deliriousga

For an '87 S4 5-speed. I've called several places here in Atlanta and they all say they won't machine a Porsche flywheel and don't know anyone who will. Does the flywheel have to be machined when replacing the clutch? I have a few very light grooves (1/4mm deep max) and no cracks anywhere. What will it do to the new clutch disc, release bearing or pilot bearing if I leave it as is?

It's currently 11mm thick on thickest point of the wear surface area (the area directly behind where the clutch disc contacts the flywheel). I read a previous post by Jim Bailey that said 27mm at the thickest point is the min. so I must be measuring wrong. Do I include the center area that bells? That's the only way I can see it getting that thick.

If it has to be done then is there anyone out there who knows of a machine shop in Atlanta that will do it?

Thanks!

Garth S

Cross hatch the surface with med- coarse emery cloth (~100 grit) using a flat wood block backer: this will clean and deglaze as req'd. A few1/4mm (10 thou) grooves are insignifigant. Test for flatness with a straight edge - and reinstall.

toofast928

I had mine machined for 40.00. the flywheel is no different than any other "flat" flywheel. Lots of shops get scared because you say "its from a Porsche......." A good machine shop will have no problem mounting and cutting the flywheel. If you decide not to cut the flywheel than must measure the flatness. This can only be done with a machinest square that is 6" long and feeler gauges.
As far as thickness, a normal cut is .002- .006" so not much metal is removed. I'm not sure of the single disc flywheel thickness but if the flywheel is under the max thickness, it must be replaced. A flywheel under the max thickness changes the slave cylinder stroke (decreases it) so the disc may drag when the clutch is released.

Chris Lockhart

John, when I replaced the clutch on my GT about 3 years ago, I had the flywheel machined. Way too many high/low spots, and the clutch was chattering prior to replacement. I took the flywheel to my local Napa Auto Parts facility that had a machine shop. (not just the regular Napa parts store) They machined about .030" from it, for around $25.00. Put her all back together, and she's been great for around 50K miles now. They knew it was for a Porsche, but didn't seem to act like it was a problem. A flywheel is a flywheel.

GlenL

What crap. Here's what I did:

Printed out the page on the specs from the manual and took it to a decent machine shop. Put 1987 "Audi 5000" on the form and attached the manual page. This way they knew exactly what to do and I didn't pay a Porsche Tax.

deliriousga

That's a great idea Glen!! That's everyone's first question..."what's it from?"

I'll take it with me to work tomorrow and drop by the local NAPA shop (they have a garage, but don't know if they do machining there) and see if they can do it.

Looking at it closely, it may have been machined before. I re-measured when I finally found everything in the WSMs and it's right on the edge of minimum. One of the POs has already changed the ball and arm to the new, larger one so I won't have to replace the ball. Maybe they had it machined when that was done. Still changing the arm as there was no bushing at all and it wore a nice cup in the top of the clutch arm.

Thanks guys!

docmirror

Since a mm is about .040", and you have approx 1/4mm scratch in it, you'll need to take about .010" off it to clean up the gouge (estimates). That's quite a lot for one cut on the flywheel machine. Find the correct location to check the thickness so you know where you are at first.

I've done the virtual "marque swap" bunches of times with the Lamborghini to make the parts an Alfa or some such. Just let the shop know what you want done, as in "Remove .006, and check for the gouge being gone". I have a few questions; before removal, did the car lurch slightly when moving off in 1st or reverse? If so, this is an indication of either strange wear on the flywheel or pressure plate. Is there any glazed looking area on the plate, or is it a uniform dull metal color? Discolored glazing, usually found around the outer perimeter is an indication of slippage, and should be machined out, or at least cleaned off with a flat bar, and some fine emory.

deliriousga

It was glazed. It never lurched, but did slip once when in reverse when I was backing up a really steep driveway.

I decided to replace the clutch because of the chirping sound I had before I put her in the garage to do catch-up from the PO. I'm replacing the release bearing, clutch plate, clutch arm w/ ball cup, pilot bearing and RMS. When I took everything out there was no ball cup so it wore a cup into the clutch arm and the release bearing had about 2-3mm of play in it.

I'm looking at replacing the flywheel with a used one if it's going to be good for a decent amount of time. I want to figure out if it's worth the extra $$$ for a new one. If two used flywheels last as long as one new one, it's still cheaper. I think the worn out clutch plate, along with everything being out of alignment due to no ball cup, wore the flywheel out. If I check the ball cup and clutch plate thickness often I think I can prevent the premature wear from happening again.