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R32 Gtr Under Steer

ripps
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ripps Collaborator

ripps

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I have an r32 gtr doing a bit of hill climb with it. I have a brand new set of kumho ku36s on it and it does nothing but understeer. Just wondering everyones thoughts and help. Obviously i will in time be getting a set of r spec tyres but wondering if there is anything i could do in the mean time be it sway bars or what ever. i do have different sway bars all round. Any help or info would be great

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blind_elk Grand Master

blind_elk

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Posted

There is a whole binch of things that can induce and/or reduce understeer.

Try inflating the front tyres about 2-4psi above the rears.

I have a GTS4, and found that a heavy rear bar, combined with the standard front bar, was good for a neutral to slightly oversteering car.

Do you have any -ve camber in the front? Try taking some -ve camber out of the rear.

What spring rates are you running?

Also, try adjusting driving style. If you are braking as you turn in, then the car is more likely to understeer as weight transfers to the front outside tyre.

MrStabby Grand Master

MrStabby

Posted
Posted

Also, checkout your front to rear ride height. 5-10mm difference can make quite a difference to how the car handles into corners.

+1 you want the wheel centerline to guard measurement to be 10mm higher at the front. Most people recommend 350mm front 340mm rear. I used to have 335mm at the front and raising to 350 made the suspension work a lot better. One you've got the ride height about right you should get it corner weighted and aligned. IIRC i'm using about 2deg negative camber at the front and 1.25 negative at the rear. Make sure you dont have any toe in at the front, or at least less than you have at the back. I'm using zero toe at the front and haven't had tramlining with either Falken rt-615s or Federal 595RS, which are similar styles of tyre to your Kumhos.

You WILL need a stiffer rear sway bar - makes a huge difference, and if you get an adjustable its easy to play with the under/over-steer balance.

EDIT: oh i see you have sway bars already - your front one may be too heavy, which will make understeer worse.

Changing the tyres is a waste of time until you get the front/rear balance right, and to make R specs work properly you need more aggressive alignment settings, which will mean more tyre wear for road use.

djr81 Grand Master

djr81

Posted
Posted

I have an r32 gtr doing a bit of hill climb with it. I have a brand new set of kumho ku36s on it and it does nothing but understeer. Just wondering everyones thoughts and help. Obviously i will in time be getting a set of r spec tyres but wondering if there is anything i could do in the mean time be it sway bars or what ever. i do have different sway bars all round. Any help or info would be great

Five questions:

So you have four tyres the same?

What sway bars have you got?

What spring rates are you running?

What alignment settings do you have?

What diffs are in the car?

Generally to reduce understeer you will need more rear roll stiffness & less front. Which you can do with springs/sway bars/ride heights. Also the way you drive it makes a huge difference. On the other hand changing four tyres for a different compound shouldnt change the balance much if at all.

Lastly check that the drop links to the sway bars are done up properly. A loose rear bar will give you massive undertsteer...

Fender braces make a world of difference too.

To what? I mean, other than your bank account.

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