dodgec68

I have a 92 dodge diesel and am getting a slight knocking and vibration at about 2000-2300 rpms, I already put new u-joints in the truck. anyone have any ideas?

2stroke

auto, or manual? 2 or 4x4?

loch

I'm guessing it was doing it before the u joints ?

dodgec68

Its a 5spd, 4x4
yah it was doing it before the u-joints were replaced
the u-joints were causing the front axle to bind when turning in four wheel drive

farmer0_1

if it has a carrier bearing in the rear drive line take a good look at the rubber and bearing.

JimmieD

The answer also depends on whether the knocking is at 2000-2500 in every gear, or only in top gear?

dodgec68

The noise is in every gear it is just more noticeable in 3rd, 4th, and 5th every once in a while I have heard it in 2nd. and the rear drive line is a one piece

JimmieD

Well if it's in all gears at the same rpm that pretty much eliminates u-joints, driveline or axle problems. It would have to be in a component that is in front of the tranny output shaft. Possibly tranny input shaft bearing? Not a good thing to hear of course

dodgec68

I was own in california for christmas and I pulled the tranny and transfer case to check and see if anything was broken worn are loose and everything seemed good, it doesn't really have any end play at all in the input shaft on the tranny. is there any way my clutch, pressure plate, or flywheel could be jacked up? didn't really have any hot spots, slight grooves on fly wheel an pressure plate byt they were mooth, also good clutch material left on both sides, It just seems to me that it should be the clutch?

thanks

JimmieD

I have very limited experience with Dodge/Cummins trucks, however I have seen in several threads that there can be a clutch plate hub problem on some models. There is an 'upgrade' clutch plate available but I saw that the warranty for it covered everything EXCEPT anything related to cltuch hub! That was a Sachs clutch far as I know and I asn't impressed with the quality.

Also I purchased a different Sachs ceramic button clutch and had to send it back. There's like 8 or 9 'ceramic buttons' on the clutch plate and the one I got had messed up rivetting on 7 out of 8 of the segments. Total junk! Would have failed within months if not weeks or days.

There is a procedure described in the FSM for checking clutch -pressure plate - flywheel runout. Runout is the relative alignment of those components in relation to bell housing adapter, bellhousing and transmission & input shaft. In the case of misalignment problems can develop over time and one of them is vibration caused by imbalance caused by uneven wear on components. You need a dial indicator and magnetic base, and tranny has to be pulled but otherwise it's fairly easy to check with FSM instructions. It's quite possible that these runout issues contribute to the known clutch hub failures in my opinion. They certainly can cause a vibration or harmonic distortion to develop at certain rpms.

In addition some of the Cummins flywheels are prone to cracking, sometimes due to improper clutch operation by the driver. I bought one that was cracked through in 3 places at 12 o'clock, 3 o'clock and 6 o'clock on face, with the obvious assumption that 9 o'clock was cracked but didn't show it yet. Extreme heat from slippage and questionable metallurgy causes this problem. The potential is that the flywheel would explode under pressure! The one I bought used was ready to grenade at any moment!

The flywheel has some special machining required to resurface. If not performed properly by a Dodge/Cummins experienced shop later failure is a sure thing. They're ground sort of like a hollow ground knife blade with a special process.

That's all I know, bro!

dpuckett

The bellhousing runout problem is associated with the NV4500s and their related parts. The stock Sachs clutch is the best clutch out there, short of going to SBC, et al. Bigger clutch disc, larger surface area, etc. The LuK upgrade is junk, IMO. I have one on my 90 from a previous owner, and I dread getting to to hold, esp i fmy experience from the ProGold line is any harbinger of things to come. But when I sell it, I can say it has the "upgraded" clutch.

Daniel

dodgec68

thanks for the input, guess I should check on the price of a flywheel. I am probably going to have to pull it again and take a real good look at it and find a shop to resurface it. and this time while its out i am going to stick a new clutch in it.

also what about the possiblity of it being the harmonic balancer?

JimmieD

Yes, Daniel, much of the runout problem was associated with the NV4500. However it's actually standard practice when doing a first class clutch job to check runout with any bellhousing, flywheel and transmission. Manufacturing methods being what they are nowadays, or even in the past, the parts don't always fit the way they should. Also from the description of his problem it's a likely candidate for suspicion.

I was surprised to find that a CTD Sachs clutch I ordered, new, was built by LUK for Sachs! I had to go through three Sachs clutches before I found one I'd put in my truck. Sure hope it holds up. The worst was the LUK/Sachs button ceramic. It wasn't even a good paperweight. Seems like anymore whenever I buy parts from almost any vendor it's like rolling the dice and holding your breath to see what you're going to get this time....?

dpuckett

JimieD- hadnt thought of it that way. It just seems that many who post replies and solutions get their generations mixed up. The 12v are all old by now, so who really cares, right? Being from Southeast MO, I wouldnt know about or have any experience in doing/ getting first class anything, so forgive my ignorance.

There is a TDR member who came across some Sachs 13" clutch overstocks. If I put anything else (non-Sachs) in my trucks, it would be a South Bend of some sort.

DP

JimmieD

Yes, DP, it was a surprise to me too!

A buddy who is a L-O-N-G time drag racer of some repute told me I needed to check runout. Yea, right I thought, I ain't racing a built 440, bro. Then a friend e-mailed me the FSM section on NV4500 and CTD clutches. Hmmmm....interesting. Then I looked in some vintage Motors and Chiltons manuals and some Haynes manuals and saw mention of checking runout. D/C's Mopar Performance books explained it too. Further research made it clear to me that it is a common problem and that around 99% of clutch jobs never include this process: even when the truck/car goes through clutches quicker than brake shoes!

So......