Reducing understeer?

[Andy13186]

I got some pp1 replica rear wheels and good sticky 315's, Potenza s007 on the back and now I have massive understeer since the rear cornering traction limit was raised so much. Whats the best way to improve grip on the front? I tried putting pp1 rear 275's on the front but they didnt fit and had to order 1" spacers for that. Rear tire pressure is 32 cold front is 37 cold. Stock PP1 suspension and currently on the stock ps4s 255's but I may put the 275's on the front with the spacers. I suppose stickier tires on the front would be the best solution, I may plan on putting s007's in 275 on the fronts when I need new tires.

Does anyone have any other suggestions?

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[Schwerin]

Something is wrong you shouldn't need a 1in spacer to run 275's in the front. What wheels are you running in the front?

 

[1 old racer]

First of all for the best handling balance you should keep use the same compound rubber on the front as the back. Once you settle on your tire/ size you are going to run with then you can start to balance your over/understeer. The simple way to reduce understeer, (by far not the only way) is to stiffen the rear. On the PP1 I would suggest getting adjustable swaybars, then try different settings set the rear to the stiffest setting and play with the front till you get the grip out of the front you want. That is the simplest and most cost effective way, but once again not the only way.

 

[Andy13186]

Something is wrong you shouldn't need a 1in spacer to run 275's in the front. What wheels are you running in the front?

pp1 rears, they didnt fit with a 5mm spacer, 1 inch spacer should make them fit and be flush with fender but we will see.

 

[CVCashmere]

1 old racer is right. Stiffen the back either with a stiffer rear sway bar or stiffer springs.
It's an old technique but still works.

CVCashmere

 

[Andy13186]

Does that somehow improve front grip or does that reduce rear grip? I suppose my goal is to increase front grip.

 

[BmacIL]

Does that somehow improve front grip or does that reduce rear grip? I suppose my goal is to increase front grip.

Tires, tires, tires.

 

[1 old racer]

My first comment was to match the tire compound if the rears are stickier the the fronts then it will push if everything is setup correctly. If both are the same compound the you adjust for understeer/oversteer.

 

[Bluemustang]

Increase your front camber and/or add a stiffer front sway bar. More front camber will help the front tires corner better with a more ideal contact patch. Stiffening the front sway bar should help reduce losing the camber angle also.

Edit: sorry I didnt read the whole thing lol. Probably tires mismatch.

 

[Andy13186]

Increase your front camber and/or add a stiffer front sway bar. More front camber will help the front tires corner better with a more ideal contact patch. Stiffening the front sway bar should help reduce losing the camber angle also.

Edit: sorry I didnt read the whole thing lol. Probably tires mismatch.

I do think increasing the amount of negative front camber may help though. I may try that eventually.


This tuning guide actually says to have a less stiff front swaybar to decrease understeer though hmm

http://www.rapid-racer.com/suspension-tuning.php

I had a 2011 GT that handled great with a staggered mixed tire setup, but it was lowered only in the front and had aftermarket caster camber plates, adjustable dampers, and stickier than my current tires on the front.

 

[Bluemustang]

Does that somehow improve front grip or does that reduce rear grip? I suppose my goal is to increase front grip.

Stiffening the rear sway bar reduces rear grip essentially. It can reduce the understeer in a way by increasing the oversteer tendency (making it more likely to unsettle the rear). With your PP springs though you don't have to worry as much about that unless you went to a very stiff rear bar I guess.

Stiffening the front sway bar seems counterintuitive but it actually works because of the dynamic camber of the MacPherson strut suspension. It sucks.

 

[Roadway 5.0]

First of all for the best handling balance you should keep use the same compound rubber on the front as the back. Once you settle on your tire/ size you are going to run with then you can start to balance your over/understeer. The simple way to reduce understeer, (by far not the only way) is to stiffen the rear. On the PP1 I would suggest getting adjustable swaybars, then try different settings set the rear to the stiffest setting and play with the front till you get the grip out of the front you want. That is the simplest and most cost effective way, but once again not the only way.

^^^ This

Rear tire pressure is 32 cold front is 37 cold.

While raising the front tire pressure helps with understeer, you may have overdone it a bit. If you're hitting ~40psi hot (maybe higher seeing as you're in Florida with boiling asphalt) your front tires may be bowing where only the center of the tire is in full contact with the ground. Less tire less traction. Try going to a cold temp psi that yields 34psi or so when hot and see how it goes. It won't solve your problem, but could be a small improvement until you get matching tires and play with the suspension.

 

[Norm Peterson]

Start with front tires wider than 275 on rims wider than 9.5". Cars like the GT350 and 1LE are only running 10 or 20 mm of nominal tire size stagger for a reason. Keep clearances on the strut side about the same, and let the extra width that's giving the front greater capability be what gives you that flush look.

Stiffening up the front bar has two effects. More understeerish in that it attracts more lateral load transfer forward, countered by less understeer due to the reduced roll putting the tires in a better camber condition while cornering. If any common front suspension type is going to benefit more from better camber than it gets hurt by more load transfer, it's going to be the MacStrut.

It might even be a good idea to "overdo" the front bar stiffness a little so that you could then start adding a little more rear bar stiffness. You'd be bringing the distribution of lateral load transfer back into better balance, while continuing to reduce roll slightly - both effects tending to improve front tire grip.


Norm

 

[BmacIL]

Start with front tires wider than 275 on rims wider than 9.5". Cars like the GT350 and 1LE are only running 10 or 20 mm of nominal tire size stagger for a reason. Keep clearances on the strut side about the same, and let the extra width that's giving the front greater capability be what gives you that flush look.

Stiffening up the front bar has two effects. More understeerish in that it attracts more lateral load transfer forward, countered by less understeer due to the reduced roll putting the tires in a better camber condition while cornering. If any common front suspension type is going to benefit more from better camber than it gets hurt by more load transfer, it's going to be the MacStrut.

It might even be a good idea to "overdo" the front bar stiffness a little so that you could then start adding a little more rear bar stiffness. You'd be bringing the distribution of lateral load transfer back into better balance, while continuing to reduce roll slightly - both effects tending to improve front tire grip.


Norm

Bingo to all points.

 

[1 old racer]

One last thing I got to inform you on. When you stiffen your suspension with stiffer sway bars you will make the car react quicker. You may think you are a racer just because you have it set up as stiff as possible and it goes around curves as flat as a pancake but the trade of is snap oversteer. This w I'll get you into trouble very fast, much faster then understeer ever will. Be careful and dont over set up your car. Make the car work for you and learn the limits before you reset them.

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