Shims for Bishop Cam steering box top plate

[Duncan M]

It has been my understanding that the TC steering box top plate adjustment
was done with steel shims, the same shape as the top plate gasket. i.e. around
the edge of the cover. I recently received some Moss shims and they are plastic and paper. Who would have thought Moss would be so sloppy? Soon they will be selling the VW box.

[frenchblatter]

Duncan, is the answer ot your question "what were the original shims made of".

I suspect they would have been steel as other materials weren't widely used then. If so I would return them.

It isn't difficult to make your own steel shims if you have a template (not that much harder if you haven't). Invest in a set of hole punches and steel cutter, buy some shim steel and in a few hours you'll have what you need.

By the way, the holes look OK to me, made on a machine which presses the hole out rather than a hole punch which will cut it out.

[Duncan M]

The shims are supposed to be steel or brass. I think Moss would prefer you buy a Thompkins kit from them, so sell this junk for the original BC box.

[frenchblatter]

Duncan, all those years ago a Gemtleman by the name of Freddie Pragnal taught me never to turn the steering whilst stationary. It will break the steering box was his wise words. He was about 70 then (1961)

[Duncan M]

Norman-
Thanks-
I was taught that, too.

[Warmuthb]

Duncan M:
Interesting. Will you discuss in particular detail the problem(s) with the Thompkins Kit? The only thing I can see is the Thompkins kit uses a thin bearing and a screw-type end float adjustment for the sector adjustment instead of shims. What am I missing here? I sure don't want to destroy my BC box! So, again exactly what is the mechanism of the Thompkins kits destruction?

Brian W.

[Warmuthb]

Not to provoke controversy...but this is what Moss has to say about the Thompkins Kit:

"The basic function of the Tompkins steering kit is to provide an adjustable bearing surface for the upper
end of the steering box sector shaft. The original MG design was such that the ‘lever” of the sector shaft
slid or more accurately was dragged along the underneath of the top cover plate as the steering wheel
was turned. As the cover plate, sector shaft, and steering column worm gear wore, increasing amounts of
play would develop at the wheel. This necessitated the removal of one or more adjusting shims from
under the original top cover plate. The Tompkins kit eliminates this major source of friction and at the
same time makes adjustments for wear quick and easy."

Understand, I am neither for nor against a Thompkins kit at this point. If I can see how the use of one would wreck my steering box then out it comes and it's back to shims!
Regards,
Brian W.

[Duncan M]

That remark comes from reading ttypes.org/ttt2 a British t-type site. In the final installment of "the seven deadly sins" keeping it on the straight and narrow, aspects that effect TA/TB/TC steering, part 7. a link to the page follows. The first section of the article, before they go into the VW conversion goes into quite a bit of detail as to how the sector actually engages the worm, and although they do not mention names.... http://ttypes.org/ttt2/?s=seven+deadly+ ... mit=Search

[frenchblatter]

Duncan, I had to go to the locker behind the seat to retrieve the brake drum the previous owner put in there and found some gasket sets. There's a pack of steering box shims!

If you can't get any, shout and I'll do my box and send you the shims left over.

[Warmuthb]

I have a Thompkins kit installed and use a metal shim or gasket between the top plate and case... The end float is taken up by adjustment of the top sector screw in the straight ahead and centered position of the sector shaft.

Brian W.

[frenchblatter]

I've read a report that the Thompkins kit wrecks the cam and peg. I'll leave mine as is (after stripping and replacing any parts worn beyond repair). It only takes a few minutes to adjust with shims (if I remember from 50 years ago)

[Duncan M]

Thanks for the reply, Brian and Norman. I did find some brass shim stock that should work into some nice shims. I will not be using the garbage Moss shims.