control arm failure at the track this weekend

STEVE_POE · Sep 18, 2012

Thought I would share a pucker moment with all you when I had a road race version BMR control arm failure this past weekend at 130mph into a heavy brake zone. Not only did the control arm fail but it drove the Tire back into the fender destroying the tire, the fender the inner fender well and lower rocker. It also did some damage to my k-member. who knows what it did to my moton triple shock as that will be another $400 to have sent in and checked for damage. all in all about $1,200 -$1,600 worth of damage or so plus the control arm itself .

Could have been worse as well. imagine this happening through a long sweeper at full power. I was lucky this was under a heavy brake zone .

These only had about 14 race weekends on them

be safe in what you choose to run on your car. Needless to say these will not be going back on my race car.

Yes , bmr is aware of this failure..........

D98GT · Sep 18, 2012

Wow that sucks but atleast you were able to keep it from causing more damage. What did BMR say about it?

VTXFrank · Sep 18, 2012

Damn! I think I'd be looking for BMR to pay up for some of the damages! That really sucks! Glad you were able to manage the car to a stop. That alone shows you have some mad skills.

Have you shit out the cushion material from your seat yet?

sheizasosay · Sep 18, 2012

Glad you are ok. That is scary. I would think the hard breaking zone would be the heaviest load that arm would see.

GrabberBlue5.0 · Sep 18, 2012

Wow good thing you're ok after that.

Sent from my iPhone using Tapatalk

DILYSI Dave · Sep 18, 2012

Looks like the HAZ where that strap ties into the rear tube is where the failure initiated. Perhaps a redesign that lengthens that strap and wraps it along the rear tube all the way back to the rear pivot. It would eliminate the HAZ at that point that is under tension, as well as double up (or more) the wall thickness dealing with that braking stress.

stkjock · Sep 18, 2012

I can't see the image (office firewall) , I presume it's a A-arm, if so not the first time I've read of them failing.

TexasKyle · Sep 18, 2012

Wow. Glad you are ok.

Have you considered taking the other one off and having it MPI'd? Wonder if there is a stress fracture from that bend during manufacture.

BMR Tech · Sep 18, 2012

This is a very unfortunate situation, and we (BMR Suspension Inc.) are very sorry that this happened on Mr. Poe’s race car.

Since 2005, we have been building and revising these arms, and we continue to revise as time passes. Unfortunately, failures have occurred.

The S197 Mustang A-Arm is unlike any other arm that we, and most manufacturers of welded tubular steel arms, have experienced. There is a reason that there are still to this date, only several companies who have even attempted to produce tubular steel units for this chassis.

Steve’s arm (pictured) is not your typical A-Arm that is shipped from our shelf, it was modified at the center gusset due to his previous experience having a crack where the “BMR” logo was. We sent him a new set about a year ago with a vertical gusset running along the BMR Gusset to prevent that gusset from excessive flexing. Needless to say, the current arms shipping from our facility, do not have the BMR logo in the center gusset and that gusset is now 1/4” plate instead of 3/16”. We have also recently revised the outer gusset as well.

Looking closely at the picture, it appears that the crack runs along that “additional” weld. This is the first A-Arm failure from hard braking, that we have seen in that area and we are currently assuming the extra gusset/weld is the culprit here. Hopefully Steve will work with us on getting this arm back so we can thoroughly analyze it.

Again, we are very sorry that this occurred on Mr. Poes car. We will continue to support our products and our customers, and we remain confident in our S197 A-Arms for most peoples desired driving conditions.

19COBRA93 · Sep 18, 2012

Can we get a pic of your A-arms as shipped?

Sam Strano · Sep 18, 2012

Sorry to see this. This is why I'm not a big fan of tubular A-arms arms in general, and never with bends in them. There is a reason the OEM arms are as heavy as they are, and considering loads put into them, I never use them (regardless of brand) on handling cars.

TGR96 · Sep 18, 2012

Man, I bet that was scary! Glad to see the folks at BMR are working on this issue. I know that I have had good luck with their products, but in fairness, I don't put my car through hard driving like Steve does.

LAStang1234 · Sep 18, 2012

Man, I'm glad you ended up alright sfter that! Could of been a lot worse for sure!

VTXFrank said:
Have you shit out the cushion material from your seat yet?

^ This made me LOL!

sheizasosay · Sep 18, 2012

BMR Tech said:
This is a very unfortunate situation, and we (BMR Suspension Inc.) are very sorry that this happened on Mr. Poe’s race car.

Since 2005, we have been building and revising these arms, and we continue to revise as time passes. Unfortunately, failures have occurred.

The S197 Mustang A-Arm is unlike any other arm that we, and most manufacturers of welded tubular steel arms, have experienced. There is a reason that there are still to this date, only several companies who have even attempted to produce tubular steel units for this chassis.

Steve’s arm (pictured) is not your typical A-Arm that is shipped from our shelf, it was modified at the center gusset due to his previous experience having a crack where the “BMR” logo was. We sent him a new set about a year ago with a vertical gusset running along the BMR Gusset to prevent that gusset from excessive flexing. Needless to say, the current arms shipping from our facility, do not have the BMR logo in the center gusset and that gusset is now 1/4” plate instead of 3/16”. We have also recently revised the outer gusset as well.

Looking closely at the picture, it appears that the crack runs along that “additional” weld. This is the first A-Arm failure from hard braking, that we have seen in that area and we are currently assuming the extra gusset/weld is the culprit here. Hopefully Steve will work with us on getting this arm back so we can thoroughly analyze it.

Again, we are very sorry that this occurred on Mr. Poes car. We will continue to support our products and our customers, and we remain confident in our S197 A-Arms for most peoples desired driving conditions.

Did you use FEA for your s197 front control arms?

ArizonaGT · Sep 19, 2012

Glad to hear you are OK.

fdjizm · Sep 19, 2012

Ouch, glad you and your car made it out somewhat OK.
I've been tempted by A-arms for weight. but OEM for me!

skwerl · Sep 19, 2012

I didn't need to hear this, just installed mine a week ago. I'll be following this thread as well.

pcdrj · Sep 19, 2012

TexasKyle said:
Wow. Glad you are ok.

Have you considered taking the other one off and having it MPI'd? Wonder if there is a stress fracture from that bend during manufacture.

You'd have to chemically strip the paint or powder coat to do any NDT. Glass beading or sand blasting could mask indications. If there were indications adding NDT in the manufacturing process could help depending on material grades being used. Some tubing material won't pass even before bending or welding. For due diligence I would think BMR would want to do FEA.

Fortunately Mr. Poe's skills prevented this from being much worse than it could have been.

Norm Peterson · Sep 19, 2012

DILYSI Dave said:
Looks like the HAZ where that strap ties into the rear tube is where the failure initiated. Perhaps a redesign that lengthens that strap and wraps it along the rear tube all the way back to the rear pivot. It would eliminate the HAZ at that point that is under tension, as well as double up (or more) the wall thickness dealing with that braking stress.

I suspect that the thick to thin structural discontinuity was involved at least as much as the HAZ effect. Won't speculate any further than that.

Norm

DILYSI Dave · Sep 19, 2012

Valid. Wrapping that vertical strap would eliminate that discontinuity as well.

control arm failure at the track this weekend

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