engine and drivetrain Clutch Wont Disengage - 5Spd Swap

[thehackmechanic]

Ben Thongsai says:

 

"A quick look through brings to mind:

 

Pilot bearing?

 

Did he answer if the pedal was firm through its entire travel? If so, could be a bad pressure plate or possible warped disc. Did he hang the trans on the disc on the way in or out with the trans? 

 

Also if the flywheel is machined too thin, sometimes the springs of the disc will catch on the flywheel bolts and cause some odd behavior."

[evanb]

Ok checked all parts and the seem ok. Pilot bearing is working fine, but seems really far out? I gave a shot with mallot and socket but it wouldn't budge. Check it out:

The clutch disk looks fine (not warped or broken) and was installed correctly.

Pressure plate looks to be working ok( I don't have a press but under my weight plus some bricks it traveled fine with no hangups).

I'm about to try the clutch disk and flywheel, see if there are any hangups. I'll report back in a second.

A shot of the flywheel lip, just for kicks I guess:

[Hans]

I take it the disc was not stuck to the flywheel or pressure plate?

 

What is that black stuff in the first pic?

Edited January 10, 2014 by Hans

[jgerock]

I wonder if the disc has become stuck to the pressure plate or flywheel. Yes, odd for fresh installation, but the end result would be the same.

That first picture clearly shows an impressive imprint of the clutch disk!  Not sure I've seen a better transfer.  Maybe that is what happened.

 

OR - maybe the inner clutch pack stuck to the flywheel (broke apart from the clutch)?????

Edited January 10, 2014 by jgerock

[evanb]

The red stuff on the flywheel is from the clutch. Red dust was present on delivery. Not dust exactly, not like it was flying of the clutch disk. But It was present as new and was transferred to flywheel.

Here's the clutch:

I also pressed the disk against the flywheel and there was no sticking. It cleared the flywheel bolts (at least under the pressure I was able to apply).

[thehackmechanic]

The pilot bearing doesn't look to far out to my eye; looks like about the right amount of room for the dust cap. I suppose you could check the pilot bearing by leaving the clutch out and putting the transmission back in, putting the trani in gear, and making sure you can rotate the transmission output flange. I guess you could even do this using the four-speed you took out, as it's smaller, lighter, and easier to muscle in for a test fit.

 

The "imprint" of the clutch disc on the flywheel is interesting. The question is, is it the cause or the effect?  Is the imprint an indication that the clutch sticking against the flywheel was the cause of the failure to disengage, or did the failure to disengage cause the imprint?

[thehackmechanic]

I have re-read every post, and I am looking at it from the "if it were my car" standpoint.

 

--It would drive me up the freaking wall if I make no changes, put the thing back together with the same parts, and it still exhibited the same problem. So you want to be as certain as possible about the components inside the bell housing. The ones outside (hydraulics), there's less downside being wrong about.

 

--Testing the throwout bearing and clutch lever consists of making sure the T/O bearing has the correct part number and measures correctly, that it spins freely, that the clutch lever moves it freely up and down the sleeve, and that the clutch lever has the pin beneath it and is held in place by the clip. You've done that.

 

--If the pilot bearing spins, it is probably fine. You've done that. You could, as I said above, pre-fit a trani without the clutch and make sure it still spins when the trani is snocked up hard against it, but I think this is unlikely to uncover an issue.

 

--You've verified that there doesn't seem to be a mechanical rotational restriction (clutch disc hitting flywheel bolts).

 

--The imprint of the clutch on the flywheel is a bit of a mystery. But it's a freshly-machined surface; it's going to be receptive. I think it's more likely its an effect and less likely it's a cause. 

 

--You have not directly tested the clutch pressure plate, and I'm not sure how you can. I suppose you could put it upside down on a hockey puck and press on it and watch to see the plate recede; I just don't know if you can push that hard, or whether an eyeball "I saw it move" is sufficient. I would call Ireland, read them the part numbers on the disc, plate discuss the problem with them, explain everything you've done. You might ask them if they have some way to test the pressure plate.

 

--If you put the pressure back in as-is and the clutch still doesn't disengage, then I think either the pressure plate is bad, or there's a hydraulic issue you/we didn't catch.

 

--If I was really quite sure the hydraulics were correctly bled and that the slave is working correctly, I would not put that clutch back in.

 

--Taking that logic and applying "if A then B means if not B then not A," I would only put that clutch back in if I learned something that made me think the slave was bad or I hadn't bled the system correctly.

 

We're pulling for you, Evan. You'll figure it out.

[skipsfcr]

I take it there was no cosmoline or other type of surface ptotectant on the freshly machined flywheel face when you installed the clutch? I'd also be strongly inclined to hold your slave cylinder up to another one to examine the pushrod length.

Edited January 10, 2014 by skipsfcr

[evanb]

I'm disinclined to think its a hydraulic issue at this point. When I did the "blade test" with the slave I got full movement, so I know the slave and master are working together to move the clutch arm.

The issue, as far as my limited knowledge takes me, has to be somewhere between the clutch arm and flywheel.

I can give the flywheel a wipe down, but as far as I can tell there's no protectant or anything on it.

The possibilities are:

Despite the slave moving a full 25-30 mm, the clutch arm isn't pushing the TOB far enough, or the TOB isn't long enough itself.

The pressure plate isn't working properly. It's not lifting enough for the clutch to release from flywheel.

The flywheel has been resurfaced improperly, and the lip for the pressure plate is not tall enough to allow its travel to release the clutch.

As far as I can tell, there is no test for any of this. I can call ie and see what they say about the flywheel, but like you said, it would come down to " well sure it moves, but is it enough?"

So! My options seem to be: devise some mad scientist tests to see into the bell housing while everything is hooked up, or just give it to a mechanic who has the time and tools figure this out, although That feels like a failure. definitely feeling beat right now!

[skipsfcr]

I was actually referring to the stationary length ofthe slave cylinder pushrod, rather than the distance of the pushrod's stroke. I don't have one in stock right now or I'd measure it for comparison. When you manually actuated the fingers of the pressure plate did you have it bolted to the flywheel? If not, I suggest properly torquing the clutch assembly, both pressure plate AND disc to the flywheel, off the car. Get your dad or another person to assist you, depress the clutch fingers as you did previously. With the fingers depressed, have your assistant use a thin screwdriver blade etc. To see if the disc can now be moved between the pressure plate and flywheel. If moves side to side freely you will effectively have verified that the clutch assembly and flywheel are functional and compatible. You can then look elsewhere. HTH

[allbim]

Slide the disc onto the input-shaft spline and spin the shaft to check if it turns without any visible fore and aft wiggle.

[allbim]

Did you use loctite on the pressure plate bolts and did it run down and get between the disk and flywheel?

[rms_sandiego]

If it helps, the extended length of the pushrod on a spare 5 speed slave cylinder I have is 62mm. 

[Hans]

Coming back to the disc markings on the flywheel that caught my attention: what if it did stick to the flywheel? Maybe the protective coating bonding with the disc.  Did you ever try starting it with the clutch pedal down (one of the ways to unstick a clutch that has stuck after storage)? A sticking disc would look like clutch not dis-engaging.

 

Another interesting experiment would be to measure the theoretical gap between the TOB and the plate fingers: bell housing edge to TOB, then fingers to block face.

[bmwfan]

Your pic of the pilot bearing, possible optical illusion, but bearing looks angled. Not sure that this would even be possible. But could bind input shaft.