Still dealing with a clunk

[Rango]

I just replaced my diff bushing on my 2000 2.8 I went the diff cover removal route and replaced the fluid with redline 75w90 the front and rear struts/shocks have been replaced by bilstein b4's I have new front control arms, tie rods, and sway bar links. I still have this clunk seemingly from the trans tunnel area to around the trunk it happens when I push my clutch in changing gears from 1-3 it sounds like a whack-clak-clak-clak (the best way I describe it) and it seems to be worse on the first drive of the day when the car is cold. Any suggestions? Guibo or csb possibly driveshaft?

 

[mikeyH]

Have looked at the universal joints on the propshaft. I had this on my Ford Anglia years ago.

 

[Sajk]

I have exactly tye same issue. It diminishes somewhat when the car is warm. We have checked the diff and center bearing. Can't find it.

 

[Geoff Crispin]

Have looked at the universal joints on the propshaft. I had this on my Ford Anglia years ago.

Thats what I was thinking

 

[Smudgemanuk]

I think I have the same issue

 

[Sajk]

I think it's pretty common. Luckily you can't hear it with the roof down. If an done has found the true cause it would be great to find out. We have pulled the diff out of mine and sent it for testing and it's all in spec. That rubber thing in the driveline is good. We just can't find it.

 

[Andyboy]

It's unlikely to be the UJ's. When they wear out (rare on a Z3) you tend to get a vibration rather than a noise and when they are really bad they make a constant noise.

I'd remove the propshaft (or driveshaft in the US) to have a look at it all but I'd be looking at the splined joint where the front and rear sections join. It may need splitting, the splined greased up and then the prop is back on and the centre bearing tensioned, do the collar nut up good and tight. It was more of an E46 issue along with knackered rear driveshaft inner and outer CV's and worth diff sun/planet gears but 2000 is E46 era. I don't know if you can get to the prop with the exhaust on but I doubt it.

 

[Rango]

I’ve seen that the 2.8’s just have some excess driveline noise but it’s still just an annoyance, thanks everyone!

 

[Lee]

Most common clunks from the Z3 6cyls are from the diff, they start to loose the pre load in the pinion, very slight clunk as the back lash is taken up when you depress the clutch pedal.

 

[Andyboy]

I’ve found that causes a whine power on/off. The main issue is wear in the sun and planet gears. The pin wears as do the bushings in the gears. This is much more common on E46’s and that era Z3. Draining and refilling with EP140 can reduce it. They’re also buggers for wear in the CV joints: hold the inner CV still and with a pair of mole grips try and turn the driveshafts back and forth. The amount of play can be alarming.
E36 stuff was much better.

 

[Lee]

When the play starts to get excessive it starts to whine.

BMW released a technical bulletin once about a particular type of grease being applied to the input flange splines that takes away the clunk and absorbs frequencies, might of been the Z4M/E46M3 gen diffs.

Look at all the cheaper solutions first. Maybe get the car in the air with someone driving it (on a car lift) and using the end of a large screw driver listening to where the clunks coming from.

 

[Sajk]

Thank you for all the suggestions. The strange thing is that it improves with some heat in the drive line. If that gives anyone a hint. Like play reduces somewhere as metal expands.

 

[Rango]

I noticed the same thing my first 1-2 shift is always the worst and after that once it warms isn't as bad but still more than noticeable

 

[Andyboy]

The clutch delay valve fitted on later cars doesn’t help.

 

[Rango]

I plan on looking at my csb and guibo, but I've driven with this issue for over 10k miles now and it hadn't gotten any worse, of course not getting any better though. If I'm smoother with my gear changes I can minimize the knocking though, almost making it go away, but it still is consistent throughout my 1-3 shifts and I don't hear it when going over bumps so I don't assume its necessarily bushing or subframe related.

 

[Sajk]

So this is a common fault I guess. I also tend to drive around it when get going but now I have solved my engine rattle on trailing throttle around 1800 rpm I want this one also gone.

 

[the Nefyn cat]

once it warms isn't as bad but still more than noticeable

Could well be the diff, then. May improve with new oil, like Mr @Andyboy suggests up above. Certainly can't do any harm, I know BMW claim life-time oil, but that depends on what you call a cars' lifetime.

 

[Rango]

I just replaced my diff bushing with a powerflex one and replaced the fluid with redline 75w90 gl5 which through my research was a popular and safe gear oil for the torsen lsd as they aren't a full clutch pack lsd like the z3m's

 

[Rango]

I live in Oklahoma for context so we don't get awfully extreme weather here so I figured the thinner 75w90 was a safer bet than going for a thicker 75w140 as winter is approaching and didn't want to have too thick of a fluid.