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Re: 75 electronic overdrive schematic

To: "6 pack list" <6pack@autox.team.net>
Subject: Re: 75 electronic overdrive schematic
From: "jhaeg" <haeg1@mninter.net>
Date: Sat, 1 Nov 2003 22:51:07 -0600
Greg, Gary and Jim,
Thanks for the replies.

Jim,
You are correct, the relay that I believed was the overdrive relay is really
the starter relay. All the wire colors match that relay, and line up with
Dan's manual.
The Bentley manual shows a picture of the overdrive relay, and I thought it
mentioned these were for later models (the manuals out in the garage at this
time.).
I didn't see the starter relay in the schematic, and assumed the second
relay that wasn't for the horn was for the overdrive. I also assumed that
Triumph added the relay to the later cars to possibly eliminate switch
failures caused by switching on/off the inductive solenoid coil.

I owe Mr. Masters an apology, because it looks like his schematic is
correct, and he even has a small write up (with detailed overdrive
schematics) on page 99.

It turns out that the later overdrive circuit is the simpler design with two
series switches supplying power to a low current OD solenoid coil. The
earlier "A" type overdrives required a much more powerful pull in solenoid
requiring the relay, and a second lower current hold in solenoid. I should
be able to get a good idea what is going wrong tomorrow.

Greg,
I will check the plunger if it looks like the solenoid is the source of the
problem.
Note: My overdrive has always worked, but I would often experience a long
turn on/off delay. This delay gets longer as the car warmed up. I always
assumed that I needed a new solenoid, but made the decision to wait until a
failure was experienced.

I'll let you know what I find. Take care,

John H. in Minneapolis




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