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.
https://www.dieseltruckresource.com/...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

 

Chrysler does not recomend resurfacing flywheel more then .003
No resurfacing on flywheels used with Cummins Engine. This was from tech connect web site.

Clean or replace flywheel as required. See note provided. Clutch surface on flywheel worn excessively or heat scored. Replace flywheel. If flywheel wear and heat scoring is minor the flywheel surface can be manually cleaned using (60) grit sandpaper. NOTE: The flywheel can be machine resurfaced by no more than (,oo3") if required to remove minor surface wear and heat scoring. IMPORTANT: Flywheel used on models with hydraulic clutch release system (non-adjustable) can not be machine resurfaced. No adjustment available to compensate for dimensional change to flywheel. Replace flywheel if clutch surface wear is excessive. CUMMINS DIESEL ENGINE MODELS: Flywheel used with Cummins diesel engine can not be resurfaced. If flywheel is resurfaced the special bolts used to retain the clutch cover will bottom out before proper clamp load on clutch disc is attained. Clutch slippage may occur. Replace flywheel if surface wear is excessive.

 

Hmmm...

Now THERE is a revelation I've never hear before!

So the PP retention bolts are only 3 thousands shorter than the depth of the tapped holes?

I'm certainly going to ask the machine shop as they knew it was from a Cummins engine. Can you provide any reference for the material so I can mention it to the shop?

 

Sounds a little like my SB OFE clutch. It's always a little grabby, but will really buck the truck when hot. Doesn't like backing 20k lb trailer uphill at all.
Agree with replacing the flywheel instead of resurfacing. Get the upgraded pilot bearing too.

 

flywheel diagnosis and testing, I would replace the flywheel, then check run out before bolting everything back up.

DIAGNOSIS AND TESTING
Check flywheel runout whenever misalignment is suspected. Flywheel runout should not exceed 0.08 mm (0.003 in.). Measure runout at the outer edge of the flywheel face with a dial indicator. Mount the indicator on a stud installed in place of one of the flywheel bolts.

Common causes of runout are:

heat warpage
improper machining
incorrect bolt tightening
improper seating on crankshaft flange shoulder
foreign material on crankshaft flange
Flywheel machining is not recommended. The flywheel clutch surface is machined to a unique contour and machining will negate this feature. Minor flywheel scoring can be cleaned up by hand with 180 grit emery or with surface grinding equipment. Remove only enough material to reduce scoring (approximately 0.001 - 0.003 in.). Heavy stock removal is not recommended. Replace the flywheel if scoring is severe and deeper than 0.076 mm (0.003 in.). Excessive stock removal can result in flywheel cracking or warpage after installation; it can also weaken the flywheel and interfere with proper clutch release.

Clean the crankshaft flange before mounting the flywheel. Dirt and grease on the flange surface may **** the flywheel causing excessive runout. Use new bolts when remounting a flywheel and secure the bolts with Mopar Lock And Seal or equivalent. Tighten flywheel bolts to specified torque only. Overtightening can distort the flywheel hub causing runout.

 

Sounds like a new flywheel may be in order.

You mentied this started when the engine was rebuilt, so I thought I'd also mention that I had a friend with a gas rig and clutch trouble, that turned out to be thrust bearing in engine way out of spec, allowing the crankshaft to move forward and aft as the throw out bearing presses into the pressure plate.

Hopefully yours is just the flywheel, but I thought I'd mention the above, as it isn't something I'd have immediately thought of.

 

Lots of things there-

The flywheel.
The first overhaul, I didn't have the flywheel resurfaced (it looked perfect) and I just de-glazed with emery cloth, and it shuddered.
Second overhaul (due to rings not seating) I did have it resurfaced (thinking the failure to have it done caused the shudder) and it shuddered.

Second overhaul the shop said they re-used NONE of the used parts, so would they have screwed up the thrust (end play) BOTH times? Hard to say.

I don't know what contour they use on the OEM flywheel, but it LOOKED flat when I deglazed the "virgin" flywheel first time.

This is the 3rd time it was out, and at least 2 of the times, I know the flywheel was installed on a clean flange and properly torqued (second time a shop did it when I wasn't present).

I am not eager to have it pulled again (since unlike THIS time when I did myself w/ a friend in a shop) I don't have a good place to R+R it and the NV 5600 is a HEAVY sucker, since I will have to pay for it. So I'd like to examine and try ANYTHING reasonable before paying big bucks for a FW swap.

Others advised me to shim the center carrier down a bit (since w/ the Steady-Loads and air bags the truck sits a tad high in back, affecting the driveline angle. If I DON'T do that, even w/ the SteadyLoads and Rancho 9000X shocks, it rides HARD with a ton of truck camper in the bed plus trailer tongue weight (or alternately the 2000 pound pin weight of my 5th wheel on the hitch) and will bottom on nasty bumps.

They also suggested that the pinion angle could be off just a tad, suggesting a 2 deg nose down static. I need a level spot to check that.

I just ordered new OEM type engine mounts. The clam-shell design precludes really checking them for sag in place, so I am just going to change 'em on suspicion seeing they're 140k/12 years old. Both were only $61 so no big expense compared to a FW at this point.

Anyone have a clue if driveline angle can cause shudder on clutch engagement at zero speed, or does it ONLY affect vibration once the truck is moving? My shudder STOPS as soon as my clutch is fully engaged and is rolling.

To ME, it seems like it would be all in the bell housing, but I confess to knowing NOTHING or I'd have this fixed and be a happy camper by now!
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BTW, I've been doing a LOT of reading, and I came across the term "Launch Shudder" and I am Googling it, but came across this post that duplicates my experience 100%, and many experiences are with a 2008 6.7 Cummins AUTO transmission:

"I get a wicked shudder sometimes on a 1st gear take off sometimes, and I really get it backing up a trailer in reverse, the truck kinda feels like its power hopping. It never did it before, would that have something to do with my clutch or would that be U-joint related too?"

https://www.dieseltruckresource.com/.../showpost.php?
p=2151017&postcount=7

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Also found THIS:

The TSB# is 03-003-04 on 6/15/04.
Launch shudder.
This bulletin involves adjusting the propeller shaft working angles and applies to vehicles
equipped with a two-piece rear driveshaft. The problem is described as a drive line shudder or
vibration while accelerating from a stop. The condition is most noticeable under heavy throttle
acceleration and is usually present only at low speeds (below 25 mph). Vehicles equipped with
a two-piece driveshaft are designed to minimize reaction forces that result from the universal
joint transmitting torque at an angle. These forces cannot be eliminated entirely because of the
necessity to compromise joint angle selection between curb and design loading conditions. Ujoint
angles change depending upon the amount of weight applied to the vehicle bed. Therefore
U-joint angle readings may need to be taken with different vehicle loads in order to obtain a
satisfactory compromise. The vehicle should be evaluated under the loaded condition that
produces the objectionable disturbance.
The repair procedure involves measurements at the transmission yoke, front propeller shaft,
rear propeller shaft and rear axle. The working angles should be adjusted to provide the lowest
angle possible for the output shaft to front propeller shaft, front propeller shaft to rear propeller
shaft, and rear propeller shaft to axle pinion. The measurements will determine which direction
to move the center bearing to optimize the angles. Install the appropriate bracket to obtain the
minimum working angle, but still maintain at least ½ degree to ensure that there will be some
movement in the U-joint bearings.
dropmech is offline Report Post
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Not sure exactly what it's saying to do, except I THINK it says to basically equalize the angles for the two halves of the driveshaft by lowering the carrier bearing using shims (since to achieve the lowest angle, they would have to be equalized)?

Any translation to non-technical appreciated!

__________________________________________________ ______________
Just found ANOTHR TSB:

http://dodgeram.info/tsb/2004/03-003-04.htm

 

I'm no expert, but if you had the same suspension and same driveshaft setup before the rebuild and before this shudder started, I wouldn't think that would be the problem- unless things didn't go back together exactly as they were.

I wonder if a person could set up a dial indicator on the front of the engine, zeroed on the crank pulley, and measure any movement when the clutch is pushed in?

 

That would show end play on the crank, OK, but the one caveat I mentioned was that before the first O/H I hadn't actually towed w/ the truck. I said the clutch FELT butter smooth solo, but w/o actually towing, I can't say for sure that it wouldn't have shuddered with a load.

More investigation has turned up a term I was previously unaware of called "Launch Shudder" that perfectly describes the condition I am experiencing, and it seems that pre-'08 trucks suffer from it due to their 2-Piece driveshaft. In '08 Dodge started using 1 piece aluminum shafts and the Launch Shudder problem basically went away.

Here is a thread that is long, but the conclusion is that the only way to eliminate it under all conditions is the later type 1-piece shaft, though those w/ the NV5600 trans have to adapt the later shaft length by cutting and welding to fit because they never fitted one-piece units to the earlier transmission.

It's worth reading a few pages of the thread to get an idea how pervasive this condition is for the earlier, 2-piece shaft trucks. The TSB to shim the center bearing down is a stop-gap that often doesn't present a true "solution," though I'm going to fool with it to see if it makes ANY difference, and if it does, it pretty much shows the problem is NOT inside the bell housing I'd say.

Many of the guys say that shimming can optimize the shaft for either loaded or unloaded conditions, but often, making the shudder go away UNLOADED caused shudder loaded, and if you set up for LOADED condition, unloaded will shudder. Maybe using my air bags, I can keep the ride height constant loaded or unloaded, so the "compromise" center carrier location will work.


Thread:

https://www.dieseltruckresource.com/...e-t202733.html

Here's a shorter thread I found on adjusting pinion angle that reaches the SAME conclusion about 1-Piece Driveshafts:

https://www.dieseltruckresource.com/...g+pinion+angle

 

Interesting. I've read about the one piece shaft conversions, but I've had two trucks with the two piece shaft and neither have ever exhibited the shudder- empty or heavily loaded.

Maybe it would be worth trying.

 

If you read the threads I linked to, a LOT of folks have had my problem I gather.

I will try the TSB 03-003-04 procedure of shimming the carrier bearing first, but if that AFFECTS, but doesn't cure the problem, the 1 pc driveshaft might be the final solution.

 

Yeah, that sounds like the most reasonable approach.

 

I have read the shudder can be cured by putting some LSD additive in the rear end. Guys on hear have done it and corrected the shudder issue.

 

If I had a LS Differential perhaps it would help.

But even a LSD shouldn't chatter if the truck is not turning, and asking for differential wheel rotational rates side-to-side. The mechanisms only are active if they are asking for slippage, if I understand things properly.

I received my new front engine mounts, and will install them in case mine have sagged a bit, and altered the axis of thrust of the powerplant/transmission. A couple of degrees there will alter the rear driveline angle as well, of course.

 

Just try what I said. Don't over analyze it.