Swapping to 5 speed, why not use an eta flywheel?

[Mr.SWISS]

Will it take the R3V away if I do? Local junkyard has a good clutch and flywheel off an 86 325es for $45 should I nab this for the auto 325is? (89)

[MR 325]

You can use it, it's just quite a bit heavier.

[Sagaris]

I have heard that a dual mass flywheel cannot be resurfaced. I know probably 90% of everyone on here just throws a budget non-oem clutch on a non-resurfaced flywheel and goes on their way, but for those who try to do things right, it is a consideration. Just remember that rotating mass has approx. 3x the effect of non-rotating mass. In other words, the effect of having a 40 lb flywheel vs a 20 lb flywheel would be like adding 60 lbs of dead weight to your car.

[MR 325]

Not all Etas had dual mass flywheels. You are correct though, you can't resurface them.

[Mr.SWISS]

You can use it, it's just quite a bit heavier.

What's the pro's and cons of the heavier flywheel? revs drop slower and raise slower vs faster with a lighter fly? Less gearbox chatter and more dampening?

[Sagaris]

Easier to start off from a stop, more stable idle (not something that you would notice unless you had a modded engines with large injectors and cams, in which case you probably wouldnt use a dual mass), and also what you listed about gearbox chatter and more damping/less drivetrain shock/smoother clutch action due to the springs inside.

[Nick_S]

They have pro's and cons. A heavier flywheel is generally easier to drive with but a lightweight one really wakes up the engine. Speaking from experience, on my SVT Focus I had. The stock flywheel was a dual mass 25lb unit, I switched to a single mass 12lb Fidanza flywheel and it was night and day difference. The engine revved so much more freely. From idle to around 5k rpm the difference was fairly dramatic in the way it ran through the gears. Downside was it chattered quite a bit and was much much more touchy to get off the line smoothly at first. Slow shifts sometimes required a bit of rev matching since they would drop off so fast. I loved it though and would like to do one for my E30 if/when I have to do a clutch anytime soon.

[Mr.SWISS]

Meh I had a swapped E30 with a 11 or 12Lb Fidanza flywheel and the chatter was more than noticeable. Never drove the car in stock form but it was no rocket.

Thanks for the input, for a DD I think the eta DM fly is my best option.

[MR 325]

Well it's not like the M20B25 flywheel is "lightweight" It's a factory part. You shouldn't get any chatter with it. Ultimately it's up to you.

[Cabriolet]

Not all Etas had dual mass flywheels. You are correct though, you can't resurface them.

what causes them to not be able to be resurfaced?

[Sagaris]

I suppose that any hunk of metal can be machined, but my understanding about resurfacing dual mass flywheels is that resurfacing them can cause balance issues. I am not certain whether this is a valid reason or not.

[J308]

Tagging this for later. I won't remember the discussion so I'll refer to it for how "street" I decide this car will be.

[smyleboyd]

http://http://m1089.photobucket.com/...e.jpg.html?o=0
I got mine resurfaced just fine. It was a little more expensive because of all the extra work of removing the pins but it looked just like a pice of candy

[MR 325]

Why on god's green earth would anyone WANT to run a dual mass flywheel?

[Wanganstyle]

Why on god's green earth would anyone WANT to run a dual mass flywheel?

I just replaced my M20 single mass clutch and flywheel setup with a dual mass setup. total clutch+flywheel rotating weight did not go up, and I like the modulation and engagement feeling of the dual mass setup better than the single mass. I could have ran a single mass setup, but decided against it as I like dual mass better.

The Dual Mass is a more modern clutch/pressure plate design, its feeling is pretty damm good. Just did a track/drift day, engine rev's faster with the dual mass unit.