I have a tranny that shifts fine (no grinding) when the clutch is engaged (engine running), but will not move. I'm thinking it's my overdrive unit.

Could it be the clutch? tranny? OD?

Paul

If I am reading this correctly, it seems you are able to move the shift lever through gears one through four with the engine running without pushing down on the clutch pedal!? Also the car does not move.

Engine clutch. Overdrive is after the transmission, your problem is before or in the transmission.

Any noise before this happened??

Duane

My mistake. I meant, when the clutch pedal is depressed.

The car shifts fine when the engine is running and the clutch pedal is depressed. No noises.

When the car is in gear and the clutch pedal is released, the car (transmission) makes a slight noise, but does not move.

In past cars, when a clutch goes out, I can't get the car to go into gear without grinding them.

Paul

With that additional information, the difficulty points to the OD more so than internal to the gearbox.

Before pulling the OD apart, try the following:

ON the left side of the OD under the solenoid is a square plug. Remove that and allow the oil within to drain. Probably a quarter cup at most is all you need to allow out. Capture so you can examine.

Replace plug and try to drive. If you can move, you will need to remove the solenoid to clean it internally and replace some O-rings as well as remove the bottom pan of the OD and clean out a passage that drains the passages behind the actuating pistons.

If you can not move after the above, look for a used OD instead of repairing the one you have. Parts that are probably damaged may be more than a used OD from a salvage yard.

Duane

Damn!

I already took the OD off and checked to see if the transmission output shaft would spin in gear or not. The output shaft spins fine when in gear and the engine is running, and impossible to move by hand when in gear and engine is off. The output shaft spins fine by hand when out of gear. The transmission seems to be in good shape.

I just got home and took the OD apart to examine. I've rebuilt a few J-type/P-type ODs (more than just replacing the O-rings, which is usually the problem with these ODs). The internals look like a normal OD in good shape.

Could a clog solenoid/passageway cause the OD to be caught in a position were the car won't move?

Now, I'm thinking it might be a bad rearend? But the rearend doesn't have any noise coming from it? The car is over at my brother's place, I'll have him try and spin the rearend flange to see if it spins freely or not.

Paul

A passage between the solenoid and the bottom of the dashpot(big thing which has the springs and the pressure valve in it) under far left plug must be clear to allow fluid to drain from behind the actuating pistons into the OD case. IF this is plugged the actuating pistons will not allow full return to rest of the cone clutch, whihc if in between engagement lock and at rest, allows everything inside the OD to spin freely.

This blockage can also be internal to the solenoid itself, which if you pull the plug as in my last post will allow that fluid to drain from behind the actuating pistons and allow the cone clutch to return to rest.

No forward gears is the Sprag one way at the end of the trans shaft. No OD or reverse is the cone clutch not making contact with the output bell in reverse (at rest) or the brake ring for OD.

If you have reverse, it is the Sprag, no gear forward or reverse, cone clutch is "in between" rest and brake.

Duane

I bet that's what happen then. It's was in between. I've never seen this before! These ODs are usually pretty reliable.

I'll rebuild the OD with a IPD kit, and make sure the passages and solenoid is clear.

Any tips?

Thanks-

Paul

A rebuild will do no good unless you correct why it got inbetween (if that is the case) in the first place.

A bit of O-ring can create a blockage, as can a blocked up solenoid keep pressure in place when it is supposed to be released.

You should clean and rebuild the solenoid while you have it apart.

Duane

Duanne-

This OD has a broken screen (the big rectangular one), which I suspect to be the cause. I have another OD that I use for parts, including a couple of good solenoids and screens. I'll make sure all the passageways are cleared out and all the screens are cleaned.

paul