[Fot] A-Type Overdrive Dilemma

[fubog1]

 I would be looking for a bleed somewhere & check the pump, valves, etc, and try to get the pressure up a bit.
Is it a big or small piston A?
Does the accumulator hold "rest" pressure for some time?


Glen
 (w/1 n)

 

 

-----Original Message-----
From: Glenn Franco via Fot <fot at autox.team.net>
To: FOT list <fot at autox.team.net>
Sent: Wed, Aug 1, 2018 2:18 pm
Subject: [Fot] A-Type Overdrive Dilemma



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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