clutch problem

[FINOCJ]

After rebuilding the transmission, transfercase and OD, replacing the clutch components and putting everything back together, I've spent over week trying to get the clutch to work. The clutch cable adjustment both seems correct and is almost in the same place it was previously. The release bearing contacts the pressure plate after just a bit of slack is removed (0.75" according to service manual) and then goes through the full range of motion to release the clutch...but the clutch doesn't release. The pressure plate may not be correct, but it sure seemed identical to the old one. The clutch fork and release bearing are also identical. Just to make sure it wasn't something it the linkage or too much slack, I removed all slack manually pulled the fork to its maximum and bottomed it out...still no release. I put my fingers in along the fork and verified its correctly sitting on the pivot. Can't truly see or verify how the release bearing is sitting on the fork and input sleeve, but from tiny hole on the top of the bellhousing, I can see that it is moving along the shaft fine with the fork, and I can feel when it engages with the diaphragm.

So, maybe the pressure plate is not functioning properly, maybe the clutch disk is somehow 'stuck' to the flywheel and doesn't release when the pressure plate releases, Or...final idea, is it possible that the pilot bushing is too tight on the input shaft tip and not allowing for rotation. The later two seem unlikely to me - a malfunctioning pressure plate, or somehow the wrong one seems more likely. Don't really know anyway to address this except to take it all apart and look at things closely and compare to the old stuff - was hoping to avoid this but.... There is also still the chance I put the clutch disk in backwards somehow even though my install pic indicates it correct.

[Jim]

Have you tried to start the motor with the jeep in gear, clutch to the floor, brakes applied? Will the motor freely spin or is the clutch wholly "connected"?

[Patrolman]

Two issues that I have run into before are putting the clutch disc in backwards or the splines on the clutch disc not fitting and sliding correctly. The disc needs to slide smoothly on the splines of the transmission.

[FINOCJ]

Jim previously posted:

[dieseldoc]

Glad things freed them selves up.
Pulling things back apart is never any fun.

Side note....luck clutches and fly wheel kits will need a luck clutch replacment later down the road.
Twice now with Cummins trucks I have had some other manufacturers clutch and the luck flywheel, no worky!
The luck flywheel the won't let the other manufacturers stuff disengage.
Ok nice a luck was installed in its place all worked just fine!

[FINOCJ]

My clutch is working fine in terms of function...but its connected in some way to a bad 'knocking' or 'tapping' noise. I had this noise before I re-did the clutch and transmission/TC rebuild, but now that I got rid of all the bad clutch noises this knocking noise is much more prevalent. I guess I originally didn't isolate the sound and assumed it was related to the rest of the clutch noise as it is directly tied to whenever the clutch pedal is pushed (doesn't have to be pushed all the way in, just lightly pushed such that the TO bearing comes in contact with the pressure plate a bit). But the new clutch is quiet and smooth, and I can really identify the sound is coming from in front of the flywheel - like up inside the back half of the oil pan.

Just because its tied to clutch pedal movement its easy to jump to the idea its the TO bearing or similar...but while its knocking I put my hand on the clutch fork and it does not have any vibration or movement - same with bellhousing. I also removed the front bellhousing dust cover and investigated flywheel and teeth as much as possible both static and while running. I was worried that it could be the ring gear teeth hitting something inside the bellhousing, but the bellhousing doesn't have any vibration either. I even loosened the starter and moved it around to see if it was hitting something, but no solution there either.

So I am worried that its something tied to the engine or crankshaft etc. Is there anything in there that could be making this noise, especially considering its directly tied to clutch movement? With the clutch engaged (pedal out), the engine just hums along smooth and quiet (even for an odd fire). As soon as pedal is pushed...clunk, clunk, clunk... The frequency is tied to engine rpm. I don't have any experience with engine internals...but feel like the next step is to drop the oil pan and just take a look. Something might be obvious (and probably expensive). I do have good rear main seal leak - not sure if that seal could be part of the problem.

Any ideas? Thanks

[redneck23ms]

it doesn't make the noise while in neutral? only when the clutch pedal is depressed? if so then i'd say its most likely not an engine problem. did you replace the pilot bearing? did you inspect the flywheel for cracks? check the flywheel to crankshaft bolts?

[Jim]

I'm not going to be much of help with this. Have you used a hose or wooden listening rod to listen / move around to locate the source of the noise?

[FINOCJ]

redneck23ms previously posted:

[Jim]

FINOCJ previously posted:

[Hypoid]

FINOCJ previously posted:

[FINOCJ]

Hypoid previously posted:

[Hypoid]

Harmonic Balancer.

Check your service manual for crankshaft end-play specifications, but a few thousandths of an inch is pretty much the norm. If you can actually see end play, you are way over those service limits.

[FINOCJ]

Thrust bearing was also suggested by a few friends from early cj5. I am not great at doing these small dial indicator measurements but here is what I got: crankshaft endplay of 0.02 (20 thousandths), and that was both prying the front crankshaft pulley in and out by hand as well as prying it in and then pushing the clutch in to move it back forward. If anything, the measurement would err on the side of too large as I couldn't put the magnetic base on the engine block and get the dial indicator to fit, so I mounted it on the front axle. I believe the 'normal' specs would be 0.004-0.008 for the Buick 225? So how serious is my extra endplay - I don't have any feel for engine tolerances.

One question that came up is that thrust bearing end play can cause a single 'thunk' or knock every time the clutch pedal is pushed in or released, but only one time. As long as the clutch is continuously disengaged (pedal in) and thus the forward pressure is not released, repeated 'knocking' cannot occur? I would really like to see if I could stop the 'knocking' by pressing/holding the crankshaft pulley in (or out) to see if its vibrating back and forth. Just not sure how to do that with it actually running and spinning and fan blade close by etc.

[Hypoid]

Yeah, it is easy to measure when your engine is on a stand. I can't find any service limits with my googler, I'll dig around to see if I still have some old manuals for your CJ.

[Hypoid]

I found that old manual (P/N SM-1046, reprinted 1973), but no service limits are listed. I don't want to speculate on acceptable wear limits.

The question remains: Is there enough end-play for something attached to the crank to be hitting? I would try to look at the back of the flywheel, see if there are any fresh witness marks. While I had the inspection cover off, I would induce the noise, just to see if it changes with the bell housing open.

Do you think it can make the drive to Golden?

[Hypoid]

FINOCJ previously posted:

[FINOCJ]

My 1970 service manual doesn't seem to have any limits either - just initial set-up specs. I had the bellhousing inspection cover off and nothing seemed unusual with the flywheel etc even when running and making the noise. That is partly why I think the noise originates in front of the flywheel in the crank area. I put my hand on the flywheel when hearing the knocking and can not even feel it in the flywheel or on the clutch fork etc. Of course, the odd fires run a super heavy flywheel to dampen the vibrations so it also may be dampening the knocking.

It can certainly make it to Golden. I actually drove it around town quite a bit today. It was doing this before I started this project and I wasn't as concerned then, so to heck with it. Worst thing that can happen is I blow up and old classic motor and have to spend more money and time. I need to change the oil pretty soon so I figure I will drop the pan and see if there is anything obvious - maybe try to 'push and pull' anything that I can to see if one of the main bearings has gone. Another CJ5 member had a similar issue/sound and it was a piston skirt issue (probably aided by wear on the pushrod and bearings). I am guessing something in that area is on its way out - not sure how long it will take - but I am guessing its got some time.

[FINOCJ]

Hypoid previously posted:

[Hypoid]

FINOCJ previously posted: