Flywheel Resurfacing Limit?

[Chunkerz]

I am getting ready to put in a new clutch/related items, but before I can do that I need to get the flywheel turned. My flywheel has already been resurfaced once (not sure how much was taken off). How many times can the flywheel be resurfaced before it's time for replacement? Is there a wear limit? If I do get it shaved again, should I have them take double off of the pressure plate since the flywheel has been resurfaced twice (if that makes any sense. It made sense in my mind).

[CHICKS]

Why do you think it needs to be resurfaced again?

[MB968]

Not sure if all flywheels are the same. But for the 968 the pressure plate bolts to a surface which is stepped down from the flywheel surface. If you resurface the flywheel surface that the clutch disc mates to, you should take the same amount of material off the surface that the pressure plate bolts to. The distance between those two surfaces should be kept the same.

[kdjones2000]

[Chunkerz]

Originally Posted by CHICKS

Why do you think it needs to be resurfaced again?

It is my understanding that the flywheel should be resurfaced each time the clutch is replaced. The PO raced this car after the clutch was replaced last time so I'm assuming the flywheel has seen some abuse. I want to do it just for piece of mind. There's no point in doing all this work then finding out my flywheel is warped or something.

Originally Posted by MB968

Not sure if all flywheels are the same. But for the 968 the pressure plate bolts to a surface which is stepped down from the flywheel surface. If you resurface the flywheel surface that the clutch disc mates to, you should take the same amount of material off the surface that the pressure plate bolts to. The distance between those two surfaces should be kept the same.

I know the same amount should be taken off of the pressure plate. My delema is the flywheel has already been shaven once and the pressure plate is brand new, so even if I take the same amount off of the pressure plate they still won't be the same.

For example, let's say they took .05mm off of the flywheel last time and they take another .05mm off when I have it turned. Should I have them take .1mm off of the pressure plate so they will both have had equal amounts shaven off?

Originally Posted by kdjones2000

Not sure what this picture is showing me?

[Rasta Monsta]

Um, it is showing you how much material can be removed from the friction surface before the flywheel is out of spec (dimension one).

[MB968]

If you take a copy of the picture to the machine shop doing the work, they will know exactly what it means, and can probably explain it to you.

And, I wasn't suggesting taking any material off the pressure plate, but rather to the surface on the flywheel that it bolts to (if different from the main surface of the flywheel). Again, the shop will understand what this means.

[Chunkerz]

Originally Posted by Rasta Monsta

Um, it is showing you how much material can be removed from the friction surface before the flywheel is out of spec (dimension one).

I see.

Originally Posted by MB968

I wasn't suggesting taking any material off the pressure plate, but rather to the surface on the flywheel that it bolts to

You're talking about the area that the red arrows are pointing to correct? If so, then that makes more sense than taking it off of the center of the plate.


My question still remains though: if they took .05mm off the flywheel last time and take .05mm off again, should I have them take .1mm off of the area that MB968 is talking about???

[MB968]

Yes, I am talking about those areas, but not on the pressure plate, but on the flywheel where those surfaces mount. In theory, you should be able to take it off of either. But, you really don't want to make a unique PP that would only work with this flywheel. If you keep the relationship correct on the flywheel, any PP would work with it, and any flywheel would work with the PP. Hope this makes sense.

[Chunkerz]

Yeah, I get it now. Thanks! I'm glad I asked before I ruined a $700 clutch kit... I'll have to inspect my flywheel for signs of being milled there by the shop that did the clutch last time. They half assed most of the job, but hopefully they didn't half ass that.

[Rasta Monsta]

FWIW, the FSM does not mention the additional machining MB968 says is required for the 968.

[MB968]

Originally Posted by Rasta Monsta

FWIW, the FSM does not mention the additional machining MB968 says is required for the 968.

Yeah, it would be good to get other comments on this, and/or to get recommendations from a clutch mfg. Sometimes we engineers are driven too much towards original condition/like new specs. Worst thing that would happen if you leave the pp mating surfaces the same, is that the pp may loose a little clamp force, sine the surface of the flywheel is below where it was in its new condition. But, this may be a minor loss. After all, this effectively happens as the clutch plate etc. wear during normal use. I wouldn't hesitate to skip removing the mat'l from the pp mount surface, but for me personally I'd probably call a tech at Sachs to see how much the clamp force falls off with these kinds of changes.

Thanks for pointing out the fallacy in my thinking.

[Rasta Monsta]

Wouldn't say it was fallacious thinking, you were simply adding information to the discussion...

Sent from my SPH-L710 using Tapatalk

[tamathumper]

Back when I was working on that part of my 968, I took my original flywheel / pressure plate in to a local shop to have them assessed (about 45K miles on them), and they said they were in good condition but if I wanted them to, they would resurface the flywheel and remove the same amount of material around the mounting points as indicated above, to retain the original dimensions.

[MB968]

Tama, I also did the same with my flywheel. On 20+ year old parts, it is hard to know what their history is. Rather than add to the offset, I paid the few extra $'s to at least keep the offset dimension the same as it was when I bought the car.