Hi Guys,

I’m assesing why my Fbody ‘91 V6 700r4 trans sometimes has a weird shifting behaviour between 3rd and 4th.

Driving 60mphs p/h, 4th gear in Overdrive.
When driving for 30 / 45 minutes all of the sudden the car shifts back to 3rd gear. When i hit the gas the car shifts back and forth from 3rd to 4th gear. After few times it sticks in 4th. But randomly it shifts back to 3rd and the culprit repeats itself.
This only happens in Overdrive, not Drive

What are possible options to start looking at?

Today, i drove for 45 minutes, 60mphs p/h and nothing happend as mentioned above🤦🏻*♂️ Only difference: I didnt used the cruisecontrol. All the other occasions where weird shiting happend the CC was on.

hope you guys can give some pointers

cheers

Don

 

Are you sure it isn't the TCC locking and unlocking?

RBob.

 

60mphs p/h = "60 Miles Per Hours Per Hour"?

ARE YOU SURE PRIVATE PYLE?!?

At any rate - what is the exact change in RPM you are seeing when it "shifts"? Does it coincide with manually shifting into drive and back into overdrive? Or is it just a few hundred RPM?

If it does not occur without using the CC..... perhaps your cruise control is accelerating to maintain speed which is essentially the same as pressing the throttle. It can cause a downshift if the CC actuator applies enough throttle.

GD

 

Before the downshift occurs, it will unlock the torque converter clutch first.

 

🤦🏻*♂️ Sorry for the mix-up. 60 miles per hour.

What happens when driving it feels like a normal downshift. And it shifts up. When downshifting RPM’s increase by a few hunder. 2100 Rpms in 4th, 2600 when it downshifts.

the TCC locking, unlocking, how can I verify that?

TCC clutch, how can check that also.

cheers

Don

 

Unplug the connector on the side of the trans. Then it can't lock the clutch.

You can't check the torque converter clutch (TCC). It's an integral sealed component of the converter.

GD