Launch Shudder from a stop

[DPKetchum]

Not sure if thats it but lots of intersting reading. The AAM units should not do this. Its NOT the launch shudder TSB I'm firmly convinced of. If it was it should do it all the time with the pin weight of the bigger trailer. It feels just like if you had it in 4x4 on dry payment and turning only from the rear. I found that one post from about 6 months ago on DTR describing the very same thing on a unloaded truch after substained interstate speeds and a few other comments about shudder on turns after changing diff oil(one insists it was the Amsoil) The u/joint posts were almost "all" commenting about when slowing down. I might still pull shafts and ask to throughly go through all old joints etc. Its a 70 mile drive to drivline shop one way and I bet I'll have to leave the shafts with them. To prove the diff. thing requires lots of interstate miles with trailer hooked. Don't know how many but a lot I think. I found a differantial/drivline spectialy shop in Arizona that I'm calling Monday a. m. to ask some questions about the AAM diff. in these trucks.

 

[JHardwick]

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!

Save yourself some headaches and head to NAPA for some u-joints! Mine has done it starting or stopping, doesn't matter. In 250,000 miles, everytime it does it, it needs ujoints or grease ... ... ... I just recently changed the carrier. It happened every 25-30,000 miles with OEM joints, but 70,000 or more with NAPA joints ... ... ..... this 80-90% towing miles.

 

[DPKetchum]

I pulled the shafts toady. Took them to a driveline shop. All they had were SPLICERS and mine felt fine. Nothing rough or binding. The man thaft works on shafts said he felt nothing unusual eaither and said NOW what? I said lets pull them and look! He did. NOTHING wrong with old joints. Full of grease,no score marks,no rust,all roller pins in place etc. So $119. 00 dollars and 1/2 tank of fuel and half a day later I have three new Splicers and the hot shudder wasn't from u/joints or carrier. Its what I finally realized what it felt like. The posi whatever its called binding just like a OLD DANA would needing a fliud change with modifer added. Now NOT sure what to do. I guess next step is a gear oil sample from rear differantial and I'm sending it to Blackstone Labs. Its Amsoil Servere Gear 80W90 thats been in it 10k.

 

[captainmike]

Driveshaft angle

See my thread; Driveline Vibration under load - captainmike



I had a similar problem with my '06 Megacab 2WD (2-piece driveshaft) when towing my 10,000 lb fiver. The dealer, Spitzer Chrysler/Jeep in Homestead, FL installed a shorter than stock support bracket for the center u-Joint, thereby raising the U-joint and changing the driveshaft angle to the rear end. The problem resolved. The truck still runs smoothly when running unloaded.

 

[DPKetchum]

Was your shudder from the get go or after towing 100 plus miles at hiway speeds?

 

[REvans8993]

Hey I have an 05 4x4 6 speed and I have a shudder when slowing down. The dealer has replaced a ujoint and it fixed the problem for about 8k and the problem is back. When I hooked up my gooseneck horse trailer the shudder went away. Is this a problem that someone has run accross before. Thanks for you help

 

[REvans8993]

shudder problem

Hey I have an 05 4x4 6 speed and I have a shudder when slowing down. The dealer has replaced a ujoint and it fixed the problem for about 8k and the problem is back. When I hooked up my gooseneck horse trailer the shudder went away. Is this a problem that someone has run accross before. Thanks for you help

 

[REvans8993]

Has your problem come back.

 

[brods]

DPKetchum, did you ever get a definitive answer on this? A google search on "launch shudder" shows you put effort into trying to track it down on several boards.



Mine seems to be getting worse so I'm going to try Mobil 1 again. The first fill was Mobil 1 75W90 and the current oil is Castrol Syntec 75W90 with about 10K miles. The Castrol shudders noticeably when hot. Maybe I'll give Mobil 1 75W140 a try just to see what happens.



Anybody have good or bad results with other brands of oil? It would be a great asset for the TDR to compile a list of oils that seem to perform better with the AAM trac rite diff.

 

[DPKetchum]

I added ONE generic bottle,I think Purolator anti chatter additive I got at AutoZone that supposedly is NOT NEEDED with AAM axles to the diff. and it went away in less then 5 miles. I did find a few other threads with same issue and results in archives and on another forum. I have stayed with the Amsoil fliud and in the 75w90 weight. I have read that the thicker fliuds do not lose heat as well. The 75w140 is only called for in Chrysler Corporate axles not the AAMs.

 

[brods]

Thanks for the update.



Nobody ever figured out why some shudder and others don’t?



I put in the 75w140 on the premise that the shudder may be related to viscosity since the shudder is much worse when the oils hot. If that is correct then the 75w140 should have less shudder than the 75w90. We’ll see. As far as heat, if the trash rite dies of heat stroke then that’ll be a good excuse to upgrade to a G80, detroit or other more effective diff.



I had 22k on the Castrol not 10k and there was some sludge on the magnet. Wonder if its from the friction surfaces?

 

[DPKetchum]

I never have read about a AAM failure with eaither weight oils.

 

[brods]

680 miles today pulling a small enclosed trailer. At the end of the trip we made the same left turn from a stop that caused pronounced shudder with the Castrol on the last trip. Not a hint of launch shudder today with the Mobil 1 75W140. We'll see if the shudder stays away... .

 

[TBartlett1]

I would first suspect the u-joints also. Remove the drive shaft & feel for freedom of movement they should not be stiff, if so they are bad. Also if there is any red colored dust (rust) near the u-joint seal it is failing. U-joints do not need to be loose to be bad.



If the driveshaft has been apart check to verify that the u-joints are aligned. 2 piece drive shafts need to be reassembled with the drive shafts properly aligned or in phase.



The yokes on the driveshaft ends should all be aligned with each other. This can be visually checked without removing the shaft. If you look at one of the u-joint caps pressed into driveshaft at the transmission end the others caps pressed into the drive shafts should all be in line with it. If not the shaft is out of phase and will certainly cause a shudder.

 

[DPKetchum]

I ruined perfectly good U joints hunting my shudder. All it took was that $5 bottle of anti chatter in the rear differential.

 

[brods]

TB, you did read the thread before posting didn't you, lol. As was the case for DPKetchum, my launch shudder is caused by the AAM trac rite limited slip differential and is especially noticeable when the gear oil is hot.



So the moral of the story here is if you have the trac rite diff and experience launch shudder, do not automatically condemn the ujoints or driveshaft angles. And if the shudder is indeed coming from the trac rite then you have the option of adding LS additive or using different gear oils.

 

[DPKetchum]

Yep. Was told several times'got to be u/joints". Mine with 26k on them were fine. Had plenty of grease in them. Then I went after drive line angles. They were in specs. Added ONE small container of Purolator anti chatter additive. Shudder was gone in a couple miles. Never has done it again.

 

[Ken55]

Just saw this thread and experienced the same thing while trying to extend my change interval using amsoil. The shudder started at around 23,000 miles. I dumped the fluid and put in Mobil 1 and all has been fine since.

I tried the extended drain interval again with the mobil 1 and all was well when I changed it at around 30,000 miles. But I don't go that long anymore staying closer to the factory recommendation. It gives me a chance to do a little inspection back there and besides I like the smell of gear oil.

Ken