instability at high speed

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Recently the rear of my mks rev1 car feels unsettled at high speeds as if I have been hit by a heavy gust of wind causing the car to wander from its straight ahead position.This normally happens when doing xx mph+ but not all the time.I have checked suspension and steering for any obvious wear or play but found nothing.I was told that the front undertray missing may cause this but it is still intact .Has anyone experienced this or can give me any hints on what may be the problem .cheers Jon

Edited by Leakie Tbar Moderator

[raptor95GTS]

welcome How are the tyres on the car, mr2's are picky about tyres and tyre condition

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The front tyres are 195/50/15 arrowspeed ditchfinders and the rear are new 225/50/15 colway remoulds .I know you may think colways are rubbish but the cornering grip is excellent since putting them on and for the price of £2.50 per tyre I couldnt resist so I bought 4.How sensitive are mr2 s on tyre pressures.I would have bought some goodyears or toyo tyres but at around £100 per tyre it was an expense I was not going to make on a £600 car which I plan to change for a turbo in a year or so or get a set of 17 inch alloys for it.

[JohnnyC]

REMOULDS

And your fronts should be 195/55/R15

[raptor95GTS]

oh boy xxxx tyres and 80+ brave boy that's for sure. Or daft

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bit of both I think but have competed on colways up to xxx mph with no problems-that was when I was younger and dafter

Edited by Leakie Tbar Moderator

[ryan]

I reckon youre tired of living fitting remoulds to a rear wheel drive sports car. When I bought my first rev1 the handling and grip was terrible, checked to tyres to find they were Q rated (mud and snow!)
Out of interest have you removed your rear spoiler. and also hows the rear geometry, any dodgy toe in/out will affect stability.

[jon_st205]

Have another look at the rear toe arms, there can be wear in the bush which is hard to identify unless you unbolt it from the subframe.

[tiny big]

HI Ryan My car is not fitted with a rear spoiler but I managed to pick up a rev 3 type spoiler this weekend which is going to be painted and fitted in the next week or so.The guy I got it off advised me to fit a rear strut brace which may help as well.I did read my manual which gave a variety of tyre pressures depending on speeds which you travel at.What is the optimum rear tyre pressure for the 225/50x15 tyres I had set them at 30psi but the manual says 38psi if at higher speeds.Any help appreciated

[Moo]

Pressures for stock 15" rims are 29psi front and 33psi rear.

Is the x brace in the engine bay still fitted?

A rev 3 spoiler may help to plant the rear end a little at speed but afaik they are more cosmetic than funtional.

I'd be looking at suspension component wear as already suggested and also get the wheel alignment settings checked.

I'd also seriously consider putting some halfway decent tyres on the car. You don't have to go crazy if you're getting shot of it soon but there's much better tyres to be had than the one's you're running that don't cost silly money.

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The car was not fitted with a rear strut brace but I acquired one and will be fitting it tomorrow+ upping the tyre pressures to see if that makes any differance

[Taylor]

I'd be looking at suspension component wear as already suggested and also get the wheel alignment settings checked.

totally agree.
i'ld be looking at droplinks & top mounts to see if they are nackered.

[dawolf]

I'm not suggesting the tyres are the sole cause of the problem but I would seriously think about changing them for a half decent brand like Toyo or Falken, any RWD car should have good rubber especially on the rear.

[BenF]

Tired lower balljoints, shocks will also cause the car to wander. Is it particularly bad on roads with tramlines in it?

Colway remoulds for competition cars are OK, but I'd think twice before using them on a road car.

I'd look seriously at some Toyo T1-Rs all around, and then check the lower balljoints / suspension out. When all done, the car should feel absolutely planted to 120+.

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I fitted a rear strut brace today,checked all rear end suspension(ALL SEEMED OK)and reset tyre pressures on rear to 35psi.On the way home I took her up to 95mph and it seemed a lot better .I will try it over the next few days to see if ok.Thanks for all the advice-Jon

[Extubby]

I bet there is more sidewall stiffness in the Colways than the S**T Toyos.
They are shocking on the MR2, really bad!
It's like driving a jelly.