1969x11

iTrader: (38)

It's a np246 autotrac case. With any boosted 4hi launch I get a loud ratcheting popping noise...cant really tell if it's the front diff or the transfer case. Also could the front diff actuator be partially locking the front? 7psi launches are fun but Im afraid something is about to give.

brent1976

iTrader: (1)

Look around on your case. My buddys truck did this, and the wear clip on the pump broke and wore a hole in the case. All the fluid leaked out, and it ruined the shifter fork, so it wasn't holding it totally in 4wd. We replaced the fork and JBWelded the case, and it's still going strong probably 5 years later.
Hopefully it's that simple for you too.

1969x11

iTrader: (38)

I'm good on the pump rub hole...I installed the case saver when the new input went in. The case does have some issues first I believe the case came off a 98 or 99 pre ls based truck because the wiring was hacked and 4lo doesnt engage. I had to rebuild the clutch pack because it was shot. Starting with another case would have been a wiser option.

trxmxzx

iTrader: (7)

Cv- shafts? Bosses 01 denali does the ratched pop noise from 30 mph if you go into first gear. Just a thought

1969x11

iTrader: (38)

I havent ruled that out, Thanks

tgui

I know the chains can stretch with time but I'm not sure if enough to start skipping teeth. With your power and launches it can't hurt to replace that chain.

Suburbazine

That chain probably isn't slipping. If it slipped, it would be a one-and-done deal. More likely one of the actuators is not engaging fully, if it was the t-case you'd lose output all together, if it was the front actuator you would still have power to the ground.

1969x11

iTrader: (38)

I believe your correct...on it being front actuator. I have pinned the noise down to the front axle anyway. Thanks

posz71

I worked at a coal mine for a while that ran all 2500 hd Chevys and we were rebuilding t-cases about once a week. I can confirm that the biggest issue we ran into majority of the was that the chains would stretch. We tried getting a few new chains cryogenically strengthened and they lasted a a little longer but they will still stretch over time causing the issue you are currently having. If I'm not mistaken I do believe the 3/4 ton t-case chains are a little wider than the 1/2 ton versions and I believe they are same physical size cases and will bolt up other than that I'd try to find an all gear case that will work.

AKlowriderZ71

iTrader: (22)

I have seen maybe 7 stretched chains in 20+ years of working on GM trucks. It can happen, but it isn't common.