| Crazy Drew |
04-06-2014 11:17 PM |
First let me say, sorry for the wall of text but I've had a few beers and this is of personal interest:cheers:
From personal experience I'd shy away from anything other than OEM control arms if driving on the street. I've picked up one friend from the side of the road that broke a lower control arm driving on the street and have had 2 others that had to be towed home.
IMO there's nothing wrong with the stock FLCA's unless you're going full blown race car, in which case my concerns have no merit.
Changing out to something aftermarket you open yourself up to failure modes that don't exist in OEM applications. 1.) Weld quality, this is a big one. and 2.) Rod ends in bending. Neither of which can really be avoided with any current aftermarket option. IMO the best option out there if you really want to get rid of the OEM FLCA's is the Robispec parts. Of course, this is all speculation as I will never change out from oem control arms as long as this car drives on the street.
Having a background in structure fabrication I do have concerns about some of the weld quality I see from time to time on here. It's one thing to have a beautiful weld to oogle over while looking at it, it's another to have a structural weld. You can have both, but understand you're paying top dollar for something like this. To have a real "welder" behind the torch that understands penetration, inclusions and the HAZ is honestly a rare thing in this day of age. Everyone who picks up a tig and lays down a good looking bead thinks they're an expert without analyzing their results. I have thousands of hours behind a TIG and I still sometimes doubt myself and if I would even trust my own welds, even if they fall within "spec" I don't always have access to the NDS tools to analyze my results.
My other concerns stems from rod ends in bending, or rather threads in bending. In structures that face repeated fatigue one area of concern is "stress risers". One of the simplest stress risers in engineering is the root, or valley of a thread, or even a scratch in a critical component. The reduction in the structure from a scratch or thread AND the fact that everything around it is stiffer will cause the stress of a component to concentrate in the weak areas. As a good general rule of thumb I always try to avoid threads and rod ends in a bending force. Imagine if you will the forces seen be the FLCA when you hit a pothole. Obviously this is one of the worst case scenarios but it must sustain G's in excess of orders of magnitude greater than would normally be seen. I'm talking hundreds of G's of acceleration here. Can the forces be calculated? Yes. Do I have the tools to do so? No. so this is all honestly nothing more than speculation with a little bit of education behind it.
On all of the racecars I've had the pleasure of working on in the past we've gone out of our way to avoid rod ends in bending, meaning all of the forces seen by the rod end were in line with the axis of the threads. So much so that many of them had totally redesigned/custom manufactured crossmembers to allow the use of adjustable clevises for the point of aligning the car. Not changing the length of the control arm itself but rather moving the mounting point.
Of course, I'm also the kind of person who thinks no car should ever have anything other than OEM swaybars...
TLDR; KISS - if you don't need the adjustment don't get it. Keep it simple, stupid.
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