New transmission - clutch only depresses halfway

[Wildthings]

[presslab]

[drivenachodrive]

Understood, but it seemed to me that the fingers were preloaded in the wrong direction. Perhaps I'm thinking of it incorrectly. When I bolted down the pressure plate the fingers depressed such that it didn't seem like there was any more room for the throw bearing to depress them any more. In the morning I'll crawl under there and see if I can see what , if anything, is wrong.
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[Vango Conversions]

What you're describing is normal, the pressure plate fingers will move closer to the flywheel as you tighten it down. Make sure to tighten it down in a cris cross pattern and do it gradually or the disk may be pulled out of center a bit and make it very hard to install the transmission. Did you install a new pilot bearing?

Now there should be plenty of clearance between the fingers and the friction disk so that the release bearing can push those fingers in a bit more to release the pressure. I don't know exactly how much there should be, but I'm installing a new clutch tonight or tomorrow am so I'll measure it and let you know. I just measured a brand new Sachs disk and it measures 9.35mm, how thick is yours? Maybe yours is too thick?

Did you have the flywheel machined? The same amount of material needs to be taken off of the outer edge near the ring gear as the center portion. If more is taken off the outer part than the inner part it could cause a problem with the clutch being unable to release. If that's the case you may be able to space the pp out with some thin washers, but I'd only do that if you're really in a bind. (no pun intended)

Make sure the disk is installed correctly, it may have been marked wrong. make sure the friction material is contacting the flywheel. If it's backwards, the hub of the disk will touch before the friction material.

[getset]

I just recently did teh same thing, except I had the engine out as well. i had reinstalled the transmission and the slave before installing the engine. I never removed the hydraulic line at the slave, so when I installed the engine I had to release the bleeder in order to release the cross shaft arms enough to get the engine to bolt up. May not be of any help, but I thought I might as well chime in.
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[Vango Conversions]

I just finished bolting up a new clutch last night so I thought I'd give you some measurements in hopes that it'll help you Identify your problem.

First, I measured the depth of a good used stock VW flywheel. The outer ridge of the fw where the pressure plate actually bolts to was 24.6 mm above the lower area where the friction disk rides. I also measured a brand new flywheel and it measured 24.24mm deep. It is a Subaru conversion flywheel but it uses a stock VW style clutch so should be made to the same specs. it measures 24.24mm deep

After bolting up a brand new Sachs clutch set, I measured from the fingers of the pp, where the release bearing touches, directly down to the hub area of the disk. It measured 26.5mm, plenty of room to allow the disk to release. Just to be clear, I measured directly down from the pp fingers, to the inner area of the clutch disk where the coil springs ride, hope that makes sense.

Let me know soon if you need any more measurements, I'm about to bolt up the transmission.

Good luck, I've been enjoying watching your travels on your website. Hope you can get back on the road soon!

[drivenachodrive]

All right, just had the transmission back out and everything looked fine within the bell housing. Thrust bearing still installed and looking fine, all movement of various parts worked fine. Pilot bearing was fine.

I don't have calipers, so I can't take measurements. However, I compared the old clutch and PP to the new, and everything looks pretty much spot on. The old clutch was about 0.5mm thinner on the flywheel side, due to wear.

I reinstalled everything, using the clutch alignment tool, and everything bolted up just right. I had very little trouble installing the tranny this time. Bolted everything up and put the wheels on. I gave the slave cylinder one more flush for good measure (we don't have access to a pressure bleeder, so we rely on Sheena pressing the clutch, then I bleed the cylinder. For good measure I end by having her press the clutch, I crack the bleeder, then I depress the slave cylinder fully by hand to evacuate all fluid out the bleeder, then I close the valve.)

Pressing the clutch gives approximately 0.3-0.5" of slave cylinder movement (~10mm).

I put it in first, press the clutch, fire it up. Van lurches forward and stalls. I turn it off, put it in reverse, press clutch, start. Van lurches backward and stalls. Pressing the clutch pedal is not enough to cause the clutch to disengage - it's stuck engaged.

What should be my next move? Is there any logical reason this should be happening? The clutch pedal seems to hit a hard stop just before the end of its stroke. Doesn't feel like a bad slave, as it seems to be functioning. Ideas?
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[Vango Conversions]

Try this. With the van off and in first gear, try pumping the clutch pedal 5 times or so, then hold it down and try starting the van. Will it run without moving? Then try easing the pedal out and see if the van takes off normally. If this works, it's definatly a hydraulic issue. If not...

Did you replace your slave cylinder? Maybe try the old one if you did or a new one if you didn't. Did you replace the rod that goes from the slave to the release bearing arm? It could be too short, you could probably fab up a new one or lengthen yours with some all thread and a coupling nut.

Other than replacing the clutch set, what else have you done? Flywheel changed or machined? Slave or master cylinders? push rods for slave or master? If you've replaced some of those bits you may want to put the old ones back on if they were working properly.

Did you take any rough measurements with a ruler or anything before putting it back together? I'm especially curious about the pressure plate fingers to clutch disk clearance as you said it looked like there was very little clearance but I measured just over an inch. This seems like something is very wrong there.

keep us updated.

[crazyvwvanman]

Before you pulled the tranny back out I asked for photos of the slave so that we could see the relationship of actuating lever to the slave piston rod. The reason for a hard stop is that you have reached the maximum extension of the slave piston. This should not be possible unless the piston was already part way though its range of travel before you even pushed the clutch pedal. Since all looked ok inside the bellhousing that still leaves a problem with the slave and lever area.

Mark

[drivenachodrive]

Pumping the clutch pedal does not fix the problem. Must be a mechanical issue.

I did not replace the slave or master cylinders. I didn't replace the rod that connects to the throwout arm either.

I replaced the transmission, clutch, and pressure plate. The flywheel is original, and was not machined. The throwout bearing is original as well.

I didn't take any measurements before reinstalling, as I don't have a caliper. However, I made a mental approximation of one measurement. When you place the pressure plate onto the flywheel, it fits over 3 roll pins for alignment. You can press it by hand onto the press pins until the pressure place comes into contact with the clutch. This is the point at which you must start using a wrench to start tightening the 6 bolts that hold the pressure plate on. This is also the point at which the PP "finger" springs start to self-compress. I took note of the distance between the flywheel rim and the PP mounting face (the amount that would have to be compressed by the bolts). I noted that this distance was approximately 4mm.

I took 2 pictures of the installed PP and clutch, with the alignment tool still in place. You can see the approximate distance between the fingers and clutch disk, and it appears to be over an inch.

Also note that when I press the clutch, it seems to hit a hard stop just before it reaches the ground. Not sure what that could be. Any thoughts?
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[drivenachodrive]

Mark,

Sorry, I forgot that you had asked for that photo. Here's a picture showing the angle of the throwout arm relative to the slave cylinder. Does it look like the slave is already partially through its stroke?

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[jordauto]

It does sound like a hydraulic problem. Your clutch pedal should have about 1/2" of free play then start moving the release lever. Have someone slowly press on the cletch pedal and see how much travel there is before the clutch lever starts to move. It sounds like there could be air in the system somewhere.Vangos suggestion of pumping the clutch pedal is a good one. You could try bleeding that way too. Pump a few times,hold pedal down,crack the bleeder open.Repeat. It's possible the master cylinder is by passing internally and not making enough pressure. With the engine off,and wheels raised,you could manually apply pressure to the clutch release lever with a pry bar or similar and see if the clutch releases then.That will isolate if the fault is inside the bell housing or in the hydraulic system. Good luck
Jeff

[Wildthings]

Pull back the boot on the slave cylinder and watch to see how far out the piston comes when someone else depresses the pedal. It shouldn't be bottoming out.

Does it look like it is retracting fully when the pedal is released?

[Vango Conversions]

You're missing part of your slave cylinder bracket too. There should be a flat bar with a bent end that goes from the forward bolt of the slave cylinder to the threaded hole on the side of the trans. If you forgot to re install it try and find it and put it back on. It shouldn't be too hard to fab one up if need be if it's missing. Watch as someone works the clutch and you'll see the bracket flex.

Seems like it should still work without the bracket though. Is this a heavy duty Pressure plate? the added force makes the missing bracket even more important if it is.

If replacing the bracket doesn't fix the problem you can lengthen the pushrod by cutting it in half, threading it with a die and using a coupling nut to make it adjustable. In a pinch you could also try puting a nut between the pushrod and slave piston as a spacer. it may fall out after a while though.

[crazyvwvanman]

Yes, it kinda looks like the slave is already partially extended and that the lever is down from the normal rest angle. I think the boot should be more compressed. To tell for sure you should measure from the bottom of the slave mounting bracket, down to the lip of the cup that sits on the lever ball. If you can get a photo of that measurement that will help us to compare ours with yours.

Without that missing support brace the bracket will flex too much and that could would force the slave to have to extend more.

Mark

[theDrew]

when I did the slave clyinder on my van, I used my iPhone to record what was happening when I pressed the clutch. At least you can get an idea of how much the piston is pushing the lever.
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[Christopher Schimke]

I agree that the slave cylinder looks at least partially extended already. One other culprit could be the shaft arm itself. There are two different arms, gas and diesel. If I'm not mistaken, the diesel arm sits one spline lower (one spline counter clockwise) than the gas arm. Since this is a fresh rebuild, I suppose it's possible that the rebuilder accidentally installed the wrong arm.
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[drivenachodrive]

I don't have any means by which to measure from the bracket to the bottom of the rod cup, but if I haven't figured it out by tomorrow I'll try to find something.

I took some photos of the rod extension length while pressing the clutch. I used a zip tie for reference.

Clutch not engaged:

Clutch engaged:

It seems to me that it's moving about 1/2" or so.

Here's a picture of the bottom of the salve piston when the clutch is depressed. I don't know if this is at the extent of its travel - do you think so? Perhaps a longer rod or repositioned throw arm would set this piston back a little.

As for the big flat bar bracket piece that's missing - it was never there. My old tranny was missing it too. I'll see about getting one in Bogota once we're on the road, or else have someone fab one while I'm there.

You guys are awesome, thanks for the help!
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[Vango Conversions]

Your slave is bottoming out for sure.

The easiest cheapest way I can think of to give you a little more throw would be to stack a bunch of washers between the slave bracket and where it bolts to the bell housing. This will pivot the bracket back a little and move the slave a little closer to the arm. Hopefully this will be enough to disengage the clutch.

As the clutch wears this will be less of an issue, so as long as it can disengage now while new, it shouldn't be an issue in the future.

[Wildthings]

Your piston appears to be fully extended, if so you may need a longer push rod. Since according to others you are missing the extra bracket maybe the existing bracket has become bent.