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!

[kilo3407]

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.

[kilo3407]

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.