Name that clunk: subframe, differential or other? | Project E46-chassis BMW M3

The look on James Clay’s face told us all we needed to know: That clunk from the rear end was serious–and wasn’t going to magically cure itself.

Differential?

Subframe?

Okay, time to dig deeper. We could hear the clunk on acceleration and deceleration. The noise was more of a deeper clunk than a higher-pitched clank. Something heavy had started to move.

The good …

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And, looking back, I should have recorded the clunk.

It was rather clunk-like.

I have this EXACT issue with my E46 touring... How long was the repair, all-in?  

golfduke said:

I have this EXACT issue with my E46 touring... How long was the repair, all-in?  

 

 

Basically pull the diff, clean out the remains of the bushing, fit the new bushing, install the diff. The new bushing just slip in place. 

But it's a major clunk, isn't it? 

In reply to golfduke :

With the correct tools (bushing extractors), it's a 3-4 hour job total. Once you have the diff out, the bushing replacement takes about 10 minutes

David S. Wallens said:

golfduke said:

I have this EXACT issue with my E46 touring... How long was the repair, all-in?  

 

 

Basically pull the diff, clean out the remains of the bushing, fit the new bushing, install the diff. The new bushing just slip in place. 

But it's a major clunk, isn't it? 

Oh yeah, followed by pretty strong driveline vibration that follows speed and not rpm.  It's... jarring. 

glyn ellis said:

In reply to golfduke :

With the correct tools (bushing extractors), it's a 3-4 hour job total. Once you have the diff out, the bushing replacement takes about 10 minutes

The e46 M3 bushings are not sold separately from the factory. You have two options; buy a new cover or buy aftermarket bushings. I chose a new cover on mine and did a differential reseal at the same time.

With that being said, no special tool is needed to remove them as the bushings fall apart and are made of a material that feels like cardboard or dried sealant. Its not like an e30 diff bushing. You do need a tool to remove the front bushing that sits in the subframe, but those do not fail as often as the cover ones.

Cant comment on the non-M e46s.

golfduke said:

David S. Wallens said:

golfduke said:

I have this EXACT issue with my E46 touring... How long was the repair, all-in?  

 

 

Basically pull the diff, clean out the remains of the bushing, fit the new bushing, install the diff. The new bushing just slip in place. 

But it's a major clunk, isn't it? 

Oh yeah, followed by pretty strong driveline vibration that follows speed and not rpm.  It's... jarring. 

 

Mine did not vibrate at all. You could only feel it upon accel/decel. It was a nasty thud and I could minimize it by being nice to the gas pedal.

I didn't notice the driveline vibration but definitely had the thud on acceleration and deceleration.

We did the two rear diff mounts soon after buying the car. As mentioned above, we replaced the entire rear diff cover: E46 Bushings and Subframe Mounts. (A new diff cover came with the car.)

Slippery said:

Mine did not vibrate at all. You could only feel it upon accel/decel. It was a nasty thud and I could minimize it by being nice to the gas pedal.

I will say that with the aluminum bushings that are in mine you hear a LOT of gear whine in the car. :)

In reply to codrus (Forum Supporter) :

Did you do the fully aluminum replacements like these from BimmerWorld? 

David S. Wallens said:

In reply to codrus (Forum Supporter) :

Did you do the fully aluminum replacements like these from BimmerWorld? 

I'm not 100% sure (the race shop installed them), but I think they are the BimmerWorld ones, yes.  They are definitely not street-friendly. :)

In reply to codrus (Forum Supporter) :

Ah, just wondering. The Powerflex urethane ones seem quite okay on the street. 

A benefit of fixing the clunks and assorted issues? Just driving it.

From last night's run to the big box store.

Needed to return some stuff–bought too much for the dryer vent redo. $36 back on the card. 

golfduke said:

David S. Wallens said:

golfduke said:

I have this EXACT issue with my E46 touring... How long was the repair, all-in?  

 

 

Basically pull the diff, clean out the remains of the bushing, fit the new bushing, install the diff. The new bushing just slip in place. 

But it's a major clunk, isn't it? 

Oh yeah, followed by pretty strong driveline vibration that follows speed and not rpm.  It's... jarring. 

 

How is your center support bearing?  The non m diffs usually wear the rear mount & it is most noticeable on load changes.  I have never seen one that would move enough to cause a vibration.

Someone asked about the mileage on our M3: 141k.

Another evening, another run to a home improvement store.