10 replies to this topic

[Magneto]

89 Mini Racing Green, this comes and goes....doesn't do it all the time.

At highway speeds it's smooth, but from about 20-35 mph the front end seems to get a shake or wobble in it that you feel clearly thru the steering wheel.

Things I have done so far.....

New front pads and rotors.

I balanced and rotated the tires, the balancer I used is a "Road Force" machine that measures for tire and wheel runout and all were well within specs. It's smooth on the highway as I said.

I'm in the process of replacing the suspension with adjustable parts, lower control arms, tie bars and coilovers all around, all new bushings etc and I'll align everything once it's done.

I don't see any evidence of bad motor mounts, engine steady bushes or broken subframe mounts.

Looking for other ideas I might have missed.....

[sledgehammer]

nylon ply tyres can give the above symptoms , when on the road , also mixed steel ply with a lot of nylon , or older tyres

 

with the car stopped , the bottom of the tyre distorts flat , when you pull away you get a wobble at lower speeds for a short while

 

but when on the balancer with no weight on it , a flat spot won't form - so you won't see any problems 

 

I've been fooled by this a few times , esp when a customer comes in for a balance & it doesn't cure the problem 

 

without the cars weight on the tyre the flat spot don't occure

 

( just a guess )

Edited by sledgehammer, 07 October 2016 - 08:42 PM.

[Cooperman]

I had that once with a 1275 Cooper SPI and it was an 'out of round' wheel. The stud holes were no concentric and, in fact, were about 2 mm out of true. I replaced the wheel and all was well again.

[Magneto]

I have decent A008's all around, and the balancer said the wheels were running true......I'll look into that tho cooperman

I did find a worn bushing on the left tie bar....

Just for fun I rotated the front tires to the back to rule out a bent or out of round wheel, still does it.

Edited by Magneto, 07 October 2016 - 10:07 PM.

[Spider]

Jack each wheel up, one at a time and spin them, eyeing off for any wobble. That might give you are starting point.

[sonikk4]

Although not on a mini this could still apply, on one of my old Cortinas I had there was a wobble felt at low speed only and had done the usual checks, bearings, worn suspension, balancing etc but it was not until I got stopped by the old Bill (Police) for a randomn check that they pointed out an issue with one of my tyres.

Bare in mind this was a remould and less than 2 thousand miles old ( all I could afford in those days) when you looked at at the tyre directly in front you could see the tread pattern forming a S shape as the wheel was rotated. Now as the tread was more than legal the Officer said it was in my best interest to get it replaced as it was starting to wear inconsistently and would soon become an issue.

Got it replaced with a decent named make and the wobble was gone, I did replace both fronts though as they were both remoulded.

Now how it happened I don't know. The tyre looked fine when it was fitted so something must have gone wrong in the remoulding process that enable something to move.

[Magneto]

I'm in process of redoing the entire front suspension now, I've found enough "eyebrow raisers" that it just made sense to go thru everything. In addition to the worn tie bar bushes, the lower control arm bushes were shot, one of the upper ball joints had no shims in it - rather they'd taken the play out and used the locktab to try and hold it in place - which didn't work of course, the ball joint was loosey goosey.

So, coilovers, new adjustable tie bars and lower control arms with all new bushes, including new offset bushes for the lowers, I rebuilt the upper arms - new shafts and bearings and I'll replace the questionable ball joints with new ones, properly set up.

I also have as et of lightly used wheels and tires that I ran on my last car and know they drive true as a control if needed.

Then I'll get it on the alignment machine and get it all set up - THEN I'll see if I still have a problem.

I won't have all this done till next week sometime so stay tuned.....more as it happens

[tiger99]

Just a quick thought. How is your subframe mounted? It could be very relevant.

You are obviously eliminating just about everything else by comprehensively overhauling the suspension.

[Magneto]

I looked at all the subframe mounts and they looked OK, nothing had come unbonded, but I have new ones if they are bad, I'll wait till I get it back on the road and aligned and see how it does.....I really think all the wore out bushes and loose ball joint had a lot to do with it.

[tiger99]

Solid subframe mounts would make more improvement than any other suspension tweak.

[Magneto]

This probably didn't help matters any.....this is the top - the bottom one wasn't any better.

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Edited by Magneto, 12 October 2016 - 07:46 PM.