Clutch/flywheel Gurus, What does this indicate? Options

[McMark]

What does the other side of the disk look like?

I'm thinking your clutch cable was maladjusted. Did your clutch release the instant you stepped on the pedal? Or was it down near the floor?

[Thorshammer]

Yes,

Mcmark does have the same valid points. But also the clutch release pivot point could be off. Or the depth of the flywheel. check it all.

Erik

[type47]

anybody have info on Sachs pressure plates, that is, i found a source of a 215mm sachs pp for very low price and was wondering if they publish the clamping "force" for their products. the pp i found was on a vw bus site. an alternate to the "force" question is: is there a difference between a 914 pp and a 74-75 vw bus pp. (both 215mm)

the clutch disk that they sell is a sachs and it has the 6 springs and the same disc is listed for the bus and the 914; same part number for both applications.

can't find a pp for a bus on any other vendor sites and the source i found lists the disc as a 021.xxx.xxx number, not as a "I2010-xxxxx" listing number like everybody else.

i'd like to save some $ on the 3 clutch parts.... CSOB, that's me......

[Joseph Mills]

QUOTE (Thorshammer @ May 8 2005, 05:54 PM)

But also the clutch release pivot point could be off. Or the depth of the flywheel. check it all. Erik

Thanks everyone for each of your suggestions. I made a list and checked each item.

The clutch cable is new and has slack in it where it connects to the clutch fork. The pivot fork seems to be properly located with space on either side of it at the bell housing. I remember installing the pivot ball all the way in with no spacers behind it.

The pressure plate tangs are even and there are no cracks in the spring pieces and the large rivets are tight.

The flywheel is brand new and has not been resurfaced.

However, I would like to check the depth of the surface to make sure I was provided the right flywheel.

I could not find any info in my Haynes manual.

Does anyone know what exactly I need to measure and what the spec should be?

[Type 4 Unleashed]

The Bus 215mm PP and flywheel are different than the 914 215mm PP and flywheel, and the THO bearing, the clutch disk should be the same.

[Thorshammer]

Yes The flywheel is different but still 215mm. I believe it is a depth difference between the two. Ed Givler has done this research look on the NHIS race thread he is edgetoo I believe. If you Pm him ,he has the depth figures written down.

Erik

[davep]

This is the flywheel specs.

Basically your disc is a 911 disc with the 6 springs. The 914/4 is 4 springs. Normally this is not a problem, and in fact, a benefit. However there are several 911 discs. One, for the 911S with the aluminum PP, is slightly thinner. Please measure the thickness of your disc.

What is puzzling is why it just became a problem instead of being a problem from the start. I would think it has to be related to the grease. That is the only clue we have. Are we sure it is the grease from the bearing, and not oil coming from somewhere else. The O-ring was in the flywheel also? Were there any loose bolts?

[Joseph Mills]

Thanks for the diagram Dave.

I am going to measure everything tomorrow morning when I have some good light.

I haven't removed the flywheel yet so am not sure about the O-ring or the 5 bolts.

That's a good point about the problem not being there at the start.

It started slipping noticeably about 1k miles ago. I have noticed that it seems to be more prone to slip when the car is hot (like at the AX or a longish drive). This could further indicate it being a oil problem? In that as the oil gets hot, it gets thinner and seeps into the clutch environment?

[bondo]

Here's something pretty easy to check that might help narrow down the problem. Install the PP and disk onto the flywheel, but only tighten the bolts finger tight. At this poing the PP should be aboput 1/4" from fully on. As you tighten the bolts, the fingers should move in towards the flywheel. If the PP ends up very close to fully on the flywheel at finger tight, or the fingers don't move as you tighten it fully, something is very wrong.

[davep]

(IMG:http://www.914world.com/bbs2/html/emoticons/agree.gif) Good point actually.

The other thing, are there burn marks on the PP? If the marks are only on the flywheel, then I'd say it has to be the grease. Perhaps it took time for the grease to build up, soak into the disc, and cause slippage. Perhaps most of the friction is now only on the PP side of the disc.

[Joseph Mills]

Today I made some real progress. This morning, while examining my various clutch issues, I immediately noticed how slick my clutch disc actually is. Saturday when I removed it, my hands were so greasy it wasn't so noticeable, but with clean dry fingers it was quickly apparent that the disc is saturated. Dragging your thumb across the plate produced a gray/black thumb. Good for fingerprinting.

Also, the pressure plate surface was coated. The entire pressure plate had a film over it. My wife, who smells real good (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif) confirmed that it was tranny fluid as opposed to engine oil.

I then removed the throw out bearing, and sure enough, there were signs of fluid seeping around the output shaft seal, and also around the pivot ball that had come slightly loose.

I took the disc to my porsche shop and ran it repeatedly thru their big hot/soapy parts washer, but it seems the disc is still leeching out oil. So it looks like I will be fitting a new disc.

While I was there, I also had them put in a new output seal in the tranny. If this sucker leaks, then I've got other problems (bent shaft/bearings out of spec?).

So tomorrow I should have everything back together.

I guess it will be a month or so before I'll know that the new seal is doing it's job, but hopefully my clutch slipping days are behind me.

Thanks to all for helping me to "grapple" with this mess. (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

[McMark]

Glad to hear it worked out... (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)

[Jake Raby]

It looks as if the disc center was interfering with the flywheel bolts...

Anyway, the off the shelf new flywheels are pretty shitty. I never trust their tolerance from the top to bottom surfaces. I do not see any signs of the disc having grease or oil on it but it has definately been slipping.. Maybe you had it slightly overadjusted. The tell tale signs of that are easy to spot on the surface that the release bearing rides on the pressure plate.. in 5K it should hardly be worn if it was not overadjusted.

The stock set up is good for 160 lb/ft of torque. With my mods to the flywheel I can push 170 through one with a stock disc. After that we can go up to 185 with my feramic disc with the stock pressure plate.. After that the stage II pressure plate is a must but can be used with a stock disc up to 225 lb/ft and thats almost enough to hold my 3 liter..

Also to all you guys changing flywheel seals:
ENSURE that you change the flywheel O Ring when doing the seal.. The O ring is the most likely source of failure and they are very non forgiving... The ones they give you with the gasket sets suck, I have had some made up that are the proper size, not .040 too big like the ones in the gasket sets...

[Reiche]

QUOTE (Jake Raby @ May 9 2005, 08:06 PM)

It looks as if the disc center was interfering with the flywheel bolts...

It does. Oh dear...did you put the disc in backwards?

[Joseph Mills]

I don't know how it is supposed to be, but here is what I found.

I placed a straight edge on the flywheel and a few of the bolts catch it just so ever slightly as the straight edge is slid across the face of the flywheel. Letting the straight edge "rock" on one of the bolts, I'd guess it protrudes a few thousands at the most. But as the photo shows on the clutch disc, there is no apparent wear in the area the bolts would contact. Plus that surface is on the back side of the disc pad. By the time it would touch the rivets would be in the flywheel surface. I'm thinking that maybe the bolts were like that originally? I can't remember. Should I hand file them down a bit or just leave them alone?

Are you referring to the "tangs" on the pressure plate that contact the release bearing? There is a slight marking on them but almost no visible wear.

I do know that the clutch cable had a good looseness that was easily moveable between the end of it's housing and the clutch fork.

I will take measurements of the flywheel depth tomorrow and take a close look at how the pressure plate snugs down and moves the tangs as it is tightened as some others have suggested. Maybe you're right and the specs on this flywheel are off.

This story may not be over yet. Damn Clutches. (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

[Joseph Mills]

QUOTE (Reiche @ May 9 2005, 10:47 PM)

QUOTE (Jake Raby @ May 9 2005, 08:06 PM) It looks as if the disc center was interfering with the flywheel bolts... It does. Oh dear...did you put the disc in backwards?

Nah. It's impossible to put them in backwards. I already tried. (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

[McMark]

I'd also check your pressure plate friction surface for flatness. Seems like the heat damage is only on the outer perimeter.

[Joseph Mills]

Installed a new clutch disc last night.

Checked the depth on the flywheel and it measured exactly 22.5mm. Also checked flywheel and pressure plate with a straight edge.

When installing the pressure plate to finger tight, it had about a 1/4" distance. Also measured the location of the tangs with a straight edge. After fully tightening the pressure plate, the tangs had moved nearly 3/8ths inch.

Everything buttoned up real well with no issues with the clutch cable/fork location, etc.

Well, there is one issue. We discovered that my clutch pedal spring is broken. What does this spring do? Does it pull down on the pedal to keep out any slack in the cable, or does it pull up to keep the pedal up (seems the pressure plate itself would do that)?

I put about a 100 miles on the car today and all seems well so far. (IMG:http://www.914world.com/bbs2/html/emoticons/unsure.gif)


And I was pretty successful in resisting the urge to thrash it about. (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

[Cap'n Krusty]

QUOTE (type47 @ May 8 2005, 04:11 PM)

anybody have info on Sachs pressure plates, that is, i found a source of a 215mm sachs pp for very low price and was wondering if they publish the clamping "force" for their products. the pp i found was on a vw bus site. an alternate to the "force" question is: is there a difference between a 914 pp and a 74-75 vw bus pp. (both 215mm) the clutch disk that they sell is a sachs and it has the 6 springs and the same disc is listed for the bus and the 914; same part number for both applications. can't find a pp for a bus on any other vendor sites and the source i found lists the disc as a 021.xxx.xxx number, not as a "I2010-xxxxx" listing number like everybody else. i'd like to save some $ on the 3 clutch parts.... CSOB, that's me......

Bus PPs look a lot different than the Porsche ones. The diaphragm is of a different design, and the release bearing is far different. The Porsche bearing doesn't mate up to the PP, and the VW bearing won't work on the 914 tranny. As I recall, the flywheel is cut differently, and the step height may be different. I know GPR sells the VW disc as a "low cost alternative", and I've used one in a "just make it run so I can sell it" situation. The savings isn't worth it, IMO. The Cap'n