Allison Tech Questions

[LSVLance]

I think my truck is having an issue with it's torque converter locking up and not locking up at the wrong times.

 

Truck has about 130,000 miles on it, the trans fluid was flushed and replaced at about 80,000 miles, other than that haven't touched the trans nor ever needed to.

 

Recently I noticed that when stopped at a stoplight, as I start to go forward again there is a pause and then a jolt as the truck starts rolling forward. It can be anywhere from a barely discernible jolt to a pretty hard bang. It seems to get softer as the truck warms up and harder when the AC is running. It does it in reverse as well.

 

I've messed around with it on the highway and at speed it does seem as if the TC is locking up and unlocking when it's supposed to. I have also noticed a somewhat abrubt or hard jolt or bang when the trans is downshifting when coasting up to a stoplight.

 

Other than what is noticed above, there are no other symptoms. The trans fluid is full and clean and trans has never been overheated.

 

Any suggestions on what to check first to see what this is all about? A lot of drivers would probably not even notice this except on the very hardest of jolts...but once I felt it once, I've been keened in on it and really want to figure out what it is before I really tear up a very expensive transmission.

 

On a side note, I did recently have the transfer case out to repair an oil pump rub issue, but I can't see that this is anyway connected to the transfer case. It operates as normal with no noises leaks or other issues. It did start not long after that repair though.