Launch/slowdown shutter

[scottmcd]

Ihave read the TSB, and done the search, but I'm not finding an answer for what I'm experiencing. I am getting the shutter mostly during slowdown w/o brakes (coasting), @ 25mph-0mph. I have had the brakes & tire balance checked and all came out fine. I am now wondering if I have the dreaded shutter. I do not get it at launch with WOL, but will experience it with slow acceleration til I get past 25mph. I do not seem to feel it when I'm towing with my 10k skid loader hooked up. TIA, Scott

 

[rbattelle]

You're not lugging the engine, are you?



-Ryan

 

[scottmcd]

Ryan,

Iam not lugging the engine, as most of the shutter is at decelaration, with the clutch pushed in, and no brake.

 

[JHardwick]

I'm bettin the farm on rear u-joints. Had mine replaced twice under warranty and have 3 Precision 351's sitting in the garage as we speak.



A dry, stiff u-joint in a 1 piece drive shaft can go un-noticed until it squeaks or falls out.



In a 2 piece driveshaft it causes the shaft to waller in the carrier causing a severe out of balance situation.



I said it felt like coming to a stop on some serious mudders over a year ago ... ... ... . somebody recently said it felt like coming to a stop on rumble strips.



If you have them replaced under warranty, ask them to put some grease in the caps before installing, there are no zerks in the factory joints ... ... ... ... or grease for that matter

 

[jwilliams3]

Its not rear u joints.

Its launch shudder, it happens on the slow down also.

I have had this with my truck. I fixed this problem myself.

I installed about . 5" of metal spacer and added longer bolts to the

carrier housing to lower the carrier/bearing about . 5".

You can add spacer or reduce spacer to your liking.



This cleared up the shudders that I was experiencing.



There is a TSB out for this problem if you want the dealer to take a stab at it.

 

[Big_H316]

I had the exact same problem with my '03 twice. Take-off and slowing down it would shake the whole truck. Had the rear joints replaced and each time the shudder went away until the joints seized up again. The last time I put marine grade wheel bearing grease in the caps and that was over 50k miles ago and no problems yet. I think the guy responsible for putting the grease in the joint caps took a pro-longed vacation because each time the joints seized up the needle bearings in the end caps were bone dry and the trunion was pitted to the point that the needles were sitting down in the pits and could not move at all.

 

[jwilliams3]

Yeah, but what is causing your U joints to go bad? Do you wonder?

Its bad driveline angle that is the root cause, not the U joint.

The U joint is the one that suffers.

Band-Aids are only temporary.

If you fix the root cause you won't have to worry about bad u joints every 20k miles.

 

[APersondek]

I just had the same thing happen to my truck about a month ago. It was the rear U-Joint. dealer said it was seized up and would not move.

 

[NDanecker]

I just had another joint go today on my way in to work. I already replaced the center one about 3k miles ago so I'm thinking its 1 of the 2 others. My first one went at 28k miles.



On my last rebuild, the driveshaft shop said he can't find an aftermarket joint and said I’ll have to get one from the dealer. It cost around $135 which I think is crazy. Dealer joint doesn’t even come with a grease fitting. Before he assembled the joint he looked at the bearing caps and there was very little grease. I'm thinking these are coming from the factory with insufficient grease and that is why they are seizing up. If it was an alignment problem, wouldn't it wear the needle bearings out and not seize up? I read about the TSB…. but is this really fixing the problem????



Either way, I'm sick of fixing this poor & finicky design that requires the center bearing to be perfectly aligned and shimmed. I’m getting a one piece shaft made for me tomorrow.

 

[jwilliams3]

Have you ever tried lining up your center bearing?

Good luck with the one piece unit.

There is all long trucks use a 2 piece unit.

 

[NDanecker]

Have you ever tried lining up your center bearing?

I aligned the shaft from left to right but not height wise. I just found out about the shim pack/TSB thing so that is an option to try, but I'm really set on a one piece design. Going with larger tube and thicker wall. Drive shaft shop says he has done this often and has no complaints. I also read that the Duramax uses a one piece for their long beds... . but just because GM does it doesn't mean its a good idea. :-laf



By design, the two piece shaft will always have move slop from the center bearing then one without. With a 1 piece this should go away.

 

[scottmcd]

I have an appointment for it on Friday, but not with the Dealer. I decided to use the DIESEL SHOP that I am going to be getting a new ATS Manifold & new Huffer from. At what milage did you starft getting the shutter. 42k on this one. TIA, Scott

 

[NDanecker]

I just had another joint go today on my way in to work. I already replaced the center one about 3k miles ago so I'm thinking its 1 of the 2 others. My first one went at 28k miles.

Removed shaft last night. It was the rear u-joint (axle) this time. Center joint that was replaced about 3k miles ago seems fine. Front joint is heavy in one direction so thinking that, if left in, would have been the third to fail.



Center joint - 28k miles

Rear (axle) joint - 31k miles

Front (transmission) joint - Still working but tight at 31k miles.



New one piece shaft being made today. I'll give update after I get it installed.



As for the shutter, it was really noticeable after pulling off the highway (72 mile trip to work) when slowing down from about 20mph to stop. Funny thing is when driving home last night it wasn't really noticeable. It appears only after heating up after a long trip it got bad.

 

[JeffreyHahn]

From one of the engineers involved in making DCX requirements work: Extra grease can cause the seal's to pop off.

If you add extra grease you need to carefully assemble and watch the seals so they do not pop off.



When the UJt is assembled feel the articulation effort.

You should feel a slight drag.



Probable cause of ujoint failure could be zero balance propshaft and noise requirements. Held tighter than any other propshaft sold by AAM.

 

[JHardwick]

I have an appointment for it on Friday, but not with the Dealer. I decided to use the DIESEL SHOP that I am going to be getting a new ATS Manifold & new Huffer from. At what milage did you starft getting the shutter. 42k on this one. TIA, Scott

So how did the joints look? I'm anxious, remember I bet the farm on bad joints

 

[GFritsch]

Mine shuddered until I had the TSB done. No shudder now unless the truck is heavily loaded. More pressure in the air bags fixes that though.

 

[JHardwick]

Mine shuddered until I had the TSB done. No shudder now unless the truck is heavily loaded. More pressure in the air bags fixes that though.

Because the load puts the driveline back out of alignment?

 

[GFritsch]

Because the load puts the driveline back out of alignment?

Thats my guess too. Before the TSB it didn't shudder when loaded heavy, but since most of the driving is empty and the air bags stop it loaded now everything worked out .

 

[JHardwick]

Thats my guess too. Before the TSB it didn't shudder when loaded heavy, but since most of the driving is empty and the air bags stop it loaded now everything worked out .

I'm guessing that the driveline should be neutral only with a light load. No load and a heavy load should create opposite misalignments. I'm still convinced that its all due to dry ujoints. If it were a one piece shaft we would never feel it. The two piece shaft wallers in the carrier when a joint gets stiff and dry.



On the one piece vs. two piece deal ... ... ... ... ... all long framed, big torque trucks had 2 piece drive shafts once upon a time ... ... ... ..... my girlfriends '02, 4x2, shortbed Chevy has a 2 piece driveshaft in it

 

[GFritsch]

I'm guessing that the driveline should be neutral only with a light load. No load and a heavy load should create opposite misalignments. I'm still convinced that its all due to dry ujoints. If it were a one piece shaft we would never feel it. The two piece shaft wallers in the carrier when a joint gets stiff and dry.



On the one piece vs. two piece deal ... ... ... ... ... all long framed, big torque trucks had 2 piece drive shafts once upon a time ... ... ... ..... my girlfriends '02, 4x2, shortbed Chevy has a 2 piece driveshaft in it

You could be right. In my case though it shuddered right away. I was told by the dealer I got it that it would go away after a few miles. Took it to Elk Grove Dodge (a dealer closer to home) after it had about 5k miles. They did the carrier alignment adding a shim and the shudder was gone unloaded. At this time the U-joints were fine. Now with 15k on the truck it might be time to have another look at them.



I wonder why the two piece design? Could 2 drivelines and the carrier assembly be cheaper than a one piece?