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Tips
Tips

Removing Stuck Overdrive Unit

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71tr

71tr

Jedi Warrior
Offline
My j-type overdrive unit is stuck to the transmission. From what I can gather the splines on the end of the mainshaft are binding with the annulus splines and other internals in the overdrive. I've read that connecting a line to the oil pressure port on the overdrive and applying pressure while actuating the solenoid should allow the mainshaft to free itself. Anyone have any experience with this? The gearbox and overdrive are out of the car.
 
The following quote is courtesy of the Buckeye Triumph Site.

The manuals tell you that before removing the gearbox you should drive the vehicle and engage OD and then disengage with the clutch depressed. This will release the spline loading between the planet carrier and unidirectional clutch, which can make removal difficult. What this means is that the unidirectional clutch and the sliding clutch can be positioned in a way that there is large rotational forces in opposite directions on the splines of the rear of the mainshaft. The forces can be so great that the mainshaft can't be slid out of the OD unit. Once you have it on the bench, you aren't going to put it back in the car and run it in OD, no way. Apparently this doesn't happen in the A Type, or if it does, the forces are less. I've never encounter this problem but I know others who have had the problem; it is real. The spline loading can be relieved by moving the sliding clutch away from the annulus (the direct drive position). The manuals suggest the following procedure if the mainshaft is hung up: operate the solenoid, remove the plug in front of the solenoid and force oil into the chamber around the operating valve at the front of the solenoid. (The adaptor hose normally used to connect a pressure gauge can be used to connect to a grease gun filled with oil.) This should shift the unit out of direct drive thus relieving the spline loading.
 
Not had the problem myself; but it seems to me it would be easier to just run the unit on the bench to relieve the load on the splines. I did this just as testing my freshly-assembled unit, and it wasn't hard at all.

What I did was link my 1/2" drill (corded, 850 rpm I think) to the input shaft of the transmission using a short length of radiator hose and hose clamps on both the input shaft and the nose of the drill chuck (the part with holes for the chuck key tip). Eventually I gripped the drill motor loosely in the vise (so I could have both hands free for testing), but it worked OK just holding the drill in my left hand. Then apply power to the solenoid using a 12vdc source of some sort (battery eliminator; or even leads from a car battery). When the OD engages, you'll hear (and feel if you're still holding it) the extra load on the drill motor.

Obviously you'll have to put the nuts back on and refill the unit with oil.

Stop the drill, turn off the power to the solenoid, the strain should be released.
 
I don't know if this would work on a Jtype but with my A type I built my test jig driving the unit from the output. That way I just took a regular V belt pulley and drilled the holes in it that match the output flange holes. Then I drove the thing with an old 1/4HP motor and a v belt. Worked like a charm. I can send/post photo's if you are interested.
 
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