DIY M20 flywheel conversion [Archive] - M42club.com

jfdublyu

04-23-2006, 09:17 PM

Whatsup guys? I was checking out the Blackforest Industries Site (formerly Lowen Design) and was looking in their tech articles and found a DIY for the M20 flywheel conversion. It's a very good write-up with part numbers of required items and a lot of pics. here's the link: http://www.blackforestindustries.com/m20flywheel.htm

2002maniac

04-23-2006, 09:38 PM

very nice write up! They have the same PN listed for the TO bearing and starter pinion though.

nickmpower

04-24-2006, 01:39 AM

its the TO bearing

http://realoem.com/bmw/partxref.do?part=21+51+1+204+525&showus=on&showeur=on

M42boy

04-25-2006, 12:23 PM

very nice write up! They have the same PN listed for the TO bearing and starter pinion though.
Yes, that's the same article that everyone just reposts from 1998. Is there nothing newer with pics? And, yeah, I noticed the wrong part number too. You'd think someone would have fixed that along the way, but like I said, everyone's just reposting the same old crap. :mad:

I may work on updating this as I'll be putting in an M20 flywheel in my M42 over the next few weeks. I'll try to at least take some pics.

jfdublyu

04-25-2006, 08:39 PM

i'm not worried about the quality. I gave in and bought the JB Racing 9lb. aluminum flywheel from TMS. But to my good fortune they charged me for the cheaper 323i flywheel and sent me the wrong one. Wait, how is this good, you ask? Well i told them they sent me the wrong one and they are now sending me the right one next day air and not charging me extra difference of the higher cost for the one I wanted (the m42). so long and short of it, I got the 9lb LWFL shipped in two days from order for $488, when it should have been around $600! It's going in tomorrow and will be ready by friday.

jbuttenshaw

05-03-2006, 06:17 AM

are all m20 flywheels the same weight?

M42boy

05-03-2006, 11:36 PM

are all m20 flywheels the same weight?
They are "roughly" 16 lbs. All will be the same when new, but age and how much you mill it down will alter the weight. I just simply had mine resurfaced and cleaned it a little.

nickmpower

05-10-2006, 12:30 AM

damn, has anyone fround a good source for the TO bearing? its listed for $67 on BMA!!!

doigal

05-20-2006, 03:37 AM

and does anyone have the actual part numbers for the flywheel and the rest? Thinking that i'll be doing this when i shoehorn an m42 in..

bmwman91

05-20-2006, 04:43 AM

damn, has anyone fround a good source for the TO bearing? its listed for $67 on BMA!!!

You will, unfortunately, just have to suck it up. I paid $50 for mine about 2 years ago. I was calling around and one dealer, after checking his system, said that there were only like 9 or 16 units left in the entire US (within the dealer system). Could explain the price.

KidneyBoy

05-20-2006, 10:46 PM

doigal

05-31-2006, 06:23 AM

I went down to a parts house here in melbourne today and got what i think are the part numbers for everything - these should be confirmed first though!

323i release bearing # 21 51 1 204 525
M20 Clutch Disc # 21 21 1 223 643
M20 Pressure Plate # 21 21 1 225 852
325i Single mass fly # 11 22 1 716 276
325i starter pinion gear # 12 41 1 268 370

hope thats of help...

M42boy

06-05-2006, 06:20 PM

I'm selling a complete M20 flywheel/clutch conversion kit. All same part numbers listed above.

I could not make it work in my car. I'm putting in an M42 dual mass. Maybe whoever buys it can do a halfway decent writeup with pics for the benefit of the rest of thier E30 bretheren... It seems my begging, groveling, countless phone calls, etc... all led to Nowhere. If so many people have done this conversion, how come there is so little information available? LACK OF INFORMATION SUCKS!!!

This is a pretty specific project and if your're spacing is off my 1-2mm, the thing is hosed. No one's mic'ed it, and given specifics. I could probably figure it out with more expertise, time and/or money, but I'm spent and too busy to deal with it. I just need my car back on the road asap!

Whoever wants to try it, contact me via PM. I've got all the parts you need.

asubimmer

06-05-2006, 07:52 PM

YGPM M42boy

doigal

06-05-2006, 09:38 PM

M42boy - were they all the same P# as the ones i listed? and where abouts did you become undone?

M42boy

06-06-2006, 12:33 AM

M42boy - were they all the same P# as the ones i listed? and where abouts did you become undone?

This is the old (new) pinion gear for the M42. The M20 one is in the M42 starter.

http://www.s-cars.org/postnuke/modules/gallery/albums/danh/IMG_5154.jpg

This is the starter I pulled the pinion gear from.

http://www.s-cars.org/postnuke/modules/gallery/albums/danh/IMG_5156.jpg

Rebuilt Bosch M42 starter (with M20 starter gear). Bosch Part # SR0445X.

http://www.s-cars.org/postnuke/modules/gallery/albums/danh/IMG_5158.jpg

I don't know where the problem is, but no one has been able to help or give additional info and I just want to drive my car again.

M42boy

06-06-2006, 12:41 AM

Here's the M20 flywheel (resurfaced):

http://www.s-cars.org/postnuke/modules/gallery/albums/danh/IMG_5092.jpg

Back of motor (crankshaft/rear main seal)

http://www.s-cars.org/postnuke/modules/gallery/albums/danh/IMG_5091.jpg

doigal

06-06-2006, 08:17 AM

The only thing that i can think of is the spacer from the m42 flywheel... did you modify that and put it all back together?

What is the problem with it? car wont start or it wont all fit?

M42boy

06-06-2006, 12:16 PM

Starter sounds like it's coming apart. Hitting on something. I was thinking it was catching on the flat metal gasket between the back of the motor and the bell housing, but when I pull out the starter, I don't see anything in the way. Starter makes a horrible noise and the car won't start.

Yes, the M42 spacer ring is on the front of the flywheel with new M20 flywheel bolts!

doigal

06-06-2006, 07:48 PM

um the only thing that i could think of, and its probably a long shot, is that the pinion gear is worn on one or two teeth, and they dont engage with the fly.... The photo was a bit blurly so its hard to see from that. Otherwise i got nothing! Sorry!

StreetSpec_iS

06-06-2006, 09:48 PM

lachlan, id say its easier for us to run with the m40 flywheel swap. heck, you will even have one to spare when you are ready to drop the m42 in.

once i get a clutch, i'l be putting my m40 fly in, i'l let you know how it goes.

doigal

06-07-2006, 01:40 AM

I've thought about that, i just dont like the idea of an m40 clutch. Are they as strong as a M42 one? and there is more out there for the m20...

However I might just do this anyway until i have the cash to get a better one.

StreetSpec_iS

06-07-2006, 02:22 AM

the m40 clutch is a similar size to the m42 piece, from what i can tell.

regardless, i am having a super heavy duty m40 clutch put together that should take any abuse that i can throw at it.

i'l keep you posted.

thejimlab

06-09-2006, 03:08 PM

Did you do this part?
"You must remove the shift lever, which looks like a wishbone,(part number 8 on the diagram) from the M42 starter pinion gear and attach it to the new M20 starter pinion gear. This is relatively straightforward. See the diagram for details (photo 12)."
http://www.blackforestindustries.com/pictures/techcontent/12starterdiagram.jpg

bmwman91

06-09-2006, 03:47 PM

www.autohausaz.com for the pinion and TOB. Pinion was 9 bucks, TOB was 56, i think

Not all flywheels are singles mass! Only the 88 to 91 325i/is models had single mass. Drops to 12lbs from 23lbs, and a HUGE improvement. Makes downshifting to second in the wet fun :smile:

The singlemass M20 FW weighs in at 19lbs, and the M42 stocker is 28.5.
The M42 clutch assembly (PP, clutch disc, FW) weighs 41lbs. The M20 assy weighs 36lbs. Weight-wise it is not sounding too radical. However, the mass on the M20 setup is concentrated closer to the center axis, greatly reducing the polar moment of inertia. So, yes as everyone who has done this knows, it makes a BIG difference in performance. Just though I would add soem actual #'s. Check out www.e30tuner.com/rebuild for pics & whatnot. I think the clutch stuff was on pages 6 & 7 or something.

Pinion fro $9?!?! Damn, that is hard to believe!

asubimmer

06-10-2006, 01:38 AM

hmmm...my guibo is REALLY cracked and I have a new one. Maybe I should put the m20 flywheel on now :) still need the starter gear and 323 TOB though.

M42boy

06-10-2006, 09:36 AM

hmmm...my guibo is REALLY cracked and I have a new one. Maybe I should put the m20 flywheel on now :) still need the starter gear and 323 TOB though.
I got both, but don't know what shipping is to the UK. Might be able to get them cheaper locally if you avoid shipping costs.

asubimmer

06-10-2006, 12:38 PM

I got both, but don't know what shipping is to the UK. Might be able to get them cheaper locally if you avoid shipping costs.I'm in the US, in NC :D

Vladi

07-14-2006, 09:09 AM

M42Boy> Did you put the spacer _between_ the flywheel and the engine?
After reading all the other material on the forum about this conversion that's how i understood it goes in.

M42boy

07-17-2006, 09:24 AM

M42Boy> Did you put the spacer _between_ the flywheel and the engine?
After reading all the other material on the forum about this conversion that's how i understood it goes in.
You want to drill out the rivets and pull the spacer off the M42 flywheel to use with the M20.

I'll take pictures of everything this week and post it in the for sale section. I've got to sell some of the pluthera of parts I've got laying around.

Vladi

08-09-2006, 04:49 PM

My engine's in, with the M20 clutch kit. E36 M42 converted to E30. :D
My dualmass flywheel didn't have any spacers.
I first bought a singlemass flywheel for which i would have needed a spacer between the flywheel and the engine which was a no go. So i found another flywheel which is about 2kg lighter and fits perfectly. :D
The first pic is of the right flywheel.
Second is of the flywheel which hit the oilpan.
Third is my dualmass M42 flywheel.
Forth is my M40 flywheel. :D

Vladi

08-09-2006, 05:05 PM

Note: the right flywheel came off a 2.0 M20.
Now the rest of the pics. Tomorrow i'll do the electrics ad i'll have to see what i'm gonna do with the exhaust, because now none of either my E30 exhaus nor my E36 one fit.

Vladi

08-09-2006, 05:11 PM

Vladi

08-10-2006, 04:30 PM

Electrics are done, engine started. Tomorrow is day 3. Final day. :D

JetBlack95

11-09-2006, 08:26 AM

i know it's an old thread but i have to ask. The Changing of the Flywheels from M20 and M42. i have an E36 M42. I see all this talk of spacers and clutches and such, all i know is my FW weighs an ass load and i know with a lighter one my accelaration would drastically increase. I was looking at buying a light weight one online, but if i can get a less expensive one i'de be interested. Now, when there's all this talk of the clutch change over, whats invloved in all that?

rob_e30

12-02-2006, 09:47 AM

Does the tranny I plan to use make a difference with the TOB when I do a M20 flywheel conversion? I'm putting a M42 into an E30 325i with the 265 tranny. I'll be using a M20 starter and flywheel. Do I need the 323 TOB?

Thanks!

Vladi

12-02-2006, 04:51 PM

I used the 240 tranny and the 316i TOB and it works fine so you shouldn't have to change it.

Teaguer

01-16-2007, 07:39 PM

I'm going to ask the obvious question which nobody has yet asked .

Can the M20i starter be bolted to the M42 ?

Seems that would cut out the hassle of switching thew gears and potentially run in to other problems .

I'm new to the 4cyl's but looking at pics on WoldPac it seems like they are laid out the same and that they could be interchanged .

If nobody has an answer then I will compare the two soon when I drop my trans .

dude8383

01-16-2007, 09:12 PM

asubimmer

01-16-2007, 09:15 PM

that would be really nice if that worked...

Teaguer

01-16-2007, 09:25 PM

that would be really nice if that worked...

Yeah that would eliminate one potentially troublesome step and make this more of a "bolt-on" swap if the M20 starter is found to work as a whole .

I figured that in the write-up that was linked theguy was a 318 guy and maybe did not have access to a spare M20 starter , especially since he bought the gear new .

I on the other hand I have plenty of M20 starters around and would be taking the gear directly froma used spare starter if need be .

Although the one guy seemed to have a used M20 starter to do the gear swap .
But I'm guessing he never thought to try the starter as a whole , I'm basing this on the fact the he was not mechanically inclined enough to even get the gear swap to work .

In any event we shall see .

nickmpower

01-16-2007, 09:30 PM

does anyone have a picture of their starter with the m20 gear? im wondering if i put mine on right

Teaguer

01-16-2007, 09:41 PM

There a pic in post# 16 .

Not a direct pic of the gear but that does not matter as it should look the same except the fact that the gear theeth are closer together on the M20's .

nickmpower

01-16-2007, 10:47 PM

yeah, from a car that wont start

nickmpower

01-21-2007, 04:27 PM

any updates on the m20 starter working?

nickmpower

01-23-2007, 04:55 PM

bump i need to know!

ScreamerBeemer

01-24-2007, 10:41 AM

I'm curious too. It would makes doing this swap a bit easier.

asubimmer

01-24-2007, 11:38 AM

teaguer?

nickmpower

01-29-2007, 01:38 AM

buuuuump

nickmpower

02-13-2007, 04:29 PM

anyone have any info? Im going home in a couple days and would like to be able to start my car!

Teaguer

02-13-2007, 09:16 PM

Sorry but I have not messed with it yet .
So I don't know .

I was planning on dropping th etrans to swap it out with a good used one for what I thougt was an internal problem .
Finally got a night to work on my own car so I got it on the lift and it turned out to be a tranny mount and linkage problem .
I cured that those issues and the problem the same night .

Still would like to swap in a lighter M20 FW so I will get around to that soon enough .
Probably within a few weeks .

m44power

02-14-2007, 05:42 PM

I Just Realize THIS!! i can't adjust my m42/m44 timing chain with a m20 Flywheel any solutions ? maybe i have to buy a cheap m42 flywheel to adjust?

dude8383

02-14-2007, 10:20 PM

I Just Realize THIS!! i can't adjust my m42/m44 timing chain with a m20 Flywheel any solutions ? maybe i have to buy a cheap m42 flywheel to adjust?

dude what?!

your flywheel has nothing to do with adjusting your timing chain.

what are you referring to?

m44power

02-15-2007, 12:44 PM

i mean to install my chain how i can put the flywheel timing pin ? the new m20 flywheel dosen't have a hole for that and how i know the engine TDC ?

(sorry for my english anyone speak french? :D )

nickmpower

02-17-2007, 09:59 PM

can anyone take a pic of an m20 starter for me? im having a problem with mine rubbing since i didnt use the spacer between the flywheel and crank because my flywheel didnt need it.

here is mine, im hoping the pinion in the m20 starter is further back

http://nicktenhulzen.com/starter.JPG

dude8383

02-18-2007, 02:20 AM

i mean to install my chain how i can put the flywheel timing pin ? the new m20 flywheel dosen't have a hole for that and how i know the engine TDC ?

(sorry for my english anyone speak french? :D )

theres a tool to align the camshafts to TDC, i guess talking to the m20 guys would be a start?

m44power

02-18-2007, 05:22 AM

theres a tool to align the camshafts to TDC, i guess talking to the m20 guys would be a start?

M20 engines use a mark on the cranshanft pulley for the TDC the m44 engine uses the cranshaft sprocket keyway at 12 o'clock position but im thinking this is not easy to do it exacly right on m42 engines is the same ? i think the better way is to install temporaly a m42 flywheel use the timing pin and after switch on M20 (Euro 320i) flywheel

m44power

03-23-2007, 01:21 PM

Some more infos today i did the m20 Flywheel convertion the e36 M43 TOB is the same an you can do the starter conversion only with a bosch starter (mine is Magneti Marreli :( so i need a bosch one ) m20 starter can work if you have space coz its lot bigger. to convert the starter its very easy part maybe i gone make i DIY the difference about 2 flywheels is only 2mm in diameter M20 is bigger so you need a 2mm smaller pinion i dont finished yes but i gone post more about this convertion for the momment i am so happy with my new flywheel and sports disk and plate

CO318is

03-26-2007, 11:05 AM

I need a new clutch and thought that this would probably would be a worthwhile upgrade, what clutch kit do you use, a m20 or can you use a m42 clutch? This uses the m20 flywheel, the starter pinion from and m20 and the tob from a 323 is there anything else that needs to be changed? What weight can the m20 flywheel be machined down to?

m44power

03-27-2007, 11:44 AM

++ swap starter gear its a big nightmare for mine e36 starter the m20 gear for this starter generation does not exist! i finaly do it i swap a bosch gear from a Mercedes 309 truck with my bottom gear from my starter! im so happy about it and in a few days my bimmer is ready

m44power

04-28-2007, 03:29 PM

the problem with the starter its much bigger a few days ago i remove my 250 getrag gearbox coz i break my cluch disk i see my flywheel hits my starter cover in right side seems to need turn it a litle bit left im gone work on it to find a solution

steve321

07-01-2007, 01:32 PM

would it be worth me going for one of the M20 flywheels for my 318is, i have a a single mass M42 one in mine, which i skimmed down to 7.4Kgs, would i be getting much lighter than that if i had an M20 one?????

steve

Shift_Now

11-06-2007, 10:52 PM

has anyone tried this flywheel and clutch set up? it says its lighter and is a direct bolt on. http://cgi.ebay.com/ebaymotors/F1-STAGE-1-CLUTCH-FLYWHEEL-90-99-BMW-318-318i-318is_W0QQcmdZViewItemQQcategoryZ33730QQihZ005QQit emZ150166174476QQrdZ1QQsspagenameZWD1V

Wise Old Dog

11-06-2007, 11:07 PM

It is a 240mm flywheel. It will not fit a E30. I have a Fidanza flywheel that was advertised as fitting a E30 also. It will not fit either. E36 used a different tranny which allows the 240mm to fit. Max you can use is a 228mm. Thats why the M20 conversion is about as good as you can get.

mgold

02-26-2008, 05:44 PM

I'm having a local shop (Valley Motorwerks) perform my conversion, probably next week, assuming they can get all the parts in. Since its all out I'm having them also replace the guibo, csb, and rebuild the shift linkages and bushings and throw in a Z3 1.9 shifter as well. I'm also throwing on new tranny mounts and E28 (535i) motor mounts as well. Any thoughts or suggestions?

Wise Old Dog

02-26-2008, 05:57 PM

New slave cylinder. They're cheap enough, and if yours is original, you are due. If one goes bad and sprays fluid all over your new clutch disc and ruins it, you'll be pissed.

mgold

02-26-2008, 06:07 PM

New slave cylinder. They're cheap enough, and if yours is original, you are due. If one goes bad and sprays fluid all over your new clutch disc and ruins it, you'll be pissed.

Hmmm, you may be right. Maybe its a better purchase than the Z3 shifter.

Wise Old Dog

02-26-2008, 06:21 PM

I love my z3 1.9 shifter. Slave cylinder is only about $30.

mgold

02-26-2008, 06:31 PM

I love my z3 1.9 shifter. Slave cylinder is only about $30.

Well, in that case, I might as well do both.

1991 E30 M42

02-26-2008, 08:07 PM

I have hear that the Z4 shifter will also fit and that it has an even shorter throw than the Z3 shifter. There should be a thread somewhere on this sight with a picture comparison.

mgold

02-27-2008, 12:41 AM

Yeah the Z4 shifter is shorter, but also sits very low which I don't like the look of. The nice thing about the Z3 1.9 is that its a big improvement over stock and retains much of the look of the stick shifter

mgold

02-27-2008, 05:15 PM

Car goes under the knife on Monday morning.

mgold

03-05-2008, 01:36 AM

A quick update... car should be finished tomorrow.

It's also getting a CSB, guibo, rebuilt shifter bits along with a Z3 1.9 lever, new tranny mounts and E28 motor mounts.
http://homepage.mac.com/mgold/.Pictures/no_stuff.jpg

After they pulled everything out, they found that pretty much all of the seals were leaking, the rear main and the input/output on the tranny.
http://homepage.mac.com/mgold/.Pictures/no_clutch.jpg

mgold

03-05-2008, 10:56 PM

Picked it up this afternoon, and wow, I am impressed. The motor spins up faster and the car has more pull in 1st gear. Awesome mod, highly recommended!! Combined with the Z3 1.9 shift lever, the joy of driving stick has returned.

dude8383

03-06-2008, 12:43 PM

Oh yes!

The difference is really incredible huh?

Very peppy!!!!

Cobra Jet

03-06-2008, 01:05 PM

Just a quick question w/ regards to the flywheel "upgrade":

When swapping out flywheels, is there no need to be concerned with the flywheel weight in relation to the engine's harmonic balancer or overall engine balance?

The reason I ask is this - when wanting to install a lighter flywheel on a Mustang, you also have to change and match the harmonic balancer to the flywheel's weight in order to retain overall engine balance and to avoid premature wear (or destruction) on the internal bearings. For example, a stock 5.0 flywheel is 50oz, so is the harmonic balancer. If wanting to swap out to a 28oz flywheel, the 50oz harmonic balancer would need to be removed and a 28oz balancer installed so that the total rotational mass was still balanced. You can't install a lighter flywheel and not change out the balancer or visa versa.

When installing an M20 flywheel on an M42, there is no need to change the harmonic balancer out as well? Going with a lighter flywheel over the heavier dual mass flywheel has no impact on overall engine balance if leaving the factory M42 balancer in place?

Does the M42 balancer weigh the same as the M20 or visa versa?

Please enlighten me a little more... I understand swapping out the flywheel in order to increase the spin up wanted for spining the rotational mass faster and the fact of "losing weight" (as this is a common upgrade or mod for MANY vehicles), however, I'm not seeing any mention of the impact to overall engine balance or any mention of the need for also upgrading the harmonic balancer. I'm only assuming that the M20 harmonic balancer and the M42 balancer weigh the same, therefore there would not be a need for swapping out this part...

mgold

03-06-2008, 03:05 PM

I'm not sure how to answer that. What I do know is that there was no noticeable increase in vibration, even with the solid M30 motor mounts. That being said, it was recommended that I not lighten up the stock M20 flywheel, probably for that very reason.

josephb983

03-16-2008, 07:09 AM

I'm thinking of doing this conversion. The post above about the harmonic balancer has me worried. Has no one thought about this? Is there a solution?

Frankie

03-16-2008, 02:28 PM

What is the verdict? What is the easiest way to do the flywheel conversion? Just to lighten the original or what?

Shift_Now

03-16-2008, 08:58 PM

well, I lightened the m20 flywheel to just over 16 lbs (minimal lightening), and right now I'm in the process of re-assembling (tranny mounts are on their way) I'll let you know how everything worked out as soon as its up and running. And abotu the harmonic balancer... Metric Mechanic originally came up with theis little mod, you don't think that they would have thought it through? I don't know though, oh well, it's too late for me to go back now...

pwforprez

03-18-2008, 09:00 PM

i picked up some 22mm flywheel bolts are they going to be too short for me?

also was i supposed to get the m20 clutch tool? because i did. im hoping if it clears up outside tomarrow to get this knocked out.

Shift_Now

03-24-2008, 11:15 AM

Well, you need teh m20 clutch tool (i just used and adjustable one). This is a very good mod. the engien revs up much quicker, and it definatley feels faster. The idle has smoothed out completely, but it did get harder to drive smoothly but maybe thats my combination of this flywheel and a 4.45 diff haha.

pwforprez

03-24-2008, 12:41 PM

well if i was to reuse my old tranny which was busted it had the smaller shaft and would have needed the m42 clutch tool. but for some reason the newer trans i got had the larger m20 shaft so i had to replace a couple things. we shaved the flywheel down and bolted the m20 starter right up. everything went together much easier then it came apart and the results were great.