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-   -   Rear Upper Ball Joint Woes (http://www.m3forum.net/m3forum/showthread.php?t=602047)

nholmes Fri, Sep-21-2018 05:37:44 PM

Rear Upper Ball Joint Woes
 
TLDR: Ball joint is now very loose inside the knuckle and I have no idea why

During my rear subframe refresh I found that one of the boots was torn on the passenger rear upper, outer ball joint. I figured now would be a great time to replace it since I had the rear suspension apart and the subframe was on the ground.

This looked like a pretty straightforward job, where you press out the old ball joint and press in the old one.

Pressing out the old one with a 32mm socket seemed okay as it covered the boot, was thick enough to press on the ball joint housing and not touch the inside of the knuckle while pressing out the old ball joint.

Once I got the old one out, I noticed it was knurled unlike the new replacement LEMFÖRDER one I picked up. I measured them and they shared the same diameter.

Pressing in the new one was way too easy, in fact I probably could have done it by tapping it in with a plastic hammer... I knew I was going to have to keep an eye on it, as there was no way track use with r-comp tires was going to keep that from moving.

Sure enough, after a weekend it had backed out.

I'm considering having my local race shop just tack weld the ball joint housing to the trailing arm knuckle to keep it in place. Most of the load is not along that axis, so I think a tack weld could work in theory. It just needs to keep it from wiggling front/rear. The downside is that I have to see if you can even weld mild steel to iron and that I will need to use a chisel to break the tack weld free if I ever need to remove the ball joint.

Thoughts? Ideas? Has anyone experienced this problem? Why is this happening and how did you fix it?

Tools:

http://img.photobucket.com/albums/v5...psqdjqmgw0.jpg

Pressing out the old one:

http://img.photobucket.com/albums/v5...ps66xtgwbo.jpg

Here you can see how the socket is smaller than the ball joint (that piece of material is rubber boot that was pinched during removal):

http://img.photobucket.com/albums/v5...psn3f4cisj.jpg

Replacement part:

http://img.photobucket.com/albums/v5...psgxleq94s.jpg

Side by side:

http://img.photobucket.com/albums/v5...pswjnnb5ue.jpg

I measured the socket and the ball joint housing:

http://img.photobucket.com/albums/v5...pshhlxnhnv.jpg

http://img.photobucket.com/albums/v5...pshogwovle.jpg

After two track days you can see that the ball joint worked itself out about a 1/4" towards the rear of the car:

http://img.photobucket.com/albums/v5...psmua8ntmd.jpg

Braymond141 Fri, Sep-21-2018 06:40:40 PM

Re: Rear Upper Ball Joint Woes
 
You don't need to weld them. You can peen the metal over locking it into place.

nholmes Fri, Sep-21-2018 06:56:31 PM

Re: Rear Upper Ball Joint Woes
 
Quote:

Originally Posted by Braymond141 (Post 1067872423)
You don't need to weld them. You can peen the metal over locking it into place.

Awesome.

Help me out here, Brett - do you have any examples of this being done for this issue I can reference? I'm going to need to communicate this to someone else if I can't do it myself so understanding the process would be very helpful.

Braymond141 Fri, Sep-21-2018 07:16:11 PM

Re: Rear Upper Ball Joint Woes
 
You take a heavy duty center punch and bash it with a hammer. You want it placed in a way that the metal pinches into the ball joint.

This is similar to the way BMW stakes the u-joints into place on the OEM driveshaft.

nholmes Fri, Sep-21-2018 07:26:22 PM

Re: Rear Upper Ball Joint Woes
 
So you're saying I strike the iron here?

http://img.photobucket.com/albums/v5...psmagmllsv.jpg

Braymond141 Fri, Sep-21-2018 07:41:25 PM

Re: Rear Upper Ball Joint Woes
 
Yes. Welding might be better because it isn't deforming the metal... but you're not going crazy either, just pinching it into the bj. Welding may not hold though.

It's weird you're having this issue. The 895 joints are the latest revision (the previous being garbage). I've always had to use press tools to get them installed.

nholmes Fri, Sep-21-2018 07:49:18 PM

Re: Rear Upper Ball Joint Woes
 
I agree, it is really strange. When googling I read somewhere that there's a chance at one point a previous owner installed an aftermarket ball joint that was larger than the OEM one, which enlarged the hole making the OEM one I'm installing no longer snug.

I double checked, there are no special instructions regarding installation, either

http://img.photobucket.com/albums/v5...ps8qh48ryt.jpg

A local friend had the exact same issue and theorized that the socket enlarged the hole, as he too used a 32mm socket to press out the old ball joint.

This is the reason why I measured the ball joint and socket prior to beginning pressing it out.

He solved it buy sourcing a used rear trailing arm with existing ball joints and just swapping trailing arms...

frbz Fri, Sep-21-2018 08:08:41 PM

Re: Rear Upper Ball Joint Woes
 
Off the topic question. Why does your lemforder box have a febi part?

nholmes Fri, Sep-21-2018 08:18:52 PM

Re: Rear Upper Ball Joint Woes
 
Quote:

Originally Posted by frbz (Post 1067872468)
Off the topic question. Why does your lemforder box have a febi part?

Good eye! I noticed that inconsistency as well.

So what I think happened is that I measured the one of the two spare Febi ones I have, after I had already installed the LEMFÖRDER one.

http://img.photobucket.com/albums/v5...pszsrrutjz.jpg

http://img.photobucket.com/albums/v5...ps99j0kyrt.jpg

nholmes Thu, Oct-25-2018 11:00:49 PM

Re: Rear Upper Ball Joint Woes
 
Just to follow-up, I'm going to try this.

http://img.photobucket.com/albums/v5...psxt4yr35g.jpg

http://img.photobucket.com/albums/v5...ps3anryduq.jpg

http://img.photobucket.com/albums/v5...psrpznbtmy.jpg

http://img.photobucket.com/albums/v5...pshex793bv.jpg

http://img.photobucket.com/albums/v5...psnu1n7yyn.jpg


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