Horrible driveline vibration... help

[1919a4]

I have a CA-emissions 02 D/A SB CC LT and have been running Juice level 1 most of the time.

I've been juiced for about 4 months. Anyhow, I towed a large trailer weighing about 12000 pounds (hitch mount) a few weeks ago. I used Juice level 2 and have an Isspro EGT and boost gauge. I noticed while accelerating, at anything over 1/2 throttle, the 1-2 shift was accompanied by a very violent high frequency shudder. There was no hint of wheelspin or wheel hop.

I just moderated the throttle, and thought to myself this must be the dreaded "fishbite" that juicers talk about.

It was pretty bad during the trip, so after getting home, I pulled off the Juice to see how the vibration improved.

It didn't. Even without juice, the 2nd gear shift (or even second gear, full acceleration) will shake the cab violently. I have a limited slip diff.
Trans levels are OK.

I'm headed to the dealer unless you guys can figure this out.

SImon

[mdrag]

1919a4,

Welcome to TDP forums. Take a look under your truck and see if you have a 1 or 2 piece drive shaft. The one piece is HUGE, so you should be able to tell easily.

There was a TSB on Launch shudder on acceleration, where the 2 piece drive shaft is replaced with the 1 piece. I don't have acces to my notes right now to see if your truck's configuration qualified for that replacement.

Try a search using driveshaft, drive shaft, or launch shudder in the 2500HD/3500 HD Trucks and Drivetrain forum and I think you will find many posts.

I'm moving this topic to the 2500HD/3500 HD Trucks and Drivetrain forum.