[Healeys] Transmission / Overdrive or Clutch slippage

Rafael Abugattas rafaelabugattas at yahoo.es
Thu May 20 15:41:56 MDT 2021

Hi all,

Last year I requestedyour help regarding a strange overdrive or slippage problem I have in my 1962Tricarb BT7. 

I received veryvaluable comments and suggestions but sadly the problem persists: Overdrivewould not activate under any circumstances and when the engine / transmissionis warm and we engage reverse, the engine revs but the car won´t move. 

There is slippagesomewhere in the transmission / clutch or overdrive. When the car is cold,reverse engages without any issues. This only happens in reverse gear after thecar has been driven a few miles and the engine and transmission are warm.Forward gears engage all the time without any issues.

The car has beenrecently restored. Before the restoration the overdrive was operational. Nowit’s not. 

The transmission andoverdrive have been taken apart and assembled twice looking for somethingvisually wrong. Everything seemed to be OK.

The clutch and platewere also removed for inspection. The clutch was recently redone, adjusted andtested.

A friend suggested weshould verify the oil pressure on the overdrive. On this link you will find acouple of videos of a test we have recently done with a manometer installed onthe overdrive to check the oil pressure at different RPM´s. 


The pressure on 3rd and 4th gears goes upto 400 psi and drops as it goes to lower gears. At idle is between 150 to 200psi

In forward gears thecar runs fine; the problem that we need to solve is that the overdrive would notactivate(even though it is connected and everything seems visually OK) and theslippage we have when engaging reverse (the car won´t move) when the engine /transmission is warm.

We are located inLima – Peru and as you may imagine, there are not many experts in thisparticular area of expertise.

Any thoughts or suggestionsfrom you collective knowledge and wisdom on how to proceed will be muchappreciated. 

Thanks in advance!



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