Author Topic: DIY M20 flywheel conversion (Read 125349 times)

M42boy · « **Reply #15 on:** June 05, 2006, 11:33:14 PM »

Quote from: doigal

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.

This is the starter I pulled the pinion gear from.

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

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 · « **Reply #16 on:** June 05, 2006, 11:41:32 PM »

Here's the M20 flywheel (resurfaced):

Back of motor (crankshaft/rear main seal)

doigal · « **Reply #17 on:** June 06, 2006, 07:17:02 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 · « **Reply #18 on:** June 06, 2006, 11:16:52 AM »

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 · « **Reply #19 on:** June 06, 2006, 06:48:57 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 · « **Reply #20 on:** June 06, 2006, 08:48:55 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 · « **Reply #21 on:** June 07, 2006, 12:40:40 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 · « **Reply #22 on:** June 07, 2006, 01:22:33 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 · « **Reply #23 on:** June 09, 2006, 02:08:22 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)."

bmwman91 · « **Reply #24 on:** June 09, 2006, 02:47:54 PM »

Quote from: KidneyBoy

http://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 http://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 · « **Reply #25 on:** June 10, 2006, 12:38:02 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 · « **Reply #26 on:** June 10, 2006, 08:36:45 AM »

Quote from: asubimmer

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 · « **Reply #27 on:** June 10, 2006, 11:38:35 AM »

Quote from: M42boy

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

Vladi · « **Reply #28 on:** July 14, 2006, 08:09:55 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 · « **Reply #29 on:** July 17, 2006, 08:24:36 AM »

Quote from: Vladi

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.