MF215 vs 228 w/ lightened flywheel for uprated motor

[BVNitta]

My non-tii '76 is getting an uprate to around 150HP and a mildly lightened flywheel (2-4lbs off) in the process. Intent is to use it for street and autox. I currently have an MF215 clutch on it (pre uprate). For this setup, is an MF228 recommended ? Did the tii come with that clutch ? What other combos would work ? E30 M3 ? Thanks guys,

Bhima

[jgerry2002]

If your flywheel is a 215mm then you have no choice other than 215mm clutch. 228 and 215 flywheels are different.

Recommendations over the years say that any uprated motor would typically receive the 228mm clutch and flywheel.

[BVNitta]

Is the 228 flywheel the same as the ones for the tii or E21s or E30s ? Thanks again,

Bhima

[BVNitta]

This is getting more involved than I expected.

1) So, if there is a consensus that for uprated motors, the 228 flywheel, disk and PP setup is optimal, the 228 FW can be lightened (within reason), I assume, without drastically impacting idle, launch, drop-rev cutoff and clutch life, right ?

2) I assume that if I retained my 215 setup, clamping force would be a bit lower, to the detriment of clutch life ? Remember, we are only talking of a 7% change in surface area between the two. In this case, lightening the 215 FW would not be a good idea, right ?

3) I got my 5spd OD tranny from a tii and not the flywheel, clutch & PP. I assume the PO used a 228 setup on his tii and the TO bearing is appropriate for it.. If it were OK to use the 215 setup (see 2 above), I imagine I can use the same TO bearing or are the PP's so different that I would need to change the TO bearing as well ?

Thanks,

Bhima

[jgerry2002]

This is getting more involved than I expected.

1) So, if there is a consensus that for uprated motors, the 228 flywheel, disk and PP setup is optimal, the 228 FW can be lightened (within reason), I assume, without drastically impacting idle, launch, drop-rev cutoff and clutch life, right ?

2) I assume that if I retained my 215 setup, clamping force would be a bit lower, to the detriment of clutch life ? Remember, we are only talking of a 7% change in surface area between the two. In this case, lightening the 215 FW would not be a good idea, right ?

3) I got my 5spd OD tranny from a tii and not the flywheel, clutch & PP. I assume the PO used a 228 setup on his tii and the TO bearing is appropriate for it.. If it were OK to use the 215 setup (see 2 above), I imagine I can use the same TO bearing or are the PP's so different that I would need to change the TO bearing as well ?

Thanks,

Bhima

With the higher torque, to me its a no brainer just put a 228 on it. Yes you can lighten them. Many vendors sell them (metric and others). I have a 215 on my '76 with 150hp metric mechanic motor and the clutch is starting to slip after about 25k miles. When I put a 5-speed in maybe next winter I'll move to a 228 flywheel.

If you use a 215mm you need a E21 320i throwout bearing. If you use the 228mm you need the E21 323i throwout. This is well documented on many websites.

[BVNitta]

Perfect ! Just the info I wanted. Thanks, mate.

Bhima