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Hi, I'm hoping somebody can help me here. I have an overdrive unit on my 1961 3,8 manual MK2 which is leaking from the joint between the overdrive unit and gearbox. The cause seems to be that the two long studs at the top, which are part of a group of 8 (I think) studs and screws that join the gearbox and overdrive are too long. One of these studs is fouling the head of a bolt on the gearbox side and looks slightly bent.

Anyway, causes of the problem asside for a moment. The manual says that I'll have to take out the engine, gearbox and overdrive as a whole. Is this necessary or can it be taken out without going to these lengths? Am I likely to be able to fix this by simply replacing the gasket and sorting out the stud issue? The unit seems to work ok otherwise but should I replace it or get it looked at while its out. The reconditioned cost of an overdrive seem to be very high but then so is the time to remove the engine and gearbox. Any advice apreciated.

Hello 470HW,

it's worth slackening the nut on the long stud (used to pull the overdrive onto the gearbox when assembling) and seeing if it will screw further into the casing to clear the conflict with the bolt on the gearbox, failing that cut a small amount off the end of the stud. Then check the tightness of all the nuts on that flange. There is no real pressure at that joint. Also check the adapter plate at the rear of the gearbox (to which the overdrive is bolted) as it is easily crcked when fitting the overdrive to the gearnbox, using the two long jacking studs.

Alec

Thanks for the response Piman. I'm pretty sure after your comments that the plate is cracked. When we inspected it we checked the nuts which were loose but tightening them didn't help. We thought that the plate may have been cracked as we were doing it. Anyway, were going to try and get it out without removing the engine - anyone managed this? Also, anybody had to repair or replace this plate. Not sure without looking at the car again but is this likely to be a cracked gearbox casing?

Hello 470HW,

the plate just unbolts from the main gearbox casing, I would say it's very unlikely that the gearbox casing has cracked.
I can't help you with whether you can remove the overdrive by itself by undoing the gear box mounting and rear engine mounting, perhaps drop the club specialist an e-mail to ask his view?
Refitting the overdrive can be tricky, it's not obvious but there are two splined sections in the overdrive and they must be lined up perfectly or the overdrive will not go back on. This is how the adapter plate gets cracked as people try and pull it on with jacking studs.

Alec