bebbetufs

I have the engine out to fix some issues and noticed the throw out bearing is a bit loose and quite dry. How long can you expect these to last? Mine has done 30K+ miles and the clutch plate itself is as new. They are very expensive, where's the best place to buy for a 951 if you recommend changing it.

Second question regards the flywheel and pressure plate. I noticed the wear pattern is uneven. There are two shiny rings on the plates, and two blue colored areas in between. Can I overlook this given that the clutch plate has so much life left in it? Machine work is very expensive over here. I did not feel any vibrations when engaging and disengaging the clutch, but I do have some low frequency vibrations around 3000rpm when accelerating.

John_AZ

Here are 2 of the best clutch resources to explain all failures...

(Big file)
http://www.schaeffler.com/remotemedi..._086_us_us.pdf

and

http://media.centerforce.com/DiagGui...cGuide04DL.pdf

It is possible to repack the TO throw out bearing. I repacked mine with 60K on it.

One side has a very thin aluminum sheild--DO NOT DAMAGE.

Separate the 2 pieces:



Inject grease with needle:


Press together.
TOs should last at least 100K

GL
John

bebbetufs

excellent tips and great links as usual. Thanks

bebbetufs

Ok, I took a look at the various failures but could not find one that exactly matches what my clutch looks like. I'll take some photos tomorrow "for your viewing pleasure".

bebbetufs

Here are some pictures of the pressure plate.

There is no shoulder on this PP at all so it must have been refaced when the clutch was changed probably 30K miles ago judging from the date written on the clutch.

There are some grooves in the outer shiny track. I Could not find anything wrong with the clutch plate itself which could have caused them.

I'm inclined to just reinstall after repacking the throwout. I did not feel anything wrong with the clutch when driving, and it does not slip.

Kerry Chadderton

+1 on repacking the bearing. Just make sure the ball bearings themselves aren't pitted from rust or scored from lack of lubrication. Otherwise, repacking should work nicely.

I'd be willing to bet those marks on your pressure plate were from the previous clutch disk. They look an awful lot like the marks that the rivets leave when a disk wears all the way down. I'd guess that the PO probably just replaced only the clutch disk. That would explain the marks and the fact that the TO bearing is dry at 30K. If the marks are uniform, and you have experienced no "chattering", slippage or noise, you will probably be fine with re-using the pieces.

That being said, I would be remiss as a 944 owner if I didn't recommend replacing the PP and resurfacing the flywheel. It's a 16 hour job to go back in if something is wrong! Of course you know that already.

On the otherhand I also understand the price of everything on these cars. Good luck. My fingers are crossed for you!

bebbetufs

Not a bad analysis, but if the grooves were from the rivets on the oil disc would not those areas be deeper in the pressure plate and hence less worn now that the new disc is installed?

On a different note, would you not expect the new disc to be almost worn out, not almost brand new at 32K miles. After all the first clutch was changed after that distance.

John_AZ

bebbetufs ,

How do the diaphram "fingers" look where they contact the TO?
Do they have TO "grooves" at the tips. Are they normal or do they look deep to you?
If too deep, the PP should be replaced.

The disc has "rivet scars" that Kerry mentioned. It may be reuseable but it should be resurfaced.

My guess is that when the clutch disc was replaced 30K ago, the PO did not do any work to the FW or PP and just installed a new disc.

If you have the PP & FW resurfaced, they should be balanced as a pair and individually.

If you just have the PP resurfaced, it should be balanced. The shop will need the FW to use a "chuck" (so you may as well pay to have them both balanced and resurfaced).



Kerry,

I just read an old post of yours. Congratulations on the shop!

GL
John

bebbetufs

Ok. I'll have a look at the fingers tomorrow.

Too bad that machine work is so expensive over here. $240 for machining plus shipping to the other side of the country...the only local machine shop had not even heard of balancing pressure plates and flywheels My guess is the common train of thought is that the extra wear is cancelled out by the cost of machining. None of the four mechanics I have spoken to had ever resurfaced anything when changing a clutch...kinda says it all...

Could i do this myself? I have access to several lathes.

Kerry Chadderton

Unforunately it has to be done with a grinding stone and lubricant. DO NOT get it cut in a lathe my friend. See the blueish spots on the flywheel/PP? They are now harder than the surrounding material due to heat. A lathe uses a cutting tool bit. That bit will skip due to the differences in material hardness. The result will be surface worse than what you have. If the machine shop does not have the equipment, experience and accountability to do this, you are better off doing nothing. I am sorry to hear about your situation. I know how hard it can be getting machine work done in parts of Europe. I was a ship's engineer before and have done work in your area.

Was the clutch slipping/chattering/making noise prior to pulling the engine?

bebbetufs

Thanks for replying.
I agree that a refutable shop is a must. I'll check around for options.

No symptoms of a bad clutch before pulling the engine.
I need to reseal the oil pump, that's why the engine is out.

INFMS

Just make sure the pressure plat surface is flat, do not machine the pressure plate as it will effect the clamping pressure on the clutch plate. If you decide to grind your flywheel you also need to grind the area where the pressure plate bolts too as well, or you will loose clamping pressure.

John_AZ

Regarding the pressure plate,

I think there may be some misunderstanding when I say "resurface" the pressure plate.

Usually, if the surface is not damaged by rivets or burn marks, very light sanding with very fine 1000 grit or finer emery paper using a flat steel block/surface will remove most marks.

If the pressure plate has surface burn marks but not deep rivet indentation, a couple of thousandths of material can be removed. INFMS is correct if any greater amount is removed.

Any damage to the diaphram springs/fingers or severe PP contact damage requires replacement.

Here is discussion on PPs:
http://ls1tech.com/forums/manual-tra...ure-plate.html

John

bebbetufs

Spoke to the only shop I trust to do this kind of work and the owner and I agreed to leave it until the next clutch change when it is time for a new PP anyway. I will lightly sand the flywheel and PP just to make sure they are clean, repack the bearing, say a little prayer and reinstall. Should be ok seeing I had no clutch related vibrations before.

Kerry Chadderton

Personally I think you'll be fine. Good luck!