NV4500 clutch issues

[E4ODnut]

First a bit of history.

Several years ago I went looking for a truck, a particular truck. I wanted a Gen 2 Dodge, 4x4, extended cab, full size box, 488 V10 with the NV4500 5 speed. Turned out these things are in rather short supply. I finally found a '95 on a used car lot. I checked it out. It was rough. Lots of rust, but it seemed to run well so I bought it. Paid too much, but sometimes you have to do that to get what you want.

Anyway, it didn't take long to realize the engine burnt oil, a lite per about 750 Km. Compression was good and it ran fine, but smoked heavily on decel. OK, I said to myself, I'd better figure on overhauling the engine sooner or later, but I digress. Another interesting problem was that the clutch would chatter on engagement. Not really bad, but it was there. Also it didn't engage until the pedal was almost all the way out. At ~265,000 Km on the odometer I figured that the clutch was probably original and just about worn out so all I would have to do would be to replace it.

The truck itself however, was really beyond economical repair so I went looking for another one, except it was just the body and frame I needed, I didn't care about the drive train. Eventually I found an '01 with a 360 auto. The body and frame were quite good but the engine had a serious knock, and it had other issues. I bought it for a fair price and the conversion project was on. Almost. I had to wait a couple of years as we had just committed to build a new house, but I digress again.

When I finally got around to cannibalizing the '95 I found that the clutch didn't look all that bad, the flywheel was a bit glazed, but I've seen a lot worse. I had the fly wheel re-surfaced just to make sure and bought a new Sachs heavy duty clutch kit. Matched unit, disc, pressure plate, pilot and throw-out bearing. I have the factory service manual for both trucks and was very careful to follow the clutch installation instructions, except I didn't check the clutch disc for run out or the transmission for alignment. This was probably a mistake, but I've installed several clutches before and never had a problem.

The day finally came for the maiden voyage. What a shock! The clutch chattered just as bad, if not worse than before. But there was a difference. Now I had to have the pedal right to the floor before it would fully disengage and yet it didn't seem to fully engage until almost fully released. The clutch actuator is hydraulic. Sealed unit. No adjustment.

What the hell? Back into the book, back on google. Turns out clutch problems can be difficult to diagnose. Tell me about it!

So, as I see it, it could be one or more of several things. Could be the transmission is out of alignment with the clutch housing. Dowels are in and snug. Could be the flywheel wasn't re-surfaced true. Could be the clutch disc has too much run out. Could be there is something wrong with the pressure plate. Could be something else I didn't think about.

Anybody gone through this before and have any suggestions?

 

[E4ODnut]

Since I posted this I've been doing as much research as I can as to the possible causes of my problem. I am hoping beyond hope that it is not the clutch, or alignment and something external because pulling the clutch is a big deal. I don't have a hoist and I only have a transmission adapter for my floor jack.

Anyway, I decided to check what I could. First I checked all the bolts for the mounts, flywheel housing , transmission and transfer case. All tight. Same for drive line bolts. U joints and steady bearing are good. Next I checked all the engine mounts. If I open the hood I can see the engine from in the cab. There is no sign of engine movement when I engage the clutch with lots of chatter. To confirm this I used a hydraulic to jack at the transmission mount point and both engine mount points. When I jacked at these points the engine and frame came up together. Same at the transmission and cross member. If I take off the sheet metal inspection plate at the bottom front of the flywheel housing I can check the crankshaft for end play and flywheel run out. The end play was ~.004". Factory spec is .003" to .012". Wear limit is .015" Run out measured at the back of the flywheel was ~.002". Limit is .003". There is no sign of any oil leakage anywhere on the engine, especially around the area of the flywheel and clutch.

Looks Like I am just going to have to man up and pull the clutch, do an inspection and check the disc run out, flywheel run out at the clutch facing, flywheel housing bore run out and face run out.

 

[E4ODnut]

Update:
OK. I finally faced the music and tore the truck apart to see if I could find out why my new clutch is shuddering on take off. To make a long story short everything looks good except for the clutch housing alignment. It is out of spec in the register runout and the face run out as well. No big deal, just get offset dowel pins for the register and shims for the face, says the factory manual. But no. I don't have dowels like the manual says, I have what looks like a big roll pin and a bolt goes through it. Maybe that's what the diesels have. The manual doesn't describe what the diesel has, but just states that if you are out of spec on a diesel replace the housing or the adapter plate. Any one run into this before?

 

[E4ODnut]

Update: Here's what I had checked. Flywheel was re-ground and in excellent condition , flywheel runout was within spec, crankshaft end play was within spec, engine mounts were good, U joints were good, drive line alignment was good, no sign of axle wrap, transmission input shaft end play was good, input shaft splines and pilot spigot was good, engine running good. The only thing left was either bell housing bore alignment, face run out or the new clutch kit itself. I measured .016" total Indicator Reading (.008" offset) on the bore. Maximum allowable is .010" TIR (.005" offset). The bell housing face was out of parallel with the flywheel face by a maximum of .014" at the bottom right transmission to housing bolt. I got a machinist to make me a set of .008" offset bushings to correct the bore offset to .0035" and I used shim packs between the transmission and bell housing to correct the out of parallel condition. I wasn't going to risk installing the Sachs clutch again so I bought a new LUK OEM replacement. Result was shudder gone, completely. I committed a cardinal sin when I changed both the alignment and clutch so I will never know for sure exactly what caused the shudder. I suspect a bit of both.