tinman944

I think You are right, the aluminum arms fail at the ball joint.

TD in DC

No, you are correct. The car drove absolutely fine. However, the steering wheel pointed a little to the right (without pulling at all). I pitted in and put the car up on jacks. Three guys did not see what was causing the problem. Obviously we did not see it. Next time I will know "another" place to look.

M758

In my first 944 spec race I had a control arm bushing blow out. It was the black weltmeister that goes into the control arm where your broke. Anyway I ran the racing and after one tight right I would have to wiggle the steering to get the car to run straight. Everything seemed fine after that and I was in the lead so I just kept running that way for 25 laps or so. (1:10-1:11 laps).
After the race I noticed the nearlly missing bushing. Dodged a bullet on that one, and was able to replace it for sunday's race.

I find it realy interesting how crappy a car you can drive if you blindly thing "everything is fine" then you realize why the car was "off" and you are scrared like hell to drive it any more.

TD in DC

At my next track event, I was getting my check out ride for the club race. I felt like something was off, so I explained to the evaluator that I was going to slow down and pit in immediately. Despite explaining my intentions, he told me that I "may" be too slow for club racing.

I put the car up on stands, and again could not find anything (apart from it looking like one side of the car had more camber than the other). I was so frustrated by the "too slow" comment that I forced myself to go out again, with the same evaluator, and then got warned not to be too aggressive

I did get my sign off though. Good thing that happened or my paranoia might have led me to put the car up on the trailer and go home.

There has to be a balance, but yes, I take the safety issue very seriously.

M758

That is one advantage to doing all the wrenching yourself on the car. If something feels wrong you know where to look and how to fix it.

RedlineMan

Alloy Arms -

The alloy arms will rarely fail in any way but catastophically. They fail in three main ways;

A) The ball joint pulls out of the socket. This can be from either excessive wear in the joint, or from a car lowered so far that the axial travel limit of the socket is exceeded and the pin binds against the socket. If this situation persists, the wear of the socket is accelerated and the ball eventually pops out. THIS CAN BE FOUND VISUALLY/PHYSICALLY IF YOU INSPECT THEM OFTEN.

B) The top of the pin snaps at the keyway. This is generally from a spindle clamp that has been left loose, allowing the hole to become ovalized internally. The pin will rock back and forth and snap at the bolt recess. THIS CAN BE FOUND VISUALLY/PHYSICALLY IF YOU INSPECT THEM OFTEN.

C) The arm snaps at the sway bar mount area. This is generally thought to happen on cars with heavy sway bars and soft springs. The soft springs allow excessive body roll, and the over active bar pulls excessively on the alloy arm, eventually snapping it due to fatigue. THIS USUALLY DOES NOT PRESENT ITSELF VISUALLY OR PHYSICALLY. IF YOU'RE REALLY LUCKY, YOU MIGHT SEE A CRACK.

THESE ARE ALL CATASTROPHIC FAILURES.

The steel arms usually only fail catastrophically in the way Todd's did. Otherwise, they usually just bend. Nice still having 4 wheels on the car, even if all of them don't quite point in the same direction. You genrally can get lots of warning that a steel arm is going to fail, but you have to look for it specifically.

kevincnc

Hi guys,
Sorry to dig up an old thread. I am welding up the control arms for a 944 spec car that a few of us are putting together. From eraly in this thread-

So is this an acceptable way to reinforce that barrel? If not, where can I get the factory procedure for reinforcing them?



TIA for any input.

RedlineMan

Hey;

As long as it looks the same on the other side, that's just fine, Kevin. As Todd's pic shows, they fatigue right after the weld. Strapping over it solves that. Here's another example. The green arrow points to the vulnerable area, boxed in solid.

930man

td i think you need to upgrade to 911

A.Wayne

Or downgrade , depending on the class

930man

lol A. wayne!!!

M758

Kevin,
That looks really good.

kurt M

It looks like you have not reinforced the barrel itself only welded to it. If so this method still relies 100% on the stock barrel which is a known weak point. I would recomend that the barrel be wrapped with another layer of metal that tabs well into the boxed area and spreads out the loading. IMO from looking at it the day in hand the day it failed Todd's failure was a mix of some cold welds at unfortunate locations, perhaps some impact related stress risers and perhaps some bushing binding that stressed the welds between the barrel and arm root. I think the barrel needs to be wraped as it is not thick or high strenght metal. Welding heat during original production and during boxing does not help.


BTW Please, for god's sake stop grinding stressed and critical welds.

kevincnc

Thanks for the input guys. I agree that it needs to be wrapped fully to prevent the failure that started this thread. Here's how mine came out (please no comments about my lack of welding skill- the picture makes the weld look worse than they are.) It looks like it would have been better to extend the side reinforcements all the way to the barrel. Maybe I'll do that on the other side.