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What to look for in overdrive inspection.

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J

John_Progess

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I am starting the rebuild/inspection of my 64 BJ8 tranny. The odometer shows 76K miles (origional ?)and the engine was in very good condition with all standard fits. I have never been into an overdrive before and I would like to know what to look for, how much can I dissassemble without the special factory tools and what should I replace regardless. I have the shop manual and also a Haynes manual and have read both. I have never seen the car run so I don't know the past history of the tranny. The past owner said it functioned OK whatever that means. Thanks for your help and have a good day!

John
 
The main wear items are the cone-clutch facings, which I'd recommend be replaced strictly on age alone, and there are a few thrust washers scattered throughout.

There are O-rings on the accumulator and operating pistons; should be rubber in your case (mine, like all older units were steel).

You don't need any special tools, at least I've never had any. Do put the planetary gearset back in the sun/annulus gear(s) with them correctly timed.

Only real headache is getting the overdrive back on the mainshaft with the two (2) internal splines aligned and depressing the pump plunger to get up on the cam). Some models, I can leave the pump out until they're mated and then install.
 
Every hour spend researching and reading the following articles was multiple hours saved in the rebuild process. The articles also cover bench testing, which might help you figure out if you need to go through the whole process.

https://www.vtr.org/maintain/TransRebuild/OverDriveA01.pdf
https://www.vtr.org/maintain/TransRebuild/OverDriveA02.pdf

and the 5! pdf's at the bottom of following page:
https://www.healey6.com/technical.htm

I printed out the articles and put them in a binder so I could use them in the garage.

I made a tool to pull the accumulator housing using a treaded rod, nut, big washers, a wing nut and a big rubber ring from the plumbing dept in my local hardware store. You might find an expansion plug that works in a plumbing store. Having a spare mainshaft helps for alignment and testing. Lastly I bought the OD oil pressure gauge from https://www.geocities.com/jholekamp/index.html

I am finishing up the OD now, I have one more adjustment washer to order based on last measurement. Then over to the bench testing. Rebuilding the OD was a first for me, so I read all the above and worked slowly but accurately.

I replaced nearly all bushings, bearings, o-rings, oil-seal, Uni-directional clutch (was shattered) Annulus steel insert ring (shattered too), most springs, balls, washers, gaskets and the pump cam.

BTW I needed to replace the whole front housing, it was hit on the bottom and JB weld applied over the lower parts that were smacked off. This probably closed off the channel that allowed the pressure to bleed off when the OD is not engaged, breaking the OD next time reverse was engaged. Hence the gearbox ended up underneath a work bench gathering dust waiting for somebody to adopt and repair it.

Bert
56 BN2 WIP
 
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