Race Tracking Your Supra - Information exchange

[visbits]

Hi guys. I've had my supra for about a year and I've done 3 track days with it. Twice at barber motorsports park and once at putnam.

Couple things I have questions about and would love some feedback.

1. I am battling under-steer, the car turns in with trail braking but if i come off the brakes the front end feels like it wants to push and if i get onto the throttle at all it pushes really hard... sometimes if i get the car turning in how i want and get on the throttle the thing just works and plants.. i suspect magic diff stuff?
2. I have a somewhat aggressive alignment and tire wear looks pretty good but would love some feedback.

Car Specs:
A91-MT
Eibach Sways (Rear tightest, front middle)
H&R Springs
Girodisc Rotors with Carbotech XP12 Pads
Verus Camber Plates

Alignment:

Rear Tires PS91 275r19

Front Tires PS91 255r19

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[FLtrackdays]

Hi guys. I've had my supra for about a year and I've done 3 track days with it. Twice at barber motorsports park and once at putnam.

Couple things I have questions about and would love some feedback.

1. I am battling under-steer, the car turns in with trail braking but if i come off the brakes the front end feels like it wants to push and if i get onto the throttle at all it pushes really hard... sometimes if i get the car turning in how i want and get on the throttle the thing just works and plants.. i suspect magic diff stuff?
2. I have a somewhat aggressive alignment and tire wear looks pretty good but would love some feedback.

Car Specs:
A91-MT
Eibach Sways (Rear tightest, front middle)
H&R Springs
Girodisc Rotors with Carbotech XP12 Pads
Verus Camber Plates

Alignment:

Rear Tires PS91 275r19

Front Tires PS91 255r19

I wish there was a magic setup for these cars or we’d all do it. We all have different driving styles, experience and mods on our cars. It can be from to several factors: weight transfer, tire conditions, your driving technique or suspension setup. But it’s usually a combination of things.

If you can add more negative camber up front and get some stickier tires, go for it. That will only help. Overheated or worn front tires can struggle to keep grip as you exit turns. As far as trail braking, releasing the brakes too abruptly or applying throttle too aggressively can induce understeer. If you’re trail braking properly after only 3 track days, you’d be the fastest learner I‘ve ever met. Assuming you‘ve done multiple track days in other cars.

 

[Todday1]

Try going to softest setting on front sway bar a 200 treadwear tire and use all the track on exit.

 

[Rob_SER]

you can also play with tire pressure. My GT4 had a tendency to understeer and I would always run a little more tire pressure in the back to help

 

[AHP]

I'd start with a better tire and seat time.

 

[razorlab]

Hi guys. I've had my supra for about a year and I've done 3 track days with it. Twice at barber motorsports park and once at putnam.

Couple things I have questions about and would love some feedback.

1. I am battling under-steer, the car turns in with trail braking but if i come off the brakes the front end feels like it wants to push and if i get onto the throttle at all it pushes really hard... sometimes if i get the car turning in how i want and get on the throttle the thing just works and plants.. i suspect magic diff stuff?
2. I have a somewhat aggressive alignment and tire wear looks pretty good but would love some feedback.

Add more negative camber in front or reduce in rear. Is this with TC fully off or one click off? one click off really hates the combo of braking and turning. It will push. Loosen up front sway bar.

 

[tomfree]

The brute force approach...more front tire/wheel width.

Freebies: Soften front sway (or stiffen rear), play with pressures - more in the rear. (what are yo ur hot pressures?)

The other thing you may be you may be unconsciously doing is adding too much steering angle. The brain tells you "The car isn't turning enough, I need to turn the wheel more" - not always the right approach. Sometimes a little lift to set the nose (without changing steering angle) will do the trick.

 

[Rob_SER]

also you can ajust your line. Noticed the Supra (in stock form at least) likes sharper initial input to get you turned in during high speed corners.

 

[Rensuhlo]

 

[Todday1]

What is your alignment set up. Did this cord on rear. I have had a few sets do this as well so interest in neg camber settings.

 

[FLtrackdays]

What is your alignment set up. Did this cord on rear. I have had a few sets do this as well so interest in neg camber settings.

Happens to me up front when I’m pushing hard, late trail braking. I need to switch up and do what you’re doing to the rear ?

 

[Todday1]

I think there is always a trade off on straight line braking and then with a lot if neg camber you are using more of inside edge under braking so best i can tell is rear likes about -2.5 to 2.6 and fronts up in the high -3.0’s to 4.0 hence why i am interested in what everyone is trying. But even with the inside corded you got pretty good wear as the outsides were close to being done at least from what i could see in the pic. So looks like they are working fairly well.

 

[tomfree]

Rarely does the inside of a tire cord from camber (stance nation -8 deg cars notwithstanding). It's almost always toe.

 

[Rensuhlo]

What is your alignment set up. Did this cord on rear. I have had a few sets do this as well so interest in neg camber settings.

-4 degrees of camber up front
0 toe up front

-2.4 rear
.25 degrees total toe in

Going to be looking into Caster bushings as theres suggestions my caster bushing may be allowing for toe changes under braking.

 

[razorlab]

Alignment, alignment, alignment, alignment. Of course, this takes into account all your bushings and such are in good condition as well.

We've already been discussing this with @Rensuhlo in another setting but I figured I would make this post for informative and discussion reasons here.

Here are some samples of tire wear from my personal supra that is tracked 95% of it's working time and is driven to/from the track. The other 5% is street driving for fun or data logging purposes.

Alignment and relevant modifications:

Front
-3.9 camber
0 toe
Turner caster spherical bushings in OEM caster arms
Verkline LCA
SPL tie rod ends
SPL endlinks
Vorshit camber plates
MCS 2WNR 650lb springs

Rear
-2.5 camber
3mm total toe in
SPL toe arms
SPL traction arms
MCS 2WNR 600lb springs (true coilover)

Tire wear examples

Nankang CRS v2
295/35/18
18x10.5 (I don't suggest this width as this tire and size need at least 11" wide to work well)
Service time: 2 track days, approx 1,000 street miles after 2nd track day, which is why they look so smooth and clean.

Bridgestone RE71RS
295/35/18
18x11
Service time: 2 track days, to/from track street miles

Kumho V730
275/35/18
18x10.5
Service time: 3 track days, to/from track street miles

Bridgestone RE71RS
295/35/18
18x11
Service time: 3 track days, to/from track street miles

Bridgestone RE71RS
295/35/18
18x11
Service time: 5 track days, to/from track street miles.

Nankang AR1
275/35/19
19x10
Service time: 2 track days, to/from track street miles.
Note: I hate these tires. They wear like crap, are slower than the good modern 200tw tires and are super noisy.

Nankand CRS v2
275/40/18
18x10.5
Service time: 5 track days, to/from track street miles

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