Whenever I pull my 33 foot 5th wheel or any type of load the truck allison tranny shudders up to about 10 mph and I do not use a lot of throttle to get it moving. In other words I am pretty easy on the truck. Secondly, and just recently on two occasions when I allow the truck to sit for more than 48 hrs or so it slips when I put it in reverse or forward, acts like it is in neutral then slowly starts to engage in either reverse or forward depending on which setting I have it on. I just took it to the Chevy dealer to look at it. The truck is a 2004 Chevy 3500 crew cab/LB/duramax/4X4/allison with 18,700 miles on it. I was wondering if anyone else has experienced these same situations.

Thanks,
ogfalconsr

I'm not sure about the first problem but the 2nd problem sounds like the False Neutral problem. I beleive there is a TSB for this problem. I couldn't find the TSB. Anyone have any info on this TSB?

I believe the shutter is in the driveline.

I believe the shutter is in the driveline.

I agree

Since you have the CC LB you have a split driveshaft.Sounds like with the trailer hooked up you have a carrier bearing alignment issue.Perhaps you can distribute the weight better on the pin.

The slow engagement could be NSBU related ans or converter drain back.I thought this was corrected after 02 .I would inquire at the dealer .

The Second problem sounds like the "converter drain back" issue or "loss of prime".

There is a TSB for it.

Problem # 1---the shutter during take off with heavy load....I was having the shutter problem with my 2001 - 2500 D/A...Got three opinions from three dealers.....1--torque slip from the rubber in the two piece drive shaft....2. Should upgrade to a nickel plated slip joint. 3.--that is just a problem with the Chevy drive train.....

I was going for the nickel plated slip joint until I decided to upgrade to a 2005 3500 DRW D/A....towed once since I've had it and no problem with the shutter with this vehicle..

Problem # 2---can't help you with that one....

Good Luck

my dads truck has the same shudder and it also is a cclb. He just gets used to the shudder. Is it something that needs fixed.

I wanted to update everyone on the issue of not engaging when cold or when the vehicle sits for extended periods of time. It is indeed a converter drain back issue and one GM is working with Allison on. So far no solutions. According to my area rep there is no immediate danger of trans failure. I wanted to know how widespread the issue is and was told virtually all Allisons have this anamoly. To satisfy me GM gave me a 100K warranty on the trans rather than do a remove & replace since he said even the replacement would probably have the same situation. I have a 2004 Chevy 3500 CC/LB 4X4 with the Allison and about 19,000 miles.

I too have this shutter pulling my 5th wheel from a stop. It seems to be present between 5 - 15 MPH under moderate acceleration. More acceleration the more severe the shutter. My truck is also a CC LB do I need to modify the drive train.

Hello, I had the same problem with the trany not going into gear after periods of sitting. Dealer pulled trany and replaced the converter relief valve spring, and a couple of other seals that they have tsb's on while the trany was out. problem solved. The bonus to this was it was done a 25,000 miles and the general also paid for the oil and filters. Free trans service, got to love it.

Don't have the first problem when I pull my fifth wheel camper but have the second problem. GM does not want to repair mine but has given me a 100k mile warrenty on the trans also which includes parts and labor with no deductable. Be sure to have trans serviced as scheduled and have records for proof in case you have trouble later. Look at my post on allison trans delay posted on 8-02-05.