Finally got my trans checked out this weekend to diagnose my truck. Been having issues with the truck vibrating at highway speeds when the lockup is engaged. Got my speedo corrected and bumped up the lockup speed which help around town but on the highway it was the same. The local trans shop told me I had a bad converter or front pump; they said I could replace those parts but there was a possibility of the whole tranny being junk as well.

Anyone had similar problems or can give me any advice on what to do? I was considering a cheap rebuild since these tranny's are fairly strong but I'm not sure what to do......replace broken parts or overhaul?

 

Are you running the stock converter?

Chris

 

drop your tranny pan and see if there is any metal in there...if not then change the converter, oil and filter...should be fine

 

Yes its a stock converter Chris. I'm gonna drop the tranny tonight and swap out the converter. How difficult is it to change the filter? I've never messed with autos...give me a T-56 and I can work on it though lol.

-Isaac-

 

Filters are a breeze. Can be messy especially if the pan doesn't have a drain plug. Pull the pan, gently pull the filter off, gently snug the new one in. They have a tube that is press fit into a seal in the valve body area.

It sounds like the converter to me also. Especially if the only issues are when the TCC is locked. Guess it could be an issue with the control circuit to the TCC though. Might not be a bad idea to replace the TCC solenoid/modulator. If the TCC is failed chances are there is going to be a lot of clutch debris in the pan. I'd try and flush things well, including the cooler lines.

 

The stock converter clutches are known for cracking. This causes a loss of apply pressure and the clutch will shudder. Chances are it did not even put off any debris. Good luck.

Chris

 

Chris, so then I'll be good with just getting a new converter, filter and oil? By chance are any diagrams to see where parts are located in the 4L80E?

Now that you mention the apply pressure, I noticed that after a long drive the tranny started shifting hard. Im assuming the PCM raised the line pressure which corrected the shudder issue cuz my tranny shifted fine the remainder of the drive. This might explain and coincide with the apply pressure issue that you mentioned Chris.

 

Thanks guys, swapped the converter and filter last night and it took care of the problem; now I just need to bump the lockup speed back down. Oh man it was a bitch to drop the trans without a tranny jack or removing the exhaust but my bro came through big on the install. Thanks again Chris and everyone else that helped me out!!!

-Isaac-