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Re: 3-Rail Gearbox Rebuild -- What Do I Need?

To: Adam Rodnitzky <arodnitzky@yahoo.com>
Subject: Re: 3-Rail Gearbox Rebuild -- What Do I Need?
From: doug@dougbraun.com
Date: Thu, 12 Feb 2004 20:46:43 -0500
First, I would at least inspect it before starting to rebuild it.  Make sure it 
is necessary.
There is a finite risk of damaging, losing, or otherwise ruining part or all of 
the gearbox during a rebuild.

You would probably need new synchros, a rear oil seal, and at least the input 
shaft ball bearing.
Needles for the countershaft bearings are also a good thing to get.

You should definitely get TWO of the special snap rings that hold the stuff on 
the mainshaft.
NEVER re-use this snap ring!

And gaskets, of course.

But I think it is better to inspect and disassemble before ordering parts, 
otherwise you will
either have wasted money buying unnecessary stuff, or have to make a second 
order for more stuff.

Also, you may be able to mix and match parts from your old and new gearbox.

BTW, I find it very unlikely that adding GL-5 oil will suddenly cause both 
synchros to fail.
But if that is all that is wrong with the old gearbox, why not simply rebuild 
it instead of
getting and rebuilding a different one?  At least take it apart for a 
post-mortem and
for practice...

Doug Braun
'72 Spit



At 04:05 PM 2/12/2004 -0800, you wrote:
>Hi Everyone,
>
>Well, first things first...I think I found out why
>both 2nd and 3rd gear synchros went at the same time
>on my gearbox. When I replaced my clutch, I refilled
>my gearbox with GL5-rated oil...and as I've found out,
>that will deteriorate the brass and bronze in these
>old Triumph gearboxes fairly quickly. 
>I've purchased a good used 3-rail 4-synchro gearbox
>from a '71 Spitfire MkIV. As a matter of course, I've
>decided to rebuild it before I drop it in my '70 Mk3.
>I haven't received it yet, so I don't know if it needs
>anything beyond ordinary service items for the
>rebuild. Is there a standard list of items one would
>buy before embarking on a rebuild?
>
>Thanks!
>
>Adam





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