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Discussion Starter #1 (Edited)
Not sure what is happening here. Left side failed, right side is bent. 2007 Shelby GT, 9xxx miles. Lots of autocrossing.

If you run a S197, you might want to inspect this area just in case. I'll post if we figure out a for sure cause. Early reports from some people close to development and racing of S197's is that "those spindles are tough" so there might be something else going on here.



Here is the whole album: http://photos.samanthawhitworth.com/v/ShelbyGT/

DaveW
 

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I would have to say "those spindles are not tough enough". The strut ear mount design doesn't look very strong. The bottom bolt mount looks strong, but then it extends to the top mount with what looks like a thin mounting arm. The break is pretty close to where the arm begins extending from the spindle. If the bottom bolt is loose enough, it may act as a pivot and cause the mounting arm to flex. Put on some big sticky tires and the car may see enough force to stress those points to failure. Ford may not have realized the amount of force they potentially would be seeing.
 

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Discussion Starter #6
I would have to say "those spindles are not tough enough". The strut ear mount design doesn't look very strong. The bottom bolt mount looks strong, but then it extends to the top mount with what looks like a thin mounting arm. The break is pretty close to where the arm begins extending from the spindle. If the bottom bolt is loose enough, it may act as a pivot and cause the mounting arm to flex. Put on some big sticky tires and the car may see enough force to stress those points to failure. Ford may not have realized the amount of force they potentially would be seeing.
That was kind of my initial read, but with some research from people I trust and who either worked on development and/or racing of these cars in GrandAm/Mustang Challenge, they have never heard of or seen this type of failure. I am pretty sure OEM testing would uncover a design issue and certainly Pro Road racing would.

It is certainly a different design compared to the older cars spindles. :)

DaveW
 

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Maybe there is a material flaw. Do you know if the strut bolts were still tight after the break? Autocross maybe introducing some forces that you wouldn't see on a road course or in OEM stress testing.

Even with all the testing companies do, sometimes big problems still arise. Some Corvettes are having the stud ring of the front hubs separating on track. The only thing that is then holding the wheel on are the calipers. The cars were obviously track tested, but it is apparent that GM didn't account for big sticky tires in their long term testing.

If there is an inherent problem with the spindle, maybe an aftermarket company like Racecraft can step in and create a worthy replacement. If you find out any more info, please let us know.

Thanks.

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I think it's clearly a casting flaw. Apparently there was rust around the failure, which tells me it was cracked for a while.

I can't think of a car with more beating on R-comps than ours and nothing. I will check them more closely, and we ordered some spares just in case, but I think this is a fluke...
 

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A loose bolt (which can and does happen) could certainly make this more prone to happening. I think that's a good catch by Diesel. I know at least two others that found the lower mount bolts to have loosened over time (myself included).

Again, we'll check ours and I'll let you all know. I really don't think this is a major panic situation. Could be wrong, but if ours are ok I think most others will be as I know that Shelby #450 (Mike's that I run) is probably the most beat on, hardest run car on R-comps out there. Made it'd debut in March 2007, been run hard ever since.
 

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Are either of those "crash bolts", for camber change?
 

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They are stock shank sized bolts with eccentric heads (lower only). Also they are Ford parts.
 

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Discussion Starter #16
Yes, this is Langley's car.

I agree with Sam, this was a fluke, possibly caused by loose bolts. Ford fixed it under warranty and claims the right side is fine, which we will double check this weekend.

I didn't mean to imply this was a panic situation, just a reminder that this is an area to be checked since these cars are becoming so popular.

DaveW
 

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And I for one appreciate Kyle and Dave letting me, and us, know respectively. Better safe than sorry... That said, it's already going around on other sites--not Mustang related sites--and while it happened it seems many think it's bound to happen to everyone.

The internet: Good, and bad. ;)
 

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Discussion Starter #18
And I for one appreciate Kyle and Dave letting me, and us, know respectively. Better safe than sorry... That said, it's already going around on other sites--not Mustang related sites--and while it happened it seems many think it's bound to happen to everyone.

The internet: Good, and bad. ;)
Yep, definitely the downside of the internet. Even with only 80 people at the event, it would have gotten around any way, so I am at least trying to get in front of it with facts rather than BS.

Speaking of facts, I just got off the phone with a trusted source with considerable experience on Mustang race cars.

They have seen this problem on Challenge/Koni cars and have investigated it extensively. The root cause, as Sam noted, it loose bolts.

The torque spec for the bolts is 200 n m/148 ft lbs. Very likely most installers do not torque to this value in the first place, and cobblestone type impacts have been proven to loosen the bolts over time.

They have also updated the bolts (new has fine thread, 225n m/166 ft lbs torque value) and changed the spindle to have a slightly thicker mounting pad which makes assembly a little harder, but has the bolt spend less time pressing the ears together and start clamping sooner.

So, one who is racing thier S197 might want to look at the 2010 spindle and the 2010 bolts in addition to regular checking of the torque (which Kyle and I were not doing). Note, there are two part numbers for spindles, one for 2010 and one for 2010 1/2 cars which has a different ball joint taper/size and will not work on the earlier cars.

HTH,

DaveW
 
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