Single Mass Flywheel Conversion

[CB750]

I've had an ECS Tuning single mass flywheel conversion kit sitting on the shelf for a couple of years, and finally installed it along with a transmission shift pin detent refresh.
My 100k mile OE S52 M clutch assembly was becoming problematic, no slipping under load, but I could feel that it was approaching end of life.
Upon disassembly it was no surprise that the clutch disc was nearly to the rivets, and the nylon clutch fork pivot and throw-out bearing guide tube were worn.

I've put 500 miles on the single mass flywheel, M5 pressure plate, and sprung-hub M5 clutch disc.
Zero gear rattle at idle running Redline D4 ATF. The M5 clutch is great, and shifting is a helluva lot better with new detent pins and sleeves.
As expected, the car feels livelier with the 16.5 lb. flywheel. Overall, the swap was well worth the effort.

30 JULY 2023 Edit:
>Well, I heard mild gear chatter / rattle today after the car sat idling in neutral for 30 minutes or so as I fiddled with INPA and a few maintenance tasks.
>The 16.5 lb flywheel and sprung hub clutch disc minimizes trans noise with a SMF flywheel but doesn't eliminate it.
>I might try the UUC trans oil mixture concoction, but the noise is pretty minimal, and I like the way the trans shifts with straight Redline D4 ATF.

[zellamay]

I agree, really like the lightweight flywheel. I also rebuilt my shifter completely, which improved the shifter feel.

[z3forlife]

I tried a single mass but the rattle was terrible. Went back to a dual mass.

[CB750]

I tried a single mass but the rattle was terrible. Went back to a dual mass.

Yeah, I've heard and read about gear rattle issues, but I think that's a consequence of going with an overly lightweight flywheel, not a single mass vs. dual mass issue.
No difference in noise with the 16.5 lb. ECS flywheel, and I am not running any sort of special anti-gear rattle trans oil concoction.

[zellamay]

Yeah, I've heard and read about gear rattle issues, but I think that's a consequence of going with an overly lightweight flywheel, not a single mass vs. dual mass issue.
No difference in noise with the 16.5 lb. ECS flywheel, and I am not running any sort of special anti-gear rattle trans oil concoction.

I have the JB flywheel, 10 lbs, and it has the gear rattle. (I don't have the oil formula that UUC recommends, but I will try it someday.) In debates about gear rattle, I've not read that weight makes much of a difference, but I sure don't know. ..... I will say that it would be better not to have it, but it is so minor that it is inconsequential to me. Doesn't begin to detract from the fun of driving that it adds. But to some, it matters. ..... I'd suggest that those considering the change should drive and listen to a couple of cars with it.

[z3forlife]

It could have had something to do with the installer too. I did like the shift action and rev speed. I had to do a engine swap and the whole process turned out poorly. A once reliable Indy shop totally fubar’d the job. I eventually filed 2 claims on his liability insurance for the 6K in damage that occurred when the driveshaft let go at 70mph. Got made whole by his insurance but a really bad experience. Mine was a 16# flywheel too.

[pine1000]

I've had an ECS Tuning single mass flywheel conversion kit sitting on the shelf for a couple of years, and finally installed it along with a transmission shift pin detent refresh.
My 100k mile OE S52 M clutch assembly was becoming problematic, no slipping under load, but I could feel that it was approaching end of life.
Upon disassembly it was no surprise that the clutch disc was nearly to the rivets, and the nylon clutch fork pivot and throw-out bearing guide tube were worn.

I've put 500 miles on the single mass flywheel, M5 pressure plate, and sprung-hub M5 clutch disc.
Zero gear rattle at idle running Redline D4 ATF. The M5 clutch is great, and shifting is a helluva lot better with new detent pins and sleeves.
As expected, the car feels livelier with the 16.5 lb. flywheel. Overall, the swap was well worth the effort.

Thanks for the review. I've been considering ordering the ECS clutch/flywheel kit for a few years. My car is at 98k miles. So, it is probably time.

[CB750]

Thanks for the review. I've been considering ordering the ECS clutch/flywheel kit for a few years. My car is at 98k miles. So, it is probably time.

I could have squeezed another year out of the OE clutch, but thin clutch disc + worn clutch fork pivot + Mason clutch pedal = annoying clutch engagement range.
I like the fact that other than the flywheel and bolts, the ECS kit uses OEM Sachs BMW M5 bits, and the sprung hub clutch disc is loaded in the proper direction rather than a "backwards" orientation used by some single mass conversions.

[sleeperz]

I have had the E36 5 spd UUC flywheel and M5 clutch conversion for many years in my MZ3. Not a lot of miles, probably 30k? When I first put it in, no problems for a while. Then I got the rattle. I thought I had some issue with my tranny, so I bought a used E36 M3 5spd and installed only to have the same issue. I learned of my errant diagnosis later from a fellow autocross club member.
I did discover the rattle is more prevalent if my car is idling below 900rpm. I have not experimented with changing the DME to increase idle rpm. For now, I just ignore it. I do like the UUC product and the clutch holds up well to autocross launches. In addition, I have a good 5spd if anyone needs one. Wink.

[zellamay]

2 thoughts: The "annoying clutch engagement" could also have been from the dual-mass flywheel developing slop from age. Mine was bad. .......... Also, there was rumor that the sprung-hub discs were "loaded" in one direction. All I can say is that the stock M5 disc I bought was not, so functionally it did not matter which way it went in. Measurements told me that it could have gone it the "correct" way, but just barely. Fearing measurement error, and because it didn't matter, I put it in "backwards". Works perfectly.

[CB750]

2 thoughts: The "annoying clutch engagement" could also have been from the dual-mass flywheel developing slop from age. Mine was bad. .......... Also, there was rumor that the sprung-hub discs were "loaded" in one direction. All I can say is that the stock M5 disc I bought was not, so functionally it did not matter which way it went in. Measurements told me that it could have gone it the "correct" way, but just barely. Fearing measurement error, and because it didn't matter, I put it in "backwards". Works perfectly.

The original dual mass flywheel was within spec and I suppose it could have been reused.
In my opinion, the dual mass flywheel is mostly intended to compensate for operator errors.
As I mentioned above, the OE clutch disc was pretty much done, and the clutch fork pivot pin was worn, as was the throw-out bearing guide tube.
Add the leverage characteristics of a Mason clutch pedal to the above and "annoying clutch engagement" is the result.

[streetmaster56]

I weighed the oem dual mass vs the Valeo single mass on the scale which both were the same in weight, i get no gear chatter with no spongy feel to the clutch peddle either.