Seanix

I've had this on going issue where the car understeers on sharp right hand turns but is very neutral around left hand turns. It makes me nervous pushing hard rights I can carry far more speed on left hand turns....

Suspension setup: BC BR coilovers which are about 1 yr old
Wheels: rpf1 17x9 +45 with 245/40/17 all round Yokohama ad08. 32psi cold.

Alignment: Front: -2.2 camber, 6.5 caster, 0 toe
Rear: -2.5 camber, 2.5mm total toe

I was suspecting a corner balance issue so got the car corner weighted (with driver). This was using a industrial weighing scale so i don't expect it to be 100% accurate but it at least gives me a reference point.

Front left: 318 kg
Front right: 368 kg
Rear left: 360 kg
Rear right: 332 kg

I used Rob Robinette's website to calculate the cross weight percentages. Thanks Rob
Based on the corner balance calculator, my cross weight is at 52.8%. I can hopefully shift the weight to the FL but I'm not sure if this will eliminate the issue with understeer
I understand that the understeer may partly be induced by driving style, so I had one of my friends who regularly tracks drive my car. It was still very apparent. So I'm left pondering what I should do next.

Is there any other areas I can look in to, to resolve this issue I have? Appreciate any input you may have.

Thank you.

06Estukay

Maybe it's a silly question, but did you check to make sure that the adjustment settings are equal between left and right dampers?

Seanix

I sure did :-)
Ive tried different settings but still no luck.

nitewing117

This may be a stab in the dark, but maybe you're getting uneven tire pressures with left vs. right sides due to whatever course configuration you're running? Do you check hot pressures? Or is this apparent even from a cold start?

Seanix

Its apparent even on cold start. Im not sure if the front left shock is playing up. Its only a yr old though.
I checked the control arms and also checked the spring preload. They seem fine.
Oddly enough I never drove on the oem shocks much. I changed to coilovers within a month from buying the car.
I could possibly swap the coilovers out and install the oem's and see how that goes. What a pain in the arse..

robrob

Big differences in turning direction are usually caused by two problems, large caster differences or a bad corner balance. Circle track guys add 'wedge' to intentionally shift their diagonal weights to favor left turns.

If the weight scales are not precisely level with one another you can do more harm than good doing a corner balance. The stiffer your springs the more critical the level.

I recommend you precisely measure your coilover extensions (so you can go back to them if you want) and set the extensions so they are the same on the front and the same on the back (both front shocks the same length, both rear shocks the same length). Then test drive the car. This is probably your issue. If the shock lengths already match left to right then make sure the springs are sitting in the spring perches properly and then corner balance the car. My car has been off around 52% cross weight before but I didn't notice a difference in handling in right and left turns.

Have you checked your subframe bolts? Loose bolts can cause strange handling quirks.

Seanix

Thanks for ur input Rob. Much appreciated.
I reset the preload just to rule that out of the equation.
Checked subframe bolts and a couple of the 17mm ones on the rear needed tightening.
I'll double check the front and rear shock lengths.

The understeer is bad when throttle is applied, but when I ease off the gas, it stabilises. Almost like it was being caused by a malfunctioning diff. I've tried searching online to see if the diff caused others the understeer issue, but it doesn't seem so. Back to the drawing board. I need to sort this out

Seanix

Update:
so i havent resolved the actual issue yet but i suspect the eps is playing up. turning left seems assisted by eps however turning right provides a little resistance. almost feels like the power steering only works in one direction. After researching further on these forums, it looks like a few ppl have experienced this and it was the torque sensor malfunctioning.

I checked for fault codes and came up with fault code 22. the code was cleared and i then performed a eps reset. The eps was reset about 4 times just to be sure
However this hasnt resolved the eps issue. car still feels assisted on left hand turns. Which sort of relates to my initial concern about the understeer on right hand turns.

anyway.. i need to track this down and get it sorted. will update further once i've found the solution.

Gottabfast

That could be a caster issue. Caster affects steering effort and camber gain under roll.

What do you have to do to correct the under steer when it occurs?

RedCelica

really intrigued by this....keep us updated!