Please check your steel A-arms asap!

[Tim Comeau]

We cracked both of mine! Not the ball joint, but inboard of that on the forward end on the A-arm (control arm).

Tom Spargo lent me one of his spares and Dwain Dement from Vision had one of his guys (Nick) weld up the second.

Please check yours out. Mine had some oil and dirt covering up the crack.

Remember, these can be reinforced legally because it's a safety thing, and not for performance.

[Tom #16]

I also had a big crack in the passenger side A-arm. After looking at it and were and how it started, it looked like it was probably caused by an off or hitting something pretty hard with that wheel.

 

Luckily I was able to go home and weld mine up so I could run on Sunday

[Spec-944#70]

That's why mine were welded even before it was leagal!!

[PeanutinCA]

Probably helps if you keep the car on the track then huh?

 

P.D.

[Tim Comeau]

Yep, Dilly. My bad. Probably "flew" the car over one too many curbs at Buttonwillow? .......

[944-Spec#94]

Well it much better to keep a spare set on the truck. I have spare set just for that reason. They are like $50 for a pair new from paragon products.

 

Note.. These will crack over time and old stock ones are probably cracked. Now the nice thing is that these don't fail and put you in the wall. Just inspect and replace. The nature of steel is that it more damage tolerant than aluminum. Alumium will crack and split in two. The steel will just crack and take some time before it fully fails.

[Tim Comeau]

Agreed. I'll modify the new set with welds along the sides and a "wrap" around the inner bearing seat. Then, I'm gonna get some damn spokes to support the inside rim of my late offset wheels!

[Danno]

"We cracked both of mine! Not the ball joint, but inboard of that on the forward end on the A-arm (control arm). "

 

This is most likely caused by braking forces and also due to the stress-risers caused by the 3-bolt attachment scheme. How about converting the end of the A-arm to accept round 911-type ball-joints that are held from below with a large ring-type nut? Spreads out the forces over a larger surface and you can put thicker metal plate to hold the ball-joint.

 

Would this be legal???

[Tim Comeau]

Not sure I follow you, Danno. I said it WASN'T the ball joint. It was the other end of the A-arm, inboard. The part that has the cylinder-shaped bearing and goes into the cross member.

[Danno]

Sorry, there's two different things going on here. Yeah the inboard spot where it meets the sleeve for the bushing would be the highest stressed point on the arm due to the leverage and concentration of torque and stress there.

[Autosport944]

Guys,

 

The number one cause of stress on the early A-arms is the weltmeister sway bar. Once you drill through the center of the A-Arm to mount the sway bar, you have created not only a weak point, but a place where the force of the sway bar is to push down when the outside of the arm at the wheel is pushing up. Eventually, it will break. Mine broke in turn 8 at willow doing over 100. Fortunately, Rick White was driving the car and was able to gather it up without destroying the car. From that day forward, we weld every Steel A-arm before it leaves our shop.

 

Don't delay... do it. It is easy to do. Any local welding shop can do it for you if you need and it will cost around $100 for both arms.

 

Glen Uslan

[944-Spec#94]

I still think it is very important to visually chech the steel arms often.

 

The nature of steel is that it is damage tolerant. It can crack long before it breaks. This means if you visually inspect for cracks often you can find it long before you have one fail at the track.

 

Aluminum is nowhere near as forgiving a material.

 

 

Now as I said most orginal arms a weak and prone to cracking or have cracked. New steels should last a long time. They are cheap new since they are really VW rabbit parts ($50 for two new ones). So you can easily keep a spare set in your parts bin. If you want you could predrill for the weltmeister sway bar. Then have them ready for change. Inspect each day. If you fine them bad, just change then in 15 min. You can do it without need for aligment afterward.

 

Note on welt bars. I honestly don't think the welt bars are that bad with the steel arms. Sure you drill, but if you run enough spring with them you are probably fine. We run light cars vs stock, we also run stiff springs and moderatly stick tires. Combine that all together and you get less load that a guy running stock weight, stock front srings, and hoosiers with his welt bar. That guy is MUCH more prone to failure at the welt mounting that we are.

 

PS.. Few things from an Engineering stand point. The load point of the welt bar is not that far from the stock load point from the stock sway bar. This means little change in loading on the stock arm. The hole is drilled through the center section. This part carries little loading. This black plastic bushings carry the load to the outsides of the arm where it is supposed to go. Note there already is a large hole in the arms. What really causes the welt bar to damage steel arms is not the hole or the mounting point. It simply is the stiffness of the bar. The bar is VERY stiff and puts much MORE load than a thin stock bar. If you use soft front springs you really put alot of load on the arm as most of the reaction to cornering loads are put through the sway bar vs the spring. This causes the arm to flex a bit then over time can fail. If you run a much stiffer spring then the less load goes through the sway bar as compared to the spring then you get a better balance between the two. Therefore less load goes through the arm. The arm then lasts much much longer.

[Tim Comeau]

Good points. Thanks for contributing AutoSports' experience, Glen.

I made a habit of scanning the entire wheel well every time I changed a tire/wheel, but the cracking evidence was covered with dirt and oil/power steering fluid.

A clean car is a happy car. I plan on paint marking all my suspension hardware for quicker visual checking, too.

I believe, along with Joe, that I will be fine with new control arms and frequent checking. At the same time, welding them is an added insurance policy. I'm sure the ones that cracked (but didn't break) were original.

[Chuck T.]

any pictures of before and after ?

 

thanks

chuck

digging up the past.

[Tim Comeau]

There is some good tech info on this forum, huh? Newer guys can benefit greatly from "digging up the past."

 

I'll put it on my list, Chuck!

I'll try to shoot pics today, post them to photobucket, then post a link here.

At your service,

[Tim Comeau]

Here's some pics of how I do things. The edges were not box welded because we only run a medium sticky 225 tire on a 2400 lb car.

Note the hole pre-drilled for the sway bars. The hardware on the ball joints is painted top and bottom for quick visual check of tightness whether the car is on the ground or in the air. The ball joints can be reversed for using the control arm on the other side of the car, can't do that with alum. arms.

This spare arm has been fitted and is ready to install quickly with Welt. red bushings at the rear (caster block) and Delrin white bushings in the front (cross member).

 

 

 

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[944-Spec#94]

The potential failure point is in the tight areas near the white delrin bushing.

[Tim Comeau]

That's where both of my failures occured. Just blast that area clean with brake cleaner and keep an eye on it, top and bottom. My "new" 944 spec cars automatically get new control arms. I swap the aluminum control arms out and replace them with new steel ones.

Anyone need some nice 85.5-86 aluminum control arms?

[Chuck T.]

ok... so on a 88 you would replace the alum arms with steel ones of the same length ? and those are for sale at paragon .... or are you using a steel a arm from a 83-85 car and swapping rims?

thanks for the pics.

chuck

more questions coming.

[Zvoiture]

Tim, do you sleeve that hole?

[944-Spec#94]

ok... so on a 88 you would replace the alum arms with steel ones of the same length ? and those are for sale at paragon .... or are you using a steel a arm from a 83-85 car and swapping rims?

thanks for the pics.

chuck

more questions coming.

 

On the 87 and 88 944 (not 924S) the aluminum arms are longer that on the 83-86 cars. Thus it is not a clean swap. If you swap arms you will need to make some other changes to make things work. This may include wheels or maybe spacers to run late offset wheels on early offset front end and keeping the late offset rear. Now this probably will require all new hubs and spindes from and early car as well as early offset tie rods.

 

So the swap is much more involved and probably not worth it. Ball joints can be replaced on the aluminum arms, athough not as easily.

[Zvoiture]

(one full set of '87 Aluminum still available here. Front and rear)

[Tim Comeau]

Steve,

Thanks for jumping in with the parts offer. Good man.

If you mean the sway bar hole, no, there's no sleeve.

 

Chuck,

If you have the 87-88 suspension on the car, I'd leave it alone. Make sure the ball joints are good.

The ABS offset cars 87-88 have different stuff and if I were doing it, I would swap out the entire front suspension. As Joe said, the steering knuckles (spindles), tie rods (longer), wheel bearings(larger-from the 928S), struts, bigger top bearings, are all different. The caster block bracket must match the type of control arm. These year cars also have very offset wheels (phonies), which are weak on the inside because all the support of the wheel center is on the very outside.

These are some of the reasons I chose to build spec cars from 1985.5-86 chassis only.