Black Death - Auto Trans Style

[paulo57509]

I just got finished tearing down the transmission this afternoon.

I didn't get the chance to disassemble the reverse input clutch pack but I don't expect to see anything bad there.

All the other clutches looked fine. Except for the 3-4 clutch pack (as I suspected). No disassembly needed to see that this is why there's no 3rd gear.



There should be "teeth" on the friction plates where the arrows are pointing.

Careful inspection of the parts will follow. I need to find out why this clutch pack failed the way it did.

 

[turtlevette]

Wouldn't it take a lot of torque to strip those tabs off? Like a whole lot.

 

[paulo57509]

Just to close the loop. Clutch pack disassembled; in the order they came out of the drum.




"Normal" appearance of ~120k mile clutches for comparison. There's traces of burned friction material on these too. Actually, it's everywhere.

 

[CBR.worm]

Did you figure out why the tabs broke? Was something wobbly?

 

[paulo57509]

I'm guessing it's heat produced by the slipping clutch pack, tempers and softens the friction plate backing steel. When the transmission tries to apply the clutch it eventually rips out the tabs on the friction plates.

The big question is why the clutch pack started slipping in the first place. I have no answer for this, other than this failure is pretty common with the 700R4/4L60/4L60E transmissions.

I didn't see anything out of the ordinary during the teardown/inspection that would indicate a mechanical failure that would cause failure of the 3-4 clutches. I didn't bother to air check the 3-4 clutch pack before I took it apart; it might have shown a hydraulic leak in the clutch apply circuit.