Help Choosing a Clutch for S54 + ZF 320Z Swap

[R3VM3UP]

I picked up an S54 a while back and I'm in the process of accumulating parts for a swap. In fact, I'm still hunting for the right chassis to put it in, but that is another topic in itself.

I decided on the ZF 320Z for the trans since they are abundant and I can source one locally for dirt cheap, plus they are reliable, smooth shifting, etc. Basically all the reasons why everyone loves the ZF. I'm trying to figure out what is the best clutch setup for me though.

The S54 I bought did not come with a clutch, flywheel or pressure plate, so everything is open ended. I've done my homework and I know that various combos will work work well. I'm just looking for some opinions on which would be best. I'm trying to keep things affordable by using stock BMW/OEM parts so I'm not really looking for a fancy lightweight flywheel, however I'm open to ideas. I own an E46 M3 as well and I think it would be nice to shed a bit of weight from the stock flywheel while keeping chatter to a minimum, so if there is a way to do that using other OEM parts that would be awesome. The car will be a weekend/backroads/track car but I'd like to maintain reasonable drivability for the nice days that I want to drive it to work in the summer. Here are some of the combos I've been considering.

1. E46 M3 dual mass FW, E36 S52 clutch and pressure plate
Pros: One of the cheapest options, great drivability
Cons: Heavy FW. Would be nice to lose a bit of weight
Questions: Is this combo possible or does the E46 M3 flywheel require an E46 M3 pressure plate

2. E36 M3 S52 dual mass flywheel, E36 S52 clutch and pressure plate
Pros: Same as above
Cons: Still dual mass FW
Questions: Is the E36 M3 flywheel any lighter than the E46 M3 flywheel?

3. E34 M5 Clutch Disk w/ E36 M3 FW and E36 M3 Pressure plate
Pros: From what I have read the sprung hub makes the clutch more friendly with lighter flywheels.
Cons: Setup will likely cost a bit more since it would need to be pieced together.

4. E34 M5 Clutch disk w/ single mass steel flywheel
Pros: Possibly the lightest flywheel using OEM parts
Cons: Possible chatter.
Questions: What is the consensus on this setup. Does the sprung hub clutch actually make a single mass flywheel tolerable with the S54? Which single mass flywheels and pressure plates would work with this combo?

Any input on the topic would be appreciated. Thanks!

[butters]

I can't recall my sources, but to my knowledge the E46 and E36 parts won't work in this scenario. The E36 M3 flywheel won't work with the S54 starter, and the E46 M3 flywheel won't work with the ZF320, I think.

I went with the clutch and flywheel from the Z3 S54 model, because that car had the ZF320 and I wanted to keep the stock feel. For what it's worth, it should be a lighter flywheel than what comes in the US E36 M3.

[dude8383]

I can't recall my sources, but to my knowledge the E46 and E36 parts won't work in this scenario. The E36 M3 flywheel won't work with the S54 starter, and the E46 M3 flywheel won't work with the ZF320, I think.

I went with the clutch and flywheel from the Z3 S54 model, because that car had the ZF320 and I wanted to keep the stock feel. For what it's worth, it should be a lighter flywheel than what comes in the US E36 M3.

You could also match the starter to the flywheel ;) Still bolts up the same way!

[butters]

You could also match the starter to the flywheel ;) Still bolts up the same way!

This is true. In my case I needed a new flywheel anyway, but if you have a good E36 flywheel you could install an E36 starter into the S54.

[R3VM3UP]

Thanks for the input guys.

IIRC the E46 M3 flywheel works fine with the ZF 320z but I can't seem to find where I read that. Plenty of E46 M3 guys swap to the ZF 320 for track use and I think they keep the same starter and flywheel, I'll have to fact check myself on that. The benefit for me of using the E46 M3 flywheel is that I can get one cheap and I don't have to buy a different starter and I think this may be the best (read cheapest) way to get this part of the project moving along. However if an E36 S52 flywheel is required then that is not a huge deal, I can just get an E36 starter and put it on the S54 since they bolt up the same. I'm not looking to spend $800 on a Z3M flywheel when I can get a good used E46 M3 flywheel for <$100, and a used Z3M flywheel is going to be hard to come by.

I guess my ideal scenario would be to find a factory single mass steel flywheel for the S54 that could be had cheaply to use with the e34 M5 clutch. I'm trying to avoid expensive aftermarket aluminum flywheels and clutches.

*Edit: Just received word from a guy on M3F that has done the s54 320z combo in an E46. The E46 M3 flywheel and pressure plate can be used with an E36 M3 clutch and throwout bearing. I'm not 100% sure if the E36 M3 pressure plate would work with the E46 M3 flywheel. The bolt pattern might be different, I'll update that if I figure it out. The E46 M3 flywheel and PP can also be used with an E34 M5 clutch.

I think I'll probably go with the E46 M3 stock flywheel and PP with the E34 M5 clutch. The M5 clutch can handle the power from the S54 better and this is one of the cheapest options at around $200. The bonus of using the sprung hub M5 clutch is that I can upgrade to a single mass flywheel at any time.

[Bimmerman325i]

I am running S54 + ZF310, with all E36 parts. JB Racing flywheel, stock e36 disk and pressure plate. S54 starter works with all E36 and E46 M3 flywheels.

US E36 M3, Euro E36 M3, Z3M S52, and Z3M S54 all use the exact same clutch, flywheel, pressure plate. Look it up in realoem if you don't believe me.

My S54 is at ~330whp and the stock E36 clutch handles it just fine.

You can probably use an E46 M3 flywheel but I'd use the E36 clutch/pressure plate if it bolts up, since the E46 pressure plate is much more complicated. I have no idea on the weights, but have both a stock E36 and E46 flywheel I can weigh later this week if it's truly relevant.

Guys doing the Getrag 6 speed swap into E36s can reuse the E36 flywheel/PP parts and just use an E46 M3 clutch disk (am in process of this one).

[R3VM3UP]

Okay, great info there. I didn't realize that the E36 flywheel would work fine with the S54 starter. I also was not aware that the S54 Z3 uses the same flywheel, clutch and pressure plate. I just double checked on RealOEM and sure enough it's true. Sounds like the E36 clutch is sufficient for the S54 after all, so I'll look around and see what setup I can piece together for the best deal.

Does anyone know if there is an inexpensive single mass flywheel available that would work with either an E36 or E46 M3 pressure plate and the S54 starter? I'd love an excuse to run a lighter flywheel with the E34 M5 clutch but if it ends up being more economical I will stick with either the E36 or E46 dual mass stock flywheel for now.

[butters]

US E36 M3, Euro E36 M3, Z3M S52, and Z3M S54 all use the exact same clutch, flywheel, pressure plate. Look it up in realoem if you don't believe me.

I don't believe you. I looked it up on realoem, and the flywheels with PN 21212229011/21212229010 are listed as applicable to only these cars: S54 Z3, euro S50 Z3, and euro S50 E36.

http://www.realoem.com/bmw/enUS/partxref?q=21212229011

Obviously your setup is working for you, but it seems BMW used a unique flywheel for the ZF with S54orS50B32 combo.

Edit: additionally, the realoem compatibility search for clutch kit 21212228289 does not indicate that it works with the E46 cars, only E36 M and Z3 M, which most would agree comes down to the difference in the input shaft of the E46 trans.

https://www.realoem.com/bmw/enUS/partxref?q=21212228289

[R3VM3UP]

Good catch when I checked it looked like the pressure plate and clutch were the same. I must have forgotten to check the flywheel. Either way it sounds like either one will work, I'm not sure the difference between the flywheel though.

[Andrew325is]

The Euro S50s (including S54) have different torque curves than the US S50 & S52 and the DMF spring rates and damping characteristics are matched to the engine so that's why they use a different DMF. The US E36 flywheel will work just fine, but it won't optimally reduce vibrations. I'm not sure how much you could notice the difference though. It's probably just a little smoother with the correct flywheel. And don't forget to only use a brand new DMF because the springs wear out. It should be replaced every other clutch change.

According to this thread, the DMF is specifically designed for the engine to counteract torque spikes produced during each cylinder combustion to protect the gearbox and other drivetrain components, and of course also reduces vibrations and engagement chatter. It could then be possible that a single mass flywheel or the wrong DMF with a powerful engine like the S54 could cause damage to the gearbox and drivetrain.

[butters]

The US E36 flywheel will work just fine, but it won't optimally reduce vibrations. I'm not sure how much you could notice the difference though. It's probably just a little smoother with the correct flywheel. And don't forget to only use a brand new DMF because the springs wear out. It should be replaced every other clutch change.

That was my thinking as well, with the difference in RPM there has to be some good reason. While not noticeable to the driver, the harmonic effect on the crank and bottom end might be significant, at least it was enough for BMW to build the cars with an entirely different flywheel.

I think on a budget you can get away with a "used" flywheel, there are specification checks for play in the assembly that can be verified. But for something that requires a transmission drop, why risk it.

[R3VM3UP]

The DMF spring rates and damping characteristics are matched to the engine to counteract torque spikes produced during each cylinder combustion to protect the gearbox and other drivetrain components

That sounds like you just described a harmonic balancer. I'm not trying to start an argument or question people unnecessarily but I would need more evidence than a few stackexhange posts to believe that. A vast array of vehicles (including BMWs) do not come equipped with dual mass flywheels, and many people switch to aftermarket single mass flywheels on vehicles that do come with DMFs. This is purely anecdotal evidence as well but I'm not the slightest bit concerned about driveline damage from not running the proper DMF.

edit: Didn't mean to come off as rude, and I don't dispute the fact that the DMF is used to damp vibrations, but I don't think it is intended to protect the drivetrain, I think it is mainly for driveability and the driver's perception of "smoothness".

[R3VM3UP]

why risk it.

Because...

a. I don't even have the car yet (still searching for the right one), only the S54 so I don't want to get too far ahead of myself yet.
b. BMW states that the DMF can be used for 2 clutches, and plenty of people on M3F do this with no issues.
c. I have 2 other vehicles already so downtime really isn't an issue if I have to drop the trans to swap clutch components sooner than I otherwise would.
d. Focusing on the essentials to get the vehicle running without excessive costs is the top priority for me. Optimizations can come later.

[Andrew325is]

Yeah a lot of BMWs have came with single mass flywheels, but I don't think any production models have since the early 90's. LuK claims "competitor solutions that use rigid disc flywheels can quickly lead to transmission damage." Maybe they just want to sell their DMFs ;), but it sounds reasonable given the science behind it.

[R3VM3UP]

Well generally what you see in production vehicles is that a solid disk is used with a dual mass flywheel while a sprung disk is used with single mass flywheels. Both are a method to damp the drivetrain and both have been implemented in millions of productions cars. While I have no doubt that a DMF helps smooth the perceived engine operation and clutch engagement I find it tough to believe that they actually improve reliability of the driveline vs. the alternative of a sprung clutch with SMF. LS engines, 4.6 modular, etc come with solid flywheels and were produced in massive numbers. Maybe that's not a good comparison because apparently inline sixes are more prone to secondary imbalance than crossplane V8s. On the other hand Ford went with a DMF on the gt350 which also uses a flat plane crank whereas the normal crossplane 5.0 uses a single mass, so I'm sure there is some relevance there. Wikipedia has some good info on this in their engine balance article and on the inline six article, but nothing conclusive.

BMWs shift to DMFs also coincides with their shift from a niche performance brand to a mass market luxury sport brand, so the switch to DMFs could be as much about customer perception as it is about reliability. We probably will never know for sure.

Regardless, plenty of people run SMFs on the S54 with seemingly no ill effects on reliability though admittedly that can be difficult to nudge accurately. I'll almost certainly end up with a DMF to start with, though I may swap to a lightweight SMF at some point in the future.