Anybody ever had the flywheel lightened? M102/717.412
 

I have a 2.3 M102 190E that I'm converting to MS2 fuel+spark. I will also put a 717.412 behind it instead of the automatic transmission. I'm not trying to achieve insane power, I just want the car to feel "crisp". The car already has the usual chassis upgrades like Sportline bushings, Bilstein B8's, Eibachs and SS brake lines. I know I can achieve that crisp feeling with the details, like delrin shifter bushing, stiff mounts, good throttle response, etc...

I have a single mass flywheel for a 8.5" clutch. I weighted it and it weights about 24 lbs. I found this picture on my computer that I probably saved from a while ago. I do not remember where it comes from or who did that or how it worked out for that person after he installed it. It looks like this flywheel had the outer part removed. From my estimations, this should reduce weight by about 5.6 lbs, bringing the total weight to 18.4 lbs.
https://i.imgur.com/PpwH4y4l.jpg

I'd like to know if anyone here did this before, how much you took off, what was the final weight, etc... It took me a while to find a flywheel for sale and I would not like to ruin this one by taking too much weight off of it.

I lightened my M103 flywheel from 21.6 lb to 17 lb

Before:

https://scontent-sjc3-1.xx.fbcdn.net...0a&oe=5BA565B0
https://scontent-sjc3-1.xx.fbcdn.net...15&oe=5BBCE1E6

After:

https://scontent-sjc3-1.xx.fbcdn.net...fc&oe=5BB994AE
https://scontent-sjc3-1.xx.fbcdn.net...1e&oe=5BBD6ECF

Been about 8 years since I did that and I recently had it resurfaced for a new clutch and pressure plate.

http://www.peachparts.com/shopforum/...1&d=1528953197

Edit: is the 717.412 a dual mass or single mass flywheel transmission?

Thanks! I wasn't expecting such a fast answer! Did it make a good difference in driving feel?

412 and 411 are single mass.

A light flywheel will:

Make for a rougher idle.

Make it more difficult to pull out on a hill.

Increase transmission gear rattle when in neutral / clutch engaged.

Increase HP if measured on an inertia dyno but make zero increase on a loading dyno.

I never drove the car without flywheel lightened so I don't have a comparison. But I don't really have any complaints about it, drives just fine and idles very smooth.

My situation is different than yours though since my motor is an inline 6 while you are on inline 4. SL320 may be right about having a rougher idle due to that difference.

A lighter flywheel will allow the engine to accelerate and decellerate faster. this will help in an autocross. It also will make the engine feel quicker and more sporty. it won't affect sustained power as noted by 320 above but it will feel quicker. With your other mods it should fit right in.

I did one for a guy who raced a 4 cyl car I believe it was a Hundi. I just put it on my 11" lathe and cut the back of it down. No balancing just cut and use as is. He had no issues with it.

A brake disc / drum lathe works just fine too.

If the profile of the fw casting does not change one can get away without a rebalance.

If the casting is off center and lightening changes the off center areas, rebalancing will be needed.

For sure I will have it rebalanced. Too much to risk! Thanks guys