TheSamba.com :: View topic - Post-rebuild clutch problems

Mon Nov 02, 2009 1:46 pm

Alright! The engine is complete and it runs beautifully, and I'm feeling really good about it. There is a major clutch issue at this point. Using a new clutch plate and the old pressure plate (coil-spring/early type), throw bearing and flywheel, the clutch will not disengage. I can shift gears while the engine is off but if I start it in 1st the bus jerks forward, and if I try to shift while the engine is running, it doesn't work, I start to get a grinding sound. Reverse sounds horrible. Much adjustment to the clutch cable in both directions, tightening until the clutch bearing begins to activate while the pedal is all the way up, and loosening until there is massive freeplay, resulted in no difference in the state of the clutch. Having read that this may be caused by aftermarket clutch discs being too thick, I pulled the engine and measured the new disc and found it to be .003" thicker than the old one, which seems like the old one could be that small amount thinner due to wear. There are some differences in the design of the clutch plate (can provide pics if necessary). I tried messing around with the pressure plate, such as lifting the central ring and locking the supporting levers in the transmission direction, but installation proved impossible - apparently, when I tighten the pressure plate down to the flywheel, the springs holding the central ring "up" (away from the flywheel) torque down to where the ring has play back and forth, while a free standing pressure plate has so much pressure on that ring that I cannot move it. Not sure if there is some specific way in which I am supposed to arrange this central ring business, or if perhaps I should be looking elsewhere in the clutch assembly for this problem, but everything I find in there leads me to believe I set it up right and it doesn't work. Something's wrong, anybody here know what it might be?

Vehicle: 68 bay window with stock 1584 engine and tranny (rebuilt engine, of course)

Mon Nov 02, 2009 2:09 pm

do you have a new spring type driven plate with a original 3-arm style pressure plate?

Mon Nov 02, 2009 2:57 pm

Quote: (coil-spring/early type),
I am thinking it is a 3-finger.

You want to look carefully at the fingers and castings to be sure none are broken or the pivots worn loose. Also you must be sure that the input shaft fits into the gland nut and spins freely. Last, if it was working before you replaced the disk then look at the new disk closely to see if it is larger in some dimension, the hub etc and hitting or of there are rub or score marks. Spin it and see if it wobbles. Look at the T/O bearing to be sure it is riding in the correct place. Something has changed in the geometry.

If this was instead a used pressure plate that you have never seen before, you would need a special tool to set the finger heights. If one finger is too high or low because the adjusting nuts were turned then that can cause one side to drag.

Personally I would not use a coil spring type unless it is all that is available. The diaphram style are far superior and more stable. It only takes a few of the coils to change tension or one finger to change height and the whole disk will act weird.

Mon Nov 02, 2009 3:20 pm

Thanks for the replys guys! I decided to go ahead and photograph all the pieces involved, and here's what I've got:

Here's the pressure plate:

And the other side of it:

The new clutch disc:

Old clutch disc on the left, new clutch disc on the right:

Flywheel:

Transmission with clutch bearing:

That lovely little wingnut:

And the mouse nest underneath the clutch pedal:

The mouse nest was removed and appears not to have had anything to do with the clutch malfunction, but just so you guys know, this is a comfy place to sleep if you're a rodent!

Mon Nov 02, 2009 3:47 pm

SGKent wrote: Quote: (coil-spring/early type),
I am thinking it is a 3-finger.

You want to look carefully at the fingers and castings to be sure none are broken or the pivots worn loose. Also you must be sure that the input shaft fits into the gland nut and spins freely. Last, if it was working before you replaced the disk then look at the new disk closely to see if it is larger in some dimension, the hub etc and hitting or of there are rub or score marks. Spin it and see if it wobbles. Look at the T/O bearing to be sure it is riding in the correct place. Something has changed in the geometry.

If this was instead a used pressure plate that you have never seen before, you would need a special tool to set the finger heights. If one finger is too high or low because the adjusting nuts were turned then that can cause one side to drag.

Personally I would not use a coil spring type unless it is all that is available. The diaphram style are far superior and more stable. It only takes a few of the coils to change tension or one finger to change height and the whole disk will act weird.

I agree with Steve, I'd ditch the old type for a diaphragm style of good quality ( Beware the cheap ASS chinese MADE ones et al :lol: :wink: ) and be done with it. I have had issues with the earlier styles more times than I care to remember.

Mon Nov 02, 2009 3:55 pm

I'll think about the new clutch, but for now, I really just need to get this one running so I can go to CA and get a winter job and a house with a garage... As you can see in the photos, the new clutch disc is a little different. I measured it and the thickness is good, but the hub is shorter and wider than the old one. Didn't see any scrapey marks or anything, and it doesn't look like it would interfere with the pressure plate...

Mon Nov 02, 2009 3:58 pm

Was the pressure plate "known good" as in you drove with it before you pulled the engine?

Mon Nov 02, 2009 4:16 pm

that pressure plate and flywheel have a lot of glazing on them. You need to take some emery cloth or aluminum oxide sand paper to both the pressure plate and the flywheel or it will chatter. Then clean it well with laquer thinner.

The central hub is much larger on the new one. Lay it in the flywheel with the alignment tool through it and see if it fits the flywheel correctly without rubbing. Then lay it on the pressure plate correctly and see if that larger central hub is touching anything and that there is room for the ring to clear it when pushed. The two disks have some significant differences. We got a new Sachs disk and it looks like your old one.

Mon Nov 02, 2009 5:33 pm

The pressure plate is "known good" as it has been in the bus functioning perfectly (more or less) for as long as I've known it. We performed a test where we suspended the pressure plate by two blocks and pushed on the central ring, and determined that the clutch disc pressure surface does rise, so the pressure plate works. The clearance between the central hub of the clutch disc (which in the new one is bigger around than the inside of the central pressure plate ring) and the central ring of the pressure plate is slightly larger than the range of motion afforded to the throwout bearing by the clutch pedal, so theoretically there should not be a problem with that. The old clutch disc has a much smaller clearance but it's also thin enough to fit inside the pressure plate ring.

Mon Nov 02, 2009 5:37 pm

and we're in Alabama right now, high humidity causes anything metal to rust within about 24 hours of exposure to the air, so every time we remove the clutch from the flywheel, we have to re-sand the surfaces. In fact, when we put the new cylinders onto the crankcase, it took them only about 2 days to start being rusty. It sucks. There are better environments for this machine.

Mon Nov 02, 2009 7:06 pm

When you installed the new clutch and tried to shift and all that did the clutch pedal feel the same as before? As in did it feel like the fingers on the pressure plate were being depressed?

Mon Nov 02, 2009 10:50 pm

Uvula wrote: I'll think about the new clutch, but for now, I really just need to get this one running so I can go to CA and get a winter job and a house with a garage...

You caught on quick to posting pics!

What's the issue with just running the old disc? Is it oil soaked? It doesn't look that worn...you said .003"? That old disc will roll 3000 miles easy...especially if I were in Alabama headed west. :wink:

Mon Nov 02, 2009 11:15 pm

take a close look at these areas and see why they look deformed or chewed up in the photo. It may just be shadows.

your old disk looks like it has life left so use it if you are trying to get on the road. Use WD40 to stop rust next time. Then just before you assemble it wipe it with laquer thinner, spray carb cleaner like Berrymans or brake cleaner etc.

Tue Nov 03, 2009 7:54 am

the new spring driven plate will not work with the three-arm PP. use a solid disc.

i actually like those old-style PP, they are still made like that by sachs and it is the only 200mm aircooled PP that is still made in germany. we use them in a bus with a solid centre disc and this combo works perfectly in a bus, but if you try to use a spring centre disc you have interference.

Tue Nov 03, 2009 8:20 am

loosen your cable