Trailing Arm -- Ball Joint Upgrade (from rubber bushes)

[RocketyMan]

I decided to upgrade the rubber bushings in the rear trailing arm to FCP-modified ball joints.

A little background:
I started to get really annoyed with going over smooth road and getting really bad bump-steer in the rear axle when going over man-holes and such. FCP had these ball joint upgrades and I was very interested since there is little to no deflection with a ball joint vs rubber bushing.
As an FYI, these seem to go out of stock every once in a while. (I got them on sale last )
https://www.fcpeuro.com/products/bmw...-33326763092sm

Figuring out how to do this, there was no great walkthru. PelicanParts had a only half-baked walkthru that I wasn't at all impressed with:
https://www.pelicanparts.com/BMW/tec...eplacement.htm

Hence my endeavor.
As for tools, I would suggest having a few key items. It is very nice having little extra tid bits around to use as a driver, spacer, etc. Needless to say, I had to do a bit of scrounging in my garage to find something that would work.

Special Tools:
1. Autozone rent-a-tool balljoint remover: Part #57023
https://www.autozone.com/test-scan-a...set/557231_0_0

2. M12X180mm bolt class 8.8 (I wish there was a 10.8..but nothing) -- I went down to local hardware store to pick this up
3. M12 flanged-nut that is hardened as well as five hardened washers (unfortunately I couldn't find a fine-thread setup)

4. A non-deep 12 pt 1-1/4 socket (1/2" drive so the m12 can fit through)

5. EP lithium grease to grease the threads of the M12 setup. This is going to need plenty of it to try and preserve the threads as long as possible. Then also some PB blaster or penetrating oil.

[RocketyMan]

My plan was to try and do this WITHOUT having to drop the rear axle carrier and/or moving the fuel tank out of the way.

DO NOTE:
When working with the threads on the carrier, pay attention to any threads before they contact the fuel tank. Having about 5 of the hardened M12 washers helps with precise positioning.
Also, the axle carrier brake line bracket can somewhat interfere with your setup. I have steel braided lines, which didn't hurt them at all...but it did rub a bit.

Take you time with this. It was a bit frustrating for me at times--but it just amounted to getting creative with my setup and the sequencing of various spacers/washers, etc.

Once the rubber bushing is removed, it's a good idea to clean up the pocket and lube it with the EP grease you have to prevent any binding. A good hint when removing the bushing is you'll bind up the aluminum outer shell of the bushing and hear it *pop* when it removes. Aluminum loves to gall. So use some spray lube.

Then take you upgraded ball joint and lube that outer shell with the grease as well. This will again help with preventing any binding. It's crucial to try and get the ball joint as perfectly square to the surface to go in smoother. Once it's in, try and center it where both sides stick out equally.

[RocketyMan]

I didn't get lucky getting every single bushing out in tact. Most of the time using the 1-1/4" socket just pushed out the inner bush. Ohwell...tapping the outer shell of the bush out wasn't too hard. Again, just be creative if this happens, try and get the socket out. Then you can fold in the out shell of the remaining bush and it comes out seamlessly.

DO NOTE:
It really helps to gain a bunch of clearance by removing the rotor, parking brake shoes, and then loosening the disc shield. It can rotate about the rear hub so that you can get the clearance to get all the adapters and such on and not be in the way of the brake shield. It's only four 10mm bolts holding it on.

I know this might be a little silly, but I had a huge 1-3/4" wrench that actually ended up making pressing the new ball joint into the receiver more "square." Again, once you press it through, make sure this is even in the receiver on both sides.

Once you get all four ball joints installed, button everything else back up. Notice that the trailing arm is free to articulate--but solid with no movement radially.


P.S. I ended up eventually rolling the threads on the M12 bolt. If it was a class 10.8, it would've def lasted much longer. But a $5 bolt sure beats spending on the bav-auto toolset. Oh...don't forget to return the Autozone rent-a-tool.

[nycplumber]

Great write up. Did you notice a difference?

[amrazM]

i just cut a tool in the lathe today to pull these things in and out. It helps to have a bearing on the assembly when pulling these joints through.

[RocketyMan]

Nice. So you basically made your own. I found that having a shallow socket helped the most.

What are you using for the "shell" portion that attaches to the housing on the other side of the housing?

[RocketyMan]

Originally Posted by nycplumber

Great write up. Did you notice a difference?

I haven't taken it out for a drive just yet. I'm working on some interior lighting issues with the door cards right now.

[danvitmon]

Sweet write up, I bought the balljoints a few months ago but have already done a subframe drop/refresh and have been procrastinating doing these because I thought I had to drop it to do them. Thanks!

[RocketyMan]

As an update, I finally got the m3 on the road again. I drove over the typical manholes on the highway and this time didn't feel the vehicle lunging or bump-steering. This is definitely a recommended upgrade on the rear end as the rear feels more planted now.

[amrazM]

I started working on this today, the ones in the subframe are completely frozen. Damn ny car.

[omgzirra_exe]

yeah was just going to order these for my "M3 refreshment" service in august... maybe September.. just another dollar in the pockets of FCP.

[danvitmon]

Originally Posted by omgzirra_exe

yeah was just going to order these for my "M3 refreshment" service in august... maybe September.. just another dollar in the pockets of FCP.

I ordered mine from Latvia on ebay and got 4x for around $90. It did take like a month to arrive but they're true made in Germany bearings.

[spammysammich]

Originally Posted by amrazM

I started working on this today, the ones in the subframe are completely frozen. Damn ny car.

PB Blaster and heat? Good luck!

[amrazM]

Originally Posted by RocketyMan

Nice. So you basically made your own. I found that having a shallow socket helped the most.

What are you using for the "shell" portion that attaches to the housing on the other side of the housing?

im using this kmac tool. getting it to budge it was just extremely tight.

[RocketyMan]

Yeah I find the aluminum shell of the bushing always seems to gall. Alot of spray lube tends to help for me.

I see you're using an allen bolt. I'm assuming its a class 12.9--which would def help in this scenario in terms of strength.