m20 singlemass flywheel machining

[ZekeTheSneak]

Has anyone had there m20 singlemass flywheel lightened instead of buying a lighter one? I'm looking for pricing and weight of flywheel after being lightened. A few local shops around me can do it just want to know of any problems I may face.

Thanks

[OrganicMechanic]

it is fine--took 11 lbs off mine 3 years ago. Have had no issue out of it yet

[kendogg]

I did it as well. Not worth it IMO. But, I strongly dislike ltw flywheels, so.... Stock flywheel weight is great for these cars on anything except an all-out racecar.

[Sean]

I did it as well. Not worth it IMO. But, I strongly dislike ltw flywheels, so.... Stock flywheel weight is great for these cars on anything except an all-out racecar.

Disagree. I don't see why you wouldn't like it? It makes rev-matching quicker and makes it fun to rev the car. Now, if you don't like rev-matching, then yes, it would be terrible and the RPMs drop off really fast.

[kishg]

disagree. I don't see why you wouldn't like it? It makes rev-matching quicker and makes it fun to rev the car. Now, if you don't like rev-matching, then yes, it would be terrible and the rpms drop off really fast.

+1

[kendogg]

Disagree. I don't see why you wouldn't like it? It makes rev-matching quicker and makes it fun to rev the car. Now, if you don't like rev-matching, then yes, it would be terrible and the RPMs drop off really fast.

I rev-match every shift I make, in pretty much every car I've ever owned. I dislike the gearbox rattle. I always felt the engine dropped rev's too quickly (for a streetcar) with the ltw flywheel, in both my last E30, as well as my E28 533i with the stock 14 lbs flywheel. On track, as I stated, is a different story. I don't shift fast on the street, I'm pretty easy overall on synchro's and gearboxes. With a ltw flywheel, I usually need to blip the throttle twice to get the rev's matched by the time I'm letting off the clutch. I'll take the ease of an ~18 lbs flywheel over the 0 performance increase of a ltw flywheel.

[KenC]

it is fine--took 11 lbs off mine 3 years ago. Have had no issue out of it yet

How did you take 11lbs off of a 17lb flywheel? I have to see pics of this.


You can easily machine a stock singlemass M20 down to 12-13lbs. Light enough to notice a difference, but not a PITA like a 7lb aluminum one.

[M-technik-3]

Hmm quicker revs vs the engine having to labor to move the flywheel is reason enough to swap em for me. When I swapped out the one on my M50 back in the day it was like night and day. The slight rattle oh wheel it's an old car.

[kendogg]

Hmm quicker revs vs the engine having to labor to move the flywheel is reason enough to swap em for me. When I swapped out the one on my M50 back in the day it was like night and day. The slight rattle oh wheel it's an old car.

You do realize it doesn't effect the acceleration of the car at all, right? Under load, the engine isn't going to accelerate any faster or slower.

[Sean]

I rev-match every shift I make, in pretty much every car I've ever owned. I dislike the gearbox rattle. I always felt the engine dropped rev's too quickly (for a streetcar) with the ltw flywheel, in both my last E30, as well as my E28 533i with the stock 14 lbs flywheel. On track, as I stated, is a different story. I don't shift fast on the street, I'm pretty easy overall on synchro's and gearboxes. With a ltw flywheel, I usually need to blip the throttle twice to get the rev's matched by the time I'm letting off the clutch. I'll take the ease of an ~18 lbs flywheel over the 0 performance increase of a ltw flywheel.

Yep, definitely a rattle and no real performance gain - but its fun! :) It's definitely all up to the individual.

I agree - there really isn't much point. But if it's out, why not?

[2002maniac]

I think it's a great way to go. I have lightened 2 stock flywheels with great results.

[kendogg]

Yep, definitely a rattle and no real performance gain - but its fun! :) It's definitely all up to the individual.

I agree - there really isn't much point. But if it's out, why not?

I'm A-ok with somebody doing anything they want to their own car :) I was just putting out my $.02. I just have to argue with the people who try to state the heavier flywheel makes some kind of difference in power or acceleration - because, well, it doesn't.

[gearheadE30]

I took a reasonably good amount of material off of the M20 single mass that went into my M42, but some of that you have to do simply because the flywheel is too thick on the back side and can hit the engine. I don't know what the difference between it and a non-lightened single mass would have been, but compared to the dual mass, it vibrates more but drops revs far faster, which is nice. In the past, on the track I would have to wait a bit to shift to wait for the revs to come down. First gear acceleration did actually improve enough to be measured on the stopwatch, though.

[7pilot]

I'm A-ok with somebody doing anything they want to their own car :) I was just putting out my $.02. I just have to argue with the people who try to state the heavier flywheel makes some kind of difference in power or acceleration - because, well, it doesn't.

I think would qualify the * no difference in power* to *no noticeable difference in power*.

The flywheel is an energy storage device.
If the flywheel is lightened, there is less energy being conserved in the flywheel and that non stored energy is now available to drive the wheels. Less power is required to accelerate the rotating mass of a lightened flywheel.
Most of us won't notice any gain in acceleration, but a lighter flywheel tends to make it easier and quicker to get the revs to match when the driving is rapid. On a race track there are time savings from the rev matching and driver confidence/attitude.
Lightened flywheels would not be so popular in racing/track cars if there were no benefits to reducing lap times.

I used a lightened flywheel in my M3 and it was an improvement.
The engine accelerates much more quickly and made the task of rev matching easier.

On a street car, I don't see much point in a lightened flywheel. I want a civilized street car on the street, not a rattly brute that I have to clutch slip and rev in order to prevent stalling.

m

[ttrousdell]

took bout 4 pounds off mine and resurfaced it. cost me 130