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MG Midget and Sprite Technical - Frogeye steering mounts shim?

When i pulled the steering apart i remember that there were a shim underneath one (or both) of the brackets can't remember if it were on both sides.

Now I can only find one shim so does that mean that it's only supposed to go on one side or have i lost one (as some parts seems to have grown legs).

If only one shim, on which side is it supposed to go? It's a LHD car.

Thanks
Alex
Alexander Sorby Wigstrom

Just one. Not sure which side it should go on, but logic would put it on the left on a LHD car so as to align to the steering wheel
Guy W

The logic is that the shim goes on the left on a LHD car, and on the right on a RHD car. The reason is that the steering rack pinion is closer to the centre line of the car, than is the centre of the steering wheel. The steering column is angled away from being parallel to the car centre line. So the steering rack needs to be slightly angled across the width of the car, and this means putting a packing shim between the bracket and the car cross member on the side nearest the pinion.

At least that is how I thought it through, and it seems to work out OK on my cars.
Guy W

On all of my RH drive cars the shim is always on the LH mount (as sitting in the drivers seat, so effectivly the passenger side). Remember the rack is from a morris minor which was wider and the steering wheel needs to be closer to the centre of the car due to the narrower width.
Mark Turner

The Moss catalogue puts it very neatly, "Passenger side mounting only". That works for both LHD and RHD cars.

This is opposite to Guy's analysis, and I think that is simply due to the position of the brackets, which are "behind" the rack rather than in front and so the shim pushes the driver's side of the rack forwards to allow the geometry to work.

Peter
Peter B

Not what I would have expected at all. In fact I have just been checking. The distances from the centre line of the car are 8.5" for the rack pinion, and 11.5" for the centre of the steering wheel. So If my theorising was correct then the shim would need to go between the chassis cross rail and the rack bracket next to the pinion in order to achieve the necessary rack and steering column alignment. If it is on the opposite side it would pull the steering column across towards the centre line of the car.

But, just realising(!doh!!!) - I was assuming that the pinion shaft is at right angle to the rack. It must have been originally engineered for the pinion shaft to operate obliquely across the rack rather than at 90 degrees, specifically to point the column outwards towards the driver's seat of the MM. And the Spridget seats being closer to the centre line then this adjustment needs to be brought back inboard by a bit. That explains it.

And Mark, now re-reading what you wrote I see that is exactly what you were getting at.

(Peter - brackets on my car bolt onto the cross member from the front - that wasn't the reason for my error of thinking!)
Guy W

Guy

Yes. Very interesting reasoning, but got there in the end.

I must now go out in the cold and wet to take a look at my rack mounting brackets!
Peter B

Alexander,

The shim is where the column is not. It is important to mount the bracket without any force. Otherwise the alu brackets will break. An other reason is that it will lead to a sticky steering wheel due to friction in the steering rack where the steering column goes in.
The right order is:
Mount the steering clamp bolt ( a special tough bolt!) straight and control it by turning the steering wheel while all te steering rack bolts and clamps are loose.
Align the steering rack after measuring the gap where shim should be (Photo). Your old shim could be to thick or thin...
Mount the steering rack clamp bolts

succes
Flip


Flip Brühl

Great, thanks guy's :-)
Alexander Sorby Wigstrom

Flip is spot on.

I re-shimmed my re-shelled car where the PO had obviously fitted the original shim and it wasn't just right. I used the method Flip describes and made a new shim from some ally.

It made the steering lighter but still didn't help the poor self centering the heritage shell seemed to have.
John Payne

John

Self centering is low at some of our cars. It can be improved by giving it more caster. I made the fulcrum pins myself (off centre) and put some washers between armstrong and trunnion link. Again to prevent premature wear: Mount everything without stress. That takes lots of time but I like to work on my car. It is never finished with this brand of car. I even have to renew the things I renewed less than 14 years ago.

Flip
Flip Brühl

I think with mine that the shell was a bit iffy. It was one of the early ones which are well known for being out in some areas. For example mine had slight negative camber on one side and lots of positive on the other which I had to correct with offset bushing.

It never drove as well steering wise as my other original cars and was one of the reasons I sold it.
John Payne

This thread was discussed between 05/11/2013 and 07/11/2013

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.