924/944/968 Frequently Asked Questions
10.0 Suspension, Steering, and Related
10.1 Whats the deal with replacement ball joints/suspension arms and what causes their failure?
Yes, ball joints are known to fail. However, it appears to occur mostly on lowered track driven cars. Larger swaybars may also contribute. When the ride height is lowered a great deal, the ball joint begins to reach the end of its travel. Eventually the ball joint can crack, and then fail entirely - possibly while you are driving very fast.
Assuming youre not doing any of the above (extreme lowering, larger swaybars, track usage) you may want to go with a reconditioned/rebuilt arm if your ball joint fails. Several vendors do this, including the pfiles recommended:
Dynamic European Technologies, Inc.
For the ultimate in control arm/ball joint assemblies, FABCAR offers their own fabricated arms with a "replaceable monoball (spherical bearing)". These are the same arms that the IMSA requires on any 944 racing in their series.
4385 West 96th Street
Indianapolis, Indiana 46268
The following is a statement released by Porsche Motorsports North America concerning the 944 Aluminum Control Arms:
To: All Porsche 944 & 968 Competitors
Re: 944 & 958 Control Arm Usage In Racing Applications
The following A arms should be installed in 944 and 968 Series vehicles according to the conditions noted:
944 341 027 02 L/S Production version arm (round groove 360 degrees on ball joint)
944 341 028 02 R/S Production version arm
These parts are good for moderate competition. (Time trials etc.)
951 341 027 32 L/S Competition version arm (slotted groove on side of ball joint)
951 341 028 32 R/S Competition version arm
These parts are recommended for long distance races or heavy competition.
Neither set of arms noted above pose a problem, as long as:
- The ride height is not lowered beyond the point which causes binding of the ball joint when the suspension reaches full travel,
- The front sway bar is not greater than the M030 package sway bar in either 0.D. or wall thickness,
- The lower bore in the strut is not worn out and 4) the parts are assembled following the steps outlined in the Porsche Service Manual. (Despite the fact that this may be slightly contrary to the Service Manual, it is imperative that the bolt and nut (original Porsche Parts) be replaced each time they are removed.
As always in racing, it is important to inspect the arms for nicks or cuts from road debris after each event to avoid development of any cracks. Please note that the leading cause of failure we have seen on both the Production and Competition version arms, in racing applications, is the failure to follow the instructions I have listed above. Please call PMNA with any racing preparation issues.
Director of Porsche Motorsport N. A..
Michael Kehr has written a detailed control arm replacement procedure for the 944/951, which you can find right here.
The first thing to do is determine where your power steering is leaking. There are three common sources:
If ATF is noticeable on the rack shaft or on the housing in the area of the pinion shaft, replace the rack.
Either you can pay a locksmith a few bucks to pick the lock, or you can take a drill and drill out the barrel of the lock. After drilling, the cover slides right off and you can remove the fastener like any other lug nut.
Ed Gibbs has written a nice little FAQ on CV joints on 944s. The most recent version can be found right here.
Jim Pasha has written up a note on this topic.
Marc Belanger has written up the procedure for changing torsion bars on 924, 944, and 968 series cars. If you're up to the challenge, you can find the procedure right here.