MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - king pin end play

with all shims removed, there is still too much verticle play up and down on king pin. Manufacturing tolerances? Is there a part number for a thicker thrust washer? Bob C
chamberlain Bob

Bob, not come acros that problem before.... Are you sure the top housing is seated correctly? I have known this to cause trouble if it hangs up on the top flange of the king pin.

Just a thought...

Mark.
M T Boldry

Bob, are you sure all the shims are removed. Some of them are very thin and sit in the top trunion un-noticed have a scratch about in the recess with a scriber to make sure.

Ian
I Pickering

I've had a set of new kingpins wich where not usable due to a fabrication fault. The top end was not machined within spec and could not be shimmed to fit.
It was a few years ago, can't remember exactly wat was wrong, but it was easy to see comparing to the old ones.
Alex G Matla

Hi Bob, When you say to much play up and down do you mean to much play up and down of the stub axle on the king pin ? As you then go on to talk about finding a thicker thrust washer to fix it ? If that is the case then surely you should be fitting shims to reduce the play not visa versus. Or maybe I have just got the wrong end of the stick.
Ben Brown

After all this time it is possible that the top of the stubaxle, where the bearing surface is, has been resurfaced and the resulting gap for the bearing is too large. That would require another thicker bearing possibly having to machine one from oilite bar stock which is available through good bearing suppliers if a suitable standard one is not available.
David Billington

Aren't there sometimes little shims on the top of the king pin and larger shims behind the thrust washer. To decrease the up and down free play you remove the former and add the latter.

Guy
Guy Weller

Bob. Ben is correct. Shims are added to the assembly, selectively, to take out the up and down movement of the kingpin. If, with no shims installed, the kingpin can move up and down, it is working in the intended manner. If it was tight, the system would not work as designed. Take a look at the illustration in the factory workshop manual and read the set up procedure. You add shims, by thickness, to achieve the proper free rotation of the stub axle with no more than .002" of up and down movement. The addition of the shims raises the position of the trunion, causing the stub axle to be forced downwards onto the kingpin. This will remove the movement you are noticing when you assemble the kingpin to the stub axle without the shim pack.

Les
Les Bengtson

Les and Ben are incorrect, I'm afraid.

With Spridgets, shims need to be removed to reduce play. With MGBs, the shims go behind the thrust washer, so they are added to reduce play.
Dave O'Neill 2

I'll take another look in the top trunion for thoses little fellows, Bob C
chamberlain Bob

Dave, pretty sure that mine has both types of shims - 'though whether that is how it should be I wouldn't know.

Guy
Guy Weller

From the factory, they had the small shim between the kingpin and the trunnion. It's possible that someone could have added shims to the thrust washer at some point in the last 40 years ;o)
Dave O'Neill 2

Dave,
Yes, you could well be right. My 1971 car has had 16 previous owners - and I have owned it since 1990!
Guy Weller

I've certainly had a midget with Shims behind the thrust washer before :-) and also on top of the kingpin as well come to think of it. But Dave is right looks like this is not standard. Maybe MGB shims will fit behind the thrust washer and provide you with a cheap and easy fix.
Ben Brown

Dave. Thank you for adding to my education. I would have thought that the B and the Sprite/Midget used the same system. It would seem that the Sprite/Midget used the earlier system similar to the MGA? Sorry to add to the confusion.

Les
Les Bengtson

Spridget uses little shims on top of the swivel pin, under the trunnion, and a single thickness Oilite thrust washer. Take shims out to tighten.

MGB use a single thickness Oilite TW and two steel mating TW - one each above and below the Oilite, which come in a bunch of sizes. Make that did come in a bunch of sizes, lately you are lucky to get two different sizes, but you get a bunch of each! Idea is that you pick two washers of thicknesses that give you the right clearance. Thicker steel washers tighten.

Shims under the TW on Spridget, or on the swivel pin shoulder on MGB are bodges.

MGA has no TW at all, since the swivel pins have threaded bearings in the links/trunnions.

FRM
Fletcher R Millmore

This thread was discussed between 14/03/2010 and 16/03/2010

MG Midget and Sprite Technical index

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