Can anybody tell me what the "lowest" speed the 48re will let the torque conv. lock up?

 

Mine will lock up at about 5 mph as long as I'm in 4X4 low range,& on the throttle.As soon as I return to idle it unlocks.But in 2nd. gear it will lock up @ 24 mph,& stay that way as long as I'm going faster than that.In 3rd. gear it locks up as low as 48 mph.But thats an 04.5. From what I've read different years shift differently.

 

I am having an issue with my tranny shifting overly firm at slow speeds between 2nd and 3rd. It shifts so hard that it creates a very loud clunk. I was just trying to figure out if it was the torque converter locking up at about 15-20mph with lite throttle. Any help or sudjestions would help alot.

 

Shift "feel" is controlled by several things such as fluid pressure, orifices in the spacer plate and cushion springs in the clutch packs. But it sounds to me as the shift accumlator has a broken spring or torn seal. The feel of the shift should be firm but not harsh.

 

I don't believe your TC is locking up under the conditions you stated. Are you sure it's the tranny? It could be a bad U-joint, or even a mount.

 

I did think about something loose in the rear end or drive line. You wouldn't think you would have the rear end or a u-joint go bad in 4000 mile. But anything is possible, I guess.