tinbanger

So i did a search and did not find the answer i was looking for......


i have a 2006 lng bed 4dr 6spd, 2" leveling kit and is otherwise stock.

i have a launch shudder problem that has gotten too anoying, so i replaced the carrier barring and its still there. do i need to replace the two piece with a one piece to get rid of this issue.

its only off launch and under 11 mph, no matter what gear...... no vibs after that on accel or decel at any speed......

i notice that on my dads 08 they got rid of the 2 piece all together and went with a one piece aluminum drive line.

so i checked the u-joints and they are all fine. what am i missing

or do i need to drop the 450 on a new one?!

dozer12216

Drive line angles change under torque and very low speed. Center bearing is being moved as ujoints turn through. One piece drive shaft should not be attempted due to excess length.

tinbanger

so how do they get away with it on the 08's???? they are not any shorter than the 06's, same distance from t-case to rear end...........

matego

How did you check the u-joints? Sometimes you need to pull down the shaft and work each joint by hand to find the culprit. What you are describing sounds like a u-joint to me.

XLR8R

This is a relatively common issue with HD Rams; Dodge designed the rear ride height higher than the front in anticipation of heavy loading, so front leveling kits have become popular to "correct" the truck's stance.

Since longbed trucks have a 2-piece driveshaft, the height of the crossmember-mounted carrier bearing between them keeps the driveline angles at the limit of the U-joints' ideal operating envelope; under acceleration - especially at low speed (i.e. take-off) - the rear axle's torque reaction deforms the leaf packs and causes the pinion angle to increase, thus driving the U-joints into shudder mode. This effect is more pronounced in manual trucks, as the stock converters act as a cushion in the driveline.

Most trucks benefit from a 1/2" carrier bearing spacer - more if you have a lift: for instance, a 2" front leveling kit raises the carrier bearing bracket by ~ 3/4". We run 1" of carrier drop on the '05 shop truck - keeps the U-joints happy with 9K# curb weight and 5K# airbags.

Of course, a device such as traction bars works well to prevent the spring wrap which allows the pinion angle to rotate out of spec.

I recommend at least a carrier drop shim(s), and of course traction bars for all of their additional benefits.

tinbanger

y had to pull it down to get the carrier baring replaced they all felt loose but snug, ya know that tight feeling that a good ujoint has.

i tried a 1/4 shim and a 1" shim neither fixed the issue..... would a 1/2" really be all that diff?

i may just drop the money on a one piece. i drive 45k+ a year so i spend a considerable time in my truck.

XLR8R

If you only get U-joint shudder on takeoff, 99% of the time it's driveline angles out of whack... and if the joints are bad, you'll usually have higher speed vibration.

A. Are you sure the noise is from the U-joints?

B. Where did you install the shims?

tinbanger

no noise just a take off shutter.

and the f-d up thing is i didn't change anything, the 2" leveling kit has been on the truck for 10k miles. i have only changed the oil since then........

so i haven't the foggiest as to what is making it shudder on takeoff

Robert373

My 06 has had this issue since new. Annoying unloaded, but it'll rattle your teeth when pulling my 5th wheel. I got mine shudder to go away unloaded with the 1/2" shim (havent found a workable solution for it being loaded yet), but instead I removed the spacers in the leaf spring pack (essentially lowering the back end to level the truck. Not really a solution for you since your already level)

I built a set of traction bars about a year ago. They are close to being finished, but I just haven't had time to do the final fit and modify the front brackets.

I'm fairly sure they will do the trick.

As far as your thought about a 1 piece drive shaft, I know the 08s have them, but I don't know how DC made it work. I heard they were aluminum, but I'm not really sure. I looked at doing that before the 08s came out, and every drive line shop I talked to would not build one cause it was too long. I even thought about having the driveshaft modified for a constant velocity joint (like the front driveshaft) at the back u-joint, but it was expensive.

I think you should look at traction bars. The driveshaft road could be rocky and expensive.

Good luck

tinbanger

well the there is a driveline shop i have been going to for years, the guy is super honest and never over charges me. the do semi drive lines as well as passenger vehicles, and he thought a one piece was the way to go, i'll cal and ask tomorrow if he has had luck in the pas with a one piece. i thought he said thats was the best way to go, but can't remember for sure.


and yes the 08 are all aluminum, he was going to build me a steel 4" for 400 bucks.

gpshemi

Let me know how you make out. I'm fighting this too in another post "Shutter on Launch". I saw a shim kit listed on google.

I suppose taking a bunch of washers and working up till you find the right stack would work. Then replace with the proper solid shim. Might take some playing around. Can there be too much drop?

Hounddog

I chased a shudder hot on take off for a month.Checked angles,took perfectly good u/joints apart and of course there ruined then etc.I put one bottle of generic posi additive in the rear and shudder gone in a few miles.Wonder of wonders.I'm not the only one thats had to use anti cchatter additive.It was also many moons after changing to Amsoil Severe gear 75w90.May not be your issue but its a $5 or $6buck deal and takes 5 minutes or less to install.Won't hurt anything being in there eaither.

gpshemi

Posi additive in the rear end? Maybe, but mine got worse with my block install. Leads me to think it's drive angles.

The vib has been in this megacab since new. Although it's been faint. I've always felt it. The dealer said it was normal for a diesel (ya right). However, after adding these 2" blocks to the rear...woooow...it's there now for sure. You know the dealer will blame the blocks though so this is something I'll have to find on my own.

tinbanger

where did you buy it and what exactly is it called? i have not changed any fluids so i can't say thats my problem, wish it where, but i'll give it a shot.

that shim deal sounds hokey, the driveline angle is always changing, loaded unloaded, what would that solve, other than just in a unloaded situation? what a BS problem to be having with a truck thats only 2 F'N years old

gpshemi

True it is always changing. I haven't tried the truck with a load in it yet. I suspect it might change. I know I had a load in it once and I thought the tranny dropped out of it from the launch shutter. It was really bad. Even my passenger said "WTH was that?" Whatever the cause, it's never been quite right.