Suspension Issue At The Track! Hr31 Gts-X

[IFRYCE]

Hi guys,

I have an R31 GTS-X (sunroof model) with S13 suspension conversion (stock swaybars). I have recently started taking it to the track and am having an issue with driving the car out of hard left hand corners. I thought it was an issue with the diff, but after having a friend follow me around Winton on Sunday it seemed that my left rear wheel sits about an inch off the ground on all hard left corners. I have checked under the car and it all seems nice and tight. I check all struts and none of them have signs of any leaking or that they are blown. After quizzing my brother, he took it to PI the week before, he said he had the same issue. I thought "Ahhhh S13 shocks might be too short", but why wouldn't this happen in right hand turns as well? It is only left turns. I asked him about when the car was pre- S13 suspension conversion and he said it still used to happen then. He had R31 JIC coilovers in it then.

Does anyone have any idea as to why this would happen? Does anyone have a similar issue?

Please help!

[Daleo]

Could the left side rear trailing arm be binding in its travel? Have you fitted aftermarket bushes to the rear arms?

If you are using OEM bushes; they could be preloaded. Reverse the car up on some ramps. Loosen the mounting bolts (don't remove) and pry open the mounts to release any tension on the bushes. These need to be tensioned at the cars driving ride height, so tension them on the ramps; not with the suspension unloaded

Jack both rear wheels off the ground (at the same time); measure any difference in droop from one side to the other. If there's no difference you may be sorted.

If there is a difference; disconnect the rear shocks from the lower mounts, measure shock overall length looking for variation.

[Duncan]

Very common for race cars to lift the inside wheel in some or all corners, it comes down to how hard your springs and sway bars are. The common, internet friendly and totally wrong approach to track suspension is to put hard shocks, springs and sway bars on for track use.

In the real world, you run the softest springs you can while keeping all 4 wheels on the ground for maximum traction (there is a lot to that too, keep in mind the inside rear wheel will never have much grip as there is little weight on it). Soft springs keep the wheels on the track over bumps/ripple strips/small cars thereby maintaining traction. Add sway bars of the correct stiffness to adjust the understeer at either front or rear to your taste.

BTW a stiff chasis makes a huge difference to whether a wheel will lift or not. It is very easy to lift a corner once a proper roll cage is installed.

Throw all of these comments out the window if the left rear shock is siezed lol. drop by your local pedders and hand over $14 of your hard earned to get the shocks checked.