318is rear end clunk

[fastestbox]

I'm having the worst clunk in the rear when I let out the clutch quickly at speed or when I'm just feathering it around a parking lot and I can't figure out why.

It really started after I did poly trailing arm/diff/and subframe bushings and originally I had thought it was related to my driveshaft, but it's rather new and the CSB is in great shape.

I put it on jack stands and let the clutch out while it was running and the noise was extremely predominant.

Is this normal or is something up? Diff related?

Thanks!

[Nairb]

Exhaust hangers all good? Rear differential mount good? Swaybars mounted properly? (I've had my rear swaybar SLIP out the actual swaybar links and cause clunking). Rear differential flange, any movement?

You could pop the rear end up on jackstands so rear wheels are off, start the car and have a friend gradually rev it up while in 1st gear and get a visual for yourself. Just be extra super careful, make sure to chock the front wheels. With the rear wheels off the ground, give the tires a good hard firm "wiggle" and see if there is any play, could be indicative of a wheel bearing.

I have poly RTAB's and rear parts as well in my 318is. It could be that you fixed all that slop in the rear, and now the next weakest link is giving out. How is your flex disk mount at the transmission?

Also, check all of your axle nuts for tightness. I had an axle cause a rear clunk in an older e30 I had that drove me nuts until I discovered it was actually just a loose rear axle!

Just some suggestions, I'm not a professional mechanic. Good luck!

[mbonanni]

Have the same issue except I have an auto. Shifting from D to R or N it clunks, and even gassing it then etting off or feathering arfound a parking lot like described. I was told my rear CV' are bad the last time I had it at a "shop". More of a small time repair shop/oil change typa place so take that with a grain of salt.

Post up what you find.

[Jokester]

Sounds like a cv axle issue, your diff could also be going but I doubt it.

Check your rear wheel bearings if you have to swap axles also.

[Fergi]

You should check all the U-joints on the driveshaft. I think there is like 3 on the 318is driveshaft? I used to have a miata that had a bad U-joint and it would clang every shift and especially bad in parking lots. My friends called me 'cow bell'.

[fastestbox]

Exhaust hangers all good? Rear differential mount good? Swaybars mounted properly? (I've had my rear swaybar SLIP out the actual swaybar links and cause clunking). Rear differential flange, any movement?

Exhaust hangers are relatively new, and I tried the 1st gear clutch release on jack stands with most of the exhaust removed (much to my neighbors' dismay) and it still made the clunk.

How is your flex disk mount at the transmission?

The flex disk looks brand new, along with every other part of the driveshaft system.

Also, check all of your axle nuts for tightness. I had an axle cause a rear clunk in an older e30 I had that drove me nuts until I discovered it was actually just a loose rear axle!

This might be it! I've yet to check it, but it's definitely making that sound around there.
Thanks for your suggestions, also beautiful 318is!

gassing it then etting off or feathering arfound a parking lot like described.

Aside from the auto/manual difference, this is exactly the problem I'm having too so let me know as well if you find a fix!

Sounds like a cv axle issue, your diff could also be going but I doubt it.

Check your rear wheel bearings if you have to swap axles also.

That's entirely possible, I'm wondering if the diff/axles were damaged in my 4 day learning experience of replacing all the damn rear bushings. I HOPE it's not wheel bearing related, although I was planning to do the nasieg style 5 lug swap relatively soon.

You should check all the U-joints on the driveshaft. I think there is like 3 on the 318is driveshaft?

I checked the u-joints with the driveshaft both in and out of the car and they seem pretty solid, I'm 98% sure the driveshaft and related articles were replaced recently by the previous owner.

[reelizmpro]

I'm troubleshooting the same issue now. I jacked up the rear and turned the wheels by hand. The drivers side spun freely but when I went to spin the passenger side, it would rotate until it hit a spot of resistance. This resistance was the source of my "clunking" sound which has gotten more pronounced. I thought it was the differential at first but I swapped it out and the problem still exists so it looks like it's the passenger side stub axle inner CV joint. Going to inspect it and swap it out when it stops raining to verify.

[mbonanni]

You mentioned you did subframe bushing and what not. Did you mess with the brakes at all?

My noise came about after I did h&r bulsteins rear suspension, new sway bar bushings and end links, new rear pads and rotors. I also think my rear wheel bearings might be bad?

[fastestbox]

I'm troubleshooting the same issue now. I jacked up the rear and turned the wheels by hand. The drivers side spun freely but when I went to spin the passenger side, it would rotate until it hit a spot of resistance. This resistance was the source of my "clunking" sound which has gotten more pronounced. I thought it was the differential at first but I swapped it out and the problem still exists so it looks like it's the passenger side stub axle inner CV joint. Going to inspect it and swap it out when it stops raining to verify.

Please let me know if that fixes it!

You mentioned you did subframe bushing and what not. Did you mess with the brakes at all?

My noise came about after I did h&r bulsteins rear suspension, new sway bar bushings and end links, new rear pads and rotors. I also think my rear wheel bearings might be bad?

I bled the rear brakes, but other than that I didn't do anything to them. There IS a rub sound (like the brake is engaged) on the drivers side when I spin the wheel by hand on jack stands, which might be related to my issue.

[mbonanni]

I thought my brakes felt a bit weird after my refresh. Buut my cv boot closest to the diff on drivers side is bad, the “shop” I was at said that was most likely my issue. Pretty sure there are full rebuilt axles for $50 at autozone.

[ForcedFirebird]

Pretty sure there are full rebuilt axles for $50 at autozone.

Box store axles are junk. Had a client come in the shop that had used them, he snapped 2 in his 318 with a 4.27 diff.

[mbonanni]

I put them on my 325es years ago. Sold it about a year after but never had any issues, they have warranty as well. Your customer must have been rippin on it or doing something wrong [emoji6] Aside from that, refurbished bmws ones for the same price or $50 more with lifetime warranty. Just gotta dig around.

[ForcedFirebird]

I put them on my 325es years ago. Sold it about a year after but never had any issues, they have warranty as well. Your customer must have been rippin on it or doing something wrong [emoji6] Aside from that, refurbished bmws ones for the same price or $50 more with lifetime warranty. Just gotta dig around.

The reference was just because it was the weak sauce m42 that snapped them (cages cracked), sure it was an auto-x, but an OEM axle with worn boots and making clicking sounds will outlast them. I have changed and rebuilt hundreds of e30 axles over the years, and the box store parts are inferior all the way around. Only place that carries OEM rebuilt axles anymore is NAPA, and it's been long enough now that people have started to turn in aftermarket axles for cores - so it's still a crap shoot. Go grab a $50-100 axle, then grab an OEM GKN axle, put them side by side and you will see what I mean (I have done this). ;) The boots are 2x thicker, less bearing play right out of the box, superior finish on the axle splines, smooth articulation, and they are about 25% thicker on the shafts themselves.



The box store axles will have play in them after just a few hours of road course racing - sure you can drive around like grandma and they will last plenty, but the first time you do some spirited driving, they are toast. To me, it makes more sense to purchase axles once, even at a $250 price tag, than to go bring axles back to the box store every time the toothpicks decide to give up the ghost.

[mbonanni]

318is rear end clunk

I mean... for $50 a pop and no rebuild/downtime required is worth it. Everyone has different requirements and in my experience they worked great. It doesnt seem like OP is autocrossing so might be worth $100 vs $500, or $100 vs a week+ of downtime.

[fastestbox]

Bumping this to say that I'm almost 95% sure it's due to problems with the differential's backlash setting. Does anyone know how to adjust a small case 4.10 LSD?