RedlineMan

Hey all;

Bill Seifert asked this question in another thread, and rather than hijack it, I started it anew here. I'm sure there is a lot of this in the archive, but maybe we'll get some new thoughts here.

First, a discussion of "failure modes"

Steel Arm -

They can bend at the sway bar mount location. The can also come apart at the inner front bushing area. Neither of these is very common.

Pros - They are light, cheap, and easily serviceable. Ball joints are cheap, rugged, and easily replaced. If you biff something and/or they fail, you usually will still have four wheels on the car.

Cons - They do not work for 87+ ABS offset cars (1" too short).

Alloy Arm -

They can fail in two main ways. 1) ball joints wear and pull out. 2) Snap at sway bar mount.

Pros - None that I can think of, except maybe that they are getting cheap to "rebuild." They are a STUPID idea - an answer to a question no one asked - in my less than humble opinion! You are stuck with them with 87+ cars.

Cons - See above. Expensive.

Other related problems with the ball joint are - 1) If the car is lowered excessively, the free travel of the joint can be exceeded. It will then bind against the socket, and eventually snap off. 2) If the knuckle pinch bolt is left loose, or the ID of the hole the ball joint shaft fits into in the knuckle is allowed to egg shape, the ball joint shaft can snap off at the keyway.

It is recommended that these arms be reinforced by welding rod or tube down the front and rear "channels formed by the two stamped pieces of the arm.

Probably as million other things I can't remember right now. I've driven my reinforced steel arms many hard miles with no problems. If you have the choice, go STEEL. If you don't, inspect your alloy arms OFTEN!!!!!

ninefiveone

John - I've been meaning to reply to the very nice email you sent me about the other thread (your rollbar design) but lost your email address. Thanks and funny you should be talking about a-arms.

I've been considering Blaszak's arms for my early offset '86. What are your thoughts?

eclou

Very happy with my Blaszak arms. Since I am not of the Hilton or Trump families, the $1500+ for alloy arms (which is 50% of the purchase price of my 951) seems ludicrous. I had Marcus Blaszak fabricate me two nice units (ltw, high quality) that fit perfectly and allow for generous caster adjustment thru usage of the 924S caster blocks. A national PCA steward tech'ed my car and said they were similar to the original Fabcar arms.

RedlineMan

Hey Hugh;

I would go with the steel VW arms. $35ea. Last I knew. Ball joints are $20-ish. The only thing I don't know of is bushings. Not sure whether the OE rubber ones are available (again), or if there are any delrins with steel sleeves. Let's check on those.

Anybody know about bushings out there??

I'd be glad to reinforce a set of Rabbit arms for you.

In fact, I have had the control arm project in my head for years. I actually have one built and ready to go. I just have not found the time to build the other side!!!

So many projects!!!!

Look Ma... No FLoor (That's a Pun!)

M758

Steel arms are pretty good.

I run these on my 944-spec car. I did notice that the stock ones were cracking at the mount to the crossmember. This was in a tight corner area. The crack was small and no failure resulted. Normally that would be a severe issue, but since the arms are so cheap I just replaced them. I doubt they will have catastrophic failure so I am not worried. I can get a spare arm from paragon for $25 (minus caster block). Thow in the $11 bal joints and you are good to go.

For that price I can keep spares in the truck just in case. Replacing them is not hard either.

Now... bushings are another issue.

The stock rubber crossmember mount sucks for track use. The arm merely slides off and contacts the crossmember. Not good. I used weltmeister black poly bushings until one failed pretty badly. Note these are no longer made as they really too brittle for the application. Weltmeister switched to red colored bushings that were a bit more plyable and not prone to cracking. I also destroyed this set due to braking loads. Essentially they were no better than stock rubber since their outer ring failed and the control arm slid back and hit the crossmember again.


After this I contacted paragon and they were able to have Karl at racer's edge whip up some delrin bushings for the crossmember mount. (class rules prevent me from using metal only) I have since used these will no issues at all. Unfortuantly they have not be able to work up and caster blocks since the tolerances are so all over the place it was hard to get a good fit. I have been using the weltmeister red caster blocks. These seem to be holding up to the stresses of racing just fine.

BTW... My arms are unmodified. They are not stiffended in anyway. While I do run a large sway bar, 28mm weltmeister, I also run stiff 350 lbs-in springs. I think most guys who have had issues run stock 140lbs-in springs and big sway bars.

Best reason to have steel arms....
I was out at willow springs in July and made a driving error in Turn 9 during qualfying. Turn 9 is 90-100 mph decreasing radius turn. The car got loose. I corrected and promptly went of track straight at about 95 or so. I got on brakes, but cars don't stop so good in the dirt and proceeded to run up into a birm about 150 yards off track. The running up birm tore-up my front spoiler and bent my left front tie rod and the control arm. I got towed back to the pits and since my friend Paul had a spare set of arms (note left & right are the same) I quickly swapped out the bent arm, banged the tie-rod back straight, quickie alignment and proceeded to win the race that day from pole. From then on I have carried spare arms just in case. That would have been a very costly day with aluminium arms.


FWIW... I believe the aluminium arms are "stiffer" than the stock steel so there is a slight performance advantage from them.

M758

I believe you can put steel arms on 87 and later cars, but also need to replace the front spindles and possibly rotor to the pre-abs setup. You would also have an issue with wheels since this changes the offset.

This could be addressed by wheel change or spacer that I don't really care for.

It is certaily not impossible on 87 and later, but just a bit more difficult.

Al P.

Hmmm... early arms on a late car

you would need to replace the arms, caster blocks, spindles, struts, deal with the brakes and then either use a one inch spacer or an early off-set wheel to get the rim centerline where it belongs.

Looks like the advantage of the inexpensive steel arm is out-weighed by the shear cost of the project. Putting steel arms on an 86 turbo makes sense but not an 87.

a4944

Are stock steel arms safe for an aggressivly driven 1986 944 Turbo on track for DEs? I went with the SSI ball joint kit for aluminum control arms this time, both ball joints were shot. I would like to go steel next time, especially if they don't need to be reinforced. Quick ball joint replacement and keeping an inexpensive spare is appealing. I was under the assumption that the steel needed reinforcement which would add expense.

Thanks,
Mark

NicolasW

You can see my limited survey results of front control arms from back in '99 at http://wes.nicolas.org/controlarm.html

I did DE events for 3 years without any problems but used stock sway bars. I did however use 255/40-17 Kuhmo track tires and the car was lowered.

If you do any track events, I suggest the Fabcar arms...however I have seen Fabcar pins break at the track. Luckily the car was only going about 90 MPH and only had front fender damage.

Good luck,
Wes

ninefiveone

M758 - Great info on bushings! After the a-arm...that was my next concern. So let me see if I can sum this up correctlly. Delrin for the a-arm bushings, red poly for the caster bushing, and steel a-arms. Maybe VW arms.

I definitely prefer steel's failure mode over aluminum's. In the last couple years at DE's I've begun to corner hard enough to drag rocker panels. Both rocker panels if I'm carrying a passenger in some corners. Plus I'm getting a clunk in the suspension under full cornering loads that I suspect is a ball joint getting bound up or a bushing going bad. Bushings look ok but I haven't dissasembled anything to confirm, yet.

Long story short, I've been thinking about suspension for the last year and a-arms/bushings were high on the list, followed by a more serious set of struts/springs/shocks.

I'll check with paragon on those bushings M758 mentioned and drop John a line about those a-arms and Leda.

howie

I have always been under the impression that it was the ultra thick sway bars on otherwise stock susp. that was the culprit. ie opposing forces on the A-arms. For that reason I run higher rate springs and stock swaybars.
John, what exactly do you look for when inspecting stock arms??

Jon Moeller

Nicolas,
That's an excellent survey, but I wish that the failure mode was also included. Do you know if most of the failures consisted of ball/socket failure, or were they related to swaybars?

ninefiveone,
I would seriously recommend that you have your arms looked at and replaced or rebuilt, if you're running your car on the track. Sounds like you're begging for an expensive failure, IMHO.

-Jon

Bill L Seifert

Thanks John, and Eclou

Eclou, can that Marcus Blaszak make some for a late offset car? If so, what is his phone number? John has me scared to death about the alloy arms, so I am going to do something else. I do have a 1987 924S parts car, and I may take the whold suspension out of it and put into the 944S, and use early offset wheels, of which I have a bunch.

After looking at the picture of what I figure is Weltmeister bushings that had shredded, I will tell you about bushings. I had the same problem, so I took an aircraft bearing (I can't remember the size, but I can take it out sometime and let you know.) that fit in the steel a arm, and had a piece of strap steel bent into a circle to hold the bushing in. One on each side. Then used a half inch bolt to take the place of the mm bolt that goes through the old bushing and the crossmember. You have to drill it out slightly, but the nut is 3/4 so the 19 mm wrench you used to remove it will put it back. On the trailing part of the arm the Weltmeister bushing works ok. There is no play or squeek, and when you reinforce the arm itself, it is really strong. I replace the ball joint every year, so I have had no problems yet. I know that sounds confusing, so if you are interested, call me at 615-746-3709 and I will try to explain it better, and even send you a picture, the next time I take it apart.

Thanks a bunch for the info guys,

Bill Seifert

1983 944 Race Car
1987 944S Race Car under const.

M758

Bill,
The simplest thing for you is to swap to the 924S suspension front and rear. With 83 race car I'd be you have plenty of early offset wheels to run. Plus you could run the fuchs wheels cleanly.

Now I don't know if this is kosher per SCCA rules. It should be a ok on a an 87 or 88 944 as it is clearly updating/backdating, but since steel arms and early offset never came on the 944S I am not sure how the SCCA would look at it. My guess is you would be fine unless some yahoo protests and then??????

Al P.

Ahh, the obligatory 924S parts car. That certainly makes things simpler. A complete suspension swap gives you the steel front arms and the aluminum trailing arms, couple that with early off-set rims and you're good. PCA specificaly states that you can replace the aluminum arms with steel or aftermarket but doesn't mention off-sets. As M758 said you're good as long as no one protests. One small thing you will wind up with a hollow left spindle aas opposed to a solid (speedo cable).