VIOLENT Clutch Shudder

[bobinyelm]

2003 Ram Cummins 3500, NV 5600 6spd trans, 139k miles total
(Eng and trans remanufactured at 109k due to blow-by from a broken ring, but was running flawlessly)

I've posted this before under driveline and clutch chatter, but I've done a LOT of reading and work since then and think the correct description is Clutch Shudder, and even found a thread from a long time ago that duplicates my situation exactly.
http://www.dieseltruckresource.com/d...er-t26249.html

I reported what I've done (as recommended by talented techs):
I ended up:

1) Checking driveline angle
2) Replaced Clutch Assembly (OEM type organic lining), PP, throwout, etc.
3) Resurfaced Flywheel
4) Replaced all driveline U-Joints and Center Carrier Bearing
5) Replaced Rear Trans Mount

The shudder is 95% GONE in forward gear, but when BACKING on a slight incline with even a light trailer, the shudder is INTENSE! It's less when cold, and worse when hot or at operating temperature.

The front of the entire truck starts hopping up and down that not only does it rattle the teeth of the driver, but observers can see the front end bouncing up/down at a very rhythmic oscillation rate. It results in basically NO movement of the truck-only violent bouncing.

There's no feedback (vibration) through he clutch pedal, or in the gearshift lever.

The movement appears to be straight up and own at the front of the truck, and you can't much rearward force to reverse the truck.

This is at idle rpm (foot OFF the throttle completely), or elevated rpm feathering the clutch.

The engine mounts LOOK good, and there's no noise from them, but I will replace them in the next few days. There's nothing else to change after that!

Any NEW ideas?

The old thread I posted showed the dealer (under warranty) replaced EVERYTHING inside the bell housing, and it evidently cured the problem.

I have replaced EVERYTHING EXCEPT the flywheel (having had it properly re-surfaced by a great machine shop that did the circular finish, and not a "lathe" type cut).

Any opinions whether it could STILL be the flywheel, or something else (rear face of the crank not perpendicular to the axis of rotation, trans not perfectly centered to crankshaft, or ).

My engine was remanufactured by a fleet shop specializing in Cummins, and it was after that the problems with shudder started. That was 5 years and 30,000mi ago, and since then the flywheel was machined twice, and the clutch assy replaced twice (as well as other "fixes" that didn't, though they made some small improvement under most circumstances).

Either I still have a flywheel problem, or something else I am only guessing at it would seem.

I've thrown a lot of money and parts at this, and I'd REALLY like to have it right.

As the guy in the linked thread said, "I bought this truck to tow, and being unable to back up with a trailer makes it useless as a tow vehicle." I AGREE more than I could say!

Any suggestions I haven't thought of, like bent trans input shaft (I also had the trans remanufactured at engine replacement), or

Thanks,
Bob

[Drew]

4wd or 2wd

If 4x4 there could be an issue in the transfer case, see how backing up acts while in 4hi and even in 4lo.

Did you also replace the hydraulics for the clutch? I'm assuming you did. If you did was the pedal adjusted properly so you have correct engagement?

Last thing I can think of would be the pinion bearing could have some slop in it, or the rear chunk has too much play between the pinion and ring gears.

[1970496STChevelle]

When you had the flywheel how did they resurface it?  Did they do it in a lathe or was it blanchard ground?  If they did it in a lathe it could have a directional pull causing chatter, just a thought.  Does it have the dual mass flywheel?

[Drew]

DMF's were on the G56's not the New Venture line of transmissions.  05.5 and up.

[kenz]

I agree, clutch shudder SUCKS! Experience it once in awhile myself. Although it sounds like yours is quite a bit more extreme than mine. As an example, drove roughly 150-175 miles pulling the 5'er. Got to camping spot and pulled into the grass opposite site to allow backing straight into the site. Forward no issues, backward she'll start to "hop"...best way to explain it. Will still move backward, seems less pronounced with more throttle. Now doing this on pavement or hard dirt surface there usually is no issues. If there is, it's hardly noticed. This is on a '05 2wd dually, original clutch, 108,000 miles. I always attributed it to a more difficult surface to push thru...as in very loose dirt, grass, etc.

Could possibly be the flywheel, but maybe the pressure plate? How heavy is the trailer? Does it happen empty? Mine almost feels like a slippage issue (grab, slip, grab, slip) might be that the trailer is heavy enough that you might need a plate with more spring pressure. Or possibly a different clutch material to hang on better.