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MG MGA - Rebuilding a rack & pinnion

Is it possible,to rebuild a rack & pinnion steering assembly,at home,back to proper specs? Are there too many "special tools" required to allow a proper rebuild? Should a mechanically informed MGA owner attempt this repair or is it more advisable to buy a new or rebuilt unit? Is there a location, where one can send their R&P for a proper rebuild? Thanks Gordon
Gordon Harrison

I just rebuilt my 1957 MGA steering rack. There is really not much to rebuild. The rack and pinion gears are very long wearing and hardly ever need replacing.
You will need new rubber gaiters (rack seals) and possibly new copper rack damper pads. Also, replace the outer ball joints.

Unless the inner ball joints are very loose (excessive end play) leave them alone. They are easy to adjust if you can get them to unscrew. I tried everything on mine, including a torch, but they wouldn't budge.

One thing to check for is whether it has mistakenly been filled with grease. This is a no-no but occurs too often. The proper lube is 90W gear oil, not grease.

Barny Gaylord has an excellent write up of this rebuild with the Chicago MG Club. Go to www.mgaguru.com/mgtech/ or www.chicagolandmgclub.com

H Speer

The original workshop manual states that there is no adjustment for bearing wear in the box, except by the fitting of the necessary new parts. It does not mention that any special tools are required.
If the rack and pinion are worn (more than 3 thou backlash), you may not be able to source NOS replacements.
Peter.
P. Tilbury

The reason I ask is that I am trying to control a shimmy that occurs at around 60 mph. I just added a set of 60 spoke wheels (had 48spk before) for extra strenght. They were worked over by New England Wheel Repair and were all within 0.30 to 0.56 run out. The frt wheel only required 3/4 oz of weight.

The balancing made a huge difference in the ride but there is still that small shimmy. Frt end has been rebuilt (king pin bushings...Mgb v8 bushings ..new rubbers seals etc). There are new ball joints with a complete frt end alignment,so about the only thing left is the R&P.

If there is no access to the critical parts, then I have to make the decision to live with the shimmy or buy a new R&P from Moss for $229.00. Seems like a very fair price.

On a seperate note, modern cars use steering stabilizers to control shake in the frt end. Do you think it would be possible to adapt one to an MGA.
Thanks Gordon
Gordon Harrison

Gordon, I also had a similar shimmy. After removing my engine because of another issue I discovered the 4 bolts securing the rack were loose. I replaced them with Stainless lock nuts and bolts. Cleared the shimmy right up.
WMR Bill




Hi Have you re-checked the balancing that was done?

Wire wheels should be specially balanced. Moss has a good diagram in their catalogue. Hate to see you spend money for a new rack if thats not the problem.

Regards. Rod.
R.A. Gregg

Could it be uneven tire wear? Try swapping fron to back?
A Pearse

R.A
Balancing was done on the "ultimate" Hunter balancer by a professional mechanic involved with British cars. The difference after the balancing was amazing but that'"oh I wish I could get rid of it shimmy" is still apparent. MUCH,MUCH,MUCH less but!

Andy,
One thing is for sure I know it's not my rear hub giving me a problem. The tires are Khumo Power Star and only have app 800 miles on them. At present the mounting of the rims & wheels is as the garage put them on. There is very little time to experimentwith rotation before I head to Stowe for TBI.

I think I will have the brake drums checked out for balance. Does anybody know how this is done?
Gordon Harrison

I very much doubt that the R&P is the cause for you "shimmy". Turn you steeing wheel. Is there any free play? With the front end off the ground grab the outer edges of the tires and check for any free play. I would not worry about brake drum balance. They are too small to cause that sort of problem. I would be a lot more concerned about trueness of the rims. Also, it would not be the first time a new tire had a belt problem causing a "squirm" issue.
Good luck,
GTF
G T Foster

Gordon

Jack the car up on one side and try to move the wheel on a horizontal plane, and then in a vertical plane.

If you can detect looseness in a horizontal plane, look at the track rod end ( the ball joint at the end of the steering rack), and if you see movement here, but not in the rack, then you have wear in that ball joint.

If this ball joint is OK, and the rod ging into the gaiter is moving, then the play is in the ball joint in the rack. Then you have to remove a shim in the joint inside the gaiter, which is easy ....if you can get the joint undone....

If you are getting no play in either of these two places, then you will have play in your wheel bearing. Check this by trying the wheel in a vertical plane and see if you get the same amount of play. If so, look to the wheel bearings as the likey culprit.

If you get no horizontal play, but do get vertical play, look at the trunnions at each end of the kingpin. If you can detect play here, you need to replace parts in that assembly.

Finally check that the rubber bushes where the lower front suspension bolts underneath the front cross member. If they are worn out, replace with polyurethane ones.

Any play in any of these places will produce a shimmy at speed. The better the overall condition of the front end, the more stable the car will be. Same goes for all the bushings in the rear springs. Makes a world of difference when they are solid....
dominic clancy

This thread was discussed between 16/09/2008 and 18/09/2008

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This thread is from the archive. The Live MG MGA BBS is active now.