IPSC

Ok the topic is 944 control arm rebuilds. Yes I did a search and...

I have heard of ONE 17mm pin failing on a rebuilt arm.

Has anyone ever had the 19 mm Geometry Correcting Kit pins or rebuild fail?

IPSC

Larry Herman

Did you mean our failure, or do we make #2? BTW I have seen a 19mm extended pin for the Charlie arms fail. It broke just below where it enters the control arm. This was on a racecar. It just seems to me that the farther you move the point of attachment from the ball joint (i.e. the longer the pin), the more leverage you get, and the more these pins fail.

IPSC

Howdy

In all my searching yours was the one reference I could find about a pin breaking.

I did find another that bent all to hell in a front end collision but the pin did not break.

IPSC

Mahler9th

Back in the day, the Fabcar arms were the only aftermarket choice available. PMNA also had some motorsports arms with a different ball joint. I saw shelves full of these parts when I visited Kelly Moss Racing back in 1994.

back in the 90's, I had low mileage 944 Turbo S arms on my car for the first few years. As the car developed I decided to have them rebuilt by a reputable parts business. At the time there were only a few choices: Fabcar, new factory, or rebuild from two different places. One of the rebuild places was priced at about 2x the other. Even though my arms were fine, I decided on the more expensive rebuild path. Right after I got them back, I sheered through a pin in an AX event. Did very modest damage to car and wheel. I contacted the rebuilder due to concerns about others having similar issues, and they responded by sending me out a fresh set of rebuilt 944 turbo S arms. After I got them, I had a failure at my very next event... on the track. The ball on the left arm pulled out. Still have the parts. A total of 2-3 weeks went by between the failures. The second failure resulted in quite a bit of damage.

During the 2-3 week period, a good friend with a similar car sheered through a pin under braking in the corkscrew at Laguna Seca. He was carrying a passenger-- another 944 turbo driver. Modest damage. The arms were Fabcars. Since he bought them used it wasn't possible for him to confirm the lineage of the pins. Seems that there were some knock-offs around.

My friend with the Fabcars is a lawyer, and instructor, and he rode with me on the track in the session before I had my failure. He was my lawyer and we had to do some "negotiating" with the rebuilder, but eventually the paid for part of the damage to my car. By that time, I had discovered that Jon Millege was working with Charlie Spira and others, and placed an order for their new arms. They weren't quite ready so I bought a new set of Fabcars from Dave Klym in the interim. I used them for a couple of events and then sold them with Charlie's became available. I bought one of the first customer sets from Millege. After about 20 hours, I sent the pins back to Charlie for analysis, and they were perfect.

That was all long ago. Now there are lots of choices/solutions. If I still had a 944-based car, I would likely stick with Charlie's product (if still available). If one/some of his pins sheered, hopefully people have made him aware of the situation.

With these types of parts, I tend to stick with folks with strong professional racing backgrounds.

By the way IPSC, I have a bunch of Guards Red magnetic number panels with the "951" number on them if you want them. Free if you pay the shipping. I am in NorCal.

RedlineMan

Hey;

The OE alloy arms can fail in so many ways. That's why I'd NEVER have them on my car, used, new or rebuilt. No way.

One thing you have to watch for is the spindle itself, specifically the pin clamp. You need to make absolutely sure the bore of that clamp is nice and cylindrical. If it is not, it can alloy the pin to rock back and forth, eventually causing the pin to fail at the bolt "keyway."

This is only one of the failure modes for these blasted arms, which - since the steel early arms were so reliable - were a bad answer to a question nobody asked.

What kind of sway bars are you using, IPSC?

kasturbo

I ran the Rennbay rebuilt arms with longer 17mm pins for two DE seasons. I would still be running them if someone didn't hit me. This picture alone shows that they are strong. I think most failures that people see are in the aluminum arm around the joint and not the pin itself.

Travis at Rennbay is very particular about what arms he will rebuild and which one's he won't. He wouldn't rebuild one of my friends because it was out of spec. Best of my knowledge he hasn't had any of his arms or pins fail yet.

Larry Herman

Kevin, our Rennbay pin failed. It broke at the groove machined into the top of the pin, and it dropped out of the spindle. Now you know of one.

Weston Dillard

If you are talking 17mm, make it 2 failures.

West

Travis - sflraver

You should always check and torque your pinch bolts especially when running longer pins. The pin should be secured by the pinch well below the groove. If the pins are secured correctly in the pinch, even under a sudden impact, they will bend a great deal before completely failing.
If memory serves, both instances listed here broke at the groove, above the bottom of the spindle's pinch.
Our 19mm versions are also available for those who want the added support of a larger pin.

gjoey66

I've been running the 19mm pins for a year...no problems yet but it's only been a year...we'll see after a few more races at TWS which was were i originally sheared my pin.

Techno Duck

Was running 17mm geometry correction pins on my n/a. Two seasons (about 20) autocrosses in some very crappy lots and about 8-10 of those runs with v710's. Never had any problems. Though i did have an encounter with a curb which tweaked a pin slightly. Drove it like that for a couple of auto-x's before i realized it and replaced it.

When the time comes, i will probably be going with the Racer's Edge arms on my 951 to replace the brand new 968 control arms. Mainly because i understand the pitfalls of the alloy arms in general. Charlie Arm's are worth there weight in gold and getting severely hard to come by, otherwise those would be my first choice.

The only thing that really makes me nervous about the 19mm pins is machining out the spindle pinch. Granted i have no empirical data to back this up, but i just feel like your machining 3mm out of an already small amount of material. I dont think i have ever read of a failure regarding the actual pinch though.

Larry Herman

Thanks for the advise. We did torque the pinch bolt to spec. It failed after day 3 on the track. Inspection of the spindle showed no elongation or deformation. Maybe we were just unlucky, but I have seen enough failures of every type of pin arrangement that I know that there are some extreme loads on an extended pin. Like I said, I have even seen a 19mm Charlie Arm pin fail at Road Atlanta last year. I'd rather run a short pin with less than optimal geometry.

IPSC

So no one has had a 19mm pin fail?

IPSC