engine and drivetrain Clutch Wont Disengage - 5Spd Swap

[evanb]

Tried the clutch in the input shaft and it spins true. Slave piston is ~75 mm.

Measurement from end of TOB to end of bell housing was 2 3/4 in. From block to front of flywheel was an inch. Pressure plate is 1 3/4 in. Seems to add up.

HOWEVER: I did use lock tight and it did drip onto the flywheel. I picked some off of the flywheel when I removed everything. As far as I can tell though, it didn't touch the disk (was just under pressure plate). There's nothing on the clutch plate, and the plate fell off under its own weight When I removed pressure plate (they came off together, same time). I feel like if it wasn't stuck enough to hang (if it was stuck at all) then it couldn't have been stuck enough to transfer power all the way to wheels (although the wheels weren't on the ground).

[thehackmechanic]

Evan, it sounds like you've verified just about everything except that the pressure plate actually releases the disc when the fingers are pushed in. Skip's idea above is kind of nifty, if in fact you can push the fingers in with a block of wood or a hockey puck or the throwout bearing itself.

[skipsfcr]

I've actually tested a pressure plate this way before (using a hydraulic press). Besides that, I don't know what else can be done except put everything back together with fingers crossed or replace everything. At least the actual clutch assembly could be verified to be operational.

[glemon]

Couple thoughts--When I got my 2002 the clutch was stuck.  I couldn't unstick it so I took the tranny out, clutch disk just fell out as yours did, so I was a bit nervous about putting it back together carefully on faith and optimism and hoping it worked.  But I did anyway, and it did in fact work, but my car had been sitting for years so a stuck clutch seemed a fairly logical conclusion, even though its "stuckness" didn't evidence itself when I took everything apart.  My point being a simple stuck clutch probably can't be ruled out entirely, but given the presumably fairly recent install it seems a little less likely to have found a way to bond to the pressure plate in your case, though the flywheel and the clutch certainly look like they got pretty friendly in there based on the picture showing the imprint.  Which leads to point two--

 

One other thing which would be fairly easy to check is when the clutch and pressure plate actually meet as you mate up the parts, i.e. what portion of the final tightening down of the pressure plate with clutch in place is actually exerting pressure, not sure exactly how far that should be with a new clutch quarter inch or so? maybe somebody knows or it is even in the manuals,but a careful check of that parameter should rule out mechanical interference in the flywheel/clutch/pressure interaction.

 

What about the tranny itself?, would seem a little odd for it to do in all the gears, but I have had trannies that won't go into one gear or another with the motor spinning due to mechanical issues.  I assume you tested it when first installed on all the gears? when you assumed the clutch was stuck was that because it would go into gear fine motor off, but not at all with motor spinning and clutch pedal down?, sorry and hope I am not insulting you with the questions, but you didn't really give much info on what led to the stuck clutch conclusion, maybe there is a clue for us there.  Also sorry if it was mentioned and I missed it, but tranny known, tested and good in the car it came out of?  I am not necessarily doubling down on it being the gearbox, just wondering if it has been considered and or ruled out as a possibility.

[Hans]

If the wheels were off the ground and the car was in neutral, nothing would happen.  If you'd tried to start it in gear - with suitable runoff area - we'd know for sure. 

 

The measurements line up, so I'd guess the fingers are moving. In the absence of any obvious mechanical or hydraulic issues, I'm leaning towards the disc getting bonded to one of those surfaces - locktite or coating, but that's a lot of clamping force that could create a temporary bond. I'd have  a last look a the pressure plate to make sure there are no obvious faults, but I don't see how you can test it without a press.

[peterschop]

What I did not see in your pictures is the black hard rubber or plastic fulcrum pin that the clutch fork pivots on. It is on the right side of the bell housing under the spring clip. If that in not in position, you would not be able to disengage the clutch. Here is a picture of mine.

 

 

One thing that I may have missed but did you say you have firm pedal all the way down? If you do and you have the right TOB and the pilot bearing is OK, I would go with the theory that your clutch disk was stuck to the flywheel.

 

If it were my car, I would find someone with a press and try testing the pressure plate with a hockey puck or block of wood to see if it releases the disk. If it does, I would put it back in the car and see if it works.

[evanb]

One thing I just noticed: the slave is off the trans but still hooked up, but the rod is extended. If the system is airless, can that happen? I guess I'm still fuzzy on whether it's a vacuum system or just airless.

Anyway, it seems like I either need to find a press or a Very Heavy Person to test out the pressure plate. In the meantime I'm going to see if I can get engine timed and bleed the brakes.

Thanks for your dedication to this thread everyone, I owe you all a (few) beers! I'll update once I get the trans back in.

[skipsfcr]

Yeah, it's normal for the slave to relax the pushrod outward when there's fluid in the system and nothing pushing back against the pushrod.

[jgerock]

Quickly reading thru a photocopy of the E21 tranny section (BMW workshop manual), it says to NOT press the clutch pedal while the slave cylinder is out of the transmission. 

 

I'm still trying to figure out why you are having issues...

[evanb]

I'm definitely not touching the clutch, but it has relaxed (great word for it).

[thehackmechanic]

Relaxed. Great. Now I can't get that stupid Frankie Goes To Hollywood song out of my head.

 

I don't think I got to this in my book, but there's a technique I often employ -- verifying the repair as early as possible. In your case, whether you put the original clutch back in or get a different one, you'll probably want to:

 

--Before you put the trani in, find neutral on the selector lever and verify that when you spin the input shaft, the output flange DOES NOT turn, then put it in gear and verify that when you spin the input shaft, the output flange DOES turn.

 

--Mate the trani up to the block and hold it in place with the two easist-to-reach bolts, one on each side.

 

--Bleed the living snot out of the clutch slave.

 

--BEFORE YOU HOOK UP ANYTHING ELSE (shift platform, linkage, rear support, driveshaft, exhaust), shove the selector lever forward to put it in gear, then have someone step on the clutch pedal and verify that you can turn the transmission's output flange.

 

At least, this way, if you've still got a problem, you won't have to undo absolutely everything.

Edited January 14, 2014 by thehackmechanic

[evanb]

YEEEHAAAAWW!!!!

Got everything back in the car yesterday, started her up in neutral, wheels were stationary.

Sloooooowly moved it into first, wheels stayed stationary.

Let the clutch out, wheels spun!

It looks like it was just a case of the clutch plate sticking to either the flywheel or pressure plate (or possibly some unknown bug somewhere that was undone in the process of removing and reinstalling everything). Either way, I'm so g darned relieved right now. I owe everyone who helped me out with this, big time.

One final question: when I stopped the engine, the trans puked up a bunch of fluid from the speedo cable hole (speedo cable not installed). Is this normal, did I just have too much fluid in the trans, or is this another issue to diagnose?

Thanks again all, you guys rule.

[bmwfan]

Congrats !!

[skipsfcr]

Excellent. Glad you got it back together. RE the m/t leak, the speedo cable drive spindle probably popped out of place since the cable wasn't installed with the set screw. Likely no big deal.

[Hans]

The stuck disc seemed to make the most sense. I guess it doesn't take much "adhesive" with that much pressure clamping it together. With hindsight, we should have suggested starting it in gear with pedal down to try and pop it loose.