Transmission Grinding

Help -- looking for answers.
I have a 1970 Commando with the Dauntless V6 and manual 3spd (I think - T-90).

When cold, the car drives fine.

Once warmed up (about 5 mins) it becomes impossible to shift without grinding gears. And, some times it just won't go in gear (any gear) without forcing it. This also includes while at a dead stop. The gear grinding is painful to hear and worse to drive.

Other details and observations...

When not running, shifts fine.
Clutch and pressure plate are relatively new - but it was doing it with the old parts as well. (Which is why we replaced them - assuming it was this.)

We have adjusted the clutch / pedal to the extremes in both directions (with no change).
We have drained all the gear oil, and replaced with new gear oil (of correct type and weight)
There are no leaks from the trans.
Once IN GEAR, car drives fine.




What's next?

Has anyone had a similar experience and have any suggestions?

 

Welcome to site; introductions are here: Introductions | ECJ5 (earlycj5.com)

 

I'ld bet Your clutch cable is stretched.

 

70 has a mechanical clutch linkage.

 

There were clutch cables on the Commandos.
One style was the 1 piece cable, pedal to fork.
The other 2 styles were a clutch cable from the pedal to the clutch bellcrank, that activated mechanical linkage to the fork.
Obviously a thorough inspection of the clutch linkage might be warranted, regardless of which set-up you have.

Is the floorboard cracked or warped where the clutch cable goes thru the floor ?
Could it also be flexing or oil canning when floor is warmed up ?

 

Start engine, with trans in neutral. Depress clutch. Can you shift into reverse without grinding?

 

This sounds like a clutch that it not fully dis-engaging when the pedal is depressed. Follow colojeepguy’s suggestion above, and report back.
Does your Jeepster use a cable from the pedal to the bellhousing, or does it use a shorter cable from the pedal to bellcrank/shift rods mechanical linkage?
-Donny

 

It sounds a lot like what I am going through except for the engine cold/engine hot variation. Mine was the cable.

 

A '70 with a V6 will be a Borg-Warner T-14, not a T-90. Only the 4-bangers got a T-90 in 1970.

You need to determine if this is a cable or mechanical linkage. Your FSM is available as a reprint: https://www.faxonautoliterature.com/Search?categoryId=226984&keywords= Likely available other places, but you should get the FSM and refer to it regarding your Jeepster.

This seems like a clutch problem. There is very little you can do for a transmission problem with the transmission in the car and assembled. The blocking rings can wear out and then the synchromesh action becomes less effective. If the transmission blocking rings are worn out, the Jeep will still shift fine if you mostly match speeds and don't shift too fast.

 

As said either clutch is not disengaging or wrong/contaminated lube. You say correct lube but don’t say what you used. More information needed.
Clutch adjustment very important but it’s possible the pilot bushing is dragging on the input or the disc is not sliding on the input shaft splines causing it to drag on the flywheel or pressure plate.