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Triumph TR3 - Bench testing trans and OD unit

Hi Guys:I am wondering if anyone out there has a successful method of bench testing a trans and overdrive unit.I have heard that it can be done with a 1/2" drill.I have some reservations about this i.e can you chuck the end of the input shaft without damaging the surface(I agree that it is hardened and may be scratch proof).With a tach or speedo connected what rpm or speed would be required to engage the OD (develop enough hydraulic pressure to activate the operating valve?The best way is probably to install it and run it before taking it off the stands But if it does't work you have to take it all apart again.
I am open to any and all suggestions.
Chuck

Chuck-Go to the Buckeye Triumph website. Nelson describes a fixture to bench test the OD.
Berry Price

Chuck - In 2000, when I was out at VTR in Portland Oregon (7220 miles round trip) in my TR3A, I had my O/D rebuilt by Ray Marty. With the O/D repaired, assembled to the gearbox and filled with oil on the bench, he connected the input shaft of the gearbox to a 1/2" chuck, driven by a large heavy-duty drill unit. He also had a 600 psi pressure gauge attached to the top right hand side where the nut should be located above the ball valve and plunger assembly. He had a special threaded tubular adapter between the O/D threads and his flex hose leading to the pressure gauge. With the gearbox in 2nd, 3rd or 4th gear and a tach connected where it normally is connected, he started the drill drive and cradled it in his arms horizontally while it was running. After a few minutes (I think the HD drill was turning at about 600 or 900 rpm), the oil pressure started to rise and got up to about 325 psi.

We knew that the O/D was working when we manually pulled up on the lever that the solenoid pulls up. We could see the tach change speed. We couldn't hear any difference.

We put it in the car and it worked fine. Then after about 15 miles on a test drive with the tunnel out and sitting on cushions on the floor, the O/D stopped engaging. Probably we should have continued to drive to see if it would start to engage O/D again, but back at the shop, we eventually had to "prime" the pressure side in the O/D. We removed the pressure gauge. We removed the drain plug below, drained the oil and with a dentist's 90 degree pick, Ray reached up and pushed back the one-way ball valve from below. Then I started to pour oil down the top hole where we had removed the pressure gauge. When Ray saw oil getting to the bottom, he relaeased the pick and we knew there was no more air in the pressure feed line between the pump at the bottom and the valve at the top rh side. We closed it up, filled it with oil and ran the engine with the TR in gear safely up on jackstands, clicked the solenoid and after about a minute, the pressure came up like it should. We had it working. This took us a day to "solve", as neither of us had ever run into this "loss of prime" problem before.

Since the gearbox was in good shape, we didn't test it. Maybe there is a way using this method. I don't know. The gear box had been overhauled in 1990 and had about 50,000 miles on it at the time. Now the gearbox has done over 70,000 miles since 1990 and is still perfect. The overdrive has done 20,000 miles since Portland and is fine.

Thus endeth my first lesson on testing an O/D.

Don Elliott, 1958 TR3A
Don Elliott

Hi Berry:Thanks for the tip on the Buckeye website .I am making up a test system the same as Nelson's.
Chuck

Chuck-I thought Nelson's idea of driving the output flange instead of the input shaft was novel. The drill motor method is a lot more convenient,but being retired, I will probably take the long route. Either way, it makes life much easier to test the OD and check for leaks before it is installed in the car.
Berry

This thread was discussed between 08/11/2002 and 11/11/2002

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