I just purchased a 2004 2500HD 6.6L w/ allison... http://www.dieselplace.com/forum/smileys/smiley7.gif


Theres a thump when I release the brake after comming from a complete stop, it seems to get worse as the Trans warms up (30 min. of drive time)...


Is this normal??? Edited by: Camillo

Hope it's normal. Mines been doing it since day one.

I seem to remember reading a TSB on this elsewhere on the forum. It is related to the spline on the drive shaft requiring lubrication. It "sticks" in a certain position while under load and then slips when you let off the brake... releasing the load and allowing it to move. Check the TSB area for full info.

Thats what I heard too...Just wanted to confirm...http://dieselplace.com/forum/smileys/smiley7.gif


I was told it's the yoke and the seal is tight...There should be a fix out in the near future, hope its soon.....


Still love the S**T out of my truck

Is there a midshart bearing with a center slip yoke if it does check it for grease my 01 would clunk when leaving from a stop no matter how easy I was on the throttle, greased the center slip yoke and smooth as silk now.

Is there a midshart bearing with a center slip yoke if it does check it for grease my 01 would clunk when leaving from a stop no matter how easy I was on the throttle, greased the center slip yoke and smooth as silk now.





I'll check when I get home but I don't remember seeing grease fitting there.

I had the dealers grease it, but no help...Still waiting for Chevy to put out a fix...http://dieselplace.com/forum/smileys/smiley7.gif

I have never heard a clunk out of my trans or driveline for 4 yrs. and 34k miles. use only for pulling.

Check you transfer case fluid level as this is what lubes the slip yoke. If you have the push button or auto transfer case the fluid is ATF. When I checked mine the first time it was low, right from the factory. I have tried a few different fluids and, believe it or not, the chevy stuff has been the best. You can try a good teflon grease on the spline. I was told to use very little. Ford sells the grease under a factory part number. Not sure about GM but I haven't had to go that far as just changing the fluid has helped. The case only holds about 2 quarts so even if it is just a little low it can make a difference. Good luck and from what I hear it's a common problem.


Anthony

I had a thump or thumping upon start up. I could feel the thing "gearing up". When I ask the dealership about this they indicated that that was exactly what it (Allison) was doing, Loading up for work. I have felt the thumping at other times and I was assured this was normal. Anything new on this subject?


Just for the record, I have pulled Wolf Creek pass CO. 6% and 7% grade UP with an 11,000 lb 5th wheel at 2000 RPM. The Duramax will continue to GAIN speed. NO bog down. On the down side 6% and 7%the Allison held the load perfectly with very little braking needed. This transmission (and Duramax) is unbeileavable. I am still learning to use this forum. I uploaded the picture and now can't get rid of it... Sorry Im sure you want to see one more truck..





http://dieselplace.com/forum/uploads/DRMTEXAS/2004-11-11_133616_grey001.JPG





04 2500 HD SB 6.6 Duramax