M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Engine + Driveline => Topic started by: M42boy on April 02, 2006, 01:21:06 AM
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I'm about to drop a clutch in my 318is. I'm interested in lightening the flywheel. Can I simply shave material off the stock flywheel or is it best to swap in a lighter flywheel?? I've heard of people with the M42 using an M20 flywheel. Does this work well. How much lighter is the M20 flywheel??
Also, wanted to know if there are any negatives or downsides to using a "lighter" flywheel? I heard someone say the stock starter won't crank the engine with the M20 cluch, so there's some modification necessary. Is this true?
Is there any of the newer cars... say, '96-'97 M42 cars with a lighter flywheel, or did they all use the same one?
Any information greatly appreciated!!!
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The M42 uses a dual mass flywheel - good luck finding a shop that will even machine it, let alone lightening it. There are places that sell lighter flywheels that you can use with the M42, but I have not heard of dramatic improvements using them, so the cost/benefit ratio is not that good considering the several hundred dollar cost of a new one. Unless, of course, you need a new flywheel, in which case the lighter one is probably cheaper than a stock replacement. Using the M20 one is possible, but IIRC you will need to change the gear on the starter to match, as well as using M20 parts rather than M42 parts. I investigated briefly when I redid my clutch this past winter (in my driveway - not fun), but I don't recall that it seemed worth the expense. Having said all that, YMMV. :)
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^^^^ I beg to differ. Changing to a light-weight flywheel makes for a drastic improvement in acceleration. Gunni's car has an m20 lightened flywheel on an otherwise stock car and is doing 0-60 in around 7 seconds!!<--Compared to stock, that is at least a 2 second difference. Also, one frees up a few hp's by reducing the amount of mass that the engine has to rotate.
benefits=Better acceleration(and deceleration when down shifting), a little more HP
Negative=City driving might get a little annoying at first, considering one has to rev more to launch. Revs will drop faster, as well as go up faster, so one must shift a little quicker than normal.
I'd say DO IT!! I'm going for it as soon as I can afford one. Aluminum one's go for around $500(check out BMP). I don't know how much the m20 set up goes for, but I imagine it is cheaper. One just need to source out the parts. I guess lightening the m20 flywheel is the cheapest route.
OH BTW, I have yet to find a shop that lightens dual mass flywheels, G'luck!
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^^^^ I beg to differ. Changing to a light-weight flywheel makes for a drastic improvement in acceleration. Gunni's car has an m20 lightened flywheel on an otherwise stock car and is doing 0-60 in around 7 seconds!!<--Compared to stock, that is at least a 2 second difference. Also, one frees up a few hp's by reducing the amount of mass that the engine has to rotate.
benefits=Better acceleration(and deceleration whenn down shifting), a little more HP
Negative=City driving might get a little more annoying at first, considering one has to rev more to launch. Revs will drop faster, as well as go up faster, so one must shift a little quicker than normal.
I'd say DO IT!! I'm going it as soon as I can afford one. Aluminum one's go for around $500(check out BMP). I don't know how much the m20 set up goes for, but I imagine it is cheaper. One just need to source out the parts. I guess lightening the m20 flywheel is the cheapest route.
OH BTW, I have yet to find a shop that lightens dual mass flywheels, G'luck!
I'll not argue that point - anything you can do to remove weight from the driveline will free up a little horsepower. I'm just saying that all the anecdotal evidence I've seen doesn't point to dramatic improvements, certainly not worth the cost of the aluminum racing ones.
I had already scored a good deal on the OEM M42 parts, considered the differences I had heard reported from those who had gone with the lightened parts, and felt it wasn't worth the effort. As I said, YMMV - a 2 second drop in 0-60 times is nothing to shake a stick at, but I'd have to see that in person. Seems to me that 2 seconds off the 0-60 equates to far more than lightening the flywheel...
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I agree, the $400+ Al FW's are not worth the $. You can get a M20 stocker lightened to within 2 or 3lbs of the Al one, for a LOT less than $400. AND, you cannot use anything other than a stock pressure plate with the Al ones (unless you spend even more $$$$$), but the steel stocker will be fine with extra strong ones.
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What is involved in using the m20 flywheel. A used one goes for about $50. What else do you need. My clutch has 200,000 miles on it so I am going to be ready for a new one any day now.
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The M40 flywheel swap is much simpler than the M20. All you require is an M40 flywheel, shorter M40 flywheel bolts and an M40 clutch kit. I realise you didn't get the M40 engine in the USA but you could probably import the parts from Australia or Europe very cheaply.
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Seems to me that 2 seconds off the 0-60 equates to far more than lightening the flywheel...
This is from Gunni's "I Gteched the car" thread:
(I Gteched the car) and got very favorurable results
average ( best )
0-60mph 7.9 (7.5 )
0-400m 16 ( 15.75) @ 88mph (90mph)
damp conditions
based on beeing 2700lbs then itīs 107rwhp
0-60mph = 7,5 (6,9)
0-400m = 15.8 (15.4)
good conditions and perfect launch
does anybody have any gtech info to share??
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m20 ltw flywheel<<<<<<<<<-----------------------
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The M20 swap requires:
M20 flywheel
M20 clutch disc & PP
E21 323i TOB...there were ~90 left in the entire US according to a BMW dealer looking through the parts inventory...2 years ago.
M20 flywheel bolts
M20 starter pinion gear
Spacer ring from M42 stock FW
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I just picked up my m20 flywheel, clutch and PP sat. All the parts are used so I don't know if I am going to use the clutch or PP again. THe PP doesn't look too bad but yeah. The clutch looks ok at best. I plan on getting a stage clutch for the turbo anyway. Maybe a 6 pluck unsprung. I got it all for a great deal so I just got everything.
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Oh, and don't forget to remove the spacer ring that is riveted onto the M42 flywheel. You will need it to keep the M20 flywheel from hitting the oil pan.
Good luck finding the E21 323i TOB. I think there may be a couple places around /online that can find them, but it is getting more & more expensive to do so. Someone should try to find another working TOB for this.
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What is the PN# for the flywheel bolts I will need? I can't seem to find the flywheel in the parts fishe.
http://www.realoem.com/bmw/showparts.do?model=1113&mospid=47309&btnr=21_0020&hg=21&fg=05
I'd also like to confirm the M20 flywheel part number, since mine will be coming from a yard. Want to double check that it's the right part before machining and reassembly.
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my bolts came w/ it ;) sorry I don't know the #ers
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The flywheel you want is from 1989+ M20's, the SINGLE MASS one. If it is huge & has 2 halves, it's not what you want. You cannot pick the wrong one, unless you are braindead or something. I ordered the bolts from Pelican Parts...they were just listed in the parts catalog there.
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my bolts came w/ it ;) sorry I don't know the #ers
did you get your setup from bret?
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The flywheel you want is from 1989+ M20's, the SINGLE MASS one. If it is huge & has 2 halves, it's not what you want. You cannot pick the wrong one, unless you are braindead or something. I ordered the bolts from Pelican Parts...they were just listed in the parts catalog there.
Okay thanks... Yeah, I'm not as concerned about the flywheel part, as the starter and other stuff. If the rednecks at the yard give me the wrong part and I have issues once installed, then I'm in a real prediciment.
What's the saying... "Measure twice. Cut once."
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did you get your setup from bret?
nahh, I was going to but I got one from a friend that went to a alum flywheel and gave me a great deal
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I got the $400 9 lb. flywheel from BMP and a stock clutch, PP, TOB. I am totally satisfied with it. I participated in a Track Day event and autox this past weekend (the last, our track is closing :( ) and I had better times then some M3s and Mini Coopers during Track Day, and won my class in autox.
I realize for some $400 may be a lot for a flywheel that will give you instant performance, but my thought is, a new set of wheels will cost 4x that much and all you get is.....eh a nice wheel!
IMO....the $400 is well worth it, but if you can put together the M20 menu and get all the parts for less, more power to you. Either way, a lightened flywheel is definitely worth the Money and/or Trouble.
As for idling....no problem, chatter too minimal to be bothered, my wipers make more nose. :D
Do it and be happy.
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The M40 flywheel swap is much simpler than the M20. All you require is an M40 flywheel, shorter M40 flywheel bolts and an M40 clutch kit. I realise you didn't get the M40 engine in the USA but you could probably import the parts from Australia or Europe very cheaply.
Im have a m40 engine in the garage, is that single or dual mass?
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I got the $400 9 lb. flywheel from BMP and a stock clutch, PP, TOB. I am totally satisfied with it. I participated in a Track Day event and autox this past weekend (the last, our track is closing :( ) and I had better times then some M3s and Mini Coopers during Track Day, and won my class in autox.
I realize for some $400 may be a lot for a flywheel that will give you instant performance, but my thought is, a new set of wheels will cost 4x that much and all you get is.....eh a nice wheel!
IMO....the $400 is well worth it, but if you can put together the M20 menu and get all the parts for less, more power to you. Either way, a lightened flywheel is definitely worth the Money and/or Trouble.
As for idling....no problem, chatter too minimal to be bothered, my wipers make more nose. :D
Do it and be happy.
Aloha Isle,
I wish I could be present to witness the chatter part. I know a lot of folks complain about the chatter. Exactly what is the chatter all about and when do you hear it the most? Sorry for the rookie chatter :)
Thanks,
Chris
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audio clip?
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318isle--I'm pretty sure I'm gonna go aluminum for my flywheel. I don't want to source out all the parts for the m20.And then there's the stupid TOB. I've been looking at the BMP one, but you said you purchased yours for $400? It is listed at $499 on there site. Did you purchase it a while back or something? Just wondering. Now that I've looked into it, the m20 swap doesn't sound drastically cheaper than the aluminum flywheel. I'm guessing that when it's all said and done, the m20 swap (still referring to the FW setup) will cost around $300ish. Hardly that big of a difference. Needless to say, there also seems to be a huge difference in labor involved. I vote aluminum m42 all the way. Unless I get an m20 set up for free!!!;)
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well you'll still have to buy a clutch.. so the m20 settup would be quite a bit cheaper. a flywheel is like 50$, and a starter is probably the same (used parts of course) the only issue is the TOB... so your still saving 300-400$ or so. plus there is more clutch options for the m20.
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Well, you don't HAVE to get a new clutch. You left out the pressure plate for the m20. From bmwman's post:
M20 flywheel
M20 clutch disc & PP
E21 323i TOB
M20 flywheel bolts
M20 starter pinion gear
And if you don't mind me quoting you bmwman91, you were selling your set up a while back for $300 right? I'm assuming that's how much you ended up spending?
$300 vs $400-500
As I mentioned before, the difference in labor alone is enough of an incentive for me though. As far as options go, you are right about m20's having more, but I have seen m42 LW flywheels from 9 to 14lbs. That's enough variety for me. I was actually quite surprised by how functional 318isle made the 9lb FW seem. I might even go that light!
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Can the M40 flywheel be lightened and by how much? Does anyone know of a source or cost. I gather you would need the FW, clutch/PP, TOB, and new FW bolts.
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was that 300$ with or without the clutch? personaly i would advise against reusing the clutch, as its already out, its not terribly expensive and at the higher milage of the car you may as well do it now then take it out in 2 years to do it again.
i didn't mean more variety of flywheels when i was ssaying that, i meant clutch's, there is more aftermarket parts available for m20's then there is m42's.
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Can the M40 flywheel be lightened and by how much? Does anyone know of a source or cost. I gather you would need the FW, clutch/PP, TOB, and new FW bolts.
The M40 flywheel is single mass type so can be lightened. The stock one that I installed was 9.7kg (21.4 lbs) but I know of someone who had theirs lightened to 7.7kg (17 lbs).
They are available second hand here in Australia for around AU$100 - US$73) but shipping to the USA would would be very expensive (about AU$160 - US$116).
I would try BMW parts recyclers in Europe, shipping should be less from there.
You just need the M40 flywheel, M40 shorter bolts, and an M40 clutch kit (clutch disc, pressure plate and throw-out bearing).
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318isle--I'm pretty sure I'm gonna go aluminum for my flywheel. I don't want to source out all the parts for the m20.And then there's the stupid TOB. I've been looking at the BMP one, but you said you purchased yours for $400? It is listed at $499 on there site. Did you purchase it a while back or something? Just wondering. Now that I've looked into it, the m20 swap doesn't sound drastically cheaper than the aluminum flywheel. I'm guessing that when it's all said and done, the m20 swap (still referring to the FW setup) will cost around $300ish. Hardly that big of a difference. Needless to say, there also seems to be a huge difference in labor involved. I vote aluminum m42 all the way. Unless I get an m20 set up for free!!!;)
I purchased it during their Holiday sale and they were offering "free shipping" just not to the middle of the Pacific! I worked with a guy named Anthony who was very helpful.
I'm sure the M20 set has it's benefits, but I don't see the need for a higher performing clutch, since the M42 doesn't put down that much HP/Trq.
As for making the Alum. FW functional, there wasn't much to it once it was installed. Instant gratification!
Chatter is very minimal. I had a LTW FW in my 2000 M Coupe, now that was chatter that was not wanted. You would think the clutch was falling apart. That's why I was so hesitant to do it with my 318is, but I thought I'd just give it a shot anyway.....and I'm glad I did.
Now, who knows how to remove the head and do some Port & Polish to this baby? Has anyone done this yet? Is this worth it?
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Quote:
Can the M40 flywheel be lightened and by how much? Does anyone know of a source or cost. I gather you would need the FW, clutch/PP, TOB, and new FW bolts.
The M40 flywheel is single mass type so can be lightened. The stock one that I installed was 9.7kg (21.4 lbs) but I know of someone who had theirs lightened to 7.7kg (17 lbs).
They are available second hand here in Australia for around AU$100 - US$73) but shipping to the USA would would be very expensive (about AU$160 - US$116).
I would try BMW parts recyclers in Europe, shipping should be less from there.
You just need the M40 flywheel, M40 shorter bolts, and an M40 clutch kit (clutch disc, pressure plate and throw-out bearing).
Excellent! that setup is sitting in my garage collecting dust. Ill take some pictures along the way. Is the M40 flywheel capable of using different clutches? O yeah and sorry for all my newbie questions too....
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Cool. Thanks for the details 318isle.
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is the m40 clutch a sprung hub like the m20?
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is the m40 clutch a sprung hub like the m20?
It sure is.
M42:
(http://home.exetel.com.au/john_avis/bmw/m42flywheel.jpg)
M40:
(http://home.exetel.com.au/john_avis/bmw/m40flywheel.jpg)
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Okay, so I ordered the 323i T/O bearing and flywheel bolts from the dealer. The throw-out bearing was about $100 alone, and it's about $25 for the bolts. I didn't order the bolts from the dealer as I figure they can be reused off the flywheel I'm pulling from the yard. Gotta save somewhere.
PN's are listed below:
21-51-1-204-525 323i Clutch Release Bearing $106.48
11-22-1-717-840 Flywheel Hex Bolt Qty 8 $3.26 (ea)
Hope this helps. My dealer, fortunately gave me a discount for BMWCCA membership. But, cost is something to think about when considering the M20 flywheel conversion. I figure about $150-200 in parts, not including the clutch. I guess this narrows the gap on the aluminum flywheel though.
I just think the aluminum flywheel is going to be TOO light for me. I think a 16 lb flywheel vs. 27 lbs, and I'll probably shave a few off. Should maintain drivabilty and give faster accelleration from a dead stop, yet not be too tricky for shifting.
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How does the m40 flywheel drive? If you could post details on how it idles, accelerates and if there is any noise with it.
It sure is.
M42:
(http://home.exetel.com.au/john_avis/bmw/m42flywheel.jpg)
M40:
(http://home.exetel.com.au/john_avis/bmw/m40flywheel.jpg)
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How does the m40 flywheel drive? If you could post details on how it idles, accelerates and if there is any noise with it.
Keep in mind my flywheel is a stock M40 flywheel, nearly 10kg. It is possible to take off around another 2kg.
I haven't noticed any difference at all with the idle or any change in noise. Under certain circumstances there is noticably more vibration - mainly at very low revs in too high a gear.
Acceleration is little changed, not really noticable. I used a Gtech to measure 0-60mph before and after and did 9.51 before and a best of 9.38 after. I also changed from 14" to 15" wheels between so that may also have some effect.
It is slightly faster to gain and lose revs so upchanges can be a little quicker.
If I could do it again I would certainly remove the extra weight.
The other advantage is that it is not possible to machine the dual mass flywheel and after changing the standard clutch you can be left with some clutch shudder. Also the M40 clutch kits are cheaper than the M42.
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I vote for a machined M20 flywheel any day, I have a 5,5gk one, and I think it makes a huge diffrence
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John418isau thanks for the desc.
im considering both the m20/40, but I like the simplicity of the m40 setup.
Can the clutch handle the power (relative) of the m42, wernt m40's about 105hp?
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115hp,
I only have a 228mm 320i (129hp ) clutch and pressure plate and it never slips
a 325i set would NEVER slip
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Can the clutch handle the power (relative) of the m42, wernt m40's about 105hp?
The M40 and M42 clutches are the same diameter. I haven't experienced any clutch slip.
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115hp,
I only have a 228mm 320i (129hp ) clutch and pressure plate and it never slips
a 325i set would NEVER slip
Do you have an M20 or other lightweight flywheel in your car?
Can you tell us, if any, effect on drivability? How fast do the revs drop. Someone scared me away from this the other day stating that driving in traffic is a real PITA with a light flywheel. But, he started with a single mass and shaved it down.
I speculate that the 318is flywheel could shed some significant weight and still be very easy driver. Just would like to here some impressions from those that actually HAVE done the M20 flywheel conversion, or are running a similar weight drop on the flywheel. So, what's it like living with on a daily basis? Do the revs fall off real quick or is it still pretty easy to drive.
I learned to double-clutch all the time on downshifts with an old Jeep with no synchros left, so it's force of habit now, but I guess I'm not exactly "track master" fast with the operation either. Heel-and-toe is a skill I have yet to master. Still very much a beginer when it comes to performance driving. :rolleyes: