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MG MGB Technical - Bent Wishbone?

I hit something on a recent rally and lost self centering. Also the track rod end rubber grease cup was rubbing the wheel. Something had moved!

It was deemed safe to continue by the mechanical support and when I got home I replaced the steering arm as recommended and had the tracking done - all seemed OK.

Further investigation and another set of eyes identified the lever arm damper was not lined up as it should be, the line in the casing and the line where the arms meet were not in line.

I took it apart this morning. I had to undo the pinch bolt to get it off the king pin and as I loosened it the arms moved apart! Once I had managed to get the arms off the top of the king pin they moved to where they wanted to be - well out of line with he king pin as shown in the att photo but back in line with the casing.

All I can think of now is one or more of the A Arms has bent? Does it need a new spring seat as well - plus of course bushes etc etc..... Could it be anything else?



Mike Dixon

Does sound like A-arms, the wheel hitting a solid object is more likely to bend those than move the damper. If they have bent it's quite possible it has buckled the spring pan.

Hopefully not the king-pin, does it stay in the same place as the wheels are moved lock to lock? You will have to rig up some support other than the damper arms. Or check relativity to the damper arms on both locks as in your image.

It's possible the damper has been damaged, a new oil leak should reveal that. You usually do have to wedge the damper arms apart in order to get them over the trunnion bush, especially a new one, even if that has been fitted with a through-bolt and large washers to press each half into the arms.

If you can afford to have the car off the road for a bit I'd take the arms and pan off and check dimensions and alignment to a straight edge.

Taking the arms off either get new lower trunnion thrust washers, they wear and can clonk under braking. Or just turn them round as they only wear on one side!
paulh4

Thanks. The king pin does not move lock to lock relative to the damper and I cannot see any obvious damage to the wishbone pivot or subframe so A arms are looking favourite?

I will get the A arms off next, and as I have gone this far I will probably re-bush both sides with mild poly bushes. Are negative camber arms a good idea if I am swapping them out anyway?
Mike Dixon

Mike,
Back in the day I had a coming together with another car in in very narrow Devon Lane - he couldn’t slow quickly and my wire wheel spinner rather opened up his cill !
This was a midget and both the steering arm and shock absorber arm were bent.
I know B’s are double arms but the metal is quite malleable so worth checking / replacing to see.
richard b

No experience of -ve camber arms, seems a trade-off between increased wear on the inner edge with touring use and sharper turn in/better cornering grip with competition use.
paulh4

The kingpin doesn't rotate, so unlikely to move when turning the steering.

If you take off both A-arms and compare them to each other, side by side, you should be able to see any difference. If they are both bent, they should be bent in opposite directions.

There is also a possibility that the A-arm pivot has been bent.
Dave O'Neill 2

The front A arm is bent, it rocks on a sheet of glass, there is 2 - 3mm clearance under part of it where there should be none. Worth changing the spring pan at the same time? I cannot see any damage but it must have moved a bit?

There do not appear to be any thrust washers on the nearside so I will order a set as well as new bushes. The seals look remarkable good!

If all of that fails I will look at replacing the pivot, it looks OK but might not be!
Mike Dixon

The pivot shaft that bolts to the cross member is prone to bending with impact--If you take it off and give it a spin you'll soon see if it's not straight- It's only four bolts at this stage so worth checking-
There are some below average polly bushes about , I'd be tempted to go for the tried and proven V8 one piece bushes.
Neg. camber arms are the go--do it. and run with just a tiddle of toe in , like 1/16" overall (1/32"each side)
William Revit

I agree, take off the pivot and check it properly. In my experience the pivot bends before the arms, so if the arms are bent it is odds-on that the pivot is.
Paul Walbran

I did it all yesterday - arms and pan changed and the king pin lined up fine with the shock - job done?.......

All bolted back up back up and no change to the position of the the TRE relative to the wheel - see pictures of both sides

I missed the advice about the pivot shaft, I will take that off next week, getting faster at this, .... and see how that looks.

I suspect I will get away with just knocking out the bottom trunnion pin and removing the arms - no need to remove the brake calipers etc or even split the TRE? Might even get away with leaving the ARB attached at the top?









Mike Dixon

Yes, just remove the trunnion pin and let the rest hang there off the top trunnion.
Best to leave the arb link attached at the bottom and release it from the top, otherwise the arm might lose its alignment with the spring pan with the spring load on the latter.
Paul Walbran

All done - I released the top of the ARB, and the whole removal did not take long. The pivot shaft is off and looks OK to me. I will take take to someone in the know for a second opinion

All that is left after this is the hub/king pin assembly or the cross member. We are only talking a couple of mm so its difficult to measure?


Mike Dixon

When you say "couple of mm" do you think you have something out of line?

Have you driven it since correcting the king-pin to damper alignment? Has the wheel angle driving in a straight line changed?

You could check the tracking, and see if it pulls to one side on a flat (no camber) level surface. Trakrite first one side then the other will probably show up any difference between sides.
paulh4

The tracking is OK and the car drives fine. Self centering seems OK.

The couple of mm I refer to is the distance between the track rod end grease rubber and the wheel, see the photos att to 30 Jul post; RH side is fine, its the LH side that is borderline on the wheel rim

All I am really bothered about is it safe ie would it pass an MOT - if the TRE rubber is contacting the wheel probably not? I will consult with my MOT tester when he get back from his hols but ideally I would like to move it away from the rim and remove all possible doubt.

A second set of eyes on the pivot shaft agree it looks OK. We made up a 3mm shim and I put the shaft back on with that at the rear with view to raising the TRE up into a wider part of the wheel - it made no difference to the TRE position wrt to the wheel rim.

I have measured the distance of the TRE from the ground and both L&R sides are the same ). So changing the angle of the hub/king pin will probably not make any difference?

I bought a Moss TRE, allegedly smaller for alloys, but the body is identical size to the standard MGOC one I have fitted, so not all lot of point in fitting that unless the compressed rubber cover is smaller which is unlikely.

Bit lost for what it might be now to be honest, Any point in measuring front to rear wheel distances and compare side to side?

Thank you all for your continued patience and thoughts!





Mike Dixon

If tracking, driving and self-centring are all OK I doubt comparing front to backs would reveal anything, rear axle alignment (with the original leaf springs at least) is a bit sketchy. I had the main leaf on a rear spring break and the car drove fine except that the steering wheel had turned about 10-15 degrees when travelling in a straight line.

The wheel, hub, king-pin and steering arm are an assembly with the only variable being wheel bearing end-float so I don't think changing king-pin angle would do anything. What would increase the clearance is shimming between wheel and hub, like a wheel spacer but thinner. You would have to do both sides though as one side only would change the geometry a bit. If both old and new steering arms show the same clearance then it's probably just down to tolerances in the king-pin and hub assembly, I doubt they were precision machined when new.

As long as there _is_ clearance it shouldn't fail an MOT, but the angle of the first pic doesn't show any. However if there are signs of rubbing on the rubber from before you changed the A-arms they may not like that.



paulh4

That was my though it is all one assembly so I have fitted the smallest dust cover I can find- the Moss one was smaller - and that just clears the rim.

All a bit of a mystery but sorted albeit by a workround?

Thank you all for your help
Mike Dixon

If the stub axle or steering arm go bent that would change the position of the wheel relative to TRE.
Twist in the steering arm happens as well as a sideways tweak.
If the clearance has changed something has deformed somewhere so it is best to try and find why in case something cracked.
Paul Walbran

Thanks first thing I changed was the steering arm, all that is left is the stub axle assmembly?
Mike Dixon

It would be worth checking.
Grip the stub in a lathe then rotate by hand to check the upright face with a dial gauge.
Paul Walbran

See Mike's post 27th July.

As far as I can see the gap Mike is talking about is between the TRE (which is attached to the steering arm that is attached to the swivel axle body) and the wheel (which is bolted to the hub which via the bearings is on the spindle which is also attached to the swivel axle body) so as such I can't see how the king-pin could affect that gap.

It could well affect the orientation of the whole wheel, swivel axle steering arm and TRE assembly to damper and A-arms as happened at the outset, but A-arm replacement seems to have corrected that. Only if Mike knew that the TRE to wheel gaps were the same both sides _before_ hitting whatever he hit can it be said that that impact has caused the gap to change.

Some distortion in the swivel axle including spindle is the only thing that I can see, or indeed the wheel, but if the gap is constant as the wheel is rotated it's unlikely to be that. Easily confirmed by swapping wheels over.
paulh4

Thanks Paul - you have summarised it well. To be honest I cannot remember what the gaps were prior to the bump. Post bump there was a very obvious new witness mark ( clean strip!) on the rim where the seal had been rubbing, so even if not even, both were clear of the rims prior to the bump I will try the wheel swapping on Monday.
Mike Dixon

This thread was discussed between 27/07/2026 and 14/08/2026

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