Just bought new '07 3500 drw with 6.7, what's up with 68re?

[PFreeman]

I just traded my '06 2500 QC 4wd with 5. 9 and 48re in on an '07 3500 QC drw with the 6. 7 and 68RE. The '06 didn't have payload capacity for my 14k 5th wheel. I'm running about 4000 lbs. pin weight. I pulled for the first time Saturday with about 600 miles on the truck. All was fine for the first 50 miles or so, then it developed a rear end shudder when moving off from a start. It doesn't made any weird noises, the engine runs fine, the truck just seems to hop or shudder just after beginning to roll. After 10 mph or so, it levels out, and all is well untill I stop, and move off again. I pulled the 5'er with the '06 with no problems, using the same hitch. The tires are at 70 lbs. As I say, this started after the first 50 miles or so of towing. Have any of you guys experienced this? Any thoughts?

 

[Gary - K7GLD]

Sounds like the old 1st generation U-joint shudder when pulling away from a stop...

 

[Sky]

Or something in the rear end. Check the fluid level maybe try some limited slip additive in there.

 

[sag2]

It's launch shudder. Have your dealer look for the TSB from a few years ago. It still applies to the third gen trucks. Also do a search and find where I posted the 1" spacer PN that is not in the TSB. As a general rule if it shudders unloaded add length to center support, if loaded remove length with one of the listed shorter brackets. It is very easily corrected. Be sure you have your truck loaded the way you will normally drive it before making any adjustments.

 

[PFreeman]

Thanks for the help! I'll take this info to my dealer and see what develops!

 

[FDavid]

My 03 shuddered and they replaced the u-joints, problem kept coming back turned out driveshaft was out of balance.

 

[Beast2B]

a set of traction bars will help. eliminate the pinion rise and the u-joint won't get out of whack.

 

[JasonCzerak]

His truck comes with a SINGLE PIECE aluminum driveshaft. There is no center support in his truck.



If you got a shutter, might have them check the u-joints or the rear end out.



the pre-6. 7's long boxes with a 2 piece drive shaft have a normal un-loaded launch shudder.

 

[PFreeman]

My '07 6. 7 dually has a TWO piece drive shaft. It's smooth as silk when unloaded, but shudders from 0 to about 15mph every time when pulling the 14k fiver with about 4k on the pin. Dealer's lot is too small and conjested to allow me to pull the trailer in, so I guess it'll be a matter of trial and error.

 

[sag2]

Have them try the next shortest center support mount. With 4000 on the rear axle I think it will be difficult to have the best of both worlds. But you should be able to make it better loaded with no or monimal shudder unloaded. The trick is to get it shudder free in the situation you drive the most in. With the long suspension travel to get a better ride you end up with greater angle changes.

 

[JasonCzerak]

My '07 6. 7 dually has a TWO piece drive shaft. It's smooth as silk when unloaded, but shudders from 0 to about 15mph every time when pulling the 14k fiver with about 4k on the pin. Dealer's lot is too small and conjested to allow me to pull the trailer in, so I guess it'll be a matter of trial and error.

I wonder if it was a supply thing or an option thing? The 6. 7 Quad cab long box SRW I drove had a large long one piece.

 

[Gary - K7GLD]

Some guys have had luck eliminating the shudder by shimming the rear axle to change angle in relation to the center support, some have shimmed the center support to lower it - in my case with my '91, the problem went away when I installed a US Gear overdrive unit, which shortened the driveshaft length and eliminated the center support.

 

[nunya]

had to shim my 06 duallie empty, then had to add airbags when I went with the 5th wheel due to pin weight, no problem now