Otto Mechanic

I rebuilt the front A-arms on my '89 S2 a few months ago using the Rennbay ball joint rebuild kit. Today I took the car in for alignment and the fellow at the shop did a very quick test on the new ball joints using a very large set of channel locks. There was about 1/4 to 1/2 inch of play in the ball joints under compression.

Should there be any play at all? If not, what might be the problem with this install?

Thanks,

SloMo228

The spindle is spring-loaded in the balljoint socket, right? So you should be able to push it down a bit. If that's what your mechanic is seeing, I don't think that's a problem. If it's anything other than axial play like that, then yeah, that's cause for concern.

Otto Mechanic

Yeah. I re-built the ball joints myself, I think they're working the way they should. This fellow makes a claim to be a Porsche expert but I don't think he understands 944 a-arms.

Oddjob

There is virtually no play in factory new arms. When squeezing with a big channel locks, there is a little bit of rocking motion, ball joint starts to roll a little because its hard not to pull it to the side slightly when compressing. But that motion should not be confused with up and down slop in the joint. If you start seeing vertical movement when compressing the joint or prying upward (trying to lift the ball out of the socket by prying between the arm and the pinch bolt), its time to replace the factory arms.

I don't know enough about the rebuild kits, but up to a 1/2" vertical movement in the joint would concern me greatly.

Otto Mechanic

So you're thinking the play I see might indicate the a-arms themselves are worn past the point they can be re-built? My understanding was the aluminum a-arms were an NLA part?

Otto Mechanic

One comment the mechanic made was he'd heard the Rennbay rebuild kits didn't work on late model S2s with aluminum arms. Can anyone confirm that? Rennbay lists them as compatible with the 944S2, I'm pretty sure all of them have aluminum arms.

Otto Mechanic

Just to clarify, neither of us tried levering between the arm and pinch bolt, he was only using the channel locks to compress the joint, putting one side of the jaws on top of the pinch bolt, the other under the arm. I couldn't tell if what we were seeing was axial motion or the lateral sliding you describe.

I do know there's a spring inside the ball joint, so compressing that spring would cause axial play I would think?

I have the car back at my shop now so I'll run further tests next week when I return from a business trip I'm leaving on tomorrow.

951and944S

Normal. Unless you assembled the kits wrong. Bottom cup is spring loaded.

To get my car off the trailer with the broken ball joint pin, I just loaded a new pin from a kit, left out the o'ring cover seal and the bottom cup spring just to make assembly easier as I was going to address the problem further once in the shop and on stands.

There was an 1/8" up and down play in the joint with the cover and lock ring in place so, even with the spring installed, I'd expect some play that is held in check by the tension of the compressed spring.

T

Oddjob

For a 1/4-1/2" movement, I was suspecting the replacement balljoint assembly not necessarily the arm socket. I haven't checked recently but thought that factory a-arms are still available (?).

S2 arms are the same as any of the 87+ 944 arms. 968 arms I think have a different balljoint socket in the arm (?).

MAGK944

I did mine a few days ago and I just bench checked them again. You should not be getting 1/2” up/down movement, it’s nominal, barely noticeable movement at most. Did you epoxy the circlip into place? Check to see it hasn’t unseated itself as that would give you your 1/2” movement if it has. S2 and earlier arms are still available and all 87+ arms are the same except 968 arms which had integrated and completely sealed ball joints, i.e: non-rebuildable.

951and944S

Whoops, didn't see the 1/2" part.

No, definitely not normal.

T

Scott at Team Harco

This is true. I discovered that I have a 968 arm on my S2. After contacting Mr. Rennbay, I got confirmation that that arm is not rebuildable - as I suspected (see lower picture).

First picture shows the P/N for the right hand LCA.





I agree - there is likely something quite wrong if there is as much as 1/2" of play in the ball joint. I'd take it off the car and have a good look at it. It could be the socket within the arm is worn. I've had at least one like this - it should be fairly obvious if this is the case. The other possibility, as mentioned, the retaining clip on the underside may have popped out and the lower cover dislodged.

Otto Mechanic

To close this thread, I was unable to reproduce the play demonstrated by Mark at Ken's Sport Tech in my shop; There was no measurable axial play on the ball joint, not even 1/4". I have no idea how that measure was demonstrated. I was watching. I'm unable to reproduce the result using the largest pair of channel locks I own. Not even a little.

The fact there was no measurable play combined with the owner's opinion that the Rennbay part was incompatible with the S2 front arm leads me to believe the owner wasn't familiar with the 944 S2 suspension.

I'll continue to operate the car, though the new owner of Ken's Sport Tech advised me not to. I'm sorry to report this.

Sincerely,

Otto Mechanic

PS: There's also no motion observed by placing a "cat's claw" pry bar between the a-arm and the pinch bolt. None at all.

I conclude the test is unreproducible.

Otto Mechanic

Double checked. Not even 1/16".

It was suggested that a large set of channel locks may have caused the internal plastic washers to crack. That apparently hasn't happened with this installation but it does act as a warning for folks who get too aggressive in testing the seal.