Clutch shudder

[JJump]

I recently bought a '93 D350 LE Dually with a 5 sp & a 4. 10 LSD rear axle. The truck has 110k miles total and there is a note in the owners manual stating that the clutch was replaced at 64k miles. My truck has a low frequency shudder from a stop that gets worse if I give it some throttle during engagement. To avoid the shudder I have to engage the clutch with the engine idling and not give it any throttle until its fully engaged. It is not really noticeable when cold but gets worse as the truck gets warmer, and is especially bad (sometimes downright violent) when I start backing up a grade. All this gets amplified when I'm towing the trailer (13,700 GCVW). Once the clutch is engaged & the truck is moving there is no problem. I have no problem with clutch slip or disengagement for shifts, and have no problem putting it into gear while stopped. It acts like there is a tight spot between the the flywheel & pressure plate that catches the friction (driven) plate in one spot. Once there is no relative motion between the driving & driven elements everything is fine. Interesting to note, I had the exact same symptom on an old '88 D150 short bed that had a 318, a granny low 4 speed, & a one piece drive shaft. I attributed the problem on the old truck to a bad spot on the flywheel or a pressure plate not lifting square- Hmm, is there a pattern here with Dodge trucks?



Today I was reading the forum for new owners. In a post written last November by Nascar Mark he said...





"2nd tip would be placing a 3/8" or 1/2" shim under half shaft steady bearing if you have a shudder in drive line, under power off the line. "





Boy, that sounds like what I'm experiencing! Is he referring to the problem that is listed in the Service bulletins for the '93 trucks? I thought that was referring to automatics and when shifting between gears. Could this be the source of my problem? Perhaps a contributor?



Any advice/comments appreciated-Thanks for the help!



Joe Jump

St Louis

 

[BCook1]

Same Shudder

Greetings,

I just bought a 92 w250 and it had the same shudder. In fact, my 82 w350 shook so violently that I had to make a custom set of ladder bars/four link bars to stop it. My 92 would shudder slightly going forward, slightly more forward with a load, even more backing up and sometimes, with a load backing, it would hop violently. First I replaced the rear springs with a softride set of 6" over stock springs and dumped the factory 6" blocks. The shudder was still there but not as bad. Next, the throwout bearing and the t-case input bearing started making noise so while the cases were out I had the flywheel resurfaced and a new con-o clutch from south bend put in. After 3000 miles of mostly towing, the shudder has been almost totally eliminated. I don't know what will happen as the clutch wears in but the improvement is significant. The problem, in my opinion, lies in a combination of factors which all amplify each other. The front spring mounts on the rear springs are too short - look at a GM truck sometime. If the mounts were longer, you could use a flatter spring without the blocks. Also, don't discount sticky u-joints. My rear is getting replaced this week because there is a shudder during turbo spool up under load. I expect the new rear joint to solve this problem.

If the problem is so violent that you think the truck is going to come apart, I can email you directions on how I built the ladder bars for my 82 - Those stopped 95% of the shudder in a 6" kit with 4" blocks and did not adversely affect the ride.

 

[Philip]

That is a TSB that was put out by Dodge. It mostly concerns the $X$ trucks. The 4x4 trucks has a 6' lift block between the springs and the axle to help level the truck out. Yours being a 2x4 model this should not be an issue.



I think you need the flywheel resurfaced. Most likely who ever replaced the clutch went cheap and didn't from the sound of it.

 

[BCook1]

Tried to reply but???

Greetings,

I tried to reply but it did not show up - sending this to see if it gets on the board.

 

[dpuckett]

JJump-

You mentioned giving it some throttle when starting. Not sure if this is right or wrong, and it probably depends on who you talk to, BUT, I never give it any fuel to start- loaded or empty. Sometimes when starting a load on a hill, I'll give it a LITTLE fuel as I engage the clutch. EMpty, I let off the pedal in 2nd, but the 4. 10s help that. If you do it like a gasser, you'll make the clutch shutter, bark tires, and in general embarass yourself. THe higher rpm engagement isnt good for it, I know, just not sure exactly how. Someone else chime in here and correct me.



I'd agree with Philip- flywheel may be glazed a bit.