DMFW Bouncy - Replacement Options for a Spirited DD

[cerealwars]

Hey all,

Since I've bought this car a bit over a year ago, I've struggled to get the car moving from a standstill without a fore/aft "bouncing" feeling. I'll let the clutch out smoothly, but as soon as it fully engages, the driveline will rebound a bit. Almost like there's undamped springs in my driveline... hey wait a minute. Originally I had thought this was a weird electronic throttle problem, almost like the Valvetronic motor was adding throttle in large bumpy steps as the revs climb. After some more thought, I'm pretty convinced this is the DMFW. Occasionally there's some minor chatter as I let the clutch out, but nothing too remarkable for a somewhat seasoned car.

I rented an ND Miata on a recent vacation for a week. I gained so much perspective from driving that car and I'm so thankful for that. Fantastic car, but DAMN I MISSED MY 128! Getting back in really drove home what I already knew - my clutch/driveline feels bouncy as hell. I could drive that Miata so much smoother, completely intuitively. It took no effort at all to be smooth and predictable with the clutch. I want that in my BMW.

So firstly, does this sound like a shot DMFW to you guys?

I've got ~130k on the clock, and I'm 99% sure the clutch/pressure plate/flywheel is original. CDV has been deleted. Fresh trans fluid was done recently.

Do the guibo joints on these cars fail often? Maybe it's something else?

I want something direct, possibly a bit more lightweight, but also not obnoxiously noisy. The Valeo SMFW conversion sounds badass, but I'm also a little apprehensive about the noise. I drive windows down April-November in this car.

If I straight replace the DMFW with a new one, can I expect to get some mileage out of it? Considering that, to put it bluntly, I drive like an asshole. Involve no others in my shenanigans, but my clutch is definitely subject to this. Any other "spirited drivers" out there replace their DMFW and can speak to how well it holds up?

Sorry for the rambling, and thanks in advance!

[mikekilo]

I'm noticing the same taking off in 1st, more noticeable after swapping to a 3.73 rear diff. Revving it to ~1.5k rpm and slipping the clutch seems to improve it over taking off <1k rpm.

It might also be due to aging engine, transmission and differential mounts. I'll be changing my engine and transmission mounts in the next few months, expecting some improvement there (can feel the transmission moving around when shifting under load).

[cerealwars]

I just did engine and trans mounts, not too bad of a job and the car feels much smoother at idle now. I did the e46 m3 trans mounts - notable difference compared to the stock ones, and no real increase in NVH.

[mikekilo]

That would mean your slop is coming from one or more of: DMFW, guibo (there is a rubber one adjacent to gearbox from memory?), rear diff bushes, and rear subframe bushes. I'm now less hopeful new engine + trans bushes will fix mine!

Playing with a throttle controller / pedal mapping to might also help.

Unless someone comes in with a definitive answer, I would be inclined to live with it. Might end up being an issue that you dump $hundreds + 10s of hours into hunting down and it may still be there.

[cerealwars]

Thanks man! Diff bushings are in good shape, and I filled in my RSFBs with aluminum inserts.

Guess I'll check my guibo and start saving up in the meantime.

[cerealwars]

Gonna bump this to try and field more opinions.

Anybody replace the dual-mass on their hard-driven NA car? How's it holding up?

[4JawChuck]

It’s the dual mass flywheel your feeling, I replaced mine for the stock mass flywheel clutch kit and am glad I did…holding up just fine too.

The noise when sitting at a light though…not sure everyone would like it especially since the stock clutch is silent.

Like all things in life it’s a compromise, I’m not sorry I changed it as I prefer the immediate response and solid engagement but if you’re picky about clutch noise you may not like it.

For performance and feel it’s the cats meow.

BTW I also drive this 128 hard as much as I can, the headers and head porting sure woke up this engine, comes on like a two stroke after 3500 rpm now with a nice ramp to 6800rpm. Hasn’t lost any luggability either, still can drive around at 1500 rpm in fourth and be grandma.

[EDIT] I should mention that I did not check the throw out bearing clearance when I installed on the engine stand, I believe that if this clearance was proper the noise from the clutch would be less, also the plastic release bearing these cars use do not inspire confidence...I would have preferred a regular bearing...would have to find a suitable one that fits from the aftermarket.

[cerealwars]

Seriously looking at the Valeo kit. It's $710 on Amazon right now.

Also trying to understand if the kit comes with two throwout bearings. Not sure what else it'd be that I'm looking at here.

Bumping this thread in case any more 6-speed N52 guys can provide input. Thanks in advance!

[MichaelScott in IL]

I went with this Turner 18.55# chromoly steel flywheel paired with the ACT clutch kit:

https://www.turnermotorsport.com/p-1...-flywheel-n52/

The flywheel price is high currently but it should go on sale again soon. At least that is what I notice with certain products on Turner/ECS. Mine was in the $400s.

One month in and I am absolutely loving it! Revs climb and drop more quickly, but not at all bad. Throttle response and acceleration are much improved and just a delight. Beyond pleased for my spirited driving around suburbia and the surrounding rural areas.

Yes, there is noticeable chatter but not objectionable to my ears. Plus, if you have a tune, just request that the idle be raised to smooth things out.

Before pulling the trigger on this, I bought the Valeo kit from am azon. It arrived in such poor shape, I immediately processed a return. No foam, packing peanuts, or bubble wrap to hold anything in place. The contents just burst right through both the product box and the packing box by the time it arrived at my door.

I was relieved that it did not work out, since that smfw is exactly the same weight (22.6#) as the stock dual mass one, so you get all the chatter and the ability to have the fw resurfaced but no real performance gain.

[cerealwars]

Originally Posted by MichaelScott in IL

I went with this Turner 18.55# chromoly steel flywheel paired with the ACT clutch kit:

Love this post. Thank you so much. Leaning towards this route now. Fingers crossed this stuff goes on sale soon.

I'm still spoiled from the days where I could buy a quality clutch and flywheel kit for a couple hundred bucks. BMWs are quite nice, but man you pay for it.

[MichaelScott in IL]

No doubt! Happy to contribute.

Searched plenty but I found no mention of anyone with this setup on any fora, so I was convinced that it was a mistake. Did the online chat and also exchanged emails with a rep at Turner who confirmed it to be accurate.

I was set on steel over aluminum, and another one I came across was the 16.5# ACT 601170 chromoly fw, but at double the cost (944 msrp, 802 on sale currently) for only two pounds lighter? Quite an easy decision for me.

TTV over in the UK have 10# and 14.33# billet steel versions, as well. Bruno at BDS has made mention of them but no idea about their streetability.

I bought a whole setup (Turner fw and ACT clutch kit) as a spare for the E86 Z4 that I do not yet have but intend to acquire in the near future. Feel free to hit me up if the sale does not happen soon and you are eager and/or pressed to move forward!

[cerealwars]

Dang dude, what a straight G!

Turner's sale started back up again literally today. So I'm ordering from there right now actually!

For a street car, you can definitely go too light. I put a ACT streetlite flywheel on my old 240sx, and it was perfect. Can't remember the exact weights, but I was very glad I didn't go too racecar with it. The engine would lug at a higher RPM and it took a few more revs to get it off the line in first. The compromises were absolutely worth it for the revhappiness though. Hoping to replicate that here.

One other question - Is the ACT clutch adjustable? I'm used to having threaded rod adjustments at the pedal and the slave, but that doesn't seem to be the case on these Bavarian creatures.

[MichaelScott in IL]

Looks like cheap Turner flywheels are back on the menu, boys!

Originally Posted by cerealwars

One other question - Is the ACT clutch adjustable?

Negative.

If you did want to make an adjustment to the clutch engagement point, have a look this post where a fellow spun up a custom piston rod for his slave to get closer to stock, after converting from the DMFW to the Valeo SMFW:

https://www.e90post.com/forums/showp...2&postcount=12

I would be curious for a machinist to have a look at the Turner fw to determine whether it could be lightened any further.

Let us all know your impressions, once you have everything installed and get some road time on it!

[cerealwars]

Jeez man, that's super helpful. I have a buddy who could machine that for me if needed. I'll let you know how I like it! Turner somehow shipped it to my house in one day, but it'll probably be a few months until I get around to installing it. Still though, I can't wait. The manual is absolutely fantastic in this car, but the clutch has always been a bit of a mess. Each mod (CDV, bumpstop) has helped tremendously. Can't wait to renew everything that affects this interaction.

Thanks again Prison Mike!

[mkeiser]

interested in your thoughts as well!

[cerealwars]

MichaelScott in IL

Hey, one more question for you!

How is the clutch pedal effort compared to stock? Any lighter or heavier? No noticeable difference?

I'm about to schedule some time on my homie's lift, so I should be doing this job pretty soon here.

[MichaelScott in IL]

Hey cerealwars !

Clutch pedal effort certainly is increased. Not by an undesirable amount. Would guesstimate it to be 17.76%?

Was not difficult to become accustomed to!

[MichaelScott in IL]

Was curious how accurate my assessment was and found this at the product page FAQ: https://www.advancedclutch.com/produ...ung-clutch-kit

[cerealwars]

Hate threads that go unresolved, so let me update this a little bit.

I installed the kit, along with a bunch of other shifting goodies (mostly OEM replacement stuff, plus a ZHP knob). More details here and here.

Long story short - this was a big improvement. Before, a bad shift felt mediocre, and a good one felt slightly better than mediocre. Now, a good shift feels bang-on, and a bad shift feels BAD! Just how it ought to be - Natural.

If I were to do this again, since it's my daily, and because of a deteriorating left knee, I might pick this flywheel and couple it with a stock pressure plate, if that's possible. I haven't really looked into the exact compatibility but I'm certain there's another BMW PP that works. Overall though, not a big deal, I am LOVING the new setup. Thanks again MichaelScott in IL!