Overdrive Fault

[garyf]

I've had issue on my TR With the Overdrive slipping when hot (Standard 'A' Type)

I was informed of this fault by the previous owner who told me he had adjusted the operating lever and cleaned everything inside the unit as per the WSM, he'd also fitted a new Solenoid and changed the Oil twice but still the problem persisted, he was advised by an Overdrive specialist that the cone clutches may be worn and the unit needs a recon.

However, whilst travelling home on Drive it day the over-drive worked all the way home with no slipping

The Over-drive always worked correctly when cold, but normally after 15-20 Miles or so it would start to slip and disengage completely with any throttle (It engaged correctly when free wheeling but as soon as power was applied would slip out?), however on the journey home on Sunday, around 35 Miles it worked all the way back even on hard acceleration?

Any ideas?  

[RobPearce]

Quoted from garyf

The Over-drive always worked correctly when cold, but normally after 15-20 Miles or so it would start to slip and disengage completely with any throttle

I had those symptoms on a D-type (GT6) and was unable to fix it. However, my conclusion was that the problem was a worn casing around the operating valve shuttle, resulting in poor oil pressure when hot. My instinct is that poor oil pressure is more likely to explain such symptoms than a worn cone clutch, as the latter should be just as bad when cold.

So the question is why your oil pressure has been poor and why it stayed good on Sunday.

[garyf]

Quoted from RobPearce

I had those symptoms on a D-type (GT6) and was unable to fix it. However, my conclusion was that the problem was a worn casing around the operating valve shuttle, resulting in poor oil pressure when hot. My instinct is that poor oil pressure is more likely to explain such symptoms than a worn cone clutch, as the latter should be just as bad when cold.

So the question is why your oil pressure has been poor and why it stayed good on Sunday.

Rob

What your saying makes sense, the Oil Pressure will be higher with cold oil.

I think I need to take the gearbox cover off and attach an oil pressure guage that reads up to 600 PSI and go for a good run (A mate I know has got a suitable guage and connection pipe)

What Oil Pressure reading should I get when Hot with a good condition 'A' Type Overdrive, I should imagine around the 450 PSI Mark?

Another suggestion I've been given is that some sort of Additive may have been added to the Gearbox oil in the past, but surely the overdrive would slip all the time if this where the case?