Chasing vibrations...Don't leave out the clutch

[389driver]

I wanted to share my recent experience in hopes it may help someone.

I have a CM871 that, thanks to Rawze - was saved from a bad delete before I suffered a cracked head and God knows how much else. Thankfully I found Rawze and was lucky enough to be one of the many recipients of his generosity and am now happily enjoying the benefits of milk ;).

About 2 years ago (shortly after Rawze got me straightened out) my original Eaton 1850 Easy pedal clutch went out at 460,000 miles - mainly from the abuse it suffered from the PukeDits delete I ignorantly subjected it to. (They crank your HP up to 750+ whether you want it or not when you bend over for their "tuning".)

I went back in with a 2050 ft-lb rated REBUILT clutch from Inland Truck Parts - which is just a run of the mill reman from Mid America Clutch in an Inland Truck Parts box.

Things were pretty good after I got the clutch in. Except for the fact that i had some shuddering and slight vibrations. Below 1300 RPM under high torque load I would get a very slight shudder. Above 1500 RPM I had a slight rumbling/vibration. It wasn't enough to really concern me, but it was noticeable enough to get my attention.

Now, what you have to remember - is that I was coming off a bad delete. The noises and sensations I was getting from my engine while running the bad delete were FAR worse than I was experiencing at this point. My thoughts were that maybe something wasn't quite right yet, or maybe even a slipped injection cam gear. I backed off the timing advance to stock levels. That seemed to help. I left it at that and had convinced myself that these vibrations and shudders were just the result of a truck with 600,000 miles on it running without the "mandate."

Boy, was I WRONG!



I made 3 huge mistakes when I put that clutch in:

1 - I chose to use a rebuilt clutch and save a paltry $250 over a brand new clutch

2 - I thought I was being smart and applied anti-seize to the input shaft of the transmission. Lubrication is always good, right? WRONG!

3 - I forgot to clean the flywheel before I installed the clutch. The flywheel has oil on it left over from the resurfacing that I neglected to clean off. Rookie mistake, right?!?!


Maybe I made a mistake choosing a rebuilt clutch, maybe not. But I'm honest enough to admit that I screwed up on a couple of points when I installed the clutch.

The anti-seize on the input shaft come to find out is a big NO-NO. Too bad I didn't learn that earlier. I thought I was being smart and lubricating the splines the clutch disks ride on. This only creates problems. The lubricant will sling off the shaft and get in the friction surfaces of the clutch/flywheel/drive plate. It will also gum up over time and actually inhibit the free movement of the clutch disks when the clutch is released.


Forgetting to clean the flywheel was neglect on my part no question about it. I knew better, but just got in a hurry and forgot to do it.

Much to my surprise, my new clutch would sometimes slip. If it was early on a damp morning before the truck had fully warmed up the clutch would let go under high loads. After things got fully warmed up the clutch would hold. I decided I would give it some time to "burn in" before I tore back into it. After about 6 months the slipping stopped and I was happy.

So I thought...

Fast forward to about a month ago and I'm having clutch trouble again. Except this time I'm having trouble getting it to release. It will stop the truck, but getting into gear from a dead stop is sometimes difficult/impossible. Pressing the pedal a few times will get it working again, so I nurse it along trying to convince myself there's no way I'll be pulling a transmission again because this clutch is too new!

Then it finally gave up the ghost. It wouldn't release and all of a sudden I had triple the free play in the pedal. Stomping the pedal like a madman made no difference, so I committed myself to the idea I was going to be dirty for the next few days.

I got the old clutch out and the failure was obvious: in one of the disks the damper spring pockets had cracked out and one spring had completely come out - wedging itself between the disk and flywheel. The other disk looked completely normal. Coincidentally it was the disk against the flywheel that had failed - the oily flywheel I forgot to clean.

Now, you may be asking yourself why I'm telling you about this. Be patient the payoff is near.

I decided I was done with rebuilt clutches. So I bought a brand new Eaton 2050 ft-lb VCT plus with pre-damper (Eaton apparently strongly recommends a clutch with pre-damper disks on ISX's as they are more prone to idle gear rattle). I installed a new input shaft in the transmission along with a new input shaft bearing.

The shudder below 1300 RPM and vibration above 1500 RPM are gone. Completely. The truck runs as smooth now as it did when it was new. I still can't believe my shudders and vibrations were coming from the clutch. Whether is was a bad clutch, my faulty installation, or a combination of both I can't say. But he moral of the story is that if you have some weird vibrations you cant trace down, DON'T LEAVE OUT THE CLUTCH in your troubleshooting!

[Wiseman]

Please post some pictures if you have any . And man , you have some real writing skills ! Thanks !

[Rawze]

That is some very good info -- Thanks!.

[NewSon]

good points! much appreciated!!

[same101us]

I am planning on installing a new clutch in my 2007 peterbilt cm870. What kind of clutch would you put in?

[Hedley]

Go with an Eaton Solo Clutch, don't forget to reseal your engine bell housing and replace the input shaft on your transmission as well.

http://www.eaton.com/Eaton/ProductsServi.../index.htm

[Waterloo]

(07-31-2016 )Hedley Wrote:  Go with an Eaton Solo Clutch, don't forget to reseal your engine bell housing and replace the input shaft on your transmission as well.

http://www.eaton.com/Eaton/ProductsServi.../index.htm

RESEAL the bell housing... My buddy just installed a new clutch and input shaft, but did not do the bell housing seal... Major oil leak and $2400 later... On top of the clutch... And down time.... You do the math.