M20 flywheel on M50?
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BornToBeE30
- E30 Zone Newbie

- Posts: 53
- Joined: Sun Apr 11, 2010 11:00 pm
Just a quick before the transplant.
I know this is shown to be the most favourable option when doing the M50 conversion.
I'd just like to know what the pro's and con's are for this set up due to having to lighten and balance the M20 fly?
Has anyone had problems with maintaining a constant speed at low or high rev's I.e. round town/motorway?
How much is affected up hills/slight inclines?
I know it will become more responsive but what will the low end torque be like? Will i constantly be shifting to a lower gear to compensait?
Has anyone here used m20 flywheel lightend/balanced and wished they hadnt?
Thanks in advance.
I know this is shown to be the most favourable option when doing the M50 conversion.
I'd just like to know what the pro's and con's are for this set up due to having to lighten and balance the M20 fly?
Has anyone had problems with maintaining a constant speed at low or high rev's I.e. round town/motorway?
How much is affected up hills/slight inclines?
I know it will become more responsive but what will the low end torque be like? Will i constantly be shifting to a lower gear to compensait?
Has anyone here used m20 flywheel lightend/balanced and wished they hadnt?
Thanks in advance.

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hongkongfuey
- Mad-tango-geezer
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You dont have to lighten the m20 fly as its lighter than the m50/52 flywheels , thats why people swap them, as far as lightened flys go, i have a 5.5kg in my m20 325 which is fine.
if there wern't people like me,
with cars like mine,
who would you put down to make yourself feel better?
with cars like mine,
who would you put down to make yourself feel better?
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DanThe
- E30 Zone Team Member

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This is bull, nothing more than internet myth, lightened flywheel does not affect torque in any way, it wont slow you down it will make you faster as the engine will speed up much quicker.BornToBeE30 wrote: How much is affected up hills/slight inclines?
I know it will become more responsive but what will the low end torque be like? Will i constantly be shifting to a lower gear to compensait?
If your fitting to an M50/M52 there are clearance issues with the sump, you can butcher the sump but its better to skim the flywheel back to the ring gear or just fully lighten it
- Brianmoooore
- E30 Zone Team Member

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Biggest advantage in MHO is getting rid of the dual mass flywheel and its inevitable problems.
- randomspeedfreak
- E30 Zone Regular

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yeah where HAS this flywheel makes torque bullshit come from?!DanThe wrote:This is bull, nothing more than internet myth, lightened flywheel does not affect torque in any way, it wont slow you down it will make you faster as the engine will speed up much quicker.BornToBeE30 wrote: How much is affected up hills/slight inclines?
I know it will become more responsive but what will the low end torque be like? Will i constantly be shifting to a lower gear to compensait?
If your fitting to an M50/M52 there are clearance issues with the sump, you can butcher the sump but its better to skim the flywheel back to the ring gear or just fully lighten it
Probs off need for speed or something. I can't think of any disadvantages of a lightened flywheel, it's a no brainer not getting it done whilst the engine's out.randomspeedfreak wrote:yeah where HAS this flywheel makes torque bullshit come from?!DanThe wrote:This is bull, nothing more than internet myth, lightened flywheel does not affect torque in any way, it wont slow you down it will make you faster as the engine will speed up much quicker.BornToBeE30 wrote: How much is affected up hills/slight inclines?
I know it will become more responsive but what will the low end torque be like? Will i constantly be shifting to a lower gear to compensait?
If your fitting to an M50/M52 there are clearance issues with the sump, you can butcher the sump but its better to skim the flywheel back to the ring gear or just fully lighten it
![]()

^ Not true
People are lazy and people like cars the drive themselves these days and car manufactures need to make changes and factor this in. A dual mass flywheel or even an E30 M20 flywheel over an E21 M20 flywheel have been designed to make it easier to set off from a standstill, on a hill etc and having a larger and heavier rotating mass makes it more difficult to stall the engine.
This doesn't mean that sticking a flywheel that weighs half the weight of a stock item is going to no negative effects but the benefits far outweigh the cons and unless you're doing this engine / flywheel swap for you 80yo gran i really would worry about it.
I can't believe these questions get asked so so much, seriously, take as much weight of an M20 flywheel as you can get away with and enjoy, it is possibly the best mod for this kind of money unless you get an M50 inlet from the breakers for a tenner.
People are lazy and people like cars the drive themselves these days and car manufactures need to make changes and factor this in. A dual mass flywheel or even an E30 M20 flywheel over an E21 M20 flywheel have been designed to make it easier to set off from a standstill, on a hill etc and having a larger and heavier rotating mass makes it more difficult to stall the engine.
This doesn't mean that sticking a flywheel that weighs half the weight of a stock item is going to no negative effects but the benefits far outweigh the cons and unless you're doing this engine / flywheel swap for you 80yo gran i really would worry about it.
I can't believe these questions get asked so so much, seriously, take as much weight of an M20 flywheel as you can get away with and enjoy, it is possibly the best mod for this kind of money unless you get an M50 inlet from the breakers for a tenner.
E21 323i with 2.8 M52 on TBs (fast road / track car)
E28 M535i (track car project)
E36 328i touring (drift wagon daily driver)
E28 M535i (track car project)
E36 328i touring (drift wagon daily driver)
- fowler
- Boost Junkie
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That is a lovely bit of kit there will it work on an M52 ??DanThe wrote:Try and get granny to do a hill start with this![]()
Complete assembly is approx 3kg, its not designed for slipping
EX A-Tech Workshop bitch !!!
325i Turbo touring (Aka Project Fridge)
gone but not forgotten
325i Turbo touring (Aka Project Fridge)
gone but not forgotten
you could always get it wrong if your thick enough.
there's plenty 5.5 kg m20 fly wheels out there to leave you wondering why you never bothered.
there's plenty 5.5 kg m20 fly wheels out there to leave you wondering why you never bothered.

m52 b30 stroker 6-speed 318is Galvanizer
m42 touring
+ a yard full of scrap turds
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HairyScreech
- Engaged to the E30 Zone

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fowler wrote:That is a lovely bit of kit there will it work on an M52 ??DanThe wrote:Try and get granny to do a hill start with this![]()
Complete assembly is approx 3kg, its not designed for slipping

Me Gusta.
anyway, totally agree with the above the flywheel is simply an energy storage device that smooths the torque variations caused by the compression/combustion events.
a lighter flywheel simply means there is less energy to simply release and a bit more finesse with the clutch is required.
infact it has been mathematically proven by geoffbob that the single mass flywheel will give a noticeable improvement in the 1st gear acceleration of the m42 engine.
2.8 development thread http://www.e30zone.net/modules.php?name ... c&t=170822
m3.3.1 m20 thread - now running, chip needed - any volunteers?
http://www.e30zone.net/modules.php?name ... =viewtopic&
m3.3.1 m20 thread - now running, chip needed - any volunteers?
http://www.e30zone.net/modules.php?name ... =viewtopic&
I'd just lauch it from 5K everytime i wanted to set off with thisDanThe wrote:Try and get granny to do a hill start with this![]()
Complete assembly is approx 3kg, its not designed for slipping
E21 323i with 2.8 M52 on TBs (fast road / track car)
E28 M535i (track car project)
E36 328i touring (drift wagon daily driver)
E28 M535i (track car project)
E36 328i touring (drift wagon daily driver)



