URGENT!!! Reverse, no forward, no lights on tcase

Black2011 · July 9, 2013

I just replaced a rear differential in a 2004 sierra 1500. the original ration was 3.73's. I spent all day today carefully washing it, painting it and replacing brakes, fluid, etc, and at 11:30 I took it for its first drive. the drive was good, until I put it in 4wd. (The place I bought it from assured me It was 3.73's) about 20 feet further there was a clunk and no forward gears. sound like a gearset in the trans anyone? due to a incorrect diff ratio? can anyone explain the 4x4 lights being off, and the reverse operating as normal? does this sound like the transfer case popped into neutral? as soon as I started rolling in 4x4 I new something was wrong, so I hit the 2wd button. It acted like 2wd engaged, but then the kind of clunky noise hit. PLEASE if anyone has better knowledge share it because this is a friends truck, I did it for cheap, and I cannot afford to buy him a transmission.

He is also flying into town tomorrow just to pick up this truck and drive it 500 miles and use it for work, and I leave town in 2 days for 5 days straight.

This is the WORST way to spend you vacation time.

Thanks all.

Duelin · July 9, 2013

Did anyone pull the cover and check to make sure it had 3.73's? The first thing I do when changing out a rear end is to pull the cover. If you don't then the one you are installing might be worse than the one you are taking out. And when you have the cover off you can check gear ration, clean every thing up inside and pull the axles. And then check the axles and the bearings. Then replace cover with a new gasket. Put in new (and correct) fluid. I have never had a problem following this procedure.

Black2011 · July 9, 2013

Did anyone pull the cover and check to make sure it had 3.73's? The first thing I do when changing out a rear end is to pull the cover. If you don't then the one you are installing might be worse than the one you are taking out. And when you have the cover off you can check gear ration, clean every thing up inside and pull the axles. And then check the axles and the bearings. Then replace cover with a new gasket. Put in new (and correct) fluid. I have never had a problem following this procedure.

I used the serial #'s of both trucks to determine ratio. It is possible to have a different ratio but both trucks were 4wd and both had stock sized tires. Unless either truck was lifted, or possibly 2wd its unlikely the ratios have changed.

However, out of curiousity this morning I checked to carrier itself. 41 tooth crown, 11 tooth pinion. (3.727:10

I also tried rotating the pinion and marked the wheels. just over 3.5 turns per wheel rotation.

For everyones info, the truck has 1st, and reverse. the transmission slips heavily in 1st, the service 4wd indicator is on, and the 4wd shift buttons do not light or indicate what gear it is in. (its in 2wd)

My guess is that when the diff piled up, it progressively damaged the transmission.

if the transfer case is damaged too it wouldn't surprise me.

Its at a transmission shop now. I managed to get ahold of him before he jumped on any planes, so that's good.

Here he was excited to get a new differential installed, next day and brakes done for less than what any small shop would do it for.

Im breathing a sigh of relief that its not my mistake and Im not stuck buying a transmission.