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RE: Transmission rebuild

To: "'gbaker@customcpu.com'" <gbaker@customcpu.com>, mgs@Autox.Team.Net
Subject: RE: Transmission rebuild
From: "Unger, Larry G" <larry.g.unger@lmco.com>
Date: Sun, 25 Oct 1998 19:25:12 -0500
> I'm doing my first transmission ever (imagine that at my age) and
> have a couple  of questions.  It's apart and so far I haven't had
> any great problems but that's probably because I've put them off
> till now.  My veh is a 1956 MGA, not chasis # but engine
> #BP15G-1444.

Hmmm ... BP15GB-1444 ... a *very* early one eh? ... cool!  What is
your gearbox number? ... stamped adjacent to the dipstick.  Check
to see if a casting date is stamped on the flange that the slave
cylinder bolts to.

First ... go to Bareny's *most excellent* web site and read his
treatise on tranny rebuilds ... it will answer alot of your
questions. http://www.ntsource.com/~barneymg/mgtech/gearbox/gt1.htm

> 1.  I've got no spacer tube on my 1st/2nd shaft (Moss 3461-140).  

Hmmm ... best I can tell the distance piece was added in
conjunction with changes in the front cover, forks and selectors
from (G)A290 ... IOW, up to (G)A289 the distance piece was not
fitted.

Unfortunately, I've only got the Service Parts List for the 1600
Series, but I doubt the 1500 series would provide any additonal
info ... just gearbox numbers.  My WAG is that the change occured
at engine number 7981 (July 56), but its just a WAG ... can't find
enough info to confirm or dispute it.  I've never found any
rational to the gearbox numbering scheme.

> 2.  I've got no shim (Moss #461-280) on the input shaft.

The shims are are fitted "as required" to adjust the clearance
between the front cover and the bearing (see Barney's treatise) ...
its possible that your cover didn't require a shim, but I've always
found at least one.

> Could these be a later or unnecessary modifications or has
> someone been there before me.

Uncertain ...

> 3.  How do you suggest one removes the circlips holding the
>     needle bearings in the laygears and once they are out can
>     they be replaced with newer encased bearings I've read about?

A real PITA ... I defer to Barney ... certain the he as a better
approach. 

> 4.  All my gears look pretty good.......to me..........but maybe
>     I'm missing what to look for.  The reverse gear does have
>     some very small "lipping" on the gears but I think I'll just
>     dress them.  Other than the minor wear on reverse the only
>     real wear is on the Baulk(Synchro) rings, the bushings and
>     the layshaft.

Barney's description of gear wear is excellent ... IMHO, you might
find some wear, but if the teeth on the first and reverse gears
(and where they engage the layshaft) aren't chipped then your "good
ta go".  

> 5.  I am in a quandry as to the Forks because I don't know what
>     to look for.  I suspect they're worn but I don't know what
>     warrants replacement.

Probably OK ... again, see Barney's page ... excellent description.

> 6.  Has anyone modified their 3rd/4th selector shaft by deepening
>     the detent so as to prevent jumping out of 3rd gear.

Nope ... I've been playing with late model trannies that include
the mods.

> 7.  I don't see a lot of wear on the thrust washers but plan on
>     mikeing them.  Is there anything to look for with these?  I
>     notice Moss sells three different sizes.

Nothing special to look for ... just that they provide the proper
clearance.  Moss lists a whole bunch of sizes, but many are NLA
... less they have gotten some back in stock recently.

> I plan on renewing baulk rings, layshaft, springs, needle
> bearings(four sets), bushings(3), gaskets, roller bearings,
> seals, and possibly thrust washers.  Any other thought?

Bushings, roller bearings, and thrust washers might be excessive,
but its really your call ... certainly wouldn't hurt.

Hope this helps ... 

**********************************************************
Safety Fast! ... larry.g.unger@lmco.com
'61 MGA 1600 MkII 

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