kauaian

iTrader: (18)

So I have an 08 with about 90,000miles and within the last week I have noticed whenever I exceed 120mph the rear end feels somewhat unstable. It feels as if the rear end is wondering or floating/sliding. I have never had this feeling in the rear end before and have taken the car up to a 168 with no such feelings.

When it started I was on stock suspension with the f-sport rear sway bar and figs racing control arms. I swapped the controlled arms back to stock and this did not fix the problem. I have had a set of RSR isport coilovers collecting dust for the longest time so I installed them and still the problem persists. There are no unusual sounds coming out of the rear or anywhere for that matter.

Anyone ever experience this? I am wondering if I have some fatigued bushings? Could this be something as simple as an alignment?

idoke1

iTrader: (5)

^^it could be your tires. Tires play a huge role when running triple digits in speed.

Vervish

iTrader: (4)

Not sure what your alignment history is - but I would start there. Especially after swapping control arms and adding coil overs.

FWIW - when I replaced my tires (but before I got an alignment) my car became pretty squirrely at high speeds. The alignment eliminated the unstable-ness. What was odd was that while on the old tires, the car drove perfect,..once I swapped the new ones on the trouble started. I think the old tires had worn in such a way that the bad alignment was not obvious.

kauaian

iTrader: (18)

Vervish, that make sense because I recently swapped over to my summer tires.

ModInJapan

iTrader: (5)

I would also recommend checking alignment first, then the condition of the tires, and lastly the suspension components and if they are worn down! Good luck!

-Josh

flowrider

iTrader: (9)

Mention should also be made that the tires should be the same make and model. Not all Max Performance tires have the same construction and mixing them could cause handling problems, especially at double nickel speeds.

Lou

Sylvan

iTrader: (6)

If the toe is out it can feel twitchy, I would get the alignment checked

FIGS

iTrader: (11)

Rear toe I suspect is the issue. it has a huge influence on overall steering feel and high speed stability due to bump steer. Sometimes the eccentric bolts can slip a bit.
Mike

ISFPOWER

iTrader: (20)

Mike, would an aftermarket toe arm solve that problem and keep toe always where it needs to be with no slipping over the eccentric bolts?

FIGS

iTrader: (11)

We set the eccentric bolts fully inward which is the best support of the bolt on the tab and locks it into place. This allows us to max out the toe link arc with a length change on the linkage vs mount position as well which reduces the inward pull as the linkage rises. We can also provide lockout plates if desired, but it has not been an issue.
Mike

I8ABMR

check alignment and tires. Dont want any issues at those speeds

kauaian

iTrader: (18)

Thank you everyone, I will get the car in for alignment and hope that resolves the issue. My tires are pretty much new and I have been in the 150 range with them a handful of times and did not experience the loose rear end.

kauaian

iTrader: (18)

Got the car in for an alignment this past week and the toe was slightly out. I can't tell you how much because I cannot read German but the tech told me it wasn't much.

I got a chance to get the car up to 160 today and it felt planted or normal!

Thanks for the recommendations.

Sylvan

iTrader: (6)

Mine is feeling the same, I am booked in for Tuesday so I hope it solves my issue as well.

MR2QIK

Go straight to basics & check alignment/tyres before you start buying anything.

You can have all the fancy goodies in the world, but if your alignment is off & you have rear toe-out, there's no way you're going to feel confident.