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TR4/4A A type Overdrive Oil Leak Fix


Jedi Hopeful
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I have been bench testing my A type over drive and have discovered a leak between the housing the solenoid mounts to and the case of the overdrive. Removing it looks fairly straight forward but I need to know if I remove the nuts and bolts that hold that housing in place are there any springs/ball bearings that are going to try and fly out of there? I hope to place the transmission nose down on the bench allowing the oil to drain from the overdrive, remove the operating arm from the shaft, remove the solenoid from the housing, remove the bolts/nuts that retain the housing, separate the housing from the OD, clean and reseal the gasket and reinstall. Does this sound right? I don't have the Laycock manual so any advice offered would be appreciated.
Steve Baker


Great Pumpkin - R.I.P
Nothing should "fly out", but there are some very strong springs behind that plate. Remove the two nuts first, then back the bolts out a little at a time to release the pressure.

Don't forget that by removing the arm, you will be disturbing a fairly finicky adjustment. In some cases, the "adjustment lever" on the other side may not be accurate, leading to further complications. I always check the "ball lift", as outlined near the end of the article at https://www.buckeyetriumphs.org/s/A-Type-Overdrive-Part-IV-cha7.pdf
(However, I view .016" as being on the small side and prefer .030".)

Here's the factory manual. Obviously written much earlier, but I don't know of any later version.


Jedi Hopeful
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Thanks for the advise and the link to the manual!!! I have read the Buckeye article and will have a look a the ball lift going back together. This one is freshly overhauled and I did use the 3/16 rig pin hole on the right side. It does go in and out of OD quite nicely using a drill to turn the tail shaft. I haven't checked pressures.

Graham H

Jedi Warrior
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If you place the box bell housing down on the bench the oil will run out the breather hole at the front of the shifter cover, better off with it on its side solenoid up.

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