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MGB Shaking at 55 mph

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Coastalman

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The front end has been rebuilt with new bushings, a rebuilt steering rack with new tie rod ends, front end aligned, new tires well balanced, new brakes all the way around and still at 55 the car shakes. Not violently, but enough to make the ride a bit uncomfortable. The car is a '77 MGB with a newly rebuilt motor and is well tuned. I sure would like to eliminate the shaking. Does anyone have any suggestions as to my next step in trying to get rid of the shake?

Thanks,
Charlie
Oriental, NC
 
Coastalman said:
The front end has been rebuilt with new bushings, a rebuilt steering rack with new tie rod ends, front end aligned, new tires well balanced, new brakes all the way around and still at 55 the car shakes. Not violently, but enough to make the ride a bit uncomfortable. The car is a '77 MGB with a newly rebuilt motor and is well tuned. I sure would like to eliminate the shaking. Does anyone have any suggestions as to my next step in trying to get rid of the shake?

Thanks,
Charlie
Oriental, NC
Click to expand...

Charlie,
Are they wire wheels, if so did the tire shop know what they were doing?
I'm not an expert but the last time I had a shake at 55 it was balance.
 
No, not wire wheels. Allen Hendrix said he could do a very good balance and check of the wheels. He did wonders on my big Healey when he balanced the wire wheels. They are the rostyle wheels.
 
I'd check for an out of true wheel - more likely to happen with wires but I have had multiple cars with a slighty out of true or out of round wheel and at certain speeds it will match a response point in the suspension and become real noticible, then fade out above or below that speed.

I had an early 90's Ford wagon like that - once I identified which wheel was out of spec and dedicated that as the spare only, it ran real smooth. I've had wire wheel "B"'s that could never be made to run smooth, one of the main reasons my current MGB project has standard lug nut wheels.

Other thing to look at is lug nut degradation or the holes in the wheels becoming elongated, which could allow the wheel to not mount perfectly true to the hub.
 
Is it worth swapping the wheels front to back to see if anything changes?
 
Had a similar issue with my TR3. Original steel wheels were out of true. The test:

Raise front or back of car so tires are off the ground.
Spin wheel with your finger pointed at the sidewall of the tire..
See if wheel seems to move toward, then away, then toward your finger.

TM
 
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Big Healeys with rear drum brakes are infamous for having out of balance drums. Never heard it being an issue on MGBs.
 
Does it stop if you go faster or increase as speed increases?
 
How'd you come out on the "finger pointing at the spinning wheel" test?
 
Coastalman said:
No, not wire wheels. Allen Hendrix said he could do a very good balance and check of the wheels. He did wonders on my big Healey when he balanced the wire wheels. They are the rostyle wheels.
Click to expand...
ROStyle wheels have to be balanced by the stud holes, not the center, as the center is not (necessarily) true on them. It's not a defect, that's just the way they were designed.

Another possibility is insufficient fluid in the shocks, which is easily corrected unless they are leaking. You can use hydraulic fluid from the auto parts store or Harley-Davidson fork oil to replenish the shocks. It would be best to drain the old oil, clean the valve bodies, and refill with new oil. If the seals around the shafts are leaking, rebuilt shocks are in order. Apple Hydraulics will send rebuilt shocks on an exchange basis.
 
I have had to put these repairs on a back burner while I am dealing with some medical issues. Hopefully I will be back working on this in a week or two. Stand by......
 
Coastalman said:
I have had to put these repairs on a back burner while I am dealing with some medical issues. Hopefully I will be back working on this in a week or two. Stand by......
Click to expand...
the car will be there - in the meantime be well
 
I'm back after a bit of a delay. The shaking appears to be coming from a bent wheel. I took my tires to my local tire store to be checked out. One wheel is bent. I have located a seemingly good wheel and am going to have it checked tomorrow. If it doesn't have any problem then I will bring the bent wheel in to have the tire swapped and balanced. I will update the forum after the swap. Hopefully, this will fix my shaking problem.
 
Good luck on your plan!

Bent steel wheels are often impossible to re-shape,, but hopefully your tire shop knows what it's doing.

Tom M.
 
Could the driveshaft be out of balance? I have seen a weight ona drive shaft fall off.
 
I have wondered that myself. I recently had the motor rebuilt and from years of tinkering with LBCs I know that you are supposed to mark the drive shavt and the yoke on the differential so that they can be reassembled correctly. I am wondering if this occurred. I guess if the replacement wheel doesn't correct the shake then I will rotate the drive shaft 90 degrees to see if that makes a difference.
Charlie
 
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