effects of rake compared with rear toe

[nomis3613]

I've done some testing of the effects of rake, compared with adding rear toe-out to get the same effect. Thought some people might be interested in the results, also I'm keen to hear your thoughts.

First step was is rake or rear toe-out more effective at reducing understeer?
So I took an RM Integra to Cape Ring Inside for the testing (using an FF to minimise the effects of the LSD). Set it up to heavily understeer so that any reductions in understeer would increase the speed through the sweeper and decrease the lap time, here are the results:
(columns are ride height, then sweeper mid-corner km/h, then lap time)

Subjectively I noticed:
- full rear rake gave lots of front grip but made handling unpredictable
- +10 / -10 improved predictability, but low-speed agility was poor compared with using rear toe
- despite recording 2km/h higher sweeper speed for 0 / -20 compared with +10 / -10, I don't think there was actually any extra mid-corner grip from 0 / 20 so I'd discount that result
- 0 / -20 improved low-speed agility, but it still felt like using rear toe gave a slightly quicker initial steering response compared with rear rake

The next question was how does the traction loss compare between toe and rake?
For this test, I used an overpowered MP4-12C and measured acceleration times from standing start. (the 3rd column is accel time 17.xxx, obviously lower means more traction)

Finally, how does braking suffer with toe and rake?
All of the above ride height and rear toe settings produced the same braking distance. The only differences was that using rear toe meant the car would pull to the left or right during braking (I'm guessing I would have spun out if I wasn't using ABS).

I'm keen to hear any experienced tuners thoughts on this.

(If you're going to reply with "you cheating-gitch-tuner-cheat", please don't. I'm just wanting to discuss how these tuning settings effect what happens in the game, so take your rant somewhere else please. Peace)

 

[XDesperado67]

Couple of thoughts.
Did you test rake the other way? i.e. lower front higher rear.
Did you test with smaller increments? (It's possible to go to far when tuning. So for example a 0 toe isn't enough but a -0.5 toe is way to much.)

Also personally I feel that optimum performance for a given car and track requires fine tuning of all aspects of the suspension. So your spring rates need to be adjusted based on the ride height, dampers may need adjusting based on spring rate and ride height, camber effects cornering and acceleration, your anti-roll bars need adjusting based on Camber and spring rates while optimum camber has to account for the more limited settings of the anti-roll bars.

Finally because of differences in chassis, weight distribution, drive train layout and wheel/tire size all the above are obviously going to differ between vehicles. So while for the FF car you tested with the greater toe out may be a better solution by itself than just rake working the whole suspension synergisticaly will actually produce the optimum results but be very different from what a FR car for example needs.

That said I don't completely discount your testing as it can show some basic patterns that can aid a tuner in trying to optimize their suspension setup.

 

[CSLACR]

I've done some testing of the effects of rake, compared with adding rear toe-out to get the same effect. Thought some people might be interested in the results, also I'm keen to hear your thoughts.

First step was is rake or rear toe-out more effective at reducing understeer?
So I took an RM Integra to Cape Ring Inside for the testing (using an FF to minimise the effects of the LSD). Set it up to heavily understeer so that any reductions in understeer would increase the speed through the sweeper and decrease the lap time, here are the results:
(columns are ride height, then sweeper mid-corner km/h, then lap time)

Subjectively I noticed:
- full rear rake gave lots of front grip but made handling unpredictable
- +10 / -10 improved predictability, but low-speed agility was poor compared with using rear toe
- despite recording 2km/h higher sweeper speed for 0 / -20 compared with +10 / -10, I don't think there was actually any extra mid-corner grip from 0 / 20 so I'd discount that result
- 0 / -20 improved low-speed agility, but it still felt like using rear toe gave a slightly quicker initial steering response compared with rear rake

The next question was how does the traction loss compare between toe and rake?
For this test, I used an overpowered MP4-12C and measured acceleration times from standing start. (the 3rd column is accel time 17.xxx, obviously lower means more traction)

Finally, how does braking suffer with toe and rake?
All of the above ride height and rear toe settings produced the same braking distance. The only differences was that using rear toe meant the car would pull to the left or right during braking (I'm guessing I would have spun out if I wasn't using ABS).

I'm keen to hear any experienced tuners thoughts on this.

(If you're going to reply with "you cheating-gitch-tuner-cheat", please don't. I'm just wanting to discuss how these tuning settings effect what happens in the game, so take your rant somewhere else please. Peace)

This confirms all my thoughts on toe I believe.
While it's a good tool to increase/decrease under-steer, it's most effective at low speeds, and when set to high, makes the car unpredictable.

You'll find a lot of my tunes have rear toe pulled down to 0.00 for these very reasons, typically to decrease low speed under-steer.
I haven't found much to be gained from going below -0.20 though, but I combine it with the rest of the tune, so I think you've made a pretty good observation here again. 👍

 

[nomis3613]

Did you test rake the other way? i.e. lower front higher rear.

Hi, nah I didn't test how it can tame oversteer. Trying to get consistent laps with a heavily oversteering car is a nightmare. Well, the drifting is great fun, but the lap times are all over the place!

Did you test with smaller increments? (It's possible to go to far when tuning. So for example a 0 toe isn't enough but a -0.5 toe is way to much.)

Nope, but I set the car to understeer so heavily that front grip was always the limiting factor. You make a good point, though.

Also personally I feel that optimum performance for a given car and track requires fine tuning of all aspects of the suspension...

...So while for the FF car you tested with the greater toe out may be a better solution by itself than just rake working the whole suspension synergisticaly will actually produce the optimum results but be very different from what a FR car for example needs.

That said I don't completely discount your testing as it can show some basic patterns that can aid a tuner in trying to optimize their suspension setup.

Thanks, that last sentence sums up what I'm trying to achieve here.

This confirms all my thoughts on toe I believe.
While it's a good tool to increase/decrease under-steer, it's most effective at low speeds, and when set to high, makes the car unpredictable.

Cool, thanks for your comments.

 

[Sail IC]

Cool test.

The effect of ridehight difference front/rear has been heavily debated and there are different opinions how it effects the car. Running higher front to cure understeer, I think it has an impact on car balance through the corner (entry/mid/esit), where rear toe-out has a bigger impact on corner exit than entry/mid corner.

That is at least how I think about it. When I add rear toe-out to combat understeer I usually have to do additional things for entry/mid corner balance.

 

[CSLACR]

Cool test.

The effect of ridehight difference front/rear has been heavily debated and there are different opinions how it effects the car. Running higher front to cure understeer, I think it has an impact on car balance through the corner (entry/mid/esit), where rear toe-out has a bigger impact on corner exit than entry/mid corner.

That is at least how I think about it. When I add rear toe-out to combat understeer I usually have to do additional things for entry/mid corner balance.

I also agree, though it does effect all, it may be be the acceleration that makes it seem to work better on exits.

 

[AssassinTuner]

I wouldn't use the same techniques for all platforms. FF's I'll put a lil negative toe, but not FR. With FF it will help rotate, but FR it will promote oversteer at exit. It has to be Tune to the car.

Testing should be more comprehensive. Doing increment testing, and standardized test across the platforms. Each subjected to the same testing.

 

[ampire]

Just posted the same question. I run massive negative toe on my Cobra R and my Skyline GTR Nur, both which have chassis stiffening. They also both have a lot of rake (-20 front +5 rear) . I can get about 1:25 on trial mountain in the skyline which is decently quick.

I also usually run 5 front sway bar 2 rear swaybar and soften my rear springs and struts. I run a mostly open differential (5/10/5) rear, (5/5/5) front if its AWD.

 

[AssassinTuner]

Just posted the same question. I run massive negative toe on my Cobra R and my Skyline GTR Nur, both which have chassis stiffening. They also both have a lot of rake (-20 front +5 rear) . I can get about 1:25 on trial mountain in the skyline which is decently quick.

I also usually run 5 front sway bar 2 rear swaybar and soften my rear springs and struts. I run a mostly open differential (5/10/5) rear, (5/5/5) front if its AWD.

What type of spring rates and dampers you running? My Cobra Oversteers with positive toe. Tranny braking makes her rotate easier. Gear ratios can help.

 

[ampire]

I don't have the game running now but its something like 60% of the front spring rate setting is set for the rear spring rate and rear dampers are about 1-2 settings below the front.

I have 3 mustang cobras: 1 drift cobra, 1 time trial cobra, and 1 stock cobra. The stock cobra understeers bad, the drift cobra I never notice because it goes sideways most of the time, and the time trial cobra understeers bad without toe and rake adjustments and an almost open differential. The 2 modified ones both have the chassis stiffening. I think the final gear is like 4.0 in the TTrial cobra.

 

[AssassinTuner]

I don't have the game running now but its something like 60% of the front spring rate setting is set for the rear spring rate and rear dampers are about 1-2 settings below the front.

I have 3 mustang cobras: 1 drift cobra, 1 time trial cobra, and 1 stock cobra. The stock cobra understeers bad, the drift cobra I never notice because it goes sideways most of the time, and the time trial cobra understeers bad without toe and rake adjustments and an almost open differential. The 2 modified ones both have the chassis stiffening. I think the final gear is like 4.0 in the TTrial cobra.

I'm not home either, but when you fire it up post up your set up for the Time Trial Edition. I have a few also, we can check it out.

 

[nomis3613]

Running higher front to cure understeer, I think it has an impact on car balance through the corner (entry/mid/esit), where rear toe-out has a bigger impact on corner exit than entry/mid corner.

I also agree, though it does effect all, it may be be the acceleration that makes it seem to work better on exits.

Just wondering, do you guys think that also applies to FF, or mainly RWD? I have a (untested) theory that
- because negative rear toe reduces traction
- an LSD works best to reduce understeer when you are close to wheelspin
- therefore rear toe has greatest effect on corner exit due to acceleration (like CSLACR says)
which would explain why I found reverse rake and negative toe to have similar effects for exit grip on a FF.

 

[AssassinTuner]

I'm not sure I follow you guys. Negative rear toe hurts acceleration, it doesn't help it. Positive toe helps acceleration. On a FR you will be able to get a higher exit speed with positive toe. With FF it won't help our exit speed per-se but rather help you rotate so you can get into the gas sooner on exit. If your FR is having understeer issues and your considering negative rear toe, you might want to check your spring rates and damper settings

 

[Motor City Hami]

- an LSD works best to reduce understeer when you are close to wheelspin

I think you may be under estimating the LSD. It can do far more that what you have written here. I can use the LSD to affect turn in at entry and, on some cars, even get it to turn in more during mid corner through exit. I like tuning at Grand Valley East reverse and Tokyo. At GVER, the 180 at the beginning of the long straight helps me to see mid corner to exit LSD settings and the two turns at the end of the long straight help me to fine tune LSD decel. Tokyo has that long sweeping left that is a good test for the LSD. Also, If I can't go full throttle through all of the winding esses near the end of the lap, then I keep working the LSD.

 

[CSLACR]

Just wondering, do you guys think that also applies to FF, or mainly RWD? I have a (untested) theory that
- because negative rear toe reduces traction
- an LSD works best to reduce understeer when you are close to wheelspin
- therefore rear toe has greatest effect on corner exit due to acceleration (like CSLACR says)
which would explain why I found reverse rake and negative toe to have similar effects for exit grip on a FF.

TBH I typically try to set my tunes with both front and rear toe at 0.00.
I progressively use everything in the suspension, brakes, and LSD to tune out over or under steer.
I say it seems to have greatest effects on acceleration because that's when under steer is strongest in FF, so any improvement helps more so then than any other time. In RWD, it can cause premature wheelspin, which again, makes it seem more dramatic.
I did some messing with full - toe on the RM Civic, verses suspension work, and all in all, a mix of everything still worked the best. I think I ended up using -0.20 for that, which is about as far as I go typically.

I'm not sure I follow you guys. Negative rear toe hurts acceleration, it doesn't help it. Positive toe helps acceleration. On a FR you will be able to get a higher exit speed with positive toe. With FF it won't help our exit speed per-se but rather help you rotate so you can get into the gas sooner on exit. If your FR is having understeer issues and your considering negative rear toe, you might want to check your spring rates and damper settings

I don't see how negative or positive toe would help or hurt acceleration, especially in a traction sense, when traction is an issue, 0.00 is the best you can get.
The part in bold is exactly how it helps your exit speed though, it just isn't needed for anything not FF or 4WD IMO. Maybe on the occasional terrible under steer dog that's RWD, but I haven't found one yet.

JMO.

 

[nomis3613]

Hi guys, I think you've misunderstood a few things (it's my fault- my last post had some very poorly worded stuff)

I'm not sure I follow you guys. Negative rear toe hurts acceleration, it doesn't help it. Positive toe helps acceleration. On a FR you will be able to get a higher exit speed with positive toe. With FF it won't help our exit speed per-se but rather help you rotate so you can get into the gas sooner on exit. If your FR is having understeer issues and your considering negative rear toe, you might want to check your spring rates and damper settings

Yes, my testing shows that negative rear toe reduces traction. But you can have all the traction in the world and the exit speed would still be slow if you have lots of understeer. But with an understeering FF, you'd want negative rear toe to help it rotate.

I'm not implying that negative rear toe is the best way to reduce understeer, just saying it is one of the options and using it as a comparison against the rake effects.

- an LSD works best to reduce understeer when you are close to wheelspin

I think you may be under estimating the LSD. It can do far more that what you have written here...

Totally agree. Poor wording on my part. What I meant was something like "the effect of LSD reducing understeer seems amplified if you are close to wheelspin"

I don't see how negative or positive toe would help or hurt acceleration, especially in a traction sense, when traction is an issue, 0.00 is the best you can get.

I've found positive rear toe improves traction for RWD. I realise the "scrub speed" theory is popular here on GT Planet, but my testing has found it to be negligable, but if anyone has GT5 testing results showing otherwise, I'm all ears...

 

[Johnnypenso]

You cheating-glitch-tuner-cheat...lol. I haven't done the testing but intuitively and through tuning I thought basically the same things as your testing seems to prove. If anything else, it proves that lowering an FF car's overall ride height and then raising the front end to assist overall front grip, is the primary factor in achieving the lowest lap times, which has been my basic conclusion for a while also.

 

[CSLACR]

I've found positive rear toe improves traction for RWD. I realise the "scrub speed" theory is popular here on GT Planet, but my testing has found it to be negligable, but if anyone has GT5 testing results showing otherwise, I'm all ears...

Positive rear toe seems to increase traction because it creates some under steer, which means while turning, the front tires are at 100% grip used, but the rear may be at 70% (example), which means you have 30% of rear traction to accelerate with.

With neutral handling, front and rear are all 100% used traction while cornering at speed, which means you have to wait until you're exiting the turn (less steering angle) to accelerate, which gives the appearance of less traction, though it's actually just using the same traction in a different way, which is cornering speed.
Whenever possible, neutral is the way to go, the extra corner speed will more than make up the difference of being able to accelerate sooner, because with the tune that allows acceleration sooner, you start accelerating out of the corner from a lower speed.

Examples: rear toe @ +0.20 on under steer tune = corner speed 71mph, can accelerate earlier than neutral by a small amount.
rear toe @ 0.00 on neutral tune = corner speed 73mph can accelerate just after under steer tune.

Not to mention a neutral tune will enter the corner faster.

 

[nomis3613]

Nice one, Johnnypenso! Thanks for your comments.

With neutral handling, front and rear are all 100% used traction while cornering at speed, which means you have to wait until you're exiting the turn (less steering angle) to accelerate, which gives the appearance of less traction, though it's actually just using the same traction in a different way, which is cornering speed.

Actually, my belief that +ve rear toe increases traction comes from straight line testing. I can see your point, though, about the trade-off between lateral grip and traction.