[DaanBMW]

OK so last week I had my mechanic install a wavetrac LSD. While at it, I also swapped several shaft items as preventative maintenance - see image below or on realoem:

• 1-guibo (flex disk),
• 7-center bearing support
• 3-that little sleeve inside shaft on guibo side
• 5-damper ring
• all the hardware per TIS

Also upgraded to M3 were the (2) tranny mounts and the (2) front diff bushings. Oils changed in both diff & tranny.

Problem is now I have a nasty Noise/Thump when engaging 1st gear. Nowhere near any BMW noises there before when shifting. You can hear it quite loudly and even feel it coming from the rear of the car. Car is manual.

Once you press the clutch and engage 1st gear - the noise/thump is there ! If you then take it out of 1st gear, and then re-do 1st or any other gear but w/o releasing the clutch in the meantime - no noise. If you let the clutch out, the press it again, the noise/thump is there again upon shifting in gear. It's almost like some gap is "eaten" up by first gear engagement then it stays put until you release the clutch anew.

I also seem to notice then when on an incline pointing uphill, this doesn't seem to happen. I'm about 90% sure of this, as I only started testing this yesterday. Mechanic checked for anything obvious (exhaust, loose parts) - nothing seem to do be visibly wrong.

[added later] Also when I upshift while driving, the entire car is jerking quite strongly. It almost like that gap is opened by pressing the clutch, then "eaten" up again when releasing the clutch. Depending on how much you feather the clutch release, you can prevent it but if you just shift and let go go the clutch - which worked for 2 years since I got the car - it now shakes the entire drivetrain for a brief moment.[added later]

What can this be ? I think there were 2 things not done as I found reading online:

1. the tightening sequence for the shaft I don't think was tranny->diff->center bearing (both mechanic and I can't recall exactly). Center bearing was def done last though...
2. we did not applly any preload on the center bearing. This is something I'm not 100% sure how it's done or it it must be done. (We did mark the spot where the old one was, but we then swapped it for a new one.) What I found is something like push it 2-3 mm or 5mm towards front of car before tightening.

Please chime in...

[HP Autosport]

Any idea what the backlash setting is on the Wavetrac install?

Sounds like bearing preload/backlash problem, where they checked within spec?

Try going to a specialist gear shop and have them check the backlash.

[DaanBMW]

Originally Posted by HP Autowerks

Any idea what the backlash setting is on the Wavetrac install?

Unfortunately my mechanic didn't measure backlash. But I already contacted wavetrac and seems backlash should not be the cause of this. They said it would manifest itself as a nasty whine esp. when decelerating. No such behaviour.

One thing I forgot to add to above is that also when I upshift, the entire car is jerking quite strongly. It almost like that gap is opened by pressing the clutch, then "eaten" up again when releasing the clutch. Depending on how much you feather the clutch release, you can prevent it but if you just shift and let go go the clutch - which worked for 2 years since I got the car - it now shakes the entire drivetrain.

[DaanBMW]

Originally Posted by index1489

Sounds like bearing preload/backlash problem, where they checked within spec?

Try going to a specialist gear shop and have them check the backlash.

See above for backlash. Seems out of question...

The brg preload is one of the things I'm suspecting too, but got no idea if this would manifest itself like this.

[HP Autosport]

Originally Posted by DaanBMW

Unfortunately my mechanic didn't measure backlash. But I already contacted wavetrac and seems backlash should not be the cause of this. They said it would manifest itself as a nasty whine esp. when decelerating. No such behaviour.

One thing I forgot to add to above is that also when I upshift, the entire car is jerking quite strongly. It almost like that gap is opened by pressing the clutch, then "eaten" up again when releasing the clutch. Depending on how much you feather the clutch release, you can prevent it but if you just shift and let go go the clutch - which worked for 2 years since I got the car - it now shakes the entire drivetrain.

Whine would happen if the backlash is too tight.

Too many components are changed here so everything must be double and triple checked, including the backlash. If the vehicle is jerking violently, your problem is else where.

[DaanBMW]

Originally Posted by HP Autowerks

Whine would happen if the backlash is too tight.

Too many components are changed here so everything must be double and triple checked, including the backlash. If the vehicle is jerking violently, your problem is else where.

Elsewhere then backlash you mean ? Yes, but what are the candidates ?

[Lifted07Duramax]

An LSD on a 328? Why? Not trash talking, Im really wondering why

[DaanBMW]

Originally Posted by Lifted07Duramax

An LSD on a 328? Why? Not trash talking, Im really wondering why

Because you can lose traction in turns easily. I know the 335i crowd thinks 230HP is not much, but in turns it's more about handling and applying the power then just having lots of it on tap. Straight line launch is fun but not like a winding road... for me that is.

But back on topic...

[Johnny D]

Try shifting into 3rd before you go to 1st for the next few times. See if that stops the clunk.

[DaanBMW]

Originally Posted by Johnny D

Try shifting into 3rd before you go to 1st for the next few times. See if that stops the clunk.

Will try it out.

What would this reveal ?

[DaanBMW]

Originally Posted by Johnny D

Try shifting into 3rd before you go to 1st for the next few times. See if that stops the clunk.

Tried it a couple of times this morning. Seems the noise/thump is a lot more muted if I go in 3rd instead of 1st gear. I'd say to the point that it's acceptable, whereas going directly 1st is a real tractor-like feel thru the drivetrain.

To be clear: If I press in the clutch, go 3rd then 1st: noise in not there when engaging 1st. If I press clutch in, go 3rd, let the clutch out, press in again: noise is there when engaging 1st. The clutch out "resets" any gains from a previous gear selection, as described in OP.

I'll keep trying whenever possible. But what does this mean ?

[Johnny D]

Can you take a few pics of the guibo, center support bearing, and diff?

[accel]

Originally Posted by DaanBMW

Once you press the clutch and engage 1st gear - the noise/thump is there !

This might be irrelevant, but after Quaife LSD was installed at my former car - Honda Prelude, I started having shifting issues exactly like yours.

I figured the shop didn't use genuine honda transmission oil when they reassembled the transmission. They just used some generic oil, and refused to accept that as possible trouble cause.

I replaced the oil myself and shifting was back to normal immediately.

Now, in FWD transmission oil lubricates both diff and the gearbox.In BMW these have to be filled separately, so, not sure if this applies to you.

[accel]

Originally Posted by DaanBMW

Because you can lose traction in turns easily. I know the 335i crowd thinks 230HP is not much, but in turns it's more about handling and applying the power then just having lots of it on tap. Straight line launch is fun but not like a winding road... for me that is.

But back on topic...

+1.

It's, probably, not really losing the control, but it's easy to get inner rear wheel to spin while accelerating out of turn. Then DSC\DTC engages, unsettles the car and annoyingly kills the acceleration. You don't have to go to the track or autocross the get this. Some spirited driving is enough.

I plan to have LSD in my 328i as well, but I prefer torsen rather than clutch types.

[DaanBMW]

Originally Posted by Johnny D

Can you take a few pics of the guibo, center support bearing, and diff?

When we did the work I somehow didn't take pics of the shaft area (dumb of me, I know). Everything is back on the car so with the heat shields etc on I can't see the center bearing support. I think I have some pics of the diff and guibo at home, I'll look it up when I get home.

[DaanBMW]

Originally Posted by accel

This might be irrelevant, but after Quaife LSD was installed at my former car - Honda Prelude, I started having shifting issues exactly like yours.

I figured the shop didn't use genuine honda transmission oil when they reassembled the transmission. They just used some generic oil, and refused to accept that as possible trouble cause.

I replaced the oil myself and shifting was back to normal immediately.

Now, in FWD transmission oil lubricates both diff and the gearbox.In BMW these have to be filled separately, so, not sure if this applies to you.

Really ?? ... That is wavetrac suggested, getting the M3 trany mounts off and replacing the tranny oil... FWIW I used Red Line D4 in the tranny, and that hi-end 75W-140 Castrol SAF-XJ in the diff.

I must admit I can't figure how oil can create mechanical noises that are this loud - let alone that the D4 oil is a bit thicker then the original MTF-LT-3 that was in my tranny; and same with the mounts - I can't even feel any additional harshness in the cabin from the mounts, so how can they induce these (perceived) drivetrain shuttling motions ?

Reg the M3 tranny mounts: we swapped them with the shaft off, so we never had to take the cross brace off. Not sure if this can cause any issues...

[accel]

Originally Posted by DaanBMW

I must admit I can't figure how oil can create mechanical noises that are this loud

I think the reason in my case was - synchronizers didn't work properly, so they didn't really do much and gears rotated at different speeds prior to engagement.

[Johnny D]

I'd like to see a pic of the CSB though because if it was installed upside down it could potentially be the solution to the second issue you're having. Are you getting any vibrations before you up shift?

[HP Autosport]

Originally Posted by DaanBMW

Really ?? ... That is wavetrac suggested, getting the M3 trany mounts off and replacing the tranny oil... FWIW I used Red Line D4 in the tranny, and that hi-end 75W-140 Castrol SAF-XJ in the diff.

I must admit I can't figure how oil can create mechanical noises that are this loud - let alone that the D4 oil is a bit thicker then the original MTF-LT-3 that was in my tranny; and same with the mounts - I can't even feel any additional harshness in the cabin from the mounts, so how can they induce these (perceived) drivetrain shuttling motions ?

Reg the M3 tranny mounts: we swapped them with the shaft off, so we never had to take the cross brace off. Not sure if this can cause any issues...

Try the 75W-140 first, that was BMW's solution to noisy M final drives.

[DaanBMW]

Originally Posted by Johnny D

I'd like to see a pic of the CSB though because if it was installed upside down it could potentially be the solution to the second issue you're having. Are you getting any vibrations before you up shift?

no vibrations. We def did not install it upside down. Backwards maybe (I doubt it but I'm not sure), but I knew about the upside down issue.

Pics I have are below, but only diff and guibo (a bit unfocused), no CSB.

[DaanBMW]

Originally Posted by HP Autowerks

Try the 75W-140 first, that was BMW's solution to noisy M final drives.

Harold - I don't really get what you're saying here. Change the diff fluid, which is 75W-140 Castrol SAF-XJ - the one BMW recommends for LSD's, along with Nissan GT-R and other applications ?

More observations:

• While the noise _seems_ to originate in the rear end when you're in the cabin, from outside the car the noise is coming from the front, likely the tranny area.
• I think that if I keep the clutch pressed down longer before engaging 1st gear, the noise is avoided. I'm not 100% yet, I just started testing this, but if do it while standing still (in garage) it seems to not do it. On the other hand, if do a rapid-fire clutch-in / 1st / out, repeat a dozen times, I can make the noise 100% of the time.
• No noise if I shift with the engine off.

OK, this should give someone in the know some more clues... I hope... but if I hear Clutch my question is why ? we did not touch anything clutch related.