Lost third and fourth - suggestions?

Ed Gasket

Ed Gasket

From England
Out in the Syclone this weekend and the trans started to briefly slip when shifting to third, but oddly only at part-throttle, never WOT. Late on Sunday third just vanished completely and I finished up with 1-2- and then a whole lot of neutrals. Managed to get the truck back by keeping the stick in '2' and stop it from trying to go higher (man that was a LONG drive) and I'm guessing a clutch pack has gone west, but I'm curious as to what might have caused this?
 
Quickstop [UK]

Quickstop [UK]

Combating adversyty.
Re: Lost third and fourth - suggestions?

Either your bands are slipping or the apply piston has blown a seal... If it's not at WOT then maybe there's enough pressure and it's the piston seal and not the bands.

Guess you just have to drive it everywhere like you stole it :D
 
DaveP

DaveP

Active member
Re: Lost third and fourth - suggestions?

3-4 clutch is fried. A very common failure in a 700/ 4L60/ 4L60e. Usually 4th starts to slip before you loose 3rd, but loss of 3rd and still have 1-2 are the symptoms of the 3-4 clutch has fried

There's only one band, and it is not applied for 3rd, Mark. It is for 4th, but you also need the 3-4 for 4th. I can't think of a failure mode where you could have 1,2 and 4, but not 3rd.

guess: It wasn't slipping at WOT because TV boost pressure raises line pressure high enough that it wouldn't slip. But at lower line (TV) it does. Another symptom of fried 3-4 is it goes away VERY quickly. I've lost a couple of 3-4's in tow rigs. Usually less than 100 miles between "what was that?" to "oh, the 3-4 is fried, that's what that was".
 
Last edited:
Ed Gasket

Ed Gasket

From England
Re: Lost third and fourth - suggestions?

Cheers Dave, that certainly sounds like the scenario. I'll post up the conclusion when I get it stripped just for others' future reference.

Thanks
Shaun
 
S

Sy1566

New member
Re: Lost third and fourth - suggestions?

So, what was the conclusion? Please post your findings.

Thanks
 
You must log in or register to reply here.
Top