Carpokes Porsche Forum

Part 1 of 3

Rebuilding your aluminum control arms is pretty fun. I used the Rennbay ball joint kit and a new set of bushings, all from 944 Online. (They also sell entirely rebuilt control arms, complete with German bushings if you'd rather not do this kind of thing yourself. Additionally, they sell a comprehensive ball joint, bushing, and castor block DIY kit. Not sponsored here - just a happy customer.)

Disassembly of the Ball Joint
Getting the securing clip out is the "hardest" aspect of this portion of the project, and it's not that hard. I drilled a shallow 1/8" diameter hole at an angle toward the thickest part of the casting. Then I could get behind the clip ring with a small punch (shown vertically in the pic, below) to lever the clip out of its groove enough to get a small screw driver behind it. From there, it was just a matter of walking the clip out with the screw driver. Disassembly of the Bushing
Ugh, this was tougher. The bushing where the control arm mounts to the cross member is a two-piece or split bushing. I know Elephant Racing sells a tool designed for indexing against the thin groove in the center, allowing for an easier approach to driving the steel bushing sleeve out of its aluminum bore. I went a different route.

I was able to grab the outer giant washer looking part and simply twist them each by hand. This was enough to separate the rubber material from the inner steel sleeve. A little WD-40 for lubrication and some twists and yanks with a big pliers allowed the rubber portion of those bushing to come right out. That left the steel sleeve still inside the control arm. Using a hack saw, I threaded the blade through the bore and cut through the steel sleeve taking great care to NOT cut into the aluminum. In the above photo, you can see the slit I cut in each steel sleeve. Using a hammer and small chisel, I bashed the outer ring of the steel sleeve until I could get progressively bigger chisels into the widening gap.
I sprayed WD-40 into the gap and took my time to walk the damn things out. The rebuild follows...

Part 2 of 3

Before rebuilding, I repainted my control arms. I wire brushed the entire control arm, using a combination of a wire wheel on a bench grinder, wire wheels in the drill press, and those same wire wheels in a hand drill. Then small wire wheels in a Dremel tool to get inside the bores and grooves and hard to reach corners.

I acid etched the parts using something like Alumiprep and a red Scotch Bright pad. Then I primed them and painted them with Rustoleum Bright Coat Aluminum and Matte Enamel Clear. Below, the control arm on the left is prior to applying the matte clear. The one on the right is the exact same base coat after applying matte clear.
I have gotten into the habit of baking my rattle can painted parts at a low temp (like 175F), which seems to harden the finish some and definitely decreases drying time as the weather turns colder. In this case, it also allowed me to press in my new bushings that I had placed in the freezer days ago. (Hot part + cold bushing + a tiny amount of ATF for lubrication = just enough clearance to press them together).
I had gotten all but the last 3mm of the bushings properly seated by padding my bench vise with some shop rags, putting the large mostly flat washer looking things in place on the rubber face of each bushing half, and squeezing them into the bore. That wasn't quite enough.

The BETTER way is to use a very large socket (1 7/16 worked for me) with enough of a tapered neck to clear the contour in the control arm and NOT have the large mostly flat washer looking thing in place at all. The lip of the large socket must rest against the metal lip of the new bushing.

They squeezed in with only minimal extra effort using the better approach. Turns out the rubber does distort and absorb energy after all - how about that.

After the parts cooled, I did the ball joint...

Part 3 of 3

The Rennbay ball joint kit is entirely DIY friendly. If you've been thinking about rebuilding your control arms, give it a go. The included instructions are brief but thorough and include a nice assembly diagram.
New Ball Joint Clamping Contraption
A deep socket for the ball joint pin side, a regular socket for the base plate, and a bench vise are all you need. Actually, having a friend/partner/spouse operate the vise while you hold the sockets in place is super helpful. Finished Shots All Done

Another stellar how-to from usary! Thanks for posting that! Both @Rennbay and @944online are members here too, so its great to see you support the home team and help allay fears about tackling this job!

brief but thorough

I like it! That will now be my response if ever I am asked to describe myself

Glad they went together well. Amazing job on the cleaning/paint. They look stellar!

Rennbay wrote: Mon Nov 07, 2022 9:18 am

brief but thorough

I like it! That will now be my response if ever I am asked to describe myself

Glad they went together well. Amazing job on the cleaning/paint. They look stellar!

I forgot to mention that -- the paint/finish looks great. In pictures, it looks like freshly blasted aluminum. What was your process for the blue Porsche letters?

Tom wrote: Mon Nov 07, 2022 10:06 am I forgot to mention that -- the paint/finish looks great. In pictures, it looks like freshly blasted aluminum. What was your process for the blue Porsche letters?

Thank you for the compliment! The finish turned out better than I expected. In person it looks remarkably like freshly blasted aluminum.

The finish would be easy enough for any DIYer to duplicate or expand upon since it uses commonly available paint.

Like all painting, the work is in the prep. It probably took 1.5 hours of wire brushing and scrubbing. Acid etching is nice if you have a auto body supply shop nearby where you can buy that kind of stuff. Otherwise, thorough cleaning with acetone and a self etching primer would likely be just fine.

I hand painted the Porsche lettering with a small art paint brush. The blue I've been using as an accent part color is another Rust-Oleum rattle can paint. I sprayed some of that into a small cap (from a carton of almond milk in my case, but anything small will suffice) and brushed it on by hand. Looks good from a foot away. Me and the oil change place will be impressed.

It was a cold and drizzly day in the PNW for laying in the driveway. Still, I got my repainted and rebuilt control arms installed. I didn't take a lot of pictures today, but I do have a finished shot.
Some advice for people doing this job...

I installed the caster block part of the control arm first, then the cross member part, and finally the ball joint pin into the spindle. I left the two caster block-to-body mounting bolts loose throughout installation to allow for slightly easier insertion of the cross member part of the control arm. Maybe there is a better order of operations, but this worked for me. Remember to tighten all your bolts to spec.

Once you think you are close, use a long screwdriver though the holes to help align the bushing holes with the cross member holes. There is no extra clearance for the bolt. Use the long (and thick) screwdriver as an internal pry bar to subtly shift the position of the control arm until the holes line up perfectly.

Getting the ball joint pin aligned with its hole in the spindle is a bit of trial and error. Gently bonk the ball joint pin with a rubber mallet to shift its position. Then offer it up to the spindle. Rinse and repeat until the ball joint pin looks like it is aligned. If you are lucky, and there is grease on the ball joint pin and hole it goes into, you may be able to wiggle it in.

If it doesn't wiggle in, use a floor jack and a 2x4 block on edge to gently jack the ball joint end of the control arm. Take care to avoid putting pressure on the grease fitting (or just unthread it and put it aside to be safe). It should take only minimal force from the floor jack to slip the ball joint pin into position.

It is possible to over-jack the ball joint pin. Remember, the groove in the ball joint pin must align with the bolt hole in the spindle.