Fronkenstein

Ok all you experts. I need a little help here. So I took her out for a ride today and I'm having a little bit of clutch problem.

The clutch engage is about an inch and a half maybe 2 inches off the floor. Could it possibly be that I have mixed up clutch component.

Remembering that the cars is a1978 ROW and that the engine was swapped with a1984 m20 ROW mill. I am pretty sure that I used the pressure plate, release arm and center plate from the 1984 and the clutch discs that were originally in the car.

I noticed that there is a difference between the two pressure plates, one has a thicker rim than the other which also changes where the adjustment forks sit .

There is a possibility that I mixed up the release arms. Could this possibly be the issue? It just seems like there's just not enough to throw in the slave cylinder.

Based on what I've read from the manual it appears that there were several different versions of the clutch in the earlier cards up to 1985 . So basically have I messed myself up bad and I have to remove the clutch now?

Fronkenstein

soontobered84

IIRC, the version of clutch used in 1978-1979 (maybe 1980) is different from 1981-1984. I know that the clutch discs have a different part number

James Bailey

OH NO !! expect Kibort in 3,2,1 ......
which bell housing did you use ?? differences there also. The early clutch disc splined hubs were a different width and can interfere as I recall. Fly wheels were centered the clutch by a lip vs pins on the later twin disc cars....very early release arms had a captive metal pin instead of the ball and plastic socket....

Fronkenstein

Ok well the spine shaft is the original 1978 as are the discs.

You have no real choice on the bell housing if you want to use the Orion starter bracket which is soooo much better than mounting to that flimsy bell housing.

Unless the distance between the slave cylinder boss to the release am is different the rest of the bell housing is dimensionally the same. I did not change the torque tube which fits perfect.

Had to use a 1984 slave cylinder as well due to the hydraulic line position.

So I guess I will have to swap out at least the pressure plate and check the release arms.

Both arms use the ball socket so they are least the same at that level.

Any other thoughts welcome. Kinda sux I gotta pull the clutch but whatever.

Had anyone ever had their flywheel Blanchard ground?

Fronkenstein

James Bailey

The flywheels can be resurfaced there are specs for minimum thickness in the workshop manuals/tech papers .

Fronkenstein

Ok so here is the official word from Dr. Ing. h.c. F. Porsche. 928 Workshop Manual Volume II Transmission, Section 30, Page 16 (30-16). And I quote:

"Parts of the modified / present and original version may not be installed together in one car."

Pages 30-16 and 30-16a provide exceptions to the rule but you need to be a German linguistics acrobat to understand the double talk.

Suffice it to say I will be removing the clutch assembly.

That said, I think I am just going to buy a completely new assembly, pressure plate, intermediate disc and friction discs. Does anyone have a recommendation on where to get this stuff at a reasonable cost. Like around $800 or less?

Fronkenstein

hwyengr

Like, brand new? You'll be hard pressed to find just the intermediate disc for that price.

Fronkenstein

Jeez I remember when you could buy the entire gig new for $1200

Fronkenstein

Dave928S

^^ The differences in the parts are quite trivial, but can give issues with adjustment.

Taking the parts one at a time .....
1. Flywheel ... yes getting it ground to no less than the thickness in the WSM will allow it to still work within tolerance (relative position of the whole pack to the rear of the motor), and will get rid of hard spots and glazing.
2. Friction discs ... later discs had additional/thicker wave springs between the friction linings and therefore were a litle 'fatter'. The later rear one had a longer hub, by about 5mm, which gave smoother travel on the stub shaft.
3. Stub shaft ... the later stub shaft had a harder nickel plating to reduce friction and wear, and the splines were a little longer to allow for the minimally fatter discs, but mainly the longer hub on the later rear friction disc.
4. Intermediate plate ... The later IP had 'H' adjusters with a little more clearance to accommodate the fatter friction linings ... about 1 - 1.5mm more. Location pinning changed between early and late.
5. Guide tube ... early was 50mm and the later was 49mm.
6. I'm not aware of any dimensional difference between early and later PP's .. the rim may be thicker but I don't believe that working dimensions altered.

All those changes were to 'allow smoother operation'.

What you have ...
1. Flywheel ... even if you resurface ... should be OK
2. Friction discs... as long as they still have some meat they should be OK.
3. Stub shaft ... a new shaft will work wonders for smooth release ... but dimensionally your old one should be OK
5. Guide tube ... if you were to change to new discs you could grind down an old guide tube a little to ensure clearance, as long as it was still serviceable. The WSM actually specifies this.
6. PP should be OK.
7. I'm not aware of release arm dimensional changes other than size of the ball socket .... but this should checked.

The changes they made were quite minor, and their blanket statement that parts shouldn't be mixed is obviously to avoid nagging minor mismatch, which would affect smooth operation, and might interfere with fit or working clearances.

I can't see that any of the components you have should give you such major pedal difference, and my guess would be that there might be an issue with the slave (but double check release arm and bearing engagement and travel).

If you wanted to go the new clutch pack way then give Roger a call. New IP would add huge $'s to a kit of PP, discs, release bearing (if available), and guide tube. I think you'd be battling to get the kit for $800, and the IP is megabucks.

Fronkenstein

Dave,

Thanks for that info. The slave is brand new or if the box. Not to say it couldn't be bad.

Can I assume that the adjustment forks have no bearing on off floor release distance?

When I first took the car out I didn't feel any drag. After 20 minutes of driving it up and down our dirt road as well as backing up a lot several times, I felt like it wasn't releasing as well. It got harder to slide into 1st gear which was really easy at the start.

Thoughts?

Fronkenstein

Dave928S

If it started out well (which is good) and then got more difficult, then that would point to the 'H' adjusters moving out of adjustment, and causing drag on one of the plates. Resistance to sliding of the friction discs on the stub shaft, from my experience, can also increase with temperature on a worn/not well lubricated stub shaft. Both those issues don't affect release distance off the floor, they just mean that after the 'normal' release point the discs still don't totally 'let go'.

Did you do a thorough bleed of the slave? Air bubbles could affect release point off the floor.

Rob Edwards

Do you still have the original 9 inch brake booster? There are comments in the WSM about the 9 inch booster, and two versions of the 10 inch booster, which have 'internal ratios' of 3.0:1 and 3.8:1. I have NFI what that means, nor the internal ratio of the 9 inch booster is. (EDIT: It's also 3.8, from the 1978 service info tech book.)

I just wonder if you're using a 1984 clutch slave that maybe a 9 inch booster doesn't move enough fluid to move the clutch slave piston enough to fully disengage (?) Might be worth measuring the 'throw' of the clutch slave rod when actuating the clutch pedal, before taking everything apart.

Dave928S

^^^ I seem to recall that info and some discussion here too ... definitely worth checking out travel you need, versus what you are getting from the slave/master combo.

As Rob said .. don't pull it apart.

The fact that you could drive it well to start with, albeit with a short release window, is a good start, and indicates it shouldn't be all that difficult to sort out.

Tony

There's an old name...good to see some "old timers" chiming in

No get back in yer hole!

hacker-pschorr

When was this? Back in the mid 90's the intermediate disc was almost $1,000 by itself.

I've never seen the clutch kit include the intermediate disc, unless the vendor was packaging them together.