Optimum Flywheel weight

[sideshowbob]

Converting my 635 CSI Highline from auto to manual.

Have all the necessary bits, but when it comes to a flywheel I have two choices....standard manual M30 flywheel or a lightened version.

The lightened version has been cleaned and skimmed to 6.6kgs (14.55lbs)

The car is basically my Sunday car and is really only used for occasional 'spirited' driving and a yearly high speed trip to Lemans. It is not used around town or as a main car.

The car has recently had a Fritz Bits manifold and stainless exhaust system fitted as well as the ECU remapped and retuned by Rich at Fritz Bits, I think it has gained about an extra 15 - 20 bhp.

Anybody on here had experience of a flywheel lightened to 14.55lbs....I read somewhere that this was a good weight for the M30 engine.

I am concerned that it might affect low speed drivability and give a lumpy tickover ?

Any comments ?

[jps635]

Nothing to worry about

[86_6series]

I think for street driving 14.55 is way to low. For the track it would be ok, but
for the street you'll always need higher revs to get moving.
17 to 18 lbs. would be my recommendation.

[jps635]

Like I already said is not a problem. I haven't had any issues. Its not like it's a super lightwight aluminium racing job

[LarryM]

14 lbs. is about the weight of a 533i/M5 flywheel, which some guys use vs. the stock 535/635 flywheel which weighs about 22 lbs. Most consider it an upgrade; you'll probably like the way the engine revs up more quickly. I'm using one and both the idle quality and low speed response are fine.

[bpoliakoff]

My 81 Euro 635 with a dogleg trans has a 17#er That is really supposed to be the desirable one from all of the posts I have read over many years. Use the search function and see what comes up

[GazM3]

i run a 12lb flywheel in my m635csi. low speed function is fine and it revs up really nice