924/944/968 Frequently Asked Questions

10.0 Suspension, Steering, and Related

10.1 What’s 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 it’s travel. Eventually the ball joint can crack, and then fail entirely - possibly while you are driving very fast.

Assuming you’re 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.
5103 Gulfton
Houston, TX

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
Fax +1.317.872.3835

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:

  1. The ride height is not lowered beyond the point which causes binding of the ball joint when the suspension reaches full travel,
  2. The front sway bar is not greater than the M030 package sway bar in either 0.D. or wall thickness,
  3. 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.

Alwin Springer
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.

10.2 My car is leaking power steering fluid. Why?

The first thing to do is determine where your power steering is leaking. There are three common sources:

  1. From the hoses on the bottom of the reservoir. This can usually be corrected by replacing the solid band clamps which Porsche originally used with more conventional "Zebra" hose clamps. Porsche provides the solution without mentioning the problem in tech bulletin book H, group 4, number 9102. The updated clamp for the supply hose is 999.512.346.02, and for the return hose it's 999.512.450.02.

    There is also one of these clamps at a banjo fitting on the power steering pump. It too leaks and should be replaced. The advantage to buying these clamps from Porsche is that they have rounded edges on the bands. The flat bands on hardware store hose clamps will cut through a hose given enough time.
  2. From the power steering pump, typically between the case halves.This is generally due to failure of a large o-ring between the case halves. The o-ring is not available from Porsche, but perhaps it can be found somewhere.
  3. From the steering rack. If you pull back one or both of the boots over the tie rods, and there is any appreciable fluid inside the boot, then it may well be that the rack must be replaced. Porsche recommends the following diagnostic steps in tech bulletin book J, group 4, number 9308:
    1. Remove both rubber bellows from the steering rack and push aside.
    2. Clean the rack thoroughly in the area of the rack shaft and seals.
    3. At an engine speed of about 1000 RPM, turn the steering to the right stop (ie, as far as it will go) and hold there under light pressure for five seconds. Repeat the procedure with the left side. Repeat eight to ten times.

    If ATF is noticeable on the rack shaft or on the housing in the area of the pinion shaft, replace the rack.

10.3 I lost my wheel lock keys, what's the easiest way to get the lock off?

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.

10.4 I could use some information about CV joints (failure mode, replacing, etc.)

Ed Gibbs has written a nice little FAQ on CV joints on 944’s. The most recent version can be found right here.

10.5 I'd like to improve the handling of my car and am considering larger torsion bars. What size is right?

Jim Pasha has written up a note on this topic.

10.6 How do I change my rear torsion bars?

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.

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