[Fot] A-Type Overdrive Dilemma

[Glenn Franco]

Looking for some help from the wisdom of the FOT List.

I have rebuilt a number of Triumph A-type overdrive transmissions in the
last few months but have one that is giving me problems.

The overdrive functions OK when applied and will go into overdrive at a
steady cruising speed.

The problem is when under load accelerating up a hill or to pick up speed
it softly drops out. When you lift throttle it will go back in.

We put a 500 psi gauge on the operating valve thinking we were losing oil
pressure when it drops out of overdrive. Gauge reading shows a pretty
steady 340 psi reading. When it drops out the gauge doesn't drop out but
remains steady.

340 psi is lower than the expected 400 - 500psi. Does that indicate oil
pump replacement is necessary? The engine rpm was approximately 2500-3000
rpm.

Since it softly drops out of overdrive I'm thinking a slipping overrunning
clutch??

Any advice would be greatly appreciated.

Thanks in advance

Glenn Franco

74 TR6 , TR250, MG TC, BMW e10 2002
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