control arm failure at the track this weekend

[Chim-Chim]

I was thinking about putting this on ebay . maybe a fixed auction price. say $1200 to help recover some of the costs to fix my race car. it weighs 9lbs

I see what you did there. I like how you think.

 

[908ssp]

I thought exactly the same thing when I saw the picture...that's why I was asking what others thought about KB's design of the a-arm...better than anything else out there? Worth the price? Or stick with stock?

The picture on the KB web site is a computer render can't go by that have to at the very least see the real thing.

 

[Gray Ghost GT]

Sorry to hear about this failure.

It's the reason why I've upgrade just about every suspension component except the OEM control arm as I felt it would not hold up to the weight and abuses of a road course.

I'm glad no one was injured. You're very lucky to have this part fail in a heavy braking zone vs. a high speed sweeping turn.

 

[Philostang]

I'm not sure that it was really "luck" as much as an indication of just when these arms are really under their max stress.

I don't actually know anything like what the precise vectors of force are under a high speed corner, but I'll wager that they don't involve the sort of torque like forces I strongly suspect they experience under braking. My old arms showed signs of this (bent steel) in the bracket that ties in the rear strut to the main arm, which suggests that under braking they're dealing with a twisting force as well as staving off direct longitudinal braking forces.

Also keep in mind that some cars will put in well over a full G of deceleration, the lion's share of which is acting through the front. Compare that to the typical "touch over" a full G of lateral acceleration in cornering where front/rear share much more of the load. My point is that for someone in Poe's position/use of a car, braking is the really brutal affair.

If others are familiar with how braking forces act through the entire suspension links, I'd love to hear them chime in on my suspicions.

Best,
-j

 

[STEVE_POE]

Just a fyi . I seen a new style failed kenny brown control arm last week so just keep that in mind as well. I've come to the conclusion that nobody on the market has a 100% safe non fail rate and from now on I will just modify my stock control arms with ball joints and bushings or source fr500 boss 302r control arms through Ford Racing.

 

[Sky Render]

Just a fyi . I seen a new style failed kenny brown control arm last week so just keep that in mind as well. I've come to the conclusion that nobody on the market has a 100% safe non fail rate and from now on I will just modify my stock control arms with ball joints and bushings or source fr500 boss 302r control arms through Ford Racing.

This.

 

[jayman33]

You hear of parts breaking all the time when racing. It's the nature of this sport.

 

[sheizasosay]

Just a fyi . I seen a new style failed kenny brown control arm last week so just keep that in mind as well. I've come to the conclusion that nobody on the market has a 100% safe non fail rate and from now on I will just modify my stock control arms with ball joints and bushings or source fr500 boss 302r control arms through Ford Racing.

What does the boss 302r control arms have on the fr500C's arms? FR500C has better bushings and a raised ball joint.

 

[Sky Render]

You hear of parts breaking all the time when racing. It's the nature of this sport.

This is true, but the OEM part would have probably held up under those stresses.

And a control arm failure could kill someone.

 

[STEVE_POE]

What does the boss 302r control arms have on the fr500C's arms? FR500C has better bushings and a raised ball joint.

a fr500c control arm will not fit in a 2011 up mustang spindle because of the ball joint. It's not the same size. They are a different stamping design as well. so depending on the year of the car would determine on a 302r or a 500c .

 

[sheizasosay]

a fr500c control arm will not fit in a 2011 up mustang spindle because of the ball joint. It's not the same size. They are a different stamping design as well. so depending on the year of the car would determine on a 302r or a 500c .

Good to know. Thanks!

 

[5.0_SD]

Stock it is then

 

[kevinatfms]

just install the x5's, and bushings front and rear and be done with it.

 

[OkieSnuffBox]

This is true, but the OEM part would have probably held up under those stresses.

And a control arm failure could kill someone.

Hence people asking about FEA being done on a critical suspension piece for sale.

 

[Sky Render]

Hence people asking about FEA being done on a critical suspension piece for sale.

Kenny Brown does FEA on their control arms.

 

[OkieSnuffBox]

^Sounds like the forces being seen by the front control arms are being under-rated.

 

[sheizasosay]

Kenny Brown does FEA on their control arms.

And Steve Poe also already pointed out that there was a KB A-arm failure that same week at the track.


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[Sky Render]

And Steve Poe also already pointed out that there was a KB A-arm failure that same week at the track.


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Yeah, that was my point. FEA isn't good enough. Obviously there is a lot more development that goes into the design of the OEM control arms than what aftermarket companies are willing (or able) to afford.

 

[skyline247]

Yeah, that was my point. FEA isn't good enough. Obviously there is a lot more development that goes into the design of the OEM control arms than what aftermarket companies are willing (or able) to afford.

+1

OEM parts go through a lot more analysis because of the risks involved. The company sells tons of cars and any problem, especially one of this magnitude, would result in a lot of PR and financial issues. Safety is number one priority for a lot of companies. I'm sure aftermarket companies are concerned as well, but the repercussions would not be as bad - mainly because its not widespread and owners buy these parts at their own risk. I'm not surprised the OEM control arms hold up better.

OP, I'm glad you got out of this ok. This could have been a terrible accident. Hope you get everything fixed up soon.

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[sheizasosay]

Yeah, that was my point. FEA isn't good enough. Obviously there is a lot more development that goes into the design of the OEM control arms than what aftermarket companies are willing (or able) to afford.

Sorry for misunderstanding. Yeah I wonder what "a lot more development" equates to.