Launch Shudder from a stop

[DPKetchum]

Help on lauch shudder with 9k trailer. Any updates to TSB 0300304? Also trying to understand the TSB if it should be checked with trailer or without. Also why would a shudder if ths TSB applieds get worse the further driven and after cool down not be present.

 

[JHardwick]

Also why would a shudder if ths TSB applieds get worse the further driven and after cool down not be present.

The hotter the ujoints are, the tighter they are.

 

[betterthanstock]

Help on lauch shudder with 9k trailer. Any updates to TSB 0300304? Also trying to understand the TSB if it should be checked with trailer or without. Also why would a shudder if ths TSB applieds get worse the further driven and after cool down not be present.

Assuming it's not a u-joint about to seize, the shock absorbers get softer when warm, and the suspension rubber bushings, and engine mounts soften too, so it may be axle wrap+engine wrap that makes it feel worse. Clutch may act differently when warm too.

 

[tkerrigan]

If you have a long bed with a two piece drive line, air bags will eliminate launch shudder caused by drive line misalignment caused by heavy load. Look at the drive line when loaded, if rear part of drive line go's uphill to rearend, air bags will definitely help.

 

[DPKetchum]

You know this is a pain in the butt. Truck is built for weight and towing. This shudder is darn severe. Its the first time truck rides level with a load and it gives me plenty of clearance from bed/tailgate area to bottom of trailer. I really don't want to spend money on air bags and raise the truck loaded. It rides level with trailer. Should'nt have to. Don't know pin weight of this trailer but it is barely on the overload spring. The deal of it having to be HOT to shudder puzzels me. Dealer claims its NOT a u/joint. I may pull shaft assy. myself and take it to a driveline shop. I will look at the alignment of shaft loaded.

 

[tkerrigan]

Both shafts should be aligned with each other within about 1. 5 degrees as follows -+------------------+-----------------+ under load. If you don't want air bags, this can be cured by having a one piece drive line made. At iedls.com (inland empire drive line service) there is a build sheet you can fill out to have a heavy 1pc drive line built.

 

[sag2]

If it shudders loaded but not unloaded, you need to shorten the center support bracket. The TSB lists the bracket lengths. It does not take a drastic change to stop the shudder.

Also the second paragraph says to evaluate the truck in the loaded condition that causes the problem.

 

[DPKetchum]

Why the further I pull the trailer the worse the shudder on take off gets. Short trips its not noticable?

 

[jwilliams3]

How many miles on U joints?

 

[DPKetchum]

24k. Dealer just checked and said felt good. No binding. First think I thought was u/joints. the further you pull on the interstate the worse it gets.

 

[jwilliams3]

You have one or more u joints that are bad.

You can't feel if they are bad... been there done that.



I had to change out my first set at 22k miles. I had one that was literally smoked (charred black inside the cups).



Getting the driveline angles set up only masks the u joint problem until complete failure of a joint. I re-adjusted my angles and it worked for a while but it only bought time with dry factory u joints.

 

[JHardwick]

The hotter the ujoints are, the tighter they are.

A dry joint causes frictrion ... ... . which causes heat ... ..... which causes swelling ... ... ... which causes a sticky joint ... ... ... . which causes launch shudder.



You don't have a "loose" joint, but I guarantee you have a dry joint! Been there and done that!! Mine felt so bad one day I was sure I had a shaft on the ground, but a few hours later I drove it home smooth as silk!

 

[Cattletrkr]

Getting the driveline angles set up only masks the u joint problem until complete failure of a joint. I re-adjusted my angles and it worked for a while but it only bought time with dry factory u joints.

Ditto. My driveline went up and down a few times to no avail. Finally the hanger assembly went out and took the two rear joints with it. Upon inspection of the center joint, there was a needle impression (laying crossways) in one of the endcaps. That joint was assembled wrong at the factory. Truck had 55K on it when this was discovered. I now have virtually no launch shudder loaded (41K) or empty.

 

[roadking]

you have to pull the shaft to check them

 

[DPKetchum]

I'm going to pull shafts Sunday and take it to the driveline shop Monday A. M. Dealer tech dropped the rear shaft from rear diff. (the 4 bolts)and nothing else.

 

[jwilliams3]

There aint no checkin to it!!



THEY ARE BAD!

 

[Cattletrkr]

Anybody here use one of those little infarred guns or whatever to check the temps of your u-joints? I've always thought that's a good way to catch a bad one early or find a bad one easily.

 

[JRensel]

DP Ketchum, replace the joints, even if they arent bad now they will be IMO.



I just replaced the three rear shafts u joints on my 2004 long bed SRW 1 ton and it solved the launch shudder i had since it was new. And i had to replace the $50 OEM only dust boot on the rear of the 6 speed too, of course DC says its not part of the drive train warrantee. It was cracked, possibly from the wobble a bad joint may have caused.



It did it hot or cold and the geniuses at DC replaced my clutch at 7500 miles instead and then told me they all do it (sure, go buy a ford). I am blown away at the incompetence of all the local Dodge dealers..... NAPA dealers here seem to know more!



I used precision 351 u joints, installed at NAPA for $15 each. they went in easy, but after reading other posts I decided not to try it myself as some folks find they bind when trying to slip into the yokes.



Upon inspecting the u joints, i found they all had some grease but one or maybe two caps were kind of sticky or rough on spinning.



Since the OEM joints are apparently such pieces of ****, I am thinking of doing the rest, front driveshaft Cardan H joint (2 each Precision #232) and at front axle (1 each Precision # 235) which should be easy. (from rockauto.com of course).



Can anyone tell me if doning the front axle U joints left and right is a tough job? I dont trust any of the original joints at this point.

 

[DPKetchum]

I'll pull the shafts and take them to a driveline shop. BUT I found a year old post in history on another site stating the exact same deal with mine and he found it to be in the differantial. Mine is hard to duplicate as it takes long interstate pull with 9k to get it to shudder. But the shudder does feel like a posi shudder but worse and does it in a straight line. The night I got home and it was shuddering in my driveway at a creep I felt all the u/joints. Not a ONE was hot or even warm. The DIFF was hot. Would like to chat with someone that really knows these AAM diffs. The other post I found with the same issue changed to 85w140 and some posi additive(which these should NOT need)and his stopped the shudder.

 

[jwilliams3]

Well, glad you got it figured out on your own.