924Board.org

[autobahnkid]

Just finished reinstalling the TTube and Clutch Bellhousing onto the engine while in the process of replacing the rubber Flex Damper to a mechanical clutch on my 1980 NA Auto.
The Flex Damper broke at the splines on the coupler. Unusual as they tend to rupture on the rubber not the metal. Looks like was brand new when it broke.



The spline section of the driveshaft is about 3/4 of an inch to far back of the teeth on the clutch disc that I sourced. Disc is the correct size 215mm 13/16 hub and 24 splines. Pressure plate is OEM Sachs type 215.




Are the splines on the Auto driveshaft cut farther back than a manual?
Is the hub of the original porsche disk higher(longer) and reaches to the spines?
Who has done this on a 924.
I am at a loss here. Any ideas Guys?
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1980 924 N/A "the beast'

[emoore924]

Ok, I'll take a crack at this...

Could the original failure have been because the splines weren't completely inserted into the collar of the original (now broken) piece. I don't see wear on the broken parts. Is this what you see too? How far into the original collar was the drive shaft before things broke?

Good question about the drive shaft, are there different part #s between the auto and manual? Do you have the right one in the car?

Could the drive shaft be shifted rearward within the torque tube?

Is there something going on with the whole assembly being shifted rearward?

Is there some thickness difference between the auto plate and the manual clutch that would cause the collar to be in the wrong place?

[autobahnkid]

Emoore
I think the colar broke because of error in installation. I think the pinch bolt was overtightened. the broken pieces were on the coupler. Here is a picture. Flex Damper on the right, Bell housing on the left.

I am thinking also of the Dshaft being too far back

Also I was unable to remove the rear flex plate. The coupler is frozen solid on the Dshaft splines. Soaking in PBlaster right now. The coupler at that end is not properly aligned on the slot on the Dshaft for the pinch bolt. Just a couple of mm off but not enough to compensate for what is missing at the other end.
I wish I had acces to a Porsche disc to compare the hight of the center where the splines are.
I have looked in the junk yards but only 944's are available.
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1980 924 N/A "the beast'

[emoore924]

So, what happened?

[!tom]

A standard clutch arrangement will have the drive shaft extend into the pilot bearing in the crank shaft. I'd imagine the drive shaft on the auto transmission would not extend into the crank shaft as it doesn't need to be stabilized in that way.

I'm guessing you'll need a drive shaft from a standard transmission, in which case who knows what troubles you'll run into at the transmission end.

You might just have to improvise something.

By the way, I've got clutch components that would have worked great for you that you could have had for free!
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78 924 NA
5-lug

[autobahnkid]

After sourcing a used clutch disc 1979 924 N?A(thanks KDJones) I still am facing problems with the fitment of a standard clutch to replace my Auto Damper.
The splines on the driveshaft do not reach the hub of the clutch disc. Eventhough the shaft is fully seated against the stop in the pilot bearing.


Picture shows the disc fully against the flywheel on the right. The splines are short by 1/2 inch.

Is there a difference in the lenght of the splines on the Driveshaft of a 5 speed vs. an Auto? Any sugestions?
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1980 924 N/A "the beast'

[autobahnkid]

Tom Thank you for the offer. I may still have to avail myself off it.
The nose of the Auto shaft does fully seat on the pilot bearing.
Here are two pictures, the first of the shaft in the bearing as it sits and the second one of the old pilot bearing and carrier sitting on the nose. I tested to see that the Drive shaft was penetrating fully. It hits the stop where the threads are in the carrier. In both instances the distance is the same.

Barring a difference in the lenght of the splines between the two types of drive shafts I am asking myself if the pilot bearing itself is fully seated on the crankshaft.
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1980 924 N/A "the beast'

[Paul]

Are you installing the clutch disc backwards?
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

[autobahnkid]

Paul
There is a sticker on the clutch disc that says this side towards flywheel, I presented it that way. See the picture above.
I wish that was the problem. It would make my life easier.
Still I will recheck. I have done worst before.


here is the side that goes towards the rear. Note the rivets.

I am loking for pictures of the nose of a standard car's driveshaft to compare with mine.
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1980 924 N/A "the beast'

[!tom]

Different flywheel?
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78 924 NA
5-lug

[autobahnkid]

Also looked into the flywheel. PET shows only one flywheel for 924 NA, part number 046 105 269 B.
I looked into one advertised for sale on the internet with a diferent number, turned out vendor was Auto Atlanta.
As you know they have a spotty reputation. I called them and they were extremely helpfull. Took the time to go look at the part, take the numbers of the flywheel. It was the same as mine. Kudos to them.

Only difference between Standard and Auto is the stop/Washer #11 and 11A, that holds the bolts to the flywheel. Even this part on the auto can be machined to match the standard. That is what I did.
The other flywheel on the PET is for the turbo.
http://www.porsche.com/all/media/pdf/originalparts/en/E_924_85_KATALOG.pdf
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1980 924 N/A "the beast'

[Paul]

Here's a crazy idea:

Buy another disk, cut out the spline and weld it to the clutch to make an extension?

It should never wear out.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

[autobahnkid]

Paul
We are on tha same page.
I already have the disc and was looking on how to remove the clip that holds the hub.

The other alternative is to machine the nose of the driveshaft, cut and weld the same length piece to the mainpart of the shaft.
Probably an expensive proposition.

Else source a TTube or shaft from a Standard.

The other idea I have been looking at, is sourcing the center portion of a trashed rubber flex damper and replace the center section of mine. What broke was the pot metal not the rubber section.
Anyone out there with one lying around?
Help save the beast from the crusher!!!!!
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1980 924 N/A "the beast'

[autobahnkid]

It does seem that the Driveshaft ends are not the same. here are several pictures, the first is of the Automatic.

Standard Notice how much they differ.

Not sure if this is from a 931 but principle is the same. The snout is much shorter.
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1980 924 N/A "the beast'

[autobahnkid]

Ok, so I dissassembled one of the used original Sachs clutch discs to harvest the Hub and the star shaped washer behind it to use in the project.
Presented the parts on the other disc and onto the drive shaft. Seems like it could work if I can figure how to attach or weld them onto the disc.

If I could weld the hub to the star washer, and the star washer to its counterpart inside the disc. But how?

To complicate matters further the star washer is cracked in several places so i am looking for another disc to take apart.

I am running out of ideas. What do you guys think?
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1980 924 N/A "the beast'