Lawrie, PaulH, and all,
As I mentioned in my emails, there is definitely no power going to the LH
overdrive (except for the reverse light switch circuit). When I first
encountered what felt like the overdrive engaging/disengaging, I unplugged
the wire to the OD from the yellow wire near the circuit box just to see if
the problem was electrical. This wire is actually just a 14 gauge wire I
have running to the cut out switch from the yellow. This was my own wiring
that I had used when I put the OD in my non-OD 71 BGT many years ago. I
taped off the wire and I have confirmed there is no way that the OD can be
getting power. Yet, since then, I have had the overdrive
engaging/disengaging on de-acceleration occur twice and have noticed
slippage in reverse twice, over a span of a month or so.
Now I also mentioned seeing a reference to the same problem in the archives
from a year or two ago. So I tried to find it again to email that person to
see what he did or found. But the archives don't seem to be working - a
search of "overdrive" and "reverse" only seemed to bring up my most recent
post. So then I went to google....
To make a long story short, I found a post that referenced a description of
the problem in "the manual." So I dug out my Bentley manual and confirmed
the description referenced in the post -
>SLIP IN REVERSE OR FREE WHEEL ON OVER-RUN
>Worn or glazed clutch lining
>Broken circlip on sun wheel
Well that sounds like it may be my problem. The sad thing is I seldom use
overdrive since I don't get out on the highway much these days. But I used
it heavily in the past when I had a 52 mile commute to work, one way. As I
mentioned before, I just had this transmission overhauled a few years ago
and have only put a few thousand miles on it since then. Which means either
the shop did not recognize the clutch lining wear or it is just a "shit
happens" kind of thing - assuming the book description of the problem is
correct. So I think I should either ship it out to a specialist for repair
or take it over to John Twist's seminar in February and learn how to fix it
myself.
Either way, my inclination would be to pull it out and put in a regular
working transmission for now. Does anyone have a good working non-OD
transmission they would sell cheap that I can use as a temporary (4-6
months or so) replacement? Its something that would likely have to be
shipped since I'd be surprised if there was one in or near Montana.
David Councill
67 BGT
72 B
At 07:07 AM 10/17/2004 -0700, Lawrie Alexander wrote:
>David,
>
>The "loss of reverse gear" has, I believe, revealed the real problem you are
>having. Your lockout switch is failing, meaning that sometimes power is
>still going to your overdrive even when the switches are all in a position
>where no power should be available. Since an overdrive unit cannot function
>in reverse (the one-way clutch makes this impossible), your car's inability
>to move in reverse tells me the overdrive was still engaged. After all,
>logic indicates that the reverse gears themselves don't disappear then
>reappear!
>
>So, replace the lockout switch on the gearbox with a new one and I believe
>your problems will go away. If that doesn't fix it, keep checking the wiring
>to the overdrive unit until you find where power still exists after things
>are supposed to be switched off.
>
>Lawrie
>British Sportscar Center
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