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MG MGB Technical - Vibration-I'm stumped..

My 1977 MGB has had a nasty vibration problem since I bought it over 3 years ago and I can't get rid of it. It starts about 55 and goes to 65 (most severe) and a little light vibration aft 65. One thing I noticed is that the vibration is almost non-existent when both the car and the weather is cool/cold. After the car warms up or the weather does the vibration is much more pronounced (I can feel it in steering wheel and see it as my mirrors do the "shake").
I have had the tires balanced, replaced the bushings and the front bearings, checked and filled the shocks, tires are only 1 year old, rims are ok, etc. What's left?
Anyone know of someplace near (within 30-50 miles of Lancaster, CA) that knows about MG front ends and can take a look and maybe fix my problem.
I'm at a loss of what else to check. Did all I could find in the archives.
Joe
Joe Fabian

You might want to check the u-joints. Over the years I've had to replace mine a couple times and when they get worn the vibration can be severe. It tends to be worse when on the gas and less when gliding. The are tough to lube because it requires a narrow grease gun fitting so I think they get neglected sometimes.
Bob Ekstrand

What kind of rims and how did you have them checked? Have you tried swapping different rims on the car?
william fox

Does your car have Rostyle wheels? They
can wear and be hard to balance. I had a similar
vibration and cured it by buying Minilite-type
wheels.

Another cause could be tread separation in the
radial tires. Even if 1 year old, one of them
could be defective.

Maybe try a different alignment/tire shop and
have them try to balance the wheels again.
Ronald



Just wondering if , while having the bad vibration,you've put the car into neutral and let the engine go to idle? Still have it?

Tom
Tom M

What tires do you have?

Some tires have been reported to have vibrations
at certain speeds (designed defect).

You might try a "Google" search of your particular tire and determine if other owners are have reported vibs with theirs.
Daniel Wong

I would go with Bob's advice about the propshaft UJs if it weren't for the temperature variation. Even a flawed tire design is an unlikely culpret unless your suspension is getting on towards refit time or you are also running a wheel bearing.

Will you post the outcome please

Roger
RMW

Had the same symptoms as you - vibration at highways speeds. It was indeed the u-joints at one point. When it returned a few years later, it seemed the splines in the driveshaft had worn to where there was some play. After replacing the driveshaft the ride was remarkably smoother.

Matt Kulka

I had an out of balance brake drum cause a nasty vibration which drove me crazy until I finally figured it out. I changed the half shafts, tires and wheels and even had my tires shaved 'true'. After all that the last thing was the brake drums and so it was.

The important key to solve the problem is the 'speed' of the vibration. Is it at prop speed or at wheel speed? As soon as you figure that out you can further deduce the problem.
Mike MaGee

Thanks for all the replies. The vibration is at wheel speed (when driving) not engine speed (idled and check rpms, reving up to 3000-5000 rpms, vs any vibration and there was none)so I ruled out anything caused by the engine. I already replaced the u-joints a few months ago so they have been eliminated. As for the rims, they are rostyle (original ones) and they checked ok. My tires are Coopers and they look good as well. I had warped brake rotors in the front but I replaced them with new rotors a month ago as well.
Oh, what was the name of the MG guy in Chatsworth, CA? (I accidently deleted the e-mail before I wrote it down).
Joe
Joe Fabian

Joe,
In replacing the u-joints, but did you make sure they were aligned?
A center line passing through a rear u-joint cup and along the shaft must also pass through a corresponding front u-joint cup.
When re-installing the splined front shaft piece, it's easy to get it off.

I had the same problem on a '67 and took the shaft to have it balanced. The shop took one look and showed me where I had done that. They did not balance it. I took it home, put it back on, problem solved.

Dave
David Steverson

This thread was discussed between 05/09/2004 and 06/09/2004

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