3rd to 4th slipping... Ideas's?

[Spooler]

I am having a 3rd to 4th slip with moderate throttle input. What controls this shift? Do I need to adjust the back band? Once it shifts it is fine and will hold the power with no issues. I only have an issue every now and then. It's not constant.

 

[Hurley]

Won't be the rear band. The OD brake clutch applies and the OD direct clutch releases all in the same movement via the OD piston.

IIRC, the converter also does some funky stuff with the 48RE TCM... 3rd, lock, unlock, shift, lock again in 4th. Wonder if that fits your symptoms.

 

[Spooler]

That could be what it does. It is a funky shift. Not really a slip, but a hard bang shift. More throttle or lesser throttle and I don't seem to have an issue. It's not the high load 4th straight to lockup shift. It could be trying to lock. It's weird. I only hit it sometimes.

 

[darederek]

alot of shift kits advertise fixing a "shuttle shift"

could this be what they are talking about?

 

[Rimcrew]

IIRC, the converter also does some funky stuff with the 48RE TCM... 3rd, lock, unlock, shift, lock again in 4th. Wonder if that fits your symptoms.

I'll bet this is it. I can see my trans go into lockup in 3rd on my insight CTS under certain conditions, then unlock and go into 4th, then lock again.

 

[mathews8pt]

alot of shift kits advertise fixing a "shuttle shift"

could this be what they are talking about?

No, thats typically a low speed 1-2, or 2-3 issue.

Probably noticing the TC lock, unlock, 3-4 shift then tc lock again.

 

[BgBlDodge]

The 47re did the same thing.