[GODDSPD]

6mt e92, stock suspension and clutch.

Ive been experiencing above average slack/slop somewhere in the drivetrain. It happens most in lower gears going a constant speed when I give it some gas then let off quickly the car jerks back and forth the moment after the throttle inputs.

It's a similar feeling to having bad motor mounts (but I have new 335is mounts and e46 m3 trans mounts so that's not my issue). And I know the stock dual mass flyweel can have this effect but it's worse than normal.

I can even "play" with this slack by going a constant speed at just the right throttle input where i can feel the slack "bouncing" back and forth lightly.

Anyone experience this? What areas of the driveline would you recommend looking at?

[Miller335]

You sure that's not your dual mass flywheel?

I would think drivetrain slop in these cars in a 6mt is more loud clunking sounds when going into gears.

What's your mileage?

[GODDSPD]

It's not so much a sound, just a feeling of slack while in gear.

I think the dual mass flywheel is making the problem more pronounced but it's not the problem directly (unless a bad flywheel can cause this).

Mileage is 85k.

[fredcase]

U joints

[Jklad]

Originally Posted by fredcase

U joints

Are the U joints on the drive shaft?

I have this feeling also at 131k miles on original clutch and flywheel. I replaced my engine mounts with the IS mounts and installed RE trans mounts which helped a little.

[austin]

This same feeling has bugged me for a while now. I have 123k on my car, so I'm just systematically replacing most bushings/mounts in the car anyway. I don't like when my car feels sloppy.

So far I've replaced: engine mounts (335is), trans mounts (e46 M3), rear diff bushings (whiteline), new driveshaft guibo and carrier bearing, and a new 335is clutch and DMFW. Also ditched the CDV (just eliminated it, no modification.)

The car feels MUCH better. But, I still feel that there is slop when accelerating, and now the issue is almost definitely worn rear suspension bushings. I also get significant tramlining, and some instability in the rear at speed. Also, despite a good alignment, I killed my last set of rear tires quite quickly. These things led me to the conclusion that my rear bushings are deflecting way too much. Particularly the RTAB and the toe arms.

So, I have sitting in my garage new rear trailing arm bushings, new rear ball joints, new toe arms with spherical rod ends rather than bushings, new subframe bushings, new shock mounts, and a set of coilovers. I can't wait to feel the difference. I may add some new rear upper arms to the list as well, but those are easy to install later.

I just need to make the tools to press out the bushings. But, I'm a working student so things don't always get installed very quickly.

Given the prevalence of this issue on aging e46 cars, I bet worn rear trailing arm bushings will become fairly common as more people have e9X cars with high mileage.

TLDR: I bet it's your rear suspension bushings.

[Rotary Rasp]

It could be your giubo failing.

[jjbmuu]

Yeah try switching to a metal guibo, it's considered an oem upgrade versus all rubber and might as well do the csb at the same time. My dmfw failed right at 85k btw. What failed were the springs internally. Most power my car ever made was 485wtq on a mustang dyno to give you an idea.

[Bob20124]

I asked the same question on Z4 forum and not 1 response. In my case most noticeable in 5th and 6th while cruising on and off gas lightly. For the DMFW 14mm of play is normal. Mileage 49k.

[trixdout]

I have this same slack that is mentioned and I have a steel SMFW. Everything regarding the u-joints to guibos to bushings are all original on the car and I'm at 68k miles.

[335NJ]

Originally Posted by J.J4ck0wsk1

Yeah try switching to a metal guibo, it's considered an oem upgrade versus all rubber and might as well do the csb at the same time. My dmfw failed right at 85k btw. What failed were the springs internally. Most power my car ever made was 485wtq on a mustang dyno to give you an idea.

What were the symptoms you had of a failed dmfw?

[mxchris727]

It could be a worn differential too... Mine was replaced at 60K for slop and vibrations. The car is mostly highway driven and is completely stock. Must have been a manufacturing defect.

[austin]

Originally Posted by mxchris727

It could be a worn differential too... Mine was replaced at 60K for slop and vibrations. The car is mostly highway driven and is completely stock. Must have been a manufacturing defect.

You had slop in your ring & pinion? If so did it whine a little too? I guess even if it did it'd be pretty quiet on these cars with so much soft rubber back there.

[austin]

Originally Posted by 335NJ

What were the symptoms you had of a failed dmfw?

Mine got a little noisy, clutch engagement got a little jerky, and I could feel the slack in the drivetrain when shifting or in traffic a lot.

[jjbmuu]

Originally Posted by 335NJ

What were the symptoms you had of a failed dmfw?

Originally Posted by austin

Mine got a little noisy, clutch engagement got a little jerky, and I could feel the slack in the drivetrain when shifting or in traffic a lot.

My experience was a bit different, entire car was shaking, rattling sound coming from the tranny, felt like the crank pulley was about to fall off or separate into two pieces. Clutch still felt fine and didn't slip at all amazingly. Literally sounded like it had morphed into a smfw. Car drove a little funny from time to time as well. Drove it like that for a little while till it got bad enough to properly diagnose. Surprised the car didn't grenade itself honestly. These cars can take a beating unlike Rihanna is all I'm gonna say. Searched and searched online never found any information on what could be wrong. Diagnosed it myself, but had my Indy fix it since the job required a lift pretty much. First time I took my car to someone else to be worked on. In the end everything was resolved and taken care of!

[335NJ]

Originally Posted by J.J4ck0wsk1

My experience was a bit different, entire car was shaking, rattling sound coming from the tranny, felt like the crank pulley was about to fall off or separate into two pieces. Clutch still felt fine and didn't slip at all amazingly. Literally sounded like it had morphed into a smfw. Car drove a little funny from time to time as well. Drove it like that for a little while till it got bad enough to properly diagnose. Surprised the car didn't grenade itself honestly. These cars can take a beating unlike Rihanna is all I'm gonna say. Searched and searched online never found any information on what could be wrong. Diagnosed it myself, but had my Indy fix it since the job required a lift pretty much. First time I took my car to someone else to be worked on. In the end everything was resolved and taken care of!

Originally Posted by austin

Mine got a little noisy, clutch engagement got a little jerky, and I could feel the slack in the drivetrain when shifting or in traffic a lot.

Thank You

Mine has 50k on it, but 39k of that was NYC.. I've been starting to notice a bit more noise in the gearbox at idle, and jerky clutch engagement. It's getting done sooner than later when I do the clutch. Appreciate the input!

[mxchris727]

Originally Posted by austin

You had slop in your ring & pinion? If so did it whine a little too? I guess even if it did it'd be pretty quiet on these cars with so much soft rubber back there.

A hum and vibration developed rather quickly, the slop came afterward. I'm lucky the differential didn't lock up!

[NotQuickEnough]

Sounds more like oscillation if you do a search on here lots of guys experience this after getting a tune. More like a software issue. Some had success with resetting adaptions.

[GODDSPD]

Originally Posted by NotQuickEnough

Sounds more like oscillation if you do a search on here lots of guys experience this after getting a tune. More like a software issue. Some had success with resetting adaptions.

Definitely not a software/engine related issue. I'm well versed in tuning and all the menu 10/12 wastegate settings and I can tell you with absolute certainty that this slack is not related, at least in my case.
Although you may be right for others.

[GODDSPD]

Playing with it more its definitely somewhere in the driveline linkage because it's only noticeable when I'm in gear, so it's likely not a bushing or something like that.

[mxchris727]

Your best bet is to get under the car and twist the driveshaft while the car is in gear.

[madmantwo]

I have this same issue, just installed an MFactory LSD a couple weeks ago and the problem persisted