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Re: 1275 Gearbox - Jumping out of 3rd

To: MG List <mgs@autox.team.net>
Subject: Re: 1275 Gearbox - Jumping out of 3rd
From: Rocky Frisco <rock@rocky-frisco.com>
Date: Mon, 10 Dec 2001 23:38:02 -0600
Bob Hamilton wrote:
> 
> Listers,
> 
>          I rebuilt this gearbox last winter to repair bad first and reverse
> gears. These gears now work fine but it now will frequently jump out of
> third while accelerating so to avoid damage, I only put 20 miles on it
> since the rebuild.
> 
>          The unit is once again on the bench and I have checked to ensure
> all the detent balls and springs are in the correct position for the 3/4
> shifting rod, which they are. My first thought is to replace the three
> detent springs with new ones to ensure maximum pressure on the balls.
> Nothing appears to be out of place.
> 
>          I would appreciate hearing from someone with experience in
> rebuilding this transmission who can perhaps suggest another reason for
> this happening.

Bob, this may be useless to you, but I do recall that when I raced
MGA's and Minis in the 60's, accepted wisdom was to have the
shifting shaft and knob be as light as possible. The problem was
jumping out of gear when we had a lot of acceleration (or sideforce
in a corner) and hit a bump of some sort. The MGs tended to pop out
in 3rd and the Minis in 2nd or 4th under high load. We noticed that
if we added some big supertrick chrome ball, the car would pop out
of gear much worse than before. I liked a big handle, so I had a
carpenter friend lathe me out some 1 3/4" and 2" balls out of nice
light pine. Since these would have too easily split, I talked a
friend at the research lab I worked at to make the teflon inserts
for the holes in the balls and drill and thread them for the shift
levers. At least one of them must be around here somewhere; that's
not the sort of thing I sell or lose or give away. I haven't seen
them in decades.

As I warned, this is really very much a side issue, but there did
seem to a tendency for the weight of the knob to adversely effect
these pop-outs. Undoubtedly, the problem exists elsewhere, but this
might help a bit.

-Rock  http://www.rocky-frisco.com
-- 
Red Dirt Rangers (Rocky on piano): http://www.reddirtrangers.com
JJ Cale Live (w/Rocky): http://www.rocky-frisco.com/calelive.htm
The Luggage Fan Club: http://groups.yahoo.com/group/luggage-fans

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