MR2 handling issue - please help diagnosis

[jaymdee]

cut and pasted from post on IMOC, as I know a lot of Supra owners traded up from MR2's and there's a lot more people on here than on the MR2 forums:

 

Basically the rear of the car feels like it is 'washing out' and under acceleration, the car feels really unstable:

 

About 4 weeks ago I was on a trackday and the car ran fine all day and then on the last session something didn't feel right. The car felt different immediately and I spent 3 laps trying to diagnose the issue with no luck.

 

Recalling that at the MOT I was told my track rod ends were on their way out, I had a local garage replace them and I also replaced the speedo converter/delimiter to one of Stefs. Took the car out and it felt pretty good just driving around normally.

 

I have since replaced the stock turbo suspension with BC coilovers and again, after a bit of playing around with the settings, the car feels good under normal town driving.

 

However, on hard accelerating it feels really really unstable. Once at speed (eg 70mph) it's fine, and cornering seems fine, but I need to back off when accelerating as it feels like it's out of control!

 

Any assistance diagnosing this would be great, if someone has had a similar experience, as I've got another trackday booked for Sat 29th, which is currently looking unlikely. Going to take it to a garage on Friday (away all week with work) but a few ideas for them to look at could help.

 

Homer suggested engine mounts when I mentioned it at Japfest?? All suspension bushes replaced with TRD kit and poly ARB bushes in the last year

 

cheers

[GreaseMonkey]

Hi jaymdee, (Just a thought) I had similar issue on my mates Rev2 Mr2. When driven around under 60mph the car handled fine/ cornered ok. But at 60mph plus, on a straight road, a skittish or loose rear end sensation was noticed, especially when sat in the passenger seat under hard acceleration. Rear end of car felt like it had shopping trolly casters on it as would slightly jerk the car from one side to another making it feel uneasy.

 

Put on his 2 poster ramp at work and couldn't see anything obvious (i.e no play/ exessive movement/ worn bushes), wasn't untill we went round to check the torque setting of all the rear suspension/ subframe bolts that we noticed the O/S/R "Strut Bar", where it mounts to the vehicle body, was loose by 1/4 of a turn.

 

We roadtested it again after tightening/ torqued it, and was ok, problem solved. Which also stopped the knocking noise it made when going over some harsh bumps, which we thought was the front engine mount at first.

 

The Torque setting was 83 ftlbs/ 113 n.m. pg SA69 in the sw20 chassis body manual or this link he got off the mr2 owners club to find the torque settings.

pdf download sw20 manual:

http://www.mediafire.com/?ax3xm4nrk9m#1

 

Useful repair manuals/ links:

http://www.mr2oc.co.uk/forums/198/80372.html

[Abz]

I am not too knowledge about suspension even though I am trialing some for Gaz Shocks. I understand though that damper settings can play havoc on suspension issues like you mentioned. Can you adjust these on yours? Also has a Geo been done since the fitting of the new BC coilovers? Might sound silly, but tyre pressure okay?

[jaymdee]

Thanks for replies. Getting everything checked on Friday so will see if there are any loose suspension nuts.

 

Tyre pressures set to 32 all round. Coilovers are set to same stock ride height, so geo 'shouldn't' be too far out, but this problem came on suddenly with stock springs and shocks fitted. The coilovers have made it less noticeable, but have masked the problem not cured it.

 

We'll see what the verdict is on Friday

 

cheers

[Abz]

Keep us updated, hopefully they will find a fix.