E46 M3 Differential Removal Guide | M-Clunk, Differential Bushings & BMW M3 9-Year Ownership Update
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- Опубліковано 30 чер 2024
- E46 M3 Differential Removal Guide | M-Clunk, Differential Bushings & BMW M3 9-Year Ownership Update
In this video, I give a brief background on my 9-year E46 M3 ownership experience, including the key maintenance and modifications I've done to this M3. I also describe the symptoms of M-clunk and the long-term issue I am having with the M3 differential which has clunked badly for a long time.
Spurred on by a diff input shaft leak, I am finally taking the dive and investigating the problems with my diff with a view to solving them.
Here's what I used in this video:
E-Torx Spanners: ebay.us/LAkQFk
E-Torx Sockets: ebay.us/YPEsBZ
Dewalt 18v 3/8 Ratchet: ebay.us/Wk14qg
First thing to cover off is that E46 M3s are notorious for their clunky diffs, they almost all have this issue and luckily it's not as bad as it sounds. It can be caused by a few different things including the fundamental design of the diff meaning one of the splined output shafts is shorter than the other, allowing for wear and movement leading to a clunk when picking up drive.
Another common cause is worn-out diff bushings. When I sent this M3 off to ETA Motorsport for the RACP boot floor reinforcement, I asked them to fit Powerflex bushings to the diff, thinking it would solve it. Unfortunately, it actually made the clunk far louder, to the point where passengers turn to see who just gave us a rear-end shunt when I change between first and reverse in a car park.
In time, I learned to live with it and drive around it, to the point where it no longer bothers me so much, especially understanding that there's nothing seriously wrong with it, just a quirk of the E46 M3. However, it taints an otherwise lovely example, and I know if it ever came down to sell, the diff would seriously put off the type of buyer I'd want to attract to this car.
With the new addition of a dripping input seal, it's time to remove the diff and investigate the clunk while I am resealing it.
In the recent past, I was fortunate enough to purchase a second E46 M3 differential which is supposedly in good condition and working well. So I have a second diff on the shelf which I can compare side by side to my original before deciding which to refit. I noticed the new diff also has an input seal leak so either one needs that replacing (in an upcoming video).
Removing the differential from an E46 M3 was actually more challenging than I anticipated. I am now spoiled by working on the E30 which is an older style car, not as tightly packaged or complicated, and with space to actually get your hands in to work.
The E46 M3 is at the turning point where cars started to get harder to work on, and everything is in the way of everything else. Thus I had to remove undertrays, the rear anti-roll bar, heat shields and even the whole exhaust from the manifold back to get the access required to drop the diff.
Once all that was out of the way, I could start work removing the diff, firstly I worked my way around the E12 e-torx bolts holding the driveshafts to the output flanges on the diff. This is where the job took a turn for the worse.
One of the half shaft bolts rounded off on me, so after some fighting, I had to use an angle grinder to cut the head off the bolt to be able to continue.
With all those out, I then removed the prop shaft bolts which came out sweet due to them being less corroded.
That left me with the three main fasteners connecting the E46 M3's differential to the rear subframe. The front and very large bolt is a 21mm head, and should be in good and tight with a 200nm torque spec, I got mine moving nicely with a breaker bar.
My rear diff bolts were hex head Powerflex items which are nicely accessed using a ring spanner, OEM bolts are E12 E-torx and can be difficult to remove thanks to the shape of the boot floor preventing you from getting a socket and a ratchet in. Although it can be done with patience and pragmatism.
Once all the bolts were out, I found my diff to be still stuck in place despite giving it a good jiggle around. With the jack beneath it, I realised there are slots on the prop shaft flange, stick a flathead screwdriver in and twist to release the diff.
Sadly my diff fell off the jack and to the floor, surprisingly with no real damage to the rear cover which was very lucky. You should be more careful, it weighs a lot!
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Nice video. I'm looking forward to the next section.
Cheers! 😃
good video. got mine booked in at ETA next month for RACP job, got a pissing diff from the input shaft seal so getting that done too. nice M3!
Cheers! Yeah the ETA lads know their way around an M3. Really happy with the work they did. I shouldn't have opted for polybushings though in hindsight. 😅
Input seal I will be tackling on whichever diff goes back on, I reckon I can DIY that. You'll see how it works out in the next vid. 😃
What a nice video, with all of its problems and even joy when working with cars of this class.
I like your channel, and also subscribe since some months back.
BMW for me is motorcycles, but all mechanic work is interresting to watch.
Good Luck and I wait for the continue video(s) of your work of your fantastic car !
Thanks for the kind words! Really glad you're enjoying the videos. We've never had a BMW motorcycle in the stable but we can really see the attraction of them. Lovely machines.
Also buy a stud kit to hold your diff in, easier to install.
Nice idea, I haven't seen those for E46 platform before but I will check that out.
@SPANNERRASH just received mine from Condor Speed Shop, American made. They have them for your set up.
nice thumbnail
be wise to get rid of that polybush in the front at 20:19, they can work their way out especially if you track it
OEM bmw bush is better, if not solid alloy
Thanks Mr DC2!
I didn't know they had a tendency to back out like that, aiming to swap it for OE along with the back plate. The clunks finally getting to me. 😆
Reckon I'll first "quickly" swap in the spare diff to keep the car mobile though, and I'm curious about whether it will be the same.
Nice M3.. 😊
Think its your longshaft CV which is causing the clunk.. when u turned the longshaft in the video, heard some faint loose clunk...and with all the loose grease, i think its best your redo the CV..
With the 341 ponies, that CV takes a lot beating.. 😮
Just a thought..
Cheers Felix! The clinking sound you hear when i turned that is actually the gearbox flange turning, the CV on the prop actually felt pretty sound. The driveshafts have a bit more play than I'd have liked, but not a crazy amount either.
It's likely a combination of a lot of small amounts of play adding up to one big clunk. But I suspect the majority of the problem is with the diff, being that they're notorious for it.
We will see how it all plays out! 😄
23:19 I have the same problem, might be your crush ring or swing arms need to be adjusted. I have a 4.10 diff. Car came with 3.73 S. My suggestion is buy rebuilt or do it yourself. Just make sure the parts go Back the same way left side, right side. Take your time. Cheers
Cheers! You have the same clunk or the same leak?
I'm a bit intimidated by rebuilding the M3 diff, but I think I might need to have a go at it. Really don't want to have the M3 down for long over the summer though, hoping to enjoy it! This is partly why I bought a "known good" diff as a spare, swapping that in in the meantime might take the pressure off. 😃
I have no leaks only clunk, big time when I back up and turning corners. When driving straight it is noisy, like bearing and gear noise.
Schims also play a big part if they are worn. I'm the original owner of my 1988 325is 147,000 miles on new motor, body has a little over a million miles. Rebuilt the old motor and sold it.
The 4.10 was used. Only put 6,000 miles on it, going to buy a shell and rebuild a 3.73 since I drive alot on highways.
Just saying, change your axle bolts, and if you ever get any bolt that is hard to remove, use a good quality heat gun, it's the best. Low heat and 30 seconds at a time, just make sure your careful around flammable products, just did my upper brake hoses on the rear, no problem came off without a hitch.
Video on those brembo calipers
Wish I'd have been pointing the camera at stuff back when I figured all that out.
They're Porsche 996 Brembo 4-pot calipers front and rear, paired with CSL discs. If I recall, I'm using Creation Motorsports adapter brackets to make them work. Unfortunately you need to get a couple of mm machined off the caliper mounting faces for a perfect fit.
Then braided lines to match. Oh and the rear pad uses a front pad from a different caliper, with a modification to get more full sweep on the disc.
Maybe I should do a vid explaining it actually, I'm now remembering there's quite a bit to it. 🤣
Check back lash
Yep, its possible there's an issue with that, the diff has done 117k miles after all. Most common with these though is the right side output shaft develops play. Either way I may need to strip the whole thing down to find out.
Lots to learn on this one I think!