Member
Soon i'll have to change my clutch, while at it i would like to get a lighter flywheel installed (not too light = chatter/noise). I read a post somewhere but can't find it.. where somebody used a M20 flywheels when they did an engine conversions in a E30 with a M50 engine.
M20 Flywheel = around 6.3 - 7.2kg
M50 Flywheel = around 12.2kg
Both Flywheels = 228mm
My question is; can i use the M20 flywheel on my M50 (e36 325i)? what parts do i need other than the flywheel?
2nd is the 1st loser
Here you go, great English guy's mod:
Originally Posted by T1000
To give some background, this wasn't a mod that I wasn't actually planning on doing......but thanks some bad influences on here it was one that I just couldn't resist taking on :twisted:
Before I start, this mod isn't exclusive to the M52 :P ! It can be done on a number of E36 BMW's. I did quite a bit of reading up before taking on this mod and in doing so found an excellent write-up that I would highly recommend: Black Forest Industries - M42 M20 flywheel install
Back to the M52:
Here's why you'd do it:
- Stock 328 M52 flywheel (dual mass) = 11 KG (just the flywheel)
- M20 flywheel (single mass) = 7 KG (just the flywheel)
- no increase in gear noise (most after market kits are affected by this)
- easy to source second hand parts
- clutches kits are VERY cheap compared to M52 kits (pressure plate, clutch etc)
The clutches are also different weight wise between the two but didn't weigh them so can't give figures - needless to say that the M20 item at 228mm as compared to 240mm for the M52 jobbie is lighter :wink:
Here's why you wouldn't:
The install is a royal pain the in the backside, equalled only my my recent fitment of M3 3.0 exhaust manifolds!!! In my case the install required:
- the engine to be lifted to gain access to the top bolts of the bell housing
- about a million extensions / knuckles to actually get onto the gearbox bolts
- fitment of an M20 starter (I cannot convey just how hard this job in itself is on the M52!!)
It doesn't sound like the above should be too much hassle, but trust me on this, this job is not to be taken lightly. If you do fancy it give yourself at least 2 full days to get it done (8 hour days).
What you need to do it (on an M52 anyway):
- M20 flywheel (must be from an 89 - 91 E30 325i)
- M20 starter motor (the M52 starter will not mesh with an M20 flywheel)
- M20 clutch kit (clutch + pressure plate)
- E21 323i release bearing (30mm height)
- M20 flywheel bolts as the M52 items are too long (I'd recommend new pressure plate bolts too)
NOTE: You MUST get the M20 flywheel machined to fit the M52. This involves removing a minimum of 4mm (from what I've read elsewhere) but I chose to remove 6.5mm to be doubly safe given the mammoth effort involved to get this job done!
To give you a rought idea of costs, I did the whole job for approximately £300 - that includes the cost of having the flywheel professionally machined and checked for re-balancing at a motor sport machine shop (£40).
The install
As hinted at above this job is a hassle on the M52.
One of the hardest battle you'll have is swapping out the starter motor. As anyone with an M52 will know the starter lives under the intake manifold :evil: ! It's actually secured by two bolts coming through from the back of the gearbox into the engine bay and into a couple of threaded bolt holes (on the starter housing). So, if you ever need to swap the starter out you need to get to the upper most face of the garbox!!
I chose to fit a brand new starter rather than risk a second hand one - I do not want to have to replace the starter in a hurry: !
The other major drawback with this mod is the lack of access to the gearbox bolts from underneath the car. The transmission itself takes up a large amount of space and without tilting the engine / gearbox down I'm not sure this job is possible.....we ended up loosening the engine mounts and using one of these to gain some angle:
Once you've got the gearbox tilted down it get easier....but this is a relative term
Once the gearbox is out the job of swapping the flywheel bits out and fitting the new ones is easy.
Re-assembly is easier than disassembly as by this time you've got an idea of what angles / tools work best to gain access to the gearbox bolts.
Driving Impressions
- clutch pedal action changes
The actual engagement is much lighter than with the stock 328 bits. This was strange at first as I was certainly used to having to exert a certain amount of force and with less force now being required I tended to almost stamp on the clutch pedal initially. After 300+ miles I've now adjusted and it's great 8) .
- a nice improvement in acceleration in pretty much any gear (more noticeable lower down the ratios)
Acceleration from a standing start it quite different. The first 3 gears are noticeably "sharper" but in a good way. The engine gets into its stride more easily and gear changes seem to require less effort somehow.
- motorway cruising is great :twisted:
I was expecting hills and steep inclines to be more of a problem thanks to the reduced mass of the flywheel. In reality the different isn't noticeable. If anything I find it easier to accelerate up hill now than I did before. The 230 mile journey home from my parents place was once of the most relaxing I've done in a long time. Obviously much of this was due to lack of traffic but the car seemed to be wafting me along more easily somehow.
- gear rattle @ idle
This was probably my biggest concern about doing this mod. I've read countless threads one other forums from people that have used the likes if UUC and Rogue lightweight flywheel kits only to be greeted with big increases in gear "rattle" at idle.
I'm pleased to report that so far I have noticed no increase in noise at idle :P !
Conclusion
This is another great mod for the M52 :mrgreen: ! The results are worth the effort but this is not a job to be underestimated in terms of the effort required to get it done.
The really nice thing about this mod for me is that I've managed to stick with all BMW parts 8) . It's a choice I've stuck to all the way through with my car and again it has served me well i.e. US S50 cams, custom M3 3.0 diff, M50 manifold, UK S50 exhaust manifolds etc.
Overall I'm delighted with the mod :thumb:
As always I have to thank plenty of people, without whom this mod would not have happened:
Jon_M3
James @ Beemer Redeemer
DTMDan
Turbo-Brown
Finally, here's some of the piccies I managed to take during the install:
M52 clutch / pressure plate / flywheel (fitted):
M20 clutch / pressure plate / flywheel (fitted):
M20 flyhweel (fitted):
M20 flyhweel (on right) vs. M52 flywheel :
M20 flyhweel (on right) vs. M52 flywheel :
M20 flyhweel (on right) vs. M52 flywheel :
M20 starter fitment:
M52 starter fitment:
Member
I might be wrong, but i think if this mod is done on a M50, theres no need to change the starter motor coz the both the M20 & M50 flywheels are 228mm, where as the M52 is 240mm.. hmmm
Member
You still have to change the starter motor, reason isn't flywheel spacing, it's the teeth on the ring gear that will not engage the ones on the M20 flywheel and vise versa.
Can't even change the ring gear between the two starters I tried.
Shaft is longer on the e36 starter (internaly) even though when all assembled they are the exact same size.
I was easily able to reach the top bolts for the starter with my intake all torn out.
Current Mods....X-Brace, Stromung Cat Back Exhaust, 17/225/45 M3 Replicas, HotBits Adjustable Coil Overs, 40% LSD 3:91 Diff, E30 Gearbox, Boosted.
Member
Sorry to revive a dead thread but I was thinking about doing this to my m52 while I have it out of the car, could you use the m52 clutch with the m20 flywheel or is the pattern different
Member
I'm doing this now. You have an e30 listed as your car. What are you working with? No one is clear about what machining does or does not need to happen to the M20 flywheel so I'll follow up with that when I learn myself.
M52 is 220mm clutch, m20 is 228mm. I can't answer whether or not it would fit or work. Have not split the gearbox from the motor yet. Often a single mass flywheel will have a sprung clutch hub like this while a dual mass flywheel will have a solid clutch disc (like this) because the DMF has the springs in the flywheel vs. clutch.
Will It fit? No idea --probably. Will it be dumb/chatter like a mofo and be a pita to drive --probably. Easiest way is to use the M20 clutch, flywheel and pressure plate. They say you'll also need an e21 m20 throw out bearing (nla) so that'll be the next fun thing to figure out.
What car do you have and what exactly are you trying to do?
Member
I have an e30 but I have an m52 that I'm putting in out of a 98 528, Im probably going to look more into it after work, get diagrams and what not ill also pull my m20 apart sometime this week and see if I can make something fit, keep me posted with your findings
Member
Thought I replied to you but not sure where it went. What transmission are you going to use? The Getrag 260/5 from your e30 (not sure if it will bolt up) or the e36 either Getrag S5D 250G (probably not since I believe that was only mated to the m50 and considered weaker box) --or the ZF S5D 320Z?
The main issues are going to be pressure plate bolt lengths, starter motor, TOB length, clutch/pp size & diameter and this mysterious 4mm you need to remove from the back of the M20 flywheel.
- PP bolt lengths: use/reuse the shorter PP bolts from the M20 flywheel
- starter motor: Use M20 starter motor because looks like the thinner M20 SMF has it's ring gear closer to the engine/starter therefore you need the solenoid push length of the m20 starter vs. the m52 starter.
- TOB length: Still a bit stumped/confused on this and will figure it out as I go. Everyone says "just run the 30mm e21 m20 TOB" but now that is allegedly NLA. That said, after quickly looking online, you can purchase OE BMW and Sachs (I assume 30mm) TOB's for 1987 528e cars. The Sachs part is less than $40. Other factor is going to be the length of the ball pin/indent pin (pin that pushes against the fork). The e21 and the e28 used 15mm pins while the e36 used a 20mm pin. Also take a look at the links below (in addition to above). Not sure if the pins are interchangeable or how much space you need to extend the TOB to the fork because I can't find how long the e36 TOB is. Either way, seems this is a non-issue between the two pin lengths, TOB's and some redneck creativity.
- clutch+pp size & diameter: The difference between 228mm & 240mm is (12mm) not that much. Unless you have a bunch more power than stock, I wouldn't worry about running a 228mm clutch+pp on a stock m52. If you have done a bunch of work to your m52 motor then run an uprated 228mm m20 clutch with a bit more grip. (my opinion) For the record: 240=m52/e36 and 228=e30/m20
- Magical 4mm shave: This link (also below) says you need to shave 4mm off the back because the m20 flywheel interferes with the m52 block. I assume that will be obvious. My approach will be to bolt the M20 flywheel on slowly and when it hits the block, back off the nuts slightly and rotate the motor (probably with plugs removed) so that I get a decent mark on the back of the flywheel where metal needs to be removed. The guy in that link said he removed 6.5mm to be safe and others say they have removed a lot more for a much lighter flywheel --all I can recommend is that you have the flywheel balanced once the metal is removed or it could be very dangerous.
Couple other links talking about s/m52 DMF to SMF conversion:
http://www.bimmerforums.co.uk/forum/...rsion-t111150/
http://www.r3vlimited.com/board/showthread.php?t=236730
Hope that helps. Happy to keep adding info here or to a DIY if people want.
Member
Thank you that's super helpful. Basically drew me a diagram haha, im using the zf that came in the donor car (98 528) as my e30 came to me as an automatic. I have the complete m20 thats out of the m20 so I can reuse as much as I need, im interested in anything else you find
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