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I've been cleaning out and selling off some of the GMH service tools that I have accumulated. In the box of "I bought it but don't know what it is" tools is a short reamer. I suspect it is a rocker stud reamer to suit red motor. When the push-in studs got sloppy, GMH supplied them in both 3-thou and 13-thou oversize. To fit, the appropriate reamer was used to open the hole, the stud lubricated with gear oil then press-fitted in.

The reamer I've got is not labelled, but I figure I can run the vernier over it. Problem is, I can't find the spec for the original, 3-thou or 13-thou over studs. Anyone know what the studs diameters were?

It's probably a redundant process... most of the time now you would tap the boss and fit screw-in studs. It irks me though that I've got a neat tool that I don't know.

Cheers,
Harv

Considering that the rocker studs are 3/8" UNF, and judging on the amount of effort it took to remove and replace a bent one, I'd be inclined to say that the diameter of a standard size rocker stud would be 0.3755" - 0.376".

Rob

Any chance that a standard rocker stud is 0.372"? The ream measures as 0.375", so could be the 3-thou over version.

The alternative is that it could be for the 4-banger early Torries. They had reams in 6-thou and 12-thou oversize, though again I don't know the base size. Less likely though... the tools in the batch I bought many years ago had lots of grey and red tools, though not much for the early Toranas.

Cheers,
Harv

It's entirely possible that the rocker stud would be 0.372" diameter. The major diameter of the thread is less than the nominal size, so why not?

Rob

I would assume the threads would be rolled not cut so it stands to reason the O.D. of the thread would be larger than the O.D. of the stud ?