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Triumph TR3 - OD Shifting

A sidescreen TR with an OD transmission is good conditioning for a boxer to prepare for kidney punches. When the OD engages you know it! Here's a technique that was passed on to me by some local guys who also fear the repercutions of the slamming engagement of the OD. The process is, clutch in, gas off, OD switch on, clutch out. Anyone think of a reason we shouldn't be doing this? I use the OD pretty much as that, once I have obtained my desired speed, I engage the OD to reduce the RPM for slightly quieter cruising. Disengaging seems smooth enough that I just flick it off as desired. Interested in any comments, concerns and/or opinions on this.
Scot Stewart

Scot - You should - if you can - have a smoothly shifting OverDrive. Any time that there is a "jolt" in a mechanical system, you risk the chance that something will wear out prematurely or even break. In July, 2000 while at VTR in Portland, Oregon with my TR3A, I found that my OverDrive was very slow to engage. I had it rebuilt and then it worked fine. The pressure build-up was so good in fact, I was getting these mechanical jolts. While this tells you that you are getting fantastic oil pressure and your O/D is in super shape, by the time I had done 3500 miles getting home from the coast, (and only 7 miles from home) this "jolt" snapped two of the leaves in my rear RHS leaf-spring. The two inner ones had (un-knowing) fractured earlier and snapping into OverDrive caused the two remaining (the outer ones) to break. Other areas I'd be concerned about would be the "U" - joints in the drive shaft, etc.

See you at Stowe.

Don Elliott, 1958 TR3A, Original Owner
Don Elliott


I agree and it sounds like I may have to explore some adjusting with the solenoid lever to lessen the engagement time and rate at which the pressurized oil is supplied to the engagement pistons. In the mean time, I think I will stay with the clutch in engagement idea to remove the jolt. Does anybody else have any experience with OD adjustments to soften the engagement? I can't see anything other than tweaking the solenoid lever on the oil valve shaft.
Scot Stewart

Some of you might think this silly, but I get my smoothest change up, with my foot flat to the floor. Changing down doesn't seem to be a problem......John
John Strange

This thread was discussed between 05/09/2001 and 17/09/2001

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