M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Engine + Driveline => Topic started by: irish44j on November 12, 2012, 09:39:10 PM
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So did a bit of mocking up, since I hadn't seen any good comparison photos of the various M20 FW conversions. Here goes:
My workbench is PERFECTLY level, first of all.
I used some blocks of EXACTLY the same thickness underneath the assemblies, simulating the mouting face of the crank. So this display shows the relative heights of the entire assemblies AS MOUNTED on the engine.
All bolts are tight, and the pressure plates are cinched down to spec, with clutch plates inside.
FIRST TEST:
This is the M42 stock assembly on the left.
On the right is the M20 assembly WITH the little spacer (off an M42 FW) underneath. As you can see, the ring gears on each are perfectly even. Both have a standard E30 TOB on top. As you can see, they are PERFECTLY level with each other.
So, the bottom line on this setup is that the full M20 assembly here, with the spacer and stock TOB, is exactly the same overall thickness as the stock M42 stuff.
M42 vs M20 w/spacer and stock TOB:
(http://i78.photobucket.com/albums/j85/irish44j/BMW%20318i%20RallyCross%20Project/IMG_1681.jpg)
(http://i78.photobucket.com/albums/j85/irish44j/BMW%20318i%20RallyCross%20Project/IMG_1682.jpg)
TEST 2:
In this test, I took out the spacer ring from below the flywheel, and put the slightly longer 323i TOB on top instead of the stock one.
Results: The ring gear is a bit off. The overall height is exactly the same. So basically, this setup should work fine as well. I'm thinking that the 323 TOB method was developed before someone thought of using the little spacer to allow use of the M42 TOB. The only thing here is that the backside of the FW would have to be milled a bit to clear the engine/sump bolts. So this method involves a BIT more work.
Also, looking at the starter pinion gear travel, it appears that the M20 starter OR the M42 starter with the M20 cone should both work perfectly. I have both sitting on my bench as well.
M42 vs M20 without spacer, with 323i TOB.
(http://i78.photobucket.com/albums/j85/irish44j/BMW%20318i%20RallyCross%20Project/IMG_1683.jpg)
(http://i78.photobucket.com/albums/j85/irish44j/BMW%20318i%20RallyCross%20Project/IMG_1684.jpg)
Hope this is of use to someone, and comments/thoughts are welcome.
Oh also, I weighed the assemblies on a well-calibrated scale. The full M20 setup is almost exactly 5lbs lighter than the M42 setup by my scale.
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I'll add that DJ Buttchugg over on R3V (here as well?) is using the spacer AND the 323 TOB and it works fine as well. So that's option #3 if you're like me and happen to have a brand-new 323 TOB sitting around :)
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Here are shots with the level of the "ears" on the TOB, which matter more than the overall height. As you can see, the 323i TOB on the right sits "higher" by exactly 3mm. According to those who use it, it still works either with or without the spacer.
(http://i78.photobucket.com/albums/j85/irish44j/BMW%20318i%20RallyCross%20Project/IMG_1685.jpg)
(http://i78.photobucket.com/albums/j85/irish44j/BMW%20318i%20RallyCross%20Project/IMG_1687.jpg)
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Great post! Especially since I haven't done a SMFW yet. Very timely!
I stickied it too, easy to lose good info otherwise.
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So, if I buy all m20 parts, I'm good? Can the m20 starter be used with an m42, or how hard is it to swap the pinion?
The other threads have confided the crap our of me to the point where I have up on this swap years ago
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You should be able to buy all M20 parts, provided you take the spacer off the M42 flywheel and use it.
I can't verify the M20 starter yet, but I did mock it up in the casing and it seems to fit fine and correctly. My install isn't done yet, though, so I'm not 100% of that YET.
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i run an m42 starter, m42 jb aluminum FW, m20 clutch and pressure plate with a g260...... And i definitely had a point i was going to make but after typing that i have forgot what it was... Ill edit this post when i remember
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it must be 4:20:D
Geoff
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The idea I was curious about, but got shit on by r3v at the time was...
What about swapping the ring gear from the m42 flywheel to the m20?
While you got the flywheels on the table, can you see where the tool inserts for cylinder 1 on the m42?
Thanks,
Dustin
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Swapping the ring gear seems like a lot more trouble than just swapping the starter (or starter pinion gear), IMO.
That said, I just measured and the inside diameter of the M42 and M20 ring gears are EXACTLY the same, so they should interchange if you want to go that route.
I think I see where the tool inserts - it's kind of a little "divot" (there is one on each side). There is not a similar "divot" on the M20, from what I can tell. IDK, I haven't needed to use it, so I never really looked for it.
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i run an m42 starter, m42 jb aluminum FW, m20 clutch and pressure plate with a g260...... And i definitely had a point i was going to make but after typing that i have forgot what it was... Ill edit this post when i remember
you point was that there are other ways that work as well, if you know what they are. I can only speak to the two or three setups I mention in the original post :)
or that you're just trying to confuse people ;)
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Swapping the ring gear seems like a lot more trouble than just swapping the starter (or starter pinion gear), IMO.
That said, I just measured and the inside diameter of the M42 and M20 ring gears are EXACTLY the same, so they should interchange if you want to go that route.
I think I see where the tool inserts - it's kind of a little "divot" (there is one on each side). There is not a similar "divot" on the M20, from what I can tell. IDK, I haven't needed to use it, so I never really looked for it.
M20 starter has different modifications and when I did my first swap I had to modify starter pinion gear. I had to make it shorter 5mm or something. When I checked my single mass flywheel ring gear inside diameter it was different from m20, it was smaller few mm. IMHO m20 starter is not a good choice because it is very rare at the moment to find and every day it becoming much more difficult to find it and because of this I would stick with m42 starter motor. I had an idea to modify m42 single mass flywheel to take m20 clutch and I think it is possible ;)
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Swapping the ring gear seems like a lot more trouble than just swapping the starter (or starter pinion gear), IMO.
That said, I just measured and the inside diameter of the M42 and M20 ring gears are EXACTLY the same, so they should interchange if you want to go that route.
I think I see where the tool inserts - it's kind of a little "divot" (there is one on each side). There is not a similar "divot" on the M20, from what I can tell. IDK, I haven't needed to use it, so I never really looked for it.
I haven't used the "divot" but if I every do the mood, would be nice to have.
Since I plan to get the flywheel shaved for weight, I doubt it's much more to have the rung gear swapped by the machine shop.
This had a major benefit in not requiring knowing all the funky special parts need when the started inevitably fails.
I'd rather just have to order m20 clutch parts and everything else be as much factory m42 as possible.
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M20 starter has different modifications and when I did my first swap I had to modify starter pinion gear. I had to make it shorter 5mm or something. When I checked my single mass flywheel ring gear inside diameter it was different from m20, it was smaller few mm. IMHO m20 starter is not a good choice because it is very rare at the moment to find and every day it becoming much more difficult to find it
Did you use the spacer? If not, then that may be why you had to shorten the pinion throw, in theory, since it may not retract enough to clear.
As to M20 starters, I only plan to use it because I have a brand-new one sitting on my workbench :D
Galbūt jie yra sunkiau rasti Baltijos šalyse....they're pretty easy to find here in the US :confused: My local auto parts store has a couple of them in stock.
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I haven't used the "divot" but if I every do the mood, would be nice to have.
Since I plan to get the flywheel shaved for weight, I doubt it's much more to have the rung gear swapped by the machine shop.
This had a major benefit in not requiring knowing all the funky special parts need when the started inevitably fails.
I'd rather just have to order m20 clutch parts and everything else be as much factory m42 as possible.
You could always also have a new "divot" milled into the M20 flywheel. You could actually just do it with a drill (though the FW would have to be re-balanced afterward, probably)
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You could always also have a new "divot" milled into the M20 flywheel. You could actually just do it with a drill (though the FW would have to be re-balanced afterward, probably)
That was the idea, seeing as I gotta have it shaved to get the weight down anyway.
I'm no where near buying any of this, but it's nice to get some of this cleared up finally.
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Did you use the spacer? If not, then that may be why you had to shorten the pinion throw, in theory, since it may not retract enough to clear.
Problem was that I was not able to install it on m42 starter shaft. Pinion was just longer...
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When you do this conversion, you might have to shave down the area where the ring gear sits on the M20 FW so that the M42 one will fit. The ring gears/flywheels are not the same size in all cases. This is the problem that I ran into when I did mine. Everyone says they are an equal swap and they are absolutely NOT. Everyone keeps talking about a "spacer"? If you're talking about the plate/big ass washer that has the holes for the FW bolts, well that's exactly what it is, a Big washer for the bolts. Other than that it's a pretty simple swap.
1. heat M20 and M42 ring gears and remove from their original FW's
2. cut M20 FW to desired weight
3. cut ring gear seat if needed
4. heat M42 ring gear and let it fall onto the M20 lightened FW
Done!
HTH
Cheers,
~Ralph
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and I think balancing after that is must!
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When you do this conversion, you might have to shave down the area where the ring gear sits on the M20 FW so that the M42 one will fit. The ring gears/flywheels are not the same size in all cases. This is the problem that I ran into when I did mine. Everyone says they are an equal swap and they are absolutely NOT. Everyone keeps talking about a "spacer"? If you're talking about the plate/big ass washer that has the holes for the FW bolts, well that's exactly what it is, a Big washer for the bolts. Other than that it's a pretty simple swap.
Cheers,
~Ralph
good advice.
we're using the term "spacer" because it is being used to space the flywheel back from the engine, and if we say "washer" people will probably be looking for something small ;) And in an engineering sense, it is actually not really a washer since it's not there to distribute load or allow rotation ;)
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Can we get pics of said spacer seeing as you have the parts all out Irish?
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Can we get pics of said spacer seeing as you have the parts all out Irish?
here you go. It's on the transmission-side of the M42 dual-mass, held on by two silver rivets. You drill out the rivets to remove it. Also you have to enlarge one of the holes to fit around the locating collar on the crankshaft if you use it as a spacer for the M20 FW.
sorry, for some reason I only took a pic of half of it last week...I'll take another if I think of it.
you can see on the left where I drilled out the rivet. The photo is showing the enlarged hole.
(http://i78.photobucket.com/albums/j85/irish44j/BMW%20318i%20RallyCross%20Project/IMG_1688.jpg)
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I am using a m20 JB racing flywheel, m3 pressure plate, m20 clutch disk, and 323 TOB. No spacer, because the jb flywheel
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That is the "washer" I was talking about and you get them when you get the M20 flywheel, or at least you should.
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That is the "washer" I was talking about and you get them when you get the M20 flywheel, or at least you should.
Mine wasn't new, so it didn't come with one (they come with them new?). But if people with M42s are doing this conversion, it's easy enough to just take the one off the M42 FW.
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I never bought one new either. Every used flywheel that I have bought always had that "spacer/washer" with it.
~Ralph
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did you guys ever get m40 engines in e30s or e36s? I got my SMFW off one of those engines and a M40 clutch kit. Eveything fits perfect, all i needed were m40 flywheel bolts. M20 stuff seems too complicated
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did you guys ever get m40 engines in e30s or e36s? I got my SMFW off one of those engines and a M40 clutch kit. Eveything fits perfect, all i needed were m40 flywheel bolts. M20 stuff seems too complicated
It depends what you are looking for, because M20 clutch is much stronger and m20 clutch plus flywheel is lighter. The only thing what you can do is to make single mass m43/m40 lighter but that it is all.
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well, everything went together nicely....
(http://i78.photobucket.com/albums/j85/irish44j/BMW%20318i%20RallyCross%20Project/IMG_1897.jpg)
(http://i78.photobucket.com/albums/j85/irish44j/BMW%20318i%20RallyCross%20Project/IMG_1898.jpg)
(http://i78.photobucket.com/albums/j85/irish44j/BMW%20318i%20RallyCross%20Project/IMG_1899.jpg)
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Hi All!
I did a little research in the weekend. I measured M42-M44 DMF and M20 L-Jet FW which is 2,5 kgs lighter than average M20 FWs, so it's 6.090 kg. M42 DMF with pressure plate and clutch disc: 16.93 kg, M20+pressure plate+clutch disc: 12.790 kg! And another advantage: the L-Jet FW's crankshaft side is thinner, and at this swap you don't need the spacer/washer removed from M42 FW.
ps: I'm a new member, don't really know how to attach pictures, but I have a lot about this swap.
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Ohne Lader,
post them on a photobucket account or imgurl and use use the insert image tag.
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Thx, so the pictures:
(http://kepfeltoltes.hu/121214/PC010557_www.kepfeltoltes.hu_.jpg)
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Ohne Lader,(http://kepfeltoltes.hu/121214/PC010582_www.kepfeltoltes.hu_.jpg)
post them on a photobucket account or imgurl and use use the insert image tag.
Thanks, here are the pics:
As you can see, the dimensions of the M20 starter are the same as the M400-42-44 starter, so plug-and-play.
(http://kepfeltoltes.hu/121214/PC010557_www.kepfeltoltes.hu_.jpg)
(http://kepfeltoltes.hu/121214/PC010560_www.kepfeltoltes.hu_.jpg)
(http://kepfeltoltes.hu/121214/PC010564_www.kepfeltoltes.hu_.jpg)
(http://kepfeltoltes.hu/121214/PC010562_www.kepfeltoltes.hu_.jpg)
(http://kepfeltoltes.hu/121214/PC010579_www.kepfeltoltes.hu_.jpg)
(http://kepfeltoltes.hu/121214/PC010583_www.kepfeltoltes.hu_.jpg)
(http://kepfeltoltes.hu/121214/PC010584_www.kepfeltoltes.hu_.jpg)
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Oops...Sorry for the way too big pics:S
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you point was that there are other ways that work as well, if you know what they are. I can only speak to the two or three setups I mention in the original post :)
or that you're just trying to confuse people ;)
Something about my setup is eating trannys.. Im thinking of swapping back to g240 but idk how much boost that will be good for. or swapping my m42fw with an m20fw and keeping the pp and clutch disk. any advice would be fantastic
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I just completed this swap and have a few points to add.
My parts list first off:
PnP M20 17 lb flywheel and short bolts $20
Late M20 starter. $20
Nearly-new Sachs M20 clutch Assy $30 shipped (thank you R3v)
Surface/balance/lighten. Around $200. Ended up around 12.5 lbs. I'd guess 11 would be perfect. There is NO loss in drive ability with 12.5. My wife could drive it and never stall, with the a/c on!
Euro 323i T/O bearing $63 on Bav auto.
Otherwise it was a straight bolt in, no shim used. The 6 cyl starter spins way faster too.
A few myths dispelled. The ring gears will not directly swap without machining as they are different internal diameters. and since the starter falls out when the trans is out, installing an M20 version seems to be the easiest route. The shim behind the flywheel isn't needed as long as it's been lightened.
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Benz-tech,
I have done the M20 to M42 swap. When I used the stock 325i TOB it worked fine. You have to use the '87-'90 year model TOB. I know everyone is using the 323 one but the 325 works as well. The M42 ring gear does fit. You have to mill down the outside ring area after you remove the M20 ring gear. Mine ended up being 12lbs. just like the E30M3 LWF.
I may have another M20/M42 set up in the parts bin. I'll have to look.
Cheers,
~Ralph
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When I got my 325i TOB it was the same height as my stock M42 bearing. I know the slave has a good range of what it will operate in since it pushed the piston in quite a bit when I installed it but I just figured that since I really didn't want to run a shim that I needed the longer setup. I'll edit my post, though.
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i ran a weld along the clutch arm both places where it meets the tob and that worked fine