Early 944 models ('83-85) and the 924S models experience control arm failure. The steel arms in these cars experience metal fatigue in the swaybar mounting area which results in cracking and ultimate failure through the mount area. This is more prominent in cars with larger swaybars and vehicles that have had the control arms drilled for the Weltmeister swaybar. The solution is to reinforce the arms as well as provide better swaybar mounting. The DE/Race solution of this problem can be seen at the right (Fig.1) . This arm has the optional 968 brake cooling scoop added as well as Racers Edge spherical bearings. The arm is also available in a Street/DE format with rubber bushings and no scoop. This arm also fits the early offset 85.5 and '86 models with the 23mm offset.
Late model cars ('87-) have a different offset (53mm) and require a longer control arm. These cars use the aluminum control arm that is longer than the aluminum arm used on the 85.5-87 cars. Failure mode of the aluminum arm cars is basically two fold. The catastrophic failure as pictured above occurs when the ball joint is literally ripped out of the top of the aluminum arm. This failure does however have a warning sign if you know how to check for it. The photo to the right of the arm shows a cracked or broken plastic socket that the joint rides in. When this socket cracks, additional movement is experienced by the joint. This ultimately progresses to the point where the ball will wear the aluminum arm and eventually pull out the top of the arm. When this happens during driving, the results are usually serious. If you have any appreciable play in your balljoints, please have a professional look at them and assess their condition.
The second common mode of failue is from the joint pin snapping off in the spindle. This failure is more commonly seen in lowered cars. As the car is lowered, the joint approaches it's limit of travel [see joint binding closeup]. It is similar to the suspension bottoming out. Couple to that the change in attitude due to caster angle and we have a potentially dangerous situation. Now under cornering, the spindle tips the joint even more to it's limit. When a bump such as curbing is encountered with the preceding conditions, the joint shaft actually binds in the opening of the arm at either the 1, 5, 7, or 11 o'clock positions[see image] (depending on the side of car and direction of turn). This stresses the pin and starts to bend it or fracture it. If you remove the boot of your joint, you can tell if this has occurred on your car. If so, it is time to have the joint replaced or replace the entire arm. I will provide photo examples in the near future. Ensure that your spindle pinch bolt is torqued to spec. and is replaced with a new Grade 10.9 bolt or better EACH time it is removed. If this bolt is not tight, the pin will shear.
To solve the problem of joint failure for late offset cars, we have developed a modified version of the early offset arm for Street and DE use for those that are on a strict budget but yet still want an upgraded option. This arm has the required late offset but still uses the stock rubber front bushing and either an early caster block design, or a Delrin insert billet block. (Fig.2)
For those that are demanding the best in both performance, safety and value, we are now proud to offer the Blaszak Spherical Race Arm. This arm is manufactured from tubular steel and utilizes MIL Spec. teflon lined spherical bearings at both the frame mount location and the caster block location as STANDARD features! In addition to that, the balljoint is a simple user bolt-on item that can be changed in 5 minutes without effecting alignment! (Fig.3) (Fig.4). This arm is rapidly becoming the control arm of choice on both the DE circuit and the Race Circuit. Performance is crisp and precise lap after lap allowing you to maximize performance and minimize lap times. Our arms include standard features not even available as options on other brands of arms at any price, and all for a price less than the competition.
Contact us for pricing and options to suit your current needs. [Markus(at)BlaszakPrecision.com] Please insert "@" in the email header before hitting send.
