015 from thread:
1-2 6050-6250 RPM (31-32 mph) (50-52 kph)
2-3 5600-5900 RPM (54-57mph) (87-90 kph)
3-4 5600-5750 RPM (77-80 mph) (124-128 kph)
4-5 5550-5600 RPM (102-103 mph) (162-165 kph)
• Aston Martin DBR9
2015s3. Post by Robert B: ( see 2016s3 results further up)
Aston Martin DBR9
Parameters: t_reaction = 280 ms
t_illumination = 560 ms
t_limiterbuffer = 70 ms
limiter_ceiling_percent = 0.996
rpm_range_percent = 0.25
Setup: baseline, 45L (s3-2015)
Rev Limit RPM: 7600
Estimated Max Power RPM: 6700
Ratio Optimal Shift RPM Adj Target RPM Tone RPM Illumination Interval
1 7600 7450 6877 [5418,6877]
2 7320 7320 6961 [6120,6961]
3 7220 7220 6995 [6474,6995]
4 7180 7180 7041 [6732,7041]
5 7280 7280 7217 [7074,7217]
6 -- -- (off) (off)
Things will vary from gearset to gearset
In general you won't want to shift at the limiter.
The data is pulled from telemetry in ATLAS of isolated full throttle runs in each gear.
Rob said he ran another gear set, one more likely to be used than the rather wide baseline spread; results:
Aston Martin DBR9
Parameters: t_reaction = 280 ms
t_illumination = 560 ms
t_limiterbuffer = 70 ms
limiter_ceiling_percent = 0.996
rpm_range_percent = 0.25
Setup: baseline, 45L, 1.389 drop, 2.167 final (s3-2015)
Rev Limit RPM: 7600
Estimated Max Power RPM: 6700
Drop Ratio: 1.389
Final Drive Ratio: 2.167
Ratio Optimal RPM Adj Target RPM Tone RPM Light Interval RPM Drop
2.857 7510 7455 6956 5739-6956 1746
2.188 7370 7370 7056 6315-7056 1344
1.789 7210 7210 7009 6562-7009 1068
1.524 7190 7190 7083 6817-7083 972
1.318 7030 7030 6967 6831-6967 683
1.190 -- -- (off) (off)
The main takeaway is that if you are aggressive with running narrow spreads in high gears,
you'll need to be equally aggressive in retarding your shift points accordingly.
The meat of the power seems to be in the 6400-7000 range.
This particular gear set is recommended for circuits with a 258-262 km/h end of straight speed.
• HPD ARX-01c
2015s3. Post by Robert B: ( see 2016s3 results further up)
HPD ARX-01c
Parameters: t_reaction = 280 ms
t_illumination = 560 ms
t_limiterbuffer = 70 ms
limiter_ceiling_percent = 0.996
rpm_range_percent = 0.25
Setup: medium_downforce, 30kg fuel (s3-2015)
Rev Limit RPM: 9800 soft
Estimated Max Power RPM: 8900
Ratio Optimal RPM Adj Target RPM Tone RPM Illumination Interval RPM Drop
2.429 9800 9672 9144 7893-9144 1931
1.944 9740 9729 9427 8705-9427 1667
1.611 9470 9470 9277 8849-9277 1070
1.429 9410 9410 9294 9027-9294 942
1.286 9390 9390 9323 9174-9323 920
1.160 -- -- (off) (off) --
Robert notes: the optimum strategy for the default ratios on the medium_downforce.sto.
Each gear set will have it's own strategy. The meat of the power curve is in the 8500-9300 range.
The HPD has a soft rev limit (like the FW31), respect 9800 as the limit despite it allowing for 10000 when pushed.
Acceleration drops hard after 9800, much like the FW31 and 17760 vs 18000.
As a general guideline, the tighter the spread (reducing RPM drops), the more you need to be backing down your shift RPMs.
At time of testing the default shift light table in the car lined up well with this strategy.
• Ruf C-Spec
Ruf RT 12R C-Spec
Parameters: t_reaction = 280 ms
t_illumination = 560 ms
t_limiterbuffer = 70 ms
limiter_ceiling_percent = 0.996
rpm_range_percent = 0.25
Setup: baseline, 45L, short
Rev Limit RPM: 8500
Estimated Max Power RPM: 7500
Ratio Optimal Shift RPM Adj Target RPM Tone RPM Illumination Interval
1 8500 8333 7616 6031-7616
2 8500 8406 8077 7364-8077
3 8370 8370 8180 7781-8180
4 8500 8466 8354 8117-8354
5 8500 8466 8422 8323-8422
6 -- -- (off) (off)
Some numbers for the C-Spec, 3rd-4th is the only noteworthy bit
From 2015s3
Thanks again to (iRacing member) Robert B for a terrific thread "GT3 Optimum Shift Points"
For detailed data and information read Robert's thread.
- Notes on the Ford: Much like the BMW, this one needs high revs but levels off sooner, allowing for marginally earlier shifts when the ratios get close.
- Notes on the McLaren: This is the most noteworthy result of this post—the McLaren stands to gain the most when shifted correctly,
and the ideal shift points do not line up well at all with iRacing's cockpit instrumentation. Don't shift on blue above second gear!
- Notes on the McLaren: This is the most noteworthy result of this post—the McLaren stands to gain the most when shifted correctly,
and the ideal shift points do not line up well at all with iRacing's
cockpit instrumentation. Don't shift oNotes on the Ruf: The shift points
are significantly lower than the rev limit RPM, but the power curve is
relatively flat so the losses aren't felt so much. The interesting thing
with this car is the result of the inflection in its torque curve from
7100-7600 RPM. This sharp dip is what causes the sudden change in shift
RPM as the ratios reach a critical distance from each other. 4th, 5th,
and 6th gears are close enough that there is [slightly] more benefit
from holding the ratio longer. blue above second gear!
BMW Z4 GT3
Parameters: t_reaction = 280 ms
t_illumination = 560 ms
t_limiterbuffer = 70 ms
limiter_ceiling_percent = 0.996
rpm_range_percent = 0.25
Setup: baseline, 58L (s3-2015)
Rev Limit RPM: 9000
Estimated Max Power RPM: 8600
Ratio Optimal Shift RPM Adj Target RPM Tone RPM Illumination Interval
1 9000 8829 8244 6904-8244
2 9000 8896 8567 7825-8567
3 9000 8948 8764 8361-8764
4 8800-9000 8850 8746 8512-8746
5 8800-9000 8850 8799 8702-8799
6 -- -- (off) (off)
Ford GT GT3 - short ratio
Parameters: t_reaction = 280 ms
t_illumination = 560 ms
t_limiterbuffer = 70 ms
limiter_ceiling_percent = 0.996
rpm_range_percent = 0.25
Setup: baseline, 58L, short ratio (s3-2015)
Rev Limit RPM: 7600
Estimated Max Power RPM: 6500
Ratio Optimal Shift RPM Adj Target RPM Tone RPM Illumination Interval
1 7600 7475 7065 6137-7065
2 7600 7532 7284 6746-7284
3 7500-7600 7525 7364 7018-7364
4 7500-7600 7525 7418 7201-7418
5 7500-7600 7525 7467 7348-7467
6 -- -- (off) (off)
Ford GT GT3 - standard ratio
Parameters: t_reaction = 280 ms
t_illumination = 560 ms
t_limiterbuffer = 70 ms
limiter_ceiling_percent = 0.996
rpm_range_percent = 0.25
Setup: baseline, 58L, standard ratio (s3-2015)
Rev Limit RPM: 7600
Estimated Max Power RPM: 6500
Ratio Optimal Shift RPM Adj Target RPM Tone RPM Illumination Interval
1 7600 7510 7167 6414-7167
2 7600 7547 7355 6923-7355
3 7500-7600 7525 7407 7149-7407
4 7500-7600 7525 7456 7311-7456
5 7500-7600 7525 7496 7435-7496
6 -- -- (off) (off)
McLaren MP4-12C GT3
Parameters: t_reaction = 280 ms
t_illumination = 560 ms
t_limiterbuffer = 70 ms
limiter_ceiling_percent = 0.996
rpm_range_percent = 0.25
Setup: baseline, 65L (s3-2015)
Rev Limit RPM: 7820
Estimated Max Power RPM: 6400
Ratio Optimal Shift RPM Adj Target RPM Tone RPM Illumination Interval
1 7110 7110 6652 5590-6652
2 7040 7040 6770 6174-6770
3 6880 6880 6718 6364-6718
4 6810 6810 6714 6502-6714
5 6730 6730 6675 6551-6675
6 -- -- (off) (off)
Ruf RT 12R Track
Parameters: t_reaction = 280 ms
t_illumination = 560 ms
t_limiterbuffer = 70 ms
limiter_ceiling_percent = 0.996
rpm_range_percent = 0.25
Setup: baseline, 50L (s3-2015)
Rev Limit RPM: 9400
Estimated Max Power RPM: 8100
Ratio Optimal Shift RPM Adj Target RPM Tone RPM Illumination Interval
1 8590 8590 7896 6309-7896
2 8490 8490 8065 7120-8065
3 8360 8360 8101 7535-8101
4 8800 8800 8670 8402-8670
5 8800 8800 8743 8626-8743
6 -- -- (off) (off)
• Corvette C7 Daytona Prototype
Corvette C7 Daytona Prototype
Parameters: t_reaction = 280 ms
t_illumination = 560 ms
t_limiterbuffer = 70 ms
limiter_ceiling_percent = 0.996
rpm_range_percent = 0.25
Setup: low_downforce, 38.1L fuel (s4-2015)
Rev Limit RPM: 7200
Estimated Max Power RPM: 6700
Ratio Optimal RPM Adj Target RPM Tone RPM Illumination Interval RPM Drop
2.600 7200 7098 6715 5896-6715 1335
2.111 7200 7143 6907 6402-6907 1052
1.800 7200 7154 7021 6706-7021 1089
1.526 7200 7171 7095 6941-7095 907
1.333 7200 7171 7139 7088-7139 812
1.182 -- -- (off) (off) --
Corvette C7 Daytona Prototype
Parameters: t_reaction = 280 ms
t_illumination = 560 ms
t_limiterbuffer = 70 ms
limiter_ceiling_percent = 0.996
rpm_range_percent = 0.25
Setup: medium_downforce, 38.1L fuel (s4-2015)
Rev Limit RPM: 7200
Estimated Max Power RPM: 6700
Ratio Optimal RPM Adj Target RPM Tone RPM Illumination Interval RPM Drop
2.500 7200 7105 6676 5736-6676 1421
2.000 7200 7132 6881 6324-6881 1187
1.667 7200 7160 7007 6687-7007 829
1.474 7200 7171 7086 6883-7086 885
1.292 7200 7171 7128 7038-7128 827
1.143 -- -- (off) (off) --
Corvette C7 Daytona Prototype
Parameters: t_reaction = 280 ms
t_illumination = 560 ms
t_limiterbuffer = 70 ms
limiter_ceiling_percent = 0.996
rpm_range_percent = 0.25
Setup: high_downforce, 38.1L fuel (s4-2015)
Rev Limit RPM: 7200
Estimated Max Power RPM: 6700
Ratio Optimal RPM Adj Target RPM Tone RPM Illumination Interval RPM Drop
2.500 7200 7089 6587 5721-6587 1418
2.000 7200 7118 6812 6129-6812 1185
1.667 7200 7159 6965 6552-6965 958
1.444 7200 7171 7061 6804-7061 1078
1.227 7200 7171 7128 7018-7128 842
1.083 -- -- (off) (off) --
• Lotus 79
Forum thread Correct RPM for Upshifting (July 2015).
Without reference telemetry one post offers:
11000 rpm rev limiter
10500 rpm peak power
Try 10800 or 10900
Another post:
The recommended upshift revs are 10600 to 10800
Where is the reference telemetry?
• Other cars
In search of a list I started a thread recommended gear shift points.
If you know a link/post to any of iRacing's cars showing optimal points, please let me know.
As the thread generated little interest, I didn't update it.
In the thread I was told to download 'Sound Shift' app; it didn't help.
From the cars I checked, 'Sound Shift' included shift points per gear which were not optimal.
'Sound Shift' announces selected gear and plays a tone for user adjustable shift points; see my apps section for links.
• Real techniques / boxes
• Shifting Shootout - Heel Toe Vs. Paddle Shifters
• http://edracing.com/DKA will get you here
If you landed here, start at the top of this page for iRacing gear shift info.
Ed: if you have not heard of Dave Kaemmer, look him up.
Asymmetry related post by iRacing staff (Dave K) S3 June 2016:
Ivan is correct that the angular momentum of the drive train components induces a pitch down torque when turning left (how much depends on speed of engine, rotating inertia of components, yaw rate of car), and a pitch up moment when turning right. We definitely model that--it's just a part of the multi-body physics.
However... in looking into it, we discovered that we were including the diff case and ring gear inertia in with the inertia of the output shaft from the gearbox. That's fine in terms of figuring out the drive train constraint torques and giving the correct acceleration rates of all the components, BUT, the ring gear and diff case generally rotate around an axis that is perpendicular to the output shaft, since most of the cars have longitudinally mounted engines. The ring gear/diff case is not modeled as a separate body with its own inertia, since its speed is completely determined by the drive train constraints. But we realized that we need to move that inertia so it contributes angular momentum around the car's y-axis (left/right) instead of the x-axis (forward/back). That should noticeably reduce this asymmetry.
The other detail we noticed is that we need to be careful about how the gearbox works for each particular car. Some have the input and output shafts in-line with each other, and a transfer shaft that is geared to the input shaft with fixed gearing, and to the output shaft through the variable gears. Other transmissions dispense with the separate transfer shaft and output shaft and simply combine them. The difference is that with the first kind the output shaft and input shaft spin the same direction (two reversals through gearing), but for the second kind the output shaft and input shaft spin in opposite directions. Again, doesn't really matter from the point of view of accelerating the masses, but the gyroscopic torques that are induced when turning the car are affected by the rotation direction. Fortunately the inertias of the gear stacks are very small compared to the inertia of the flywheel, clutch, and ring gear. So this second detail is a lot less important. But we plan to fix it anyway! (Next season, we won't make a mid-season change to all the cars like that.)
It's a pretty small effect--will probably still be there to some degree (engine/flywheel and clutch are still rotating the same way), but essentially removing the ring gear inertia and angular momentum from the car's x-axis may lessen it noticeably. The Spec Racer has a transverse-mounted engine so it shouldn't have this asymmetry, as a point of interest.
There is also an asymmetry introduced by the drive torque. This is more noticeable on cars with a rear axle, since the diff is mounted on the axle, not the chassis, so drive torques more directly transfer weight between the rear wheels. For independent suspension, the diff is usually bolted to the chassis. Since we now have chassis flex, drive torque will twist the chassis a bit, giving some crossweight, although that is pretty small. That torque will depend on the rotation direction of the output shaft, i.e. the type of gearbox.
Follow up post by Dave K:
Gave this more thought last week and this weekend and there is more to add. Basically, what I posted before is correct in that we were treating some of the driveline inertia incorrectly in terms of how it contributes angular momentum (properly a vector). In the driveline there is a lot of what what might be called "apparent" inertia. It appears to be inertia because when applying a torque, it reduces the acceleration due to that torque.
In my original post I was focused on the ring gear and diff case, whose "apparent" inertia was assigned to the output shaft. Again, completely reasonable from the point of view of accelerating the output shaft (which is geared to the ring gear). In that case, the problem arises because the angular momentum that should result from accelerating the whole assembly (output shaft, ring gear + diff case) isn't all pointed in the same direction. We figured that splitting the ring gear/diff case inertia between the two driven wheels was a pretty good solution, since it gets the angular momentum pointed in the right direction, and still appears as inertia due to the driveline constraints, which keep all the parts rotating at the right speeds.
But I was bothered by the fact that this fix--while it would reduce the "lefty-loosy, righty-tighty" behavior of the cars with longitudinally mounted engines--didn't seem like it would reduce the asymmetry very much. So I thought more about the other components and had a realization: the engine "rotor", which models the rotation of the masses that rotate at engine speed, includes some apparent inertia from the pistons and connecting rods. Again, perfectly reasonable to model the engine this way from the point of view of how much it accelerates in response to a given torque. The piston and connecting rod masses do need to be accelerated, and consume power in doing so.
However, they are not rotating parts. At least the pistons (and a portion of the connecting rods) are not rotating, only a portion of the connecting rods nearer to the crank journal may be considered to be rotating. The pistons shouldn't be contributing any angular momentum at all. This is because gyroscopic torque arises from the fact that the linear forces required to change the linear momentum of the top and bottom of a rotating wheel when steering it, say, are not in line with each other. The top of a rolling wheel has forward momentum, and the bottom has rearward momentum. So to turn the wheel a force must be applied near the top to "turn" the momentum at the top of the wheel, and an opposite force must be applied near the bottom to turn the oppositely facing momentum at the bottom. Those two equal but opposite forces are not in line with each other, but in fact require a torque that keeps the wheel from leaning over. This is why on a bicycle or a motorcycle you need to turn the handlebars left to initiate a right turn, and vice versa.
But because the forces required to change the direction of the pistons when turning the car are in line with each other (at least averaged over time), no torque is induced. So no gyroscopic torque should result from the reciprocating pistons in the engine, even though they contribute apparent inertia that slows acceleration. Now we have figured out a way to properly model all these driveline inertias so their apparent inertias don't contribute angular momentum, and it gives us a better way to model the ring gear and diff case, to boot! As well as the counter-rotating gear stacks.
All this being said, the left/right asymmetry is still an effect that we expect to see in cars with longitudinally mounted engines. It just should be a fair bit smaller than it has been. Thinking back to when I was racing the Skip Barber cars, they definitely had an easier time turning left than right. That car has a stock engine, flywheel and clutch, and it is a very lightweight car, so the effect should be more pronounced.
Just to put some rough numbers on it (and these are rough, depend on many things, engine speed, drive line inertias, wheel base) the current build gives an effect that is in the 40 lb range of weight transfer: +20 to the front wheels, -20 rears in a left turn, and vice versa in rights. When this is corrected, it should be more like 10 lbs, +5, -5. But that remains to be seen; haven't fully fixed it yet. But soon.
Follow up post by Dave K:
... I was talking mainly about the gyro effects; car with a transaxle has all the same issues--piston inertia included with engine rotor so too much angular momentum, also ring gear inertia appearing to rotate around the wrong axis. So that effect would be similar.
For the other asymmetric handling cause--differential rear wheel loads due to drivetrain torque--currently the sim should be handling these properly. Cars with a live rear axle should have more left/right load transfer since the axle (and therefore the two rear tires) has to produce all the counter torque, whereas in a car with the diff mounted to the chassis, the chassis will to a large extent generate the counter torque and that tends to cancel the torque out since the engine is doing the same but opposite thing to the chassis (chassis twist would allow some unequal rear wheel loads). So there'd be more equal rear wheel loads under power in a car with IRS.
Ed: Dik (iRacing member) posted clip of a '70s Aussie made V8 Holden Monaro
" Twisted Monaro torque monster! Part 2"
Source: iRacing's 2010s3 release notes
- This information may be outdated
Transmission and Shifting Model
We have replaced our model of a car's transmission and how the driver causes the car to shift gears.
Previously, clicking out of a gear or into another gear would instantly do just that - regardless of whether or not such a gear change was actually physically possible.
Now, your shifting inputs tell the sim what you're trying to do, and the sim tries to do what you ask - the sim no longer instantly just shifts.
Think of your shifting inputs as telling the sim, "I am pushing/pulling on the shift lever."
You will often need to hold the shift control for little while as the shift goes through to completion before releasing, if you let go too early the sim will interpret that as you letting go of the shift before the shift completes, probably leaving you hanging in neutral.
If you use an h-pattern shifter, then the shifter is automatically holding the next gear which makes it more comfortable.
This is likely to require some time to adjust to, so do not be afraid of turning on the auto-clutch and auto-blip shift aids when you need reliable shifting while you're still learning to feel out shifting with lower levels of aids in practice and testing.
The currently engaged gear will not disengage unless the transmission is sufficiently unloaded:
- For upshifts, full throttle will definitely hold the current gear engaged. You will need to lift, use the clutch, or hit the rev limiter to unload the transmission enough for the current gear to disengage.
- For downshifts, engine braking when fully off-throttle especially at higher rpm may well be sufficient to prevent the current gear from releasing.
You will likely need to use a little bit of throttle (which will happen anyway if you are blipping on downshifts), or use the clutch to disengage the current gear.
If you are braking while holding down some throttle it will quite likely be too much throttle to allow the current gear to disengage, unless you use the clutch to unload the transmission.
If you are using an h-pattern shifter control to shift with, moving the stick into neutral will ask the sim to try to leave the current gear if it can.
Selecting the next gear will tell the sim to attempt to engage that gear once it succeeds in getting into neutral.
If you are using sequential controls to shift with, holding down the shift button is equivalent to pushing on the shift lever to the next gear.
If you let go of the button before the shift completes, you may not have even left the current gear yet, or may end up in a neutral between the two gears.
Cars that have a sequential transmission can no longer be shifted with an h-pattern shifter.
If you have your h-pattern set as the preferred shifting method, the sim will give you a warning message when you first get into a sequential car to start driving advising you that you will have to use your configured sequential controls.
If you try to engage the next gear when the rpms are too mismatched, the gears will just grind and the next gear will not engage.
So that means that smash-it-into-1st race starts don't work any more, as trying to grab 1st at high rpm is not healthy for the gearbox and you will hear nasty grinding sounds.
You'll want to engage 1st gear while the motor is not revved up and the clutch is pushed in (the anti-stall clutch conveniently holds the clutch in for you if you are stopped and not revving the motor).
Then you do a race start via revving up the motor with the clutch pushed in, and doing some kind of clutch drop.
If you use the auto-clutch shift aid, it will hold the clutch in for you while you are revving in neutral, so selecting 1st gear for your launch is acceptable.
The auto-clutch shift aid will release the clutch for you, but with a fractional delay.
For a dog-box transmission, the next gear can typically engage when the revs are within a few thousand rpm - a pretty broad rpm range.
You don't need to bother with the clutch, just appropriate throttle lifts or blips to disengage the previous gear are all it takes to shift.
This also means that you can quite comfortably left foot brake with dog-box cars.
- Upshifts you want to do as fast as possible: press and hold your upshift a moment before you lift to preload the shifter, then do the fastest lift you can for a really quick shift.
It is possible to use the rev limiter to unload the transmission and cause the upshift instead of lifting.
If you are using sequential controls, remember to press and hold the upshift button until the gear change finishes.
Some race cars have a built in throttle cut that engages when it detects pressure on the gear lever.
For these cars you don't need to lift at all, just clicking the button will trigger the throttle cut.
But make sure not to release too rapidly, or the shift may not be fully completed as you release pressure from the shift lever.
- Downshifts can be done very quickly too.
Press and hold your downshift a moment before you blip to preload the shifter, then tap the throttle for a blip of the motor to minimize upsetting the car's balance as the next gear engages.
In most cars there will be enough engine braking torque that the gear won't disengage until you tap the throttle for the blip, and remember to press and hold the downshift button until the gear change finishes.
For the Solstice and other cars with synchromesh gears, the synchros do all the work when the revs are mismatched.
You won't hear a grind when you select the next gear while the synchros are doing their thing, so the neutral timing isn't the same as a crash box.
You don't absolutely have to use a clutch for a synchro box - but the synchros are not even remotely close to being strong enough to overcome the entire motor when trying to rev match so you have to get the entire motor to match the correct rpms for the next gear yourself, but if you use a clutch pedal then the synchros can easily match the transmission input shaft for you and make shifting a much faster and reliable experience.
When shifting with a real synchromesh gearbox, you engage the next gear's synchros by lightly pulling the stick against the next gear, until the gear clicks into place.
Unfortunately, the sim has no ability to know that you're trying to select the next gear until you actually select the next gear, and only then can the sim start working the simulated synchros.
With sequential controls, the sim knows you are trying for the next gear up or down, so you just need to press and hold the shift button until the gear engages.
With an h-pattern you need to actually click your next gear into place quite quickly so the sim can start pushing it's simulated shifter against that gear's synchro.
The timing of the shifting process feels a little different to a real car.
You'll have to get used to the timing of your shift request but continuing to hold the clutch in until the gear finally engages before letting the clutch out, unlike in a real car where you can feel the shifter clicking into place as the gear finally engages.
- Upshifts you typically want to do as fast as possible, but it's not as fast as a dog-box transmission can do it:
press and hold your upshift a moment before you lift to preload the shifter, then lift the throttle while pushing in the clutch.
As the next gear engages, you can push the throttle down again and release the clutch.
You could also choose to not lift, and just push in the clutch pedal until the next gear engages.
This method of power shifting will not make your clutch want to be friends with you for very long.
Or you could not use the clutch at all, but you have to lift off the throttle and wait for what will feel like forever and ever until the engine drops enough rpm for the next gear to engage.
Remember to hold the shift button until the gear shift completes.
- Downshifts you will also want to shift as quickly as you can, to start working the next gear's synchro.
Press and hold your downshift a moment before you blip to preload the shifter while braking with your right foot, then press the clutch pedal in with your left foot and roll your right foot somehow to blip the throttle while maintaining smooth brake pressure at the same time, and when the next gear catches, release the clutch pedal smoothly.
This is called heel-toe downshifting, and it's very hard to get a good feel for in the sim due to not being able to physically feel the response of the car and the shift lever.
It is possible to left foot brake and not use the clutch on downshifts, but it's hard work on the synchros and you must make sure to blip the engine rpm well enough to match revs or you'll be stuck in neutral fishing for a gear.
Remember to hold the shift button until the gear shift completes.
Sometimes if you mis-time your synchromesh gear shifts (particular if you don't use a clutch) you can clear the synchro but still miss the gear engagement, and you will hear nasty grinding sounds from your gearbox.
Some of the higher end race cars with sequential gearboxes can have fully automated shifting.
You just bang the shifter button and it does whatever it needs to do with the throttle to get the next gear for you in a very short amount of time.
Key points:
- If you are struggling to adapt to shifting with no shift aids, don't be afraid to turn on the auto-clutch shift aid and perhaps even the auto-blip shift aid for important sessions where you need reliable shifting.
Like any physical activity you may have been doing for a long time it can take a while to unlearn your old muscle memory habits and learn new ones.
- Sequential cars will not allow the use of h-pattern controls, like the Jetta has been doing for a while now.
- Remember to think "press and hold" for sequential shift buttons until the shift is complete, it's not just "click".
- Practice your timing so you press and hold the shift button before you blip on downshifts or lift on downshifts.
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