[discodan]

Hi guys,

So I'm starting to get to the point to push the car well enough that the factory 'understeer' noticeable on the exits of corners is affecting me. I am aware of the following two measures to aid with this:
1. Toe/Camber adjustments on the factory suspension setup (available from dealer).
2. Square tire setup on all corners.

I don't really want to run the extra toe/camber at this stage due to the faster wear on the inner edges of the tires (have done setups like this in the past on other rides inc GTR and found the wear very fast). I'm also not to sure about the use of the square setup but I am keeping this as an option.

I'd like some feedback from members here on other measures inc sleeve kits, coil over, sway bars etc and what is a good setup for street and 4 track visits a year?

Thanks.

 

[Jon H]

I'm running a square tire set up Michelin PSSs 285 with Whiteline F&R bars. Try F&R sway bars first and see how that treats you, the more common config is full stiff front and soft in the rear. If you want a more neutral setup, I'd step up to a square tire setup.

 

[DocNrock]

+1 to what Jon said above. I'm not familiar with the Whiteline bars, but I'm sure they are quality. I have the Stillens. For a 285 square setup, which I have, I run the middle setting in front and full soft in the rear. If you are going to stay with the 255's in front, then I would go full soft front and rear. This is specific to the Stillen sways. If you go with the Whitelines, I would listen to Jon's recommended setup. The stiffness of the two brands are different, so the settings will be different, as well.

My car handles very neutrally on the track, with no push. In large part, I attribute this to the 285 square setup and the properly dialed in Stillen sways. I also have the KW coilover sleeve kit. I think this improves overall handling and cornering, but I think it plays much less of a role in dialing out any understeer than the square setup and sways.

 

[paparazzi]

I run 285 square with kansai sway bars. Only the back bar is adjustable. I have it set firm in the rear (200% stock stiffness) and my car has almost no understeer. Comes in and out very neutral.

I think a stiffer rear will help more with understeer as opposed to a softer rear.

 

[SleeprZ]

+1 above. Do you also monitor hot and cold inflation temps on your tires? It may be worthwhile to just increase the rear pressure relative to the front and evaluate the differences.

 

[discodan]

Thanks everyone for the good advice given. So looks like the definite answers lie in Sway bars and a square setup.

 

[DocNrock]

I run 285 square with kansai sway bars. Only the back bar is adjustable. I have it set firm in the rear (200% stock stiffness) and my car has almost no understeer. Comes in and out very neutral.

I think a stiffer rear will help more with understeer as opposed to a softer rear.

Some body roll is good as it will allow the suspension to absorb some lateral g's. If the rear is stiffened too much, you will begin to decrease rear grip. This can make handling more neutral, as the lack of front grip that led to the understeer is now compensated for by a decrease in rear grip. The result is more neutral handling, but possibly also lower overall cornering g ability. I'm not saying this is what is going on with your setup, as I have not driven your car. I'm just trying to make sure the OP knows that stiffer is not always bettter.

The Stillen sways on full soft are still 67% stiffer than OEM. Starting with them on full soft maximizes rear grip, then one can adjust the fronts until understeer is dialed out. I know you said your front Kansai sways are not adjustable, so stiffening the rear may be your only option. Before I went to a square setup, I had my sways full soft front and full stiff rear. The car was very neutral, but my maximal cornering g's measured by my Traqmate was about 1.1. I also got a lot of power-on oversteer at corner exit. After going to a square setup and changing to full soft rear and middle setting front, my maximal cornering g's are now about 1.2 to 1.3 sustained, with peaks to 1.5; this is also with the KW sleeve kit. There is no push, no power-on oversteer, and very neutral handling.

 

[Jon H]

If the rear is stiffened too much, you will begin to decrease rear grip.

+1

This can eventually lead to your rear tires overheating and start to get "greasy." A stiffer rear is generally something that the GTR doesn't need.

 

[donutbob]

Love this topic, thank you all for your input and experience, please provide alignment data as well if its not too much trouble.

Don

 

[DocNrock]

Hey Don, glad to see you here! I'll give you my alignment data, but the front camber is only possible if the car is lowered a bit, I believe. Front I have -2 deg camber and 1.5 mm toe OUT on each side. Rear I have -1.8 deg and 1mm toe IN on each side. The Top Speed guys with their OLOA build were able to get -2.4 in front and -2.2 in the rear, but their car was lowered more than mine.

Edited to correct dyslexic error on toe settings.

 

[donutbob]

Wow, toe in at the front at out in the rear, thats the opposite of what I'd think to do, will try, as you know im trying to stay as stock as I can. I'm square now thanks to you advice, and my next track day is next week at thunderhill again. I'm hosting a day at buttonwillow on black Friday, if you can make it I'd enjoy the GTR company.

Don

 

[DocNrock]

Wow, toe in at the front at out in the rear, thats the opposite of what I'd think to do, will try, as you know im trying to stay as stock as I can. I'm square now thanks to you advice, and my next track day is next week at thunderhill again. I'm hosting a day at buttonwillow on black Friday, if you can make it I'd enjoy the GTR company.

Don

Oops, my dyslexic bad. You are correct: toe OUT in front and tow IN at rear. The numbers were correct, front and rear. I will edit my post to reflect that.

 

[Jon H]

I'm hosting a day at buttonwillow on black Friday, if you can make it I'd enjoy the GTR company.

Don

Oooo what config?

 

[donutbob]

The standard, Hehe. I read about cw13 all year and naturally I want to see how I measure up to the best. I spend most of my time at thill or infineon, brp is an annual treat for me. Pm me for the details if interested.

Don

 

[Jon H]

PM Sent!

 

[shawnhayes]

Square 285 setup and Forged Performance swaybars all around for me. Had the Whitelines, and in the back to back test at VIR, the Forged's are better. The endlinks on the Forged sways are MUCH better than the stock ones, which are left stock by the Whitelines. Understeer gone.

Shawn

 

[donutbob]

Hey Shawn, square on stock wheels? And do you have alignment specs to share?

 

[[email protected]]

Square 285 setup and Forged Performance swaybars all around for me. Had the Whitelines, and in the back to back test at VIR, the Forged's are better. The endlinks on the Forged sways are MUCH better than the stock ones, which are left stock by the Whitelines. Understeer gone.

Shawn

Thanks Shawn. Here is a link with quite a few pics and some facts: http://www.forgedperformance.com/store/product.php?productid=17997&cat=436&page=1

 

[Cicio]

Square 285 setup and Forged Performance swaybars all around for me. Had the Whitelines, and in the back to back test at VIR, the Forged's are better. The endlinks on the Forged sways are MUCH better than the stock ones, which are left stock by the Whitelines. Understeer gone.

Shawn

Shawn,

What were your lap time improvements at VIR during your back to back test? How much time did you pick up using the Forged bars, and do you have any track data from the test you did? A Traqmate overlay of the two sets of bars would be really cool to see if you guys got it. We could see mid corner speed improvements due to the lack of understeer, and also look at corner exit speeds as the car tried to put down the power.....if that hasn't been done it should be for sure.

~Cicio

 

[celsius]

Shawn,

What were your lap time improvements at VIR during your back to back test? How much time did you pick up using the Forged bars, and do you have any track data from the test you did? A Traqmate overlay of the two sets of bars would be really cool to see if you guys got it. We could see mid corner speed improvements due to the lack of understeer, and also look at corner exit speeds as the car tried to put down the power.....if that hasn't been done it should be for sure.

~Cicio

+1, I would like to know how much better they are also?