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MG MGB Technical - Diagnosing Loose Steering

Hi All. My '63 roadster has a lot of shake in the front end, especially at 60 MPH and above.

Sitting still, I can turn the steering wheel left and right and there are a few degrees of free movement, then a bit of noise when it catches up either side. Not really a "clunk" or anything, just the sound of slop being taken up (if that makes any sense).

I had the tires re-balanced when I got it 14 months ago, and that helped some. I suspect it's mechanical, like the rack and pinion, kingpin bushings, or, hopefully, just the ball joints.

Before I start buying parts, are there some diagnostics I can do to find out where the problem is?

Thanks a lot, Cheers,
Greg

Greg Van Hook

Vibration at 60 at the front is traditionally associated with tyre balance .......or toe-in

The following is based on the UK MOT Test

The only way to properly test the front (standard) suspension requires jacking up the car in 2 different places. I would suggest that you grease all 3 (or maybe there are only 2) grease nipples on both sides.

To check for play, jack up one side under the front wishbone. Grasp the road wheel at "quarter to three" and rock; this tests for play in the track rod end, rack, and possibly the wishbone pivots (see below). Now grasp it at 6 oclock and rock; it will indicate play in the bearings and/or king pin. Finally put a bar under the tyre and lift; indicates play in the bottom joint and /or bolt and whether the spring pan arms holes are elongated. (This may show on the side to side test too)

Lower the car and now jack it up under the chassis rail so the wheel "hangs". Repeat all 3 tests. Play may show and it will also give a better indication of play on the inboard wishbone pivot condition/bushes/attachment.

Ideally rock it yourself and see if you can feel play; then get an assistant to rock it and get underneath and see if you can see the play. (Axlestand!!)

Without teaching my grandmother etc, make sure the trolley jack itself doesn't rock about. Obviously for safety but it makes checking for play a lot more difficult!

The rim of the wheel can rotate a few degrees before actually turning the road wheels. Observation should show play in the UJ. How much play is acceptable in the rack is more difficult to quantify.
Michael Beswick

Wheel wobble due to tyre imbalance over a long time can wear the rack and the UJ to give play. Collapsible columns seem to have play built in, my Celica manual quoted something like up to 1/2" at the wheel rim was OK, and my V8 is similar. There shouldn't really be any play in the upper and lower column bushes, nor in the UJ which can be checked by grasping the two shafts and trying to turn them in opposite directions. Rack play can be felt either as sideways movement of the rack shaft relative to the body, or slop in the gear i.e. turning the shaft but keeping the track-rods still or vice-versa. That can be too many shims under the damper cover, but if the gears are worn taking shims out to correct that in the straight-ahead position can cause the rack to bind either side of that. The passenger side rack bush can wear allowing up and down movement of the track-rod that side. The track-rod ends can wear developing slop, as can the king-pins, upper (rubber) and lower (steel) trunnions, links to A-arms, and A-arms to crossmember pin. Could even be wheel bearings with too much end-float. It's basically a matter of gripping each side of each possible point of wear and turning or moving them in different directions looking for movement.
Paul Hunt 2010

Thanks guys,

Well for starters, I just measured the toe using the wooden-stick gauge I had made up for the TC a few years ago. It's a little more difficult to use on the B tho' because the tires are not nearly as exposed!

Anyway, I've got 1/2-inch toe out!

There is a bit of play in the U-joint, but not enough to account for all of the slop in the steering wheel. I need to wait for a helper, but the "sound" seems to come from right front. Maybe the ball joint.

Haven't counted tie rod threads or anything yet. I suspect that when it's all balanced out with correct toe-in, the steering wheel will be centered again (I forgot to mention, it points to the right a bit while driving).

Cheers,
Greg
Greg Van Hook

Toe will have no effect on steering slop, just tyre wear.

If you take the car to the right alignment place they will centre the steering wheel and hold it there with a clamp, then adjust the track-rods both sides to get the front wheels aligned with the rears as well as with the correct toe. That is if the chassis is straight and the rear wheels are following the fronts!
Paul Hunt 2010

Don't forget that the rack has an adjustable damper. However, if you tighten it up (by removing a shim) make sure that it doesn't bind when the steering is not in the straight ahead position. Check the wheel balance first though - that's the most likely culprit for shake at 60mph. I once had a tyre that developed a slight flat spot - it was fine on the rear, but if I put it on the front it caused a bad shake.
Miles Banister

Geez, I had the fronts balanced when I got the car 4 months ago. I'm starting to think the guy didn't do a very good job.....
Greg Van Hook

Greg: I had similar issues with my 1979 MGB.

A few items:

Play in the steering rack which was inner tie rod ends requiring tightening followed by a wheel alignment.

Rebushed front end.

Universal joints both front and rear replaced.

Wheel balancing. It was discovered my two of the Rostyle wheels are "out of true" That condition creates a "wobble shake" after 65 mph. Still need to relace the wheels.

Steering is now tight and precise, droneing noise has subsided.

cheers

Gary
79MGB
gary hansen

Hi Gary, You mean A-arm bushings? That's on my to-do list.

Thanks,
Greg
Greg Van Hook

Yes. Sorry I was not clear.

cheers

Gary
79 mgb
gary hansen

"I'm starting to think the guy didn't do a very good job"

Quite possible. For years I was plagued with wheel wobble between 65 and 85, that no amount of rebalancing, new tyres, swapping wheels front to back cured it. Then I found a place that mounted the wheels by the stud holes and bliss, no more wobble. However one of the wheels had a massive weight on the inside, which eventually fell off, and I was gobsmacked to find still no wobble, and I tried believe me. Got those tyres replaced recently but asked them to check the balance first and they came back with 10gms under on one wheel and 150gms under on the wheel that had lost the weight. Why this didn't cause a problem I have no idea. The new tyres were balanced on the centre holes and so far are fine.
Paul Hunt 2010

This thread was discussed between 27/05/2010 and 29/05/2010

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