Re: TR6 overdrive.

[John Duhart <duhart@symbol.com>]

Hey All,

 Ya know, I've seen a lot of people asking this question, and I was thinking 
about it this week, and I came to a potentially interesting conclusion...   The 
OD CANNOT engage in reverse, unless you are driving at speed!

 Let me explain. (Please rememer I have a self-thought knowledge of the OD, so 
if you want to shoot this down feel free).  OK, the OD needs pressure from the 
pump to be engaged.  I've read that it needs about 400psi from the pump to 
function.  I have read that one of the reasons both the A and J-type OD's are 
locked out in 1st gear is because the pump cannot produce that kind of 
pressure.  If this is true, then it should also not be possible to build up 
400psi of pressure while drving in reverse out of your driveway, so the OD will 
not engage.

 Now I can think of two possiblities were you could get the OD to engage in 
reverse.

1) You drive in reverse for about a mile doing around 30-40mph.  This may build 
up enough pressure

2) While driving down the highway you decide to through it into reverse to see 
what will happen, and forget to shut-off the OD.  (Of course your OD exploding 
will be the least of your problems!)

 Anyway I think this is why we have seen people reporting they have driven in 
reverse with the OD on without destroying it.  These people were only do a 
short drive (i.e. out of the driveway), and at a very low speed, so the OD pump 
couldn't build up pressure to 400psi, and so the OD WAS NOT engaged.

 What does everyone the.

 (Yes another complex problem solved in the shower!)

Later,
JHD IV

>>> Bollen <bollen@ibm.net> 05/16 7:42 PM >>>

Today I tried to reverse with the  O/D engaged. Luckily it does not seem
to have done any damage. (J type).Is there supposed to be any kind of
electrical lockout when reverse is engaged? I never did this before,
wondering if a wire has come off somewhere.
Stu
74 Tr6 80 TR8