Lightweight flywheels: worth the money?

[Jay 535i]

Now that my transmission swap is looking like a 'go', I'm wondering about, well, all sorts of stuff.

For instance, are any manual-tranny guys out there running lightweight flywheels? What kind of improvement did you notice?

It looks like quality third-party lightweight flywheels for the E34 go for about $4-500. Are they worth it?

The alternative is an E28 flywheel, which will probably still cost $200. So the difference is about $300. Worth it for the performance difference?

[Martin in Bellevue]

E28 flywheels are around for about $100. A machinist cut mine down to 15 lbs. It is nice to have the revs raise & drop quicker, & there is no noisy shutdown. You have a good opportunity with this gearbox swap to get the preferred flywheel.

[Jay 535i]

Thanks Martin.

If I got an E28 flywheel, I'd probably do as you did. When I said $200 for the E28 flywheel, I was including the cost of having it worked a bit, as you did.

You said 15 pounds was the result. The "lightweight" items I was referring to are below 9 pounds. I'm really curious as to perceived differences from behind the wheel, both in terms of performance and refinement.

[DanDombrowski]

Jay,

If you get a manual trans and a limited slip from the donor car, you're probably going to be faster than me, so I'm gonna have to encourage you not to do that

Seriously, I don't know, but good luck, let us know how it turns out.

[Martin in Bellevue]

The stock e34 m30 flywheel is 32 lbs. The 15 lb flywheel provides noticeably quicker throttle response out of gear. Rev-matching shifts are more enjoyable & easier with a lighter flywheel.
A 9 lb flywheel may be tough on a daily driver. Metric Mechanic has a lightened harmonic balancer that loses 4 lbs, I think. I don't know of anybody with this part.

[Blitzkrieg Bob]

The RPMs moves quicker up & down, but down shifting and hill climbing changes as you go lighter.

You begin to lose the hang on a down shift,and steep/long hills take higher revs to climb.

[Scott H]

your chances of stalling it are higher with a lighter flywheel as you lose the rotational inertia that something with more mass has.

The RPMs moves quicker up & down, but down shifting and hill climbing changes as you go lighter.

You begin to lose the hang on a down shift,and steep/long hills take higher revs to climb.

[Jay 535i]

Thanks everyone. Please keep the input coming.

What's the stock weight of the E28 flywheel, BTW?

[Scott H]

per ETK

sounds about right from the general feel of my E28 stuff

stock dual mass is roughly 33lbs

Thanks everyone. Please keep the input coming.

What's the stock weight of the E28 flywheel, BTW?

[rob101]

The RPMs moves quicker up & down, but down shifting and hill climbing changes as you go lighter.

You begin to lose the hang on a down shift,and steep/long hills take higher revs to climb.

oh so thats why my e28 is more involving to double clutch on the downshift than my e34, well you learn something new everyday