[TR] ZS 175 piston issue

Randall TR3driver at ca.rr.com
Wed Oct 24 09:36:00 MDT 2018

> I 
> don't know how far into the screw the plunger goes so I don't 
> know how much there is for the drill to catch, so any been 
> there and done that suggestions would be welcome. 

I wouldn't worry about it, just go ahead and drill into the inner cavity.
Open it up with slightly larger and larger bits until you can knock the
spring & plunger out, then keep going until the screw falls apart.  Then
clean the threads with a dental pick, and a suitable tap.

I don't recall the thread size offhand, but I assume that by 1976, they
weren't BA threads.  As long as they are metric or SAE, you should be able
to buy a heli-coil kit (to repair the threads if the above method doesn't
work out).

Worst case, contact the usual suspects (eg Marv Gruber)  for a used piston

-- 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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