Resurfacing dual mass flywheel

[dlmrun2002]

Just took my flywheel  to local shop to have it resurfaced before  I put my new rebuilt track motor back in.  Said he couldn't cut it  because  the dual mass  actually moves when spun. Do you need a special machine for this?Thanks for the help...

[johna]

I have also been told that dual-mass flywheels cannot be resurfaced. "If reusing, use 600-grit sandpaper on a DA sander and clean throughly before fitting."

Otherwise replace it with a new dual-mass flywheel, or fit a lighter conventional flywheel and clutch from an M40 engine, or do the M20 flywheel conversion.

[christophbmw]

got mine re-surfaced. cost about $80. turned out nice, i took it to my local machine shop (i dont think they used a special lathe).

[Alpine003]

"If reusing, use 600-grit sandpaper on a DA sander and clean throughly before fitting."

I did something like this recently. As long as you don't have any major hotspots, your should be fine.

[dlmrun2002]

Well it cleaned up well with a wire brush.. then went  with 400 to  600 grit using a block...then   I scuffed it up with 80.....smooth, flat  and a slight scuff edge like it came off  a machine. Don't want  it to shiney or the clutch might glaze it.. I'm done... time to pick up motor

[turbo_negro69]

Just took my flywheel  to local shop to have it resurfaced before  I put my new rebuilt track motor back in.  Said he couldn't cut it  because  the dual mass  actually moves when spun. Do you need a special machine for this?Thanks for the help...

this is good old fashioned BULL$H1T!!!1! I had my flywheel turned for $40 at a local machine shop. came out perfect, took about 30 minutes and I havent had any problems!

[tophertii]

dlmrun2002, Sweet ride, I want your car!

[Blackice]

Why do some 318's have daul mass and other's do not ? What is the differance ? How does one know if they have or don't have a daul mass unit ?

[dlmrun2002]

That  wagons not mine..Some Euro owner I think  It has an M50 motor I think in it. These are my toys.

[D. Clay]

Why do some 318's have daul mass and other's do not ? What is the differance ? How does one know if they have or don't have a daul mass unit ?

I'm not sure but I think all the US model 318is's were Dual Mass. With Dual Mass setup the shock absorbing function is handled in the flywheel rather than the clutch. As a result a Dual Mass clutch disc is a solid plate that does not have springs in it. For some pictures of a Dual Mass flywheel:
http://www.m42club.com/forums/showthread.php?t=2135 Post #1 is a dual mass flywheel. It has two parts (mass's) that you can see in the photo. The clutch that goes with this flywheel is a solid disc. Post #38 is a single mass flywheel (1 piece)  with the clutch disc beside it. You can see the springs in the clutch disc.
The clutch disc springs or the flywheel internal springs absorb the shock of the initial clutch engagement.  I have driven a car with a Tilton 3-disc racing clutch with a single mass flywheel and no springs in the disc's either. It's more like an on/off switch.  Bang-you're off and you better be in the gas. I now understand how even professional drivers kill the motor leaving the pits and why they always seem to burn rubber taking off. I had never heard of a dual mass flywheel until I got mt my 318is.

[dude8383]

Why do some 318's have daul mass and other's do not ? What is the differance ? How does one know if they have or don't have a daul mass unit ?

The car's without a/c i believe didn't come with a dual mass flywheel. To my understanding though, every m42 in the U.S. should have a/c or at least should have come with a/c from the factory.

That  wagons not mine..Some Euro owner I think  It has an M50 motor I think in it. These are my toys.

Lol if that was an m50 motor, I would have picked one up a LONG time ago.

Thats a euro s50b30 motor...320hp of inline 6 goodness.

[turbo_negro69]

The car's with a/c i believe didn't come with a dual mass flywheel. To my understanding though, every m42 in the U.S. should have a/c or at least should have come with a/c from the factory.

M42's with A/C DO have dual mass flywheels, both of my cars have 'em.

[Blackice]

I'm not sure but I think all the US model 318is's were Dual Mass. With Dual Mass setup the shock absorbing function is handled in the flywheel

Thanks for the info, and the great photo links. The info on realoem.com shows cars with A/C to have Dual mass and cars without A/C to have a single mass unit , Is this the correct term ?  I assume that USA and Canadian cars are the same spec. They show my 91' 318 i w/o ac { Canada } to be a single mass. But I am not sure. Since the clutch will have to be done this summer, It would be nice to know. Where would one confirm this ? Can the fly wheel of a dual mass be lightened ? Was the dual mass used for A/C cars for better holding power ? Since there is a A/C unit adding drag ?

[Vladi]

1.6 m40, 1.8 m40 and 1.8is m42 in Europe also have Dualmass Flywheels and the cars don't have a/c.

[dude8383]

M42's with A/C DO have dual mass flywheels, both of my cars have 'em.

edited my post..i missed the word "without"

on realoem it listed two different flywheels for cars with a/c and without a/c