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Re: Overdrive Woes

To: "Robert M. Lang" <lang@ISIS.MIT.EDU>
Subject: Re: Overdrive Woes
From: "Brian S. Thomas" <thomasb@post.queensu.ca>
Date: Thu, 08 Apr 1999 08:16:56 -0400
Cc: triumphs@autox.team.net
Hi Bob:

I thing the "article" yo want is the one Brad Kahler provided a while ago.

His note follows.  Enjoy!

Brian

From: "Brad Kahler" <Brad.Kahler@141.com>
To: triumphs@autox.team.net
Date: Wed, 14 Oct 1998 11:21:22 -0500
Subject: Additional Results = OD - first use questions
CC: spitfires@autox.team.net


Listers,  

This write up was faxed to me by Carl Sereda who recieved it from someone 
else on the list.  I would like to thank both of them for providing the info.

I could be wrong but I would think that this same information would apply 
to the D-type and the J-type OD's as well.

Below is the write up reproduced exactly as it was sent to me.  Any typos  
were probably added by me however!!

=====

It is possible to "bench test" a transmission with an A-type overdrive and 
insure the overdrive mechanicals are functioning, before the unit is 
installed in the car.  I ALWAYS do this before installing an OD tranny.  It
is 
easy to do, and is much preferred to discovering a mechanical problem after 
the tranny is installed.

You'll need, of course, the assembled tranny with the overdrive; a 1/2" 
chuck drill (the higher RPM, the better); and a functional tachometer or 
speedometer with drive cable.

First fill the transmission with the recommended grade of oil.  By the way, 
the OD manufacturer Laycock recommends SAE 30 whilst the car manuals 
usually call for SAE 90!  I usually run SAE 50.  Chuck the 1/2" drill to the 
transmission input shaft.  Screw the tachometer/speedometer to a drive 
cable - any length will do - and screw the other end of the cable to the 
speedo drive on the tranny.  

With the tranny full of oil you're ready to test the overdrive.  First make 
sure the tranny IS NOT IN REVERSE!  Engage any of the forward gears 1 
thru 4 and turn the transmission with the drill.  There should be some kind 
of reading on the tach/speedo when this is done.  Note this reading.  Now 
with the drill turning the tranny over, engage the overdrive manually by 
rotating the operating lever clockwise.  This is the little lever mounted to 
the operating shaft, on the side opposite where the solenoid goes.  It will 
have a small hole in the end which when aligned with a similar hole in the 
side of the OD should engage the overdrive.  A 12% lower reading should 
result on the tach/speedo when the overdrive is engaged.

Actually I usually dispense with the gauge when performing this test, 
having found that in first gear it is easy to discern the change in the pitch 
of the whine the drill makes when the OD is engaged.  Since the reduction 
is a simple ratio, first gear gives the most change in RPM.

If you have a battery laying about you can use this setup to adjust the 
solenoid operating lever and make sure it actually works.  I have found a 
few instances when simply aligning the holes in the operating lever and OD 
block was not sufficient to engage the unit.  You can also wire up the 
inhibitor switches and insure they work too.


Brad  (Lincoln Nebraska 402-464-1502)

1964 Spitfire4           BFC25720L
1966 TR4A               CT72398L (Now a parts car)
1961 TR4                  CT288L (Now with OD!!)
1959 TR3                  TS41311L (Rusting Hulk)
1951 Dodge Truck    82217766  B-3-B-108 



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Brian S. Thomas                 e-mail: ThomasB@Post.QueensU.Ca
Y2K Project Manager             v-mail: 613-533-2228
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Queen's University                home: 613-542-8110
Kingston, Ontario CANADA K7L 3N6  toys: '54 TR2,'56 TR3,'67 TR4A,'80 TR8

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