4r55e lockup issue?

[syn-]

Well after 2 weeks of being in and out of trans shops I am looking to see if anyone could help. I recently rebuilt my trans with a central VB, custom TC w/ 2200 stall. Truck shifts fine except for 3rd to OD and OD with re-lock of the TC. Best I can explain is I can be doing 70mph and tap the breaks, see/hear the TC unlock, but when I get back into it rpms could go up to 3 or little over 2500 and after a little acceleration the TC lock occurs. Though the rpms drop by about 5-600 before it locks and the truck will start moving. No issues after that unless I back off and try to get into the throttle. Sometimes I will see a shorter rpm drop while I am applying moderate throttle in city driving. It's like a drop and no issue and may not happen when stop/slow down and apply the throttle from a stop. Now this only happens when the trans fluid reaches temps above 165. As a final thought I know there could be less than half a quart of mercon-v that is the old fluid that was not flushed. I added just under 12 quarts after installing an 11x8 stacked plate cooler. Any help would be great, also planetaries were not replaced in the rebuild.

 

[PopRichie77]

Did you do a complete rebuild or just the VB and TC? It sounds like you have internal leakage.

 

[syn-]

I took it to a shop that used raysbestos parts, new bands, clutches, etc. Essentially everything replaced except planetaries. When you say internal leakage? What do you mean?


Here is a video I did to show how I can cause it to happen on the hwy. I have another that shows it happen while in low rpm (2000) and it drop about 3-400 rpm.

 

[PopRichie77]

Ok, I fail to understand your problem? The TC will unlock when you tap the brake pedal, it also unlocks if you leave up on the gas pedal or you press down on the gas pedal quickly, this is normal. The TC will lock in 3rd gear also, which you will see in city driving. The TC only locks when there is light power being applied. You also have overdrive which is 4th gear, that locks and unlocks, both change the tack RPM about the same amount.

 

[syn-]

So based on the video, would you say that's normal behavior for a 2200 stall converter with no changes to the PCM? Or should I look into possibly taking the converter back? As the lock just seems rougher than my stock 1900 with 150k miles on the trans before it was rebuilt.

 

[PopRichie77]

A 2200 stall convertor has more slippage than the 1900 and the lock up will be felt more, internal trans seals were replaced and the VB is back to original spec. so seal and VB leakage is back to original factory spec. meaning better pressure, also the TC is new so the lock up will be firmer than a trans with 150k miles. Explorer shifts are meant to be felt. Is yours not normal, I have no way of knowing. But from what you say and what I saw, I would say it is ok.