a-arm failures
 

just talked to a guy about 944T's. He said that in his race cars they fail all the time. The epoxy in the ball joint goes bad and POP they come out at the track while you're in a turn!! ANy second opinions? He felt the steel ones were a helluva lot better and lasted forever!

I've never see a ball come thru an arm. That doesn't mean it hasnt happened. On the track, the arms should be upgraded. Porsche used a nylon bushing in between the ball and arm inside the joint. Over time, this breaks down and wears allowing the ball to be loose in the joint. The ones I've seen apart, the ball is too big to come thru the hole in the arm.

A arm ball joint failure is a known issue with these cars. It occurs on cars that are track driven, lowered, and/or with upgraded swaybars and suspension. I do not know of the frequency of this happening, I have never seen one fail. The arms in my 951 were replaced with the billet aluminum Charley Arms. Some replace theirs with units from Fabcar(?). Others replace theirs with the earlier steel units. It should be one of those things that gets regularly checked, better safe than sorry.

How do you "check" them? Is there a easy way?

If your car decides that it wants to go in some other direction then where you have the wheel pointed, (like after going thru a pothole...) it's time to replace them.

[quote]Originally posted by 2+2:
<strong>How do you "check" them? Is there a easy way?</strong><hr></blockquote>

Lift the wheel off the ground. Get a pry-bar or large (hear-LARGE) screwdriver between the pinch-bolt and the arm and pry up. Generally, any movement means worn bushing.

Heh, mine were so bad that once the wheels were off the ground, I could rock the wheel a good 3~5 degrees. I used replacement balls/bushines from SSI Auto in Marlynad (NOT a track car, not even an AutoX car yet... still stock as far as suspension, wheels and height goes).

"He said that in his race cars they fail all the time. The epoxy in the ball joint goes bad and POP they come out at the track while you're in a turn!!"

Well that's not possible! For the balljoint to simply fall out the bottom that is. The epoxy is used on the bottom to hold the circlip in the groove which keeps the bottom cap in place. If the epoxy were to fail and the circlip and cap came out, nothing awful would happen except for some major rattling due to the lost of spring-tension pushing the ball-joint into the upper cup. You'd have to be able to yank the entire spindle, brake-rotors and calipers, strut and entire wheel through the small hole in the top of the A-arm in order for the balljoint to fall out the bottom! ;) :p

"How do you "check" them? Is there a easy way?"

The failure that occurs due to excessive lowering or bottoming of the suspension is actually in the A-arm itself. When the ball-joint is rotated beyond its maximum rotational angle, it contacts the A-arm and dents it or even break a piece off. Eventually the hole in the top of the A-arm gets large enough for the ball of the ball-joint to fit through and that's it. But more than likely, you'll have damaged the ball-joint enough with banging it against the A-arm that the ball-joint just snaps in two. :(

Now this is different than the kinds of failure you can detect with the wiggle test. That just shows if your plastic ball-joint cups have failed. But to see if your A-arms and ball-joints are damaged, you should take the spindle off, then carefully remove the rubber cup over the ball-joint. Wipe off all the grease around the top of the A-arm and you'll see a reinforced aluminum ring. Make sure this ring is Ok and in one piece!

Danno,

How far can one go in lowering the car with aftermarket a arms and still have a reasonable margin?

Peter

I used to have my stock a-arms magnafluxed anually to check for stress cracks.

MikeA - I'll guess your no longer running the stock arms anymore but for how many years did you send them out to get magnafluxed? Did they ever find any stress cracks? What kind of usage did you put them through?

Hugh,
I just posted on the other "control arm" thread on this forum. It answers your questions.
Mike

Actually, some guy posted that he had one fail catastrophically just after he finished a track session and was backing into his spot.


Jason

Someone told me he had a catastrophic failure with a billet a-arm going into Big Bend at Lime Rock. It must have been ugly.

[quote]Originally posted by Mike A.:
<strong>Someone told me he had a catastrophic failure with a billet a-arm going into Big Bend at Lime Rock. It must have been ugly.</strong><hr></blockquote>

Did it break at the anti roll bar mounting point?