Flywheel re-surface questions - Help me understand

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jjs2800cs

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Just removed flywheel as part of 5-speed conversion on 70 2800CS. Attached is photo of flywheel and it is worn. The friction wear surface is scarred. Estimate the wear from the bolt surface where pressure plate attaches is .030" to .040" down.

Can we have the wear surface smoothed by a shop as long as we do not go beyond the .532" distance shown from the factory manual diagram which is attached?

The question is the manual diagram actually shows the friction surface raised from the pressure plate bolting surface whereas mine is recessed the .030" plus..

Is mine worn that much or am I missing something here?

It appears that my distance "A" from the diagram will be just a few thousands less that the minuimum .532" specified after the friction surface is machined.

Also does the surface that the pressure plate bolts to also gets shaved along with the friction surface?

If mine is shot where can I get a good used one?

Thanks

jjs2800CS
 

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Not sure about the minimum thickness. There may be adequate meat. I had mine lightened, so they took quite a bit off the front side (opposite the pressure plate).

Also does the surface that the pressure plate bolts to also gets shaved along with the friction surface?
Click to expand...

Yes, they do. They will remove the 3 pins to do this.
 
Sven

From your reply am I to assume then both surfaces get machined? Do they get machined so they end up being flush (at the same level), or both get machined the same amount from where they are now, with the amount determined just enough to get the friction surface smooth?

Thanks for the response

jjs2800cs
 
Make sure it wasn't overheated before investing in that flywheel. If it has had hot spots, machining might not give you a smooth flywheel.
 
Both surfaces are machined (the outer ring where the flange of the pressure plate bolts to and the clutch mating surface). They are offset, but I do know by how much. They should not be machined by the same amount since the outer portion has no wear relative the worn clutch mating surface.
 
Thanks for all the replies thus far. Does anyone have a new one or a refinished one available that they could take some measurements? Specifically the dimension A (see diagram in intial post) and the step down or offset Sven mentions to the friction surface.

Also anyone know why the diagram shows the friction surface raised instead of recessed?

Before I have to get another one $$$, I would like to make sure this one is still usable.

Thanks again.

jjs2800cs
 
A few comments for you-
Throw the old bolts away, always use new clutch bolts as ordered from the etk
There needs to be a 1mm step down from the working surface
to the mounting surface so that the mounting surface does not
interfere with the working surface.
Be aware that there can be be drivability issues with lightened
Flywheels - a 17lb flywheel is very light already. Compare this
To the 28 lb dual mass unit in a '89 535i
Double o2 salvage has stacks and stacks of good flywheels
Available- ask for Marshall
Have you asked your local machinest to look at it
 
sfdon

Thanks for the detail info

I have new flywheel bolts and will not lighten the flywheel.

From what you say then the friction surface is acutally higher that the pressure plate mounting surface by 1 mm. This is the opposite of my piece as the friction surface is a good .030 to .040 inches (.75 to 1 mm) lower (worn?) than the mounting bolting surface.

Is this correct?

Thanks

jjs2800cs
 
You got the idea- my guess is that last machine shop screwed the pooch somehow.
Any competent shop will fix you up for 50 bucks.
 
Thanks for all the replies,

Flywheel is at local experienced machine shop. First they will shave the flywheel down flush cleaning up the scars on the friction surface. Measurements revealed this will leave us with almost exactly .532" thickness of "meat" as specified by the workshop manual as minimum thickness at that point.

Then they will step the pressure plate bolting surface. We are not going a full 1 mm but a half mm at the recommendation of the shop. This should not be an issue as there was no problem with clutch slippage prior to removal. Thus the as found condition was the surface of the flywheel had already worn down the 1mm (040") step plus the .030" of additional wear. Throw in an almost worn out clutch disc and one would have expected some issues, but there were none.

We estimate the total that will be taken off of the bolting surface will be .060-070" and the friction surface ~.035".

Thanks again,

jjs2800cs
 
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