[Fot] J type overdrive pump

[Steve Yott]

Larry,
Sounds like a very destructive occurrence!

I have had a number of "J" Types fail to develop pressure over the years and
about 90% of the time the problem is a bad seal on the one way valve from
the pump also called the non-return valve.  These can look good by the eye
but under a magnifying glass I have found many to be scored and the old
"seat" the ball trick just doesn't work.  I made a tool from brass stock
that is angled to fit the valve seat and has a small pilot that fits in the
hole.  I run this on the mill with "Clover" compound and polish in a new
seat for the ball.  Since I have had this happen so many times now I have
made this a standard practice on the overhauls I do.  

This is not a large an issue with the "A" types and I think that the pump
body may be a bit harder in the "A" and not tend to score as much.  I
recently had a goofy "A" that would not produce pressure and it drove me
crazy until I realized that at one time the seat in the pump body had been
reworked and was too deep so that as the pump plunger came down it would
just touch the ball and release all the pressure it had developed.

Check out the non-return valve on the "J"!


Steve Yott
Silver Lake Triumph Centre

-----Original Message-----
From: Fot [mailto:fot-bounces at autox.team.net] On Behalf Of Larry Young
Sent: Thursday, May 22, 2014 5:28 PM
To: FOT; Triumph
Cc: Mike Piggot (new)
Subject: [Fot] J type overdrive pump

I'm helping a friend with a J type overdrive in a TR6.  The old one suffered
a broken transmission output shaft inside the overdrive. It was trashed so
we are using a Volvo unit that I happened to have.  I tore it down part way,
but it was so clean I didn't take it all the way.  We replaced most of the
rubber o-rings, rebuilt the tranny with a new output shaft and put it on my
test stand. The solenoid clicks when 12v is applied, but it does not develop
pressure.  I am much more familiar with the A type than the J type, so I
need help.  I took the pressure gauge off and when I spin the overrdrive  it
first spit a few bubbles and then oil came out very slowly.  It is my
understanding that it should always pump whether overdrive is engaged or
not, so I believe this confirms the pump is not pumping.  We have tried
packing the pump with vaseline, a trick that has worked in the past, but
that has had no effect.  Can anyone suggest how I should proceed to get this
thing going?
Thanks,
Larry Young
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