[Fot] TR4/6 Transmission, Catastrophic failure

[fubog1]

+1
I polish the bushes for clearance as well.
Glen

 

 

 

-----Original
Message-----
From: Jeff Durant <jeff_durant at comcast.net>
To: Scott Janzen
<sjanzen at me.com>
Cc: 'Friends of Triumph' Triumph <fot at autox.team.net>
Sent:
Tue, Nov 4, 2014 4:23 pm
Subject: Re: [Fot] TR4/6 Transmission, Catastrophic
failure


Scott,
Was the MS 2nd gear steel bush the stock "top hat" version or
the 2 piece
version (bush and thrust washer)? I ask because I've found the
steel bushing
and thrust washer offered as an upgrade for the earlier MS 2nd
gear have some
running clearance issues.  Specifically, the OD of the bush is
very tight when
fitted to MS 2nd gear in some cases.
I just built a CR TR box
using the 2 piece steel bush/washer arrangement from
Rimmer Bros. and had to
polish both the OD of the bush and ID of 2nd gear to
gain an acceptable level
of clearance for adequate lubrication.  The bush ID
to mainshaft was good
after minor deburring and polish. Had I not done so, I'm
certain it would have
seized resulting in a failure similar to what you have
experienced.
As a
general rule, I spend lots of time deburring and polishing the mainshaft,
bushes and all gears before final clean and assembly.  So far, no catastrophic
trans failures!  Now if I just had better syncros.

Regards,
Jeff Durant
TR4a/250/6 and #12 TR6

Sent from my iPhone

On Nov 4, 2014, at 10:28 AM,
Scott Janzen <sjanzen at me.com> wrote:

> I had a freshly rebuilt transmission
with mostly new parts, including a new
> close ratio gear set, fail
spectacularly after only a few laps of use.
Second
> gear "welded" itself onto
the mainshaft, with the result that the gearbox
was
> effectively in two gears
at the same time (car was under power in third
gear)
> and all of the teeth
were stripped off of the 2nd gear set.
>
> The gearbox was filled with fresh
Redline MTL (75-90)  - it was still
filled
> well above the side fill plug
when I took the top off the box.  What could
> cause this failure - chalk it
up to a defective bushing?  The bushing was
> steel (?), not the bronze
variety.
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