Lightened flywheel 325i

[chatstar123]

I'm think about manual swapping my 325i auto and have been reading about lightened flywheels. Is it a worthwhile mod? What are peoples real world experience with these on their cars compared to standard? I'll most likely not be tracking my car but it'll be used for some spirited road driving when it's eventually back on the road.

[flybynite]

Drove one for years but up to '84 the 323i had one as standard, Can't remember what it weighed but I don't think it is recommended to go much below that weight.

I think aircon cars had lighter ones too but not as light as the early 323i

Faster revving but easier to stall, depends on what you do with the car. IMHO you don't get the full benefit unless properly balanced up with the rest of the rotating mass.

[DanThe]

I get the best part of 3kg out of a standard M20 flywheel and there are no downsides, as said definitely balance afterwards, a flywheel out of balance saps power and shortens engine life

If you already have an old flywheel you can buy an exchange unit here

https://bmconversions-uk.co.uk/product/ ... e-service/

[chatstar123]

Thanks for the responses and nice plug Dan! I don't have a flywheel or any of the parts at the moment as this is still very much in the thinking about/planning stage

Excuse my ignorance but to balance the flywheel on the engine does the engine need to be out of the car or can it be done in situ?

[flybynite]

Excuse my ignorance but to balance the flywheel on the engine does the engine need to be out of the car or can it be done in situ?

The flywheel can be balanced on its own and that will help and likely be no worse than the original one coming out.

Most people won't put a lightened flywheel on a tired old engine so if you are refreshing the engine with shells in the bottom end then take the opportunity to balance the crank with the flywheel

The place I use takes everything, crankshaft, timing gears, flywheel, clutch pressure plate, crank pulley and pulley bolt.

[chatstar123]

That makes sense now. Thanks for the explanation.

I don't plan on taking the engine apart any time soon but this gives me something to consider.