96 M3 LCA rebuild

[chrisbec]

So, I've been working on these '96 M3 LCA's for a little while now and I just finished boring one of them so that I can install Meyle all metal outer ball joints. I salvaged these from a buddy who was chucking these in the trash since the BJ's were worn. I figured what the heck since the arms were free I'll give rebuilding these a shot.
I bought a set of new inner and outer Meyle all metal ball joints off of eBay (I think that just the outer ball joints are all metal, the inners aren't) This is not a simple job BTW, to do this job correctly the holes either need to be reamed, or bored on a milling machine (which I did). Since these parts have an interference fit making the holes to just the right size is definitely tricky and requires a lot of patients.

[chrisbec]

I pressed out the old ball joints, they were tight but the job was straight forward. I mic'd the outer hole at 1.6114". I measured the Meyle ball joint at 1.9097" just above the knurls since this was the base diameter that was going to use to size the hole. I bored the LCA 0.2993" to 1.9107" (.001" oversize to the base diameter) so that the knurls will be fully engaged when the ball joint is pressed in the LCA.
I'm going to add a small chamfer to the bottom of the hole and press in the new joints. I'll post again once I get it assembled.

[BimmerBum]

Very nice... you should have told me. I have a set of outers sitting on the shelf.

[chrisbec]

I ground the chamfer in the bottom of the outer BJ hole with my die grinder and a well dressed stone. Then I went over it with a flap disk to remove any burrs left over from grinding. To chamfer the sharp 90 degree edge that was left after boring is important so that the knurls on the ball joints don't get sheared off when the parts are pressed together. The chamfer will allow the knurls to dig into the inner bore of the arm so they remain effective in retaining the ball joint in the arm.

[chrisbec]

I also did a little general clean up on the arm. Once the weather warms up a little (probably this weekend), I'm gonna paint the black metal parts with some Rust-Oleum spray paint

Here are all the parts for the LCA rebuild. I'm on the fence with the '95 M3 rubber bushing, I may change my mind and go with a Delrin version before I put them together. Think that I'm going to avoid Poly since I've heard that these particular bushings tend to squeek soon after they are installed.

[chrisbec]

A little further along and a little smarter now too

The press fit was OK for the outer ball joint. I didn't have it completely square when I started pressing, so it probably tried to go in at an angle and I was fighting it because of that. It is installed and sitting flush now but it took a HUGE amount of force to get the joint together. I also used Loctite 609 which is retaining compound for press fit parts. The specs say that it adds up to 3,000psi to the retaining strength for press fit parts. I calculated the outer joint surface area and it has almost 3 square inches of contact surface. This equals 9,000 pounds of additional retaining strength on top of the press fit for this joint.