Early steel control arm as a mechanical fuse
02-26-2013, 10:27 PM
#1
Three Wheelin'
Thread Starter
Early steel control arm as a mechanical fuse
I have been running early steel control arms on my '86 951 for almost 2 seasons now, as I broke a factory aluminum arm at Laguna Seca in the past.
I have had no issues until this past weekend when I hit a large "pothole" or missing chunk of pavement to the inside of a curb at Streets of Willow. I was braking hard, traveling about 40-50 MPH, and as shown in the picture below, the right front control arm took the brunt of the impact. I was above to limp the remainder of the lap back to the paddock.
Since I always carry a spare control arm and ball joint ($25 and $12, respectively), I was able to swap out the control arm between sessions. I even had time to eat lunch and instruct my student before my next run. Nothing else was bent or damaged, and I was back on track for the next session and for the rest of the weekend with the car handling normally.
The incident made me wonder what would have happened if I had the same impact with either a factory aluminum arm, or one of the various stronger aftermarket arms out there. I am willing to bet that a factory aluminum arm would have broken, and most of the aftermarket arms would have also bent, at least slightly, and would be very expensive to replace. I also wonder if a much stiffer arm would have possibly shifted the force of the impact to something else, like a ball joint, which could have damaged a lot more. I feel that the sheet metal steel arms will bend, but not break, which could save the front subframe from shifting if a front corner were to hit a tire wall, for example.
The point of this post is to gather the collective wisdom of the group and see if my thoughts are valid. I would like to hear the experience of those of you who have raced/tracked these cars for longer than I have, and any stories about damaged/bent control arms and ball joints.
I have run the early steel arms for 2 seasons worth of track events and daily driving on the horrible roads of Santa Barbara, with a large Tarett front sway bar twisting them the entire time (the drop links mount on the same plane as the ball joints and forward bushings), and they have held up well through this. Of course, this is only applicable to those of us with '86 early offset arms, but food for thought nonetheless.
I have had no issues until this past weekend when I hit a large "pothole" or missing chunk of pavement to the inside of a curb at Streets of Willow. I was braking hard, traveling about 40-50 MPH, and as shown in the picture below, the right front control arm took the brunt of the impact. I was above to limp the remainder of the lap back to the paddock.
Since I always carry a spare control arm and ball joint ($25 and $12, respectively), I was able to swap out the control arm between sessions. I even had time to eat lunch and instruct my student before my next run. Nothing else was bent or damaged, and I was back on track for the next session and for the rest of the weekend with the car handling normally.
The incident made me wonder what would have happened if I had the same impact with either a factory aluminum arm, or one of the various stronger aftermarket arms out there. I am willing to bet that a factory aluminum arm would have broken, and most of the aftermarket arms would have also bent, at least slightly, and would be very expensive to replace. I also wonder if a much stiffer arm would have possibly shifted the force of the impact to something else, like a ball joint, which could have damaged a lot more. I feel that the sheet metal steel arms will bend, but not break, which could save the front subframe from shifting if a front corner were to hit a tire wall, for example.
The point of this post is to gather the collective wisdom of the group and see if my thoughts are valid. I would like to hear the experience of those of you who have raced/tracked these cars for longer than I have, and any stories about damaged/bent control arms and ball joints.
I have run the early steel arms for 2 seasons worth of track events and daily driving on the horrible roads of Santa Barbara, with a large Tarett front sway bar twisting them the entire time (the drop links mount on the same plane as the ball joints and forward bushings), and they have held up well through this. Of course, this is only applicable to those of us with '86 early offset arms, but food for thought nonetheless.
02-27-2013, 01:16 AM
#3
Three Wheelin'
02-27-2013, 05:37 AM
#4
RL Community Team
Rennlist Member
Rennlist Member
I wish someone would modify the early steel arm setup to work on a late suspension. I'm sure there's a cheap ball joint out there with the right size pin, and all it would take is adding some length to the part that mounts to the control arm.
02-27-2013, 05:42 AM
#5
Three Wheelin'
It should not be too hard to produce them yourselves. You just have to think a bit about how to produce them!
02-27-2013, 11:51 AM
#6
Take care,
02-27-2013, 12:00 PM
#7
Three Wheelin'
Trending Topics
02-27-2013, 03:36 PM
#9
I have been running early steel control arms on my '86 951 for almost 2 seasons now, as I broke a factory aluminum arm at Laguna Seca in the past.
I have had no issues until this past weekend when I hit a large "pothole" or missing chunk of pavement to the inside of a curb at Streets of Willow. I was braking hard, traveling about 40-50 MPH, and as shown in the picture below, the right front control arm took the brunt of the impact. I was above to limp the remainder of the lap back to the paddock.
Since I always carry a spare control arm and ball joint ($25 and $12, respectively), I was able to swap out the control arm between sessions. I even had time to eat lunch and instruct my student before my next run. Nothing else was bent or damaged, and I was back on track for the next session and for the rest of the weekend with the car handling normally.
The incident made me wonder what would have happened if I had the same impact with either a factory aluminum arm, or one of the various stronger aftermarket arms out there. I am willing to bet that a factory aluminum arm would have broken, and most of the aftermarket arms would have also bent, at least slightly, and would be very expensive to replace. I also wonder if a much stiffer arm would have possibly shifted the force of the impact to something else, like a ball joint, which could have damaged a lot more. I feel that the sheet metal steel arms will bend, but not break, which could save the front subframe from shifting if a front corner were to hit a tire wall, for example.
The point of this post is to gather the collective wisdom of the group and see if my thoughts are valid. I would like to hear the experience of those of you who have raced/tracked these cars for longer than I have, and any stories about damaged/bent control arms and ball joints.
I have run the early steel arms for 2 seasons worth of track events and daily driving on the horrible roads of Santa Barbara, with a large Tarett front sway bar twisting them the entire time (the drop links mount on the same plane as the ball joints and forward bushings), and they have held up well through this. Of course, this is only applicable to those of us with '86 early offset arms, but food for thought nonetheless.
I have had no issues until this past weekend when I hit a large "pothole" or missing chunk of pavement to the inside of a curb at Streets of Willow. I was braking hard, traveling about 40-50 MPH, and as shown in the picture below, the right front control arm took the brunt of the impact. I was above to limp the remainder of the lap back to the paddock.
Since I always carry a spare control arm and ball joint ($25 and $12, respectively), I was able to swap out the control arm between sessions. I even had time to eat lunch and instruct my student before my next run. Nothing else was bent or damaged, and I was back on track for the next session and for the rest of the weekend with the car handling normally.
The incident made me wonder what would have happened if I had the same impact with either a factory aluminum arm, or one of the various stronger aftermarket arms out there. I am willing to bet that a factory aluminum arm would have broken, and most of the aftermarket arms would have also bent, at least slightly, and would be very expensive to replace. I also wonder if a much stiffer arm would have possibly shifted the force of the impact to something else, like a ball joint, which could have damaged a lot more. I feel that the sheet metal steel arms will bend, but not break, which could save the front subframe from shifting if a front corner were to hit a tire wall, for example.
The point of this post is to gather the collective wisdom of the group and see if my thoughts are valid. I would like to hear the experience of those of you who have raced/tracked these cars for longer than I have, and any stories about damaged/bent control arms and ball joints.
I have run the early steel arms for 2 seasons worth of track events and daily driving on the horrible roads of Santa Barbara, with a large Tarett front sway bar twisting them the entire time (the drop links mount on the same plane as the ball joints and forward bushings), and they have held up well through this. Of course, this is only applicable to those of us with '86 early offset arms, but food for thought nonetheless.
02-27-2013, 05:15 PM
#11
Three Wheelin'
Thread Starter
I will certainly experiment with reinforcing these arms, but as I said in the first post, I have run the same pair of arms for almost 2 years with hard track use and daily driving, all with a big sway bar. I inspect them regularly and they have shown no signs of bending or flexing. I will say that I only use Lemforder arms, which are the only ones that the Tarett sway bar adapter blocks fit onto. They are certainly higher quality than the other brands I looked at.
Have you or any of your customers had bad experiences with unmodified steel arms on the track? If so I would like to hear about them, so that I can make an informed decision for the future.
Thanks for the replies.
02-27-2013, 05:42 PM
#12
Three Wheelin'
When you check all of these parts and the time needed.. I would say that anyone would be able to produce them for about 150 a piece.. That's a lot less than what most control arms go for!
02-27-2013, 05:45 PM
#13
Three Wheelin'
Thread Starter
Use the Racer's Edge delrin bushings for the front. You will also need adapter brackets for the front sway bar that you are using. You can get the factory brackets if you run the stock front sway bar (part # 944.343.735.01). They mount underneath the arm instead of on top like the brackets on the aluminum arms, and you will have to hone out the bushings so the larger Turbo sway bar ends fit. I wouldn't recommend running a 30MM 968 M030 bar, as the geometry won't be correct and it will bind and cause lots of understeer (in fact I don't like this bar for aluminum bars either. Get an adjustable front sway bar if you can
02-27-2013, 06:52 PM
#14
You will need early 944 rear bushing/caster block brackets (part # 477.407.169, get them used from a salvage yard). The only performance rear bushings that I have seen available are the red polyurethene Weltmeister bushings, and this is what all of the 944 Spec guys have used for years. They work well, but can get torn up fairly quickly with hard track use (I have replaced mine twice so far). Luckily they are cheap at less than $20 each and easy to replace.
Use the Racer's Edge delrin bushings for the front. You will also need adapter brackets for the front sway bar that you are using. You can get the factory brackets if you run the stock front sway bar (part # 944.343.735.01). They mount underneath the arm instead of on top like the brackets on the aluminum arms, and you will have to hone out the bushings so the larger Turbo sway bar ends fit. I wouldn't recommend running a 30MM 968 M030 bar, as the geometry won't be correct and it will bind and cause lots of understeer (in fact I don't like this bar for aluminum bars either. Get an adjustable front sway bar if you can
Use the Racer's Edge delrin bushings for the front. You will also need adapter brackets for the front sway bar that you are using. You can get the factory brackets if you run the stock front sway bar (part # 944.343.735.01). They mount underneath the arm instead of on top like the brackets on the aluminum arms, and you will have to hone out the bushings so the larger Turbo sway bar ends fit. I wouldn't recommend running a 30MM 968 M030 bar, as the geometry won't be correct and it will bind and cause lots of understeer (in fact I don't like this bar for aluminum bars either. Get an adjustable front sway bar if you can
I will be doing my suspension refresh this spring(been 2 years in the making) and I have the choice of rebuilding my current arms or converting to steel. New aluminum arms are just too damn expensive.