understeer on 17 brz

[Racecomp Engineering]

Originally Posted by jmark

Alignment specs to shoot for with OEM setup plus camber bolts? Tires 225/45/R17 Pirelli P Zero AS Plus with 7.5" wide PP rims.

What he said.

Originally Posted by strat61caster

tl;dr

Max negative camber up front, should be somewhere between -1.0 and -1.8 or so, get as much as you can. If they need a number to shoot for just say -2.0, you probably can't get that much with just one set of camber bolts, but I think I've heard 2 sets of camber bolts can get up to -2.2

Zero toe front, somewhere between zero toe rear and some toe in on the rear depending on how lively you want it, maybe start with 0.2 degrees total toe in (0.1 degree in on each wheel) and see how it feels.

If it wanders too much in DD or on the freeway add some toe-in, this also applies if it's a bit too darty and nervous when driving it hard. You can toe in on front and rear. If you feel the car is dull to turn in, the back end isn't moving enough then add some toe-out. Don't go toe out on the rear unless you want something very exciting to drive to work in the morning, zero toe on the rear should be lively enough but if you feel like experimenting I think it's worth trying in the right environment (test n tune, autox, etc.).

[JazzleSAURUS]

Awesome advice ITT.

An alignment with camber bolts I think will resolve your issue.

What are your future mod plans, and intended use case of the vehicle? If you plan on getting coilovers eventually, or stick with struts and springs, it could change the overall setup recommendation.

I'm a huge fan of a basic setup, Like ST's, V1's, or T0's with some crash bolts, and a basic rear LCA. Very OEM+/"feels like a performance pack car" to drive on the street, and gives you the adjustability to get a good handling, comfortable setup that will shine when you drive from work, to home, to the track.

[Racecomp Engineering]

Also, if the surface of the track was indeed really slippery, you'll feel some extra understeer compared to if you were driving it the same way as usual.

- Andrew

[alex.s]

Originally Posted by Racecomp Engineering

Also, if the surface of the track was indeed really slippery, you'll feel some extra understeer compared to if you were driving it the same way as usual.

- Andrew

Any strategy for dealing with it? Just try to deal with it? More trail brake?

Sent from my Nexus 5X using Tapatalk

[wparsons]

Originally Posted by alex.s

Any strategy for dealing with it? Just try to deal with it? More trail brake?

Sent from my Nexus 5X using Tapatalk

If the track has a noticeable amount less grip and your entry speeds are the same as before you're now over driving the front end grip and no simple adjustment will take away the understeer.

[Icecreamtruk]

If you what you want is to get rid of understeer, I would say 0 toe rear and a touch of negative toe out in front, in addition to the extra camber everyone already suggested.

[churchx]

Icecreamtruk: or zero toe front and slight toe in rear. Imho that's a bit safer setup due self stabilizing & allows opening throttle sooner / works better at low grip (wet or winter).

BTW, if road surface lacks of grip (wet/gravel/ice/snow), imho camber is less effective. Tire looses grip before it may see enough side-Gs for tire-flex to even out negative camber and thus to result in even contact patch.

[Icecreamtruk]

Originally Posted by churchx

Icecreamtruk: or zero toe front and slight toe in rear. Imho that's a bit safer setup due self stabilizing & allows opening throttle sooner / works better at low grip (wet or winter).

BTW, if road surface lacks of grip (wet/gravel/ice/snow), imho camber is less effective. Tire looses grip before it may see enough side-Gs for tire-flex to even out negative camber and thus to result in even contact patch.

Zero toe front and slight toe in rear will allow you to open throttle earlier, if your goal is to end up about 10 feet outside of the track. The car will feel more stable, but it will understeer on throtle application, which is one of the things OP is trying to cure.

You are right about the surface part too, but it also has nothing to do with OP, who just wants less understeer on track.

Like im not dissagreeing with you or anything, but I think it doesnt answer what OP is looking for.

[alex.s]

well! -2 degrees camber in the front. it's crazy how much better the front grips in a turn now. i had no idea such a small adjustment would make such a big difference. and installing and aligning was really pretty easy.

[churchx]

alex.s: and it's not just more grip front .. due grip bias now being opposite to stock alignment (IIRC stock was 0 camber front, -1.5 camber rear) it's also easier to rotate car without excessive inertia throwing. Once i got more camber front it was enough to adjust entry and mid-turn with brakes or accel lift-off. Camber bolts for their price/extra camber front may enhance handling enormously vs stock, even on very same tires. Pitty that toyota/subaru didn't include any camber adjustment stock, only toe, but luckily camberbolts are cheap enough.