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[TR] Need help sourcing special gearbox to engine alignment bolts

Subject: [TR] Need help sourcing special gearbox to engine alignment bolts
From: TR3driver at ca.rr.com (Randall)
Date: Fri, 30 Mar 2018 18:39:39 -0700
References: <CANLCLaFFia1m2s-qT_Yw=7j5K84mdyzr88mjZr=UvVZJrogkKQ@mail.gmail.com>
> The Stag has 2 special machined alignment bell housing bolts. I'm assuming
> the TR6 and other Triumph used similar.  Are these available anywhere?

I could not find any that I trusted when I was doing my Stag.  Rimmers had
them listed as being superceded to ordinary bolts.  And if memory serves, I
determined that the TR6 ones are different (as well as being NLA at that
time).  They have a different part number, and IIRC are slightly shorter
because they clamp to the TR6 engine rear plate, which is steel and thinner
than the Stag's aluminum flywheel housing.

Many TR6 builders have used ordinary dowels instead (which is also what the
earlier TRs used in those same holes).  But I know that flange is a bit of a
weak area (and in fact was broken on my Stag), and I felt that Triumph
probably had a valid reason for using "dowel bolts" instead of ordinary
dowels.

So what I did was to buy some precision drill rod (in annealed condition),
cut to length, and thread both ends for nuts.  I didn't bother hardening it,
since my feeling was that it was strong enough in the annealed state.
https://www.mcmaster.com/?m=true#8893k239/=1c79urh

Probably best to use a new die to cut the threads.  My old die had a really
hard time of it.

BTW, there is no shoulder involved.  The special bolts just have a precision
ground .3750" shank with an extra long grip length (so it goes through both
flanges).  

-- Randall 
56 TR3 TS13571L once and future daily driver
71 Stag LE1473 - awaiting engine rebuild
71-2-3 Stag - awaiting gearbox rebuild


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