The following note was created by Michael Kehr. It applies to 85/2-forward 944-series cars.
The purpose of this procedure is to supply basic but complete information for the removal and installation of aluminum 944 control arms installed on 1985/2 and newer 944-series cars. The procedure is intended for the amateur/novice home mechanic with a basic set of metric tools.
For the 1985/2 model year, the 944-series front control arms were changed from a steel design to a light alloy aluminum design. The rubber bushing/bearing mount was redesigned and the caster eccentric modified.
Prior to the 1985/2 model year, steel control arms were used in the 944. This note does not cover replacement of steel arms.
All 944-series control arms have a larg ball joint that connects the outboard end of the arm to the steering knuckle. Over time, this ball joint can develop free-play that indicates wear and possibly damage inside the joint. The shaft or "stud" at the top of the ball can also fatigue and fracture, particularly in high mileage cars, and cars that see a lot of stress at the race track.
On the earlier steel arm, the ball joint is available separately as a service/repair part, and can be replaced in the arm, as is the case with 911's. With the later aluminum control arm, the ball joint is not available as a separate part. The "cup" of the ball joint is the control arm itself. The complete arm must be replaced, or it can be sent out and rebuilt (not authorized by Porsche). One of the rebuilders offers a three year warranty. Call and ask about their rebuilding techniques, not all do it the same and quality varies. These rebuilt arms are not recommended for serious racing. I would buy a new unit, or get the steel Fabcar arms with the replaceable ball joint and high quality bushings.
In the past few years, Porsche Cars North America (PCNA) has lowered the price of their control arms to compete in the rebuilding market. The difference in cost between a rebuilt unit and a new one is not all that great, so shop around to get the best price. Keep in mind that the new part carries a warranty backed up by Porsche.
When purchasing the arm, make sure that you have the right part number for the model and year of your car. Part numbers change over time as supersessions and improved versions of parts become available. There is a list below, but double-check with your favorite Porsche dealership's parts department to confirm the correct current part number for your Porsche.
There is a rubber boot that encloses the joint; inspect the boot for cracks or other damage. Another sign is clunking in the left or right front suspension; it starts off very subtle but will get worse as time goes on. I damaged my left ball joint when I hit a pot hole, it hit real hard!
You can also check for free-play in the ball joint. Use a large pair of pipe wrench pliers (commonly called "channel lock pliers"). Put the upper jaw on the steering knuckle tab into which the ball stud is inserted. Put the lower jaw of the pliers on the underside of the control arm. Compress the pliers. If you see more than roughly a millimeter of play, the ball joint requires replacement. (Many manufacturers publish specifications for allowed play in ball joints. Unfortunately Porsche does not.)
You cannot measure fatigue or damage to the ball joint stud. It would be possible to check it using a dye penetrant test, but this is beyond most shade tree mechanics' abilities. The only realistic approach to this problem is probably automatic replacement as some service interval, perhaps 100,000 miles for street-only cars, 50,000 miles for track cars.
It is not strictly necessary. If you have the funds it would probably be a good idea, since the other arm is likely to be of the same age and not far behind the first in needing replacement. Moreover, replacing either arm required realignment, and so doing both at once can help you avoid a second trip to get the car aligned.
Prior to removing parts, apply penatrant to all fasteners, let chemical soak, repeat. Rost Off by Wurth or PB works great. Make sure that you have all required parts that are needed for the job before you start.
About 2.5 hours, without any major problems.
As covered above, there have been a number of versions of the aluminum control arm. Check with your Porsche dealership parts department for the latest and correct part numbers for your particular model. At the time of writing, the FAQ maintainer's best understanding of the correct part numbers is as follows:
944, 944 Turbo, model years 85/2 through 86
- track control arm, left 951.341.027.00
- track control arm, right 951.341.028.00
944-series cars, model years 87-forward
- track control arm, left 951.341.027.02
- track control arm, right 951.341.028.02
944-series cars, model years 87-forward, with M030 or M758 options
This covers both cars with the "sports chassis" competition package (M030), the model year '88 944 Turbo S (M758), and all 944 Turbo cars from model year '89-forward.
- track control arm, left 951.341.027.31
- track control arm, right 951.341.028.31
These parts differ from the above only in the stiffness of the front bushing pressed into the arm. For this reason, they may be used to upgrade the suspension on cars not delivered from the factory with options M030 or M758.
Updated M030, M758 Arms
The following parts are reportedly available as supersessions to the M030, M758 parts listed above.
- track control arm, left 944.341.927.31
- track control arm, right 944.341.928.31
Common hard parts
- lock nut, M12 x 1.5 mm, N.021.131.1, control arm to cross member
- lock nut, VM12 x 1.5 mm, N.022.141.4, 2 required, caster eccentric
- spring washer, A13, 900.025.009.02, 2 required
- lock nut, M10, N.900.876.01, sway bar bushing assembly
- lock nuts M8, N.022.146.4, 2 required, sway bar clamp
The two VM12 x 1.5 lock nuts (N.022.141.4) on the caster eccentric (rubber mount at rear of the control arm) supersede the original use of two M12 x 1.5 lock nuts (N.021.131.1) in this application. The torque value for them has been increased accordingly, noted below.
|Dynamic European Technologies Inc.||$149.00||+1.713.661.2780|
All of the prices are US$, and are with exhange of your old control arm.
|Fabcar racing control arm||OG Racing||+1.800.934.9112|
|original equipment||PCNA dealer||$355.00||+1.800.PORSCHE|
Look for dealer discounts of 10% - 25%.
|If you are not replacing the rear bushing mount assembly it is only necessary to remove the front most nut/washer of the rear part of the control arm. You can then transfer this assembly to the new control arm without moving the eccentric bolt position, relative to the bushing/bearing mount.|
|If you are removing the rear bushing mount from the eccentric bolt, make sure the eccentric bolt center is marked in relation to the rear of the arm! You will transfer this mark to the new arm. Remove both nuts from eccentric and mount, remove from arm.|
I know I am making a big deal concerning the eccentric and it seems confusing, but it will all come together when you actually see how it works.
All lock nuts must be replaced. The lock nuts are not reusable! Use anti-seize on the bolts, thus preventing future problems with stuck nuts.
|Control arm to cross member, lock nut||M12 x 1.5 mm||48 ftlb, 65 Nm|
|Control arm bearing assembly (caster eccentric) to body, bolt||M10||34 ftlb, 46 Nm|
|Control arm bearing to control arm, lock nut||VM12 x 1.5||74 ftlb, 100 Nm|
|Clamp for stabilizer (sway bar), lock nut||M8||17 ftlb, 23 Nm|
|Stabilizer linkage to control arm, lock nut||M10||18 ftlb, 24 Nm|
|Control arm ball joint to steering knuckle, lock nut||M10||37 ftlb, 50 Nm|
|Light alloy wheel to hub, lug nut||M14||96 ftlb, 130 Nm|
Note that the torque spec for the control arm bearing assembly to the control arm is for the updated VM12 x 1.5 lock nuts. The older style M12 x 1.5 lock nuts were torqued to 63 ftlb, 85 Nm.
If you have any questions/corrections/suggestions please feel
free to contact me, Mike Kehr
home phone: +1.609.645.8167