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Re: mgb overdrive

To: ramsmgb@cox.net
Subject: Re: mgb overdrive
From: Bob Howard <mgbob@juno.com>
Date: Sun, 28 Sep 2003 22:09:57 -0400
Hi Richard,
   You wrote 'nothing'.  Did you mean that the car won't drive in either
OD or Normal,  or that the OD won't engage?   If power won't go through
the gearbox/OD at all, chances are that it's a trashed OD clutch.  But
the good news is that it didn't suddenly croak---if it worked last week
without slipping it's going to work today. I suspect that the problem is
something simple and cheap. Let's hope so.
   Do you know that the solenoid is working?   While it's said that you
can hear it click when it shifts position, I have never been able to hear
mine. But listen anyway. If it clicks, it's working.   If you have to
remove it for inspection, don't pull on the black wire. Try pulling it
out with a magnet. If you can't get it to come out, leave it alone for a
while---it may drop out of its own accord.  
   When it is out, look for the ball bearing. Since it's in oil, it
should be as good as new, but inspect it anyway and replace if it does
not appear perfect.  
   When you had the filter off, did you touch the pump piston?  It will
fit in the bore in either of two directions relative to the offset of the
roller, but it will operate in only one of them.  If you may have turned
it, check the illustration in the manual to note which way the offset of
the roller should fit.  If it's reversed, the piston gets pushed and
sticks in the bore.  
   Is there enough oil in the gearbox?  Did you drive it around after
filling it, then check level again?  Low level can cause it to not
pressurise to the ~400 psi that the book specifies.  
   What oil is in the gearbox?  Engine oil 20-50 is OK, straight 30 is
recommended by many, but 90w gear oil can give erratic action.
Bob

On Sun, 28 Sep 2003 12:01:41 -0700 "Richard" <ramsmgb@cox.net> writes:
> Hi listers's:
>  
> I have a 1972 with an original Laycock overdrive and od gearbox. I 
> had the overdrive fail recently. It was working intermittently. I have
> replaced the isolation switch, all the o rings, sump filter, and the
> solenoid. It worked intermittently after I replaced the isolation
> switch, but now nothing. All the wiring checks hot down to the 
> solenoid with the ignition key on, the overdrive switch on, and the
gearbox 
> in 4th. 
> Any ideas?
> Rich in Tucson




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