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That arm certainly seems to have been seasoned with road salt... it looks as bad as mine did with 40yrs of use on them.
I am no engineer.. but that design goes from a what looks like square 1" to 1 1/2" square stock steel down to a piece of flat stamped out steel and where that transition occurred you have the hole for the traverse leaf spring pulling down on it to keep the front end up and the ball joint pushing back in the other direction. You have several welds in that area and just constant fatiguing of that stamped section. That big hole for the leaf spring makes that area real weak for a piece of flat stock trying to do what they are asking it to.
Just doesn't seem it was up to the task as is confirmed with another members crack in the same spot. Probably needed to be twice as thick in that area or gusseted somehow around the spring hole.
Maybe with low profile tires and stiffer shocks you guys are just pushing that design past what its capable of. Wonder if VBP went out due to something like this failing on other cars.
I forgot to add:
From the records I have, I believe these arms (and whole suspension) was installed in the mid 90s.
The car has over 200k miles on it and lived mostly in California with some short stints in Arizona and St Louis as well as one year here in Ohio all as a daily driver.
Well the Ohio DD part certainly explains the rust some of the CA boys were curious about!
25 years and 200k miles explains the fatique portion.
I remember once readng that GM designed their cars to have an expected lifetime of 10 years. I don't know if this is true, and more importantly, I don't know if there were some qualifications associated with the putative 10 year rule. Look at this part and the dimpled surface salt corrosion. I suspect this part has exceeded it's design life.
It looks like those arms are from a VB&P Dual-Mount Transverse Spring conversion, and unfortunately, cracking in that location was common on the earlier versions. I believe VBP added a doubler in that location on the later versions, which is what I did to mine too.
A couple years ago, I was doing a check after a weekend of autocross and found cracks in both arms. We pulled them from the car, put them in a press to straighten them and close up the gap in the crack, then welded them closed and welded on a doubler plate to reinforce them. Since then I've put about 6,000 miles on the car, as well as about 20 autocross days and two track days at Willow Springs without any further trouble.
Good Luck with your project,
Chris
Hey Chris, have you got more details on the repair and doubler you put on your VBP arms? I am reconsidering using these ones I have.
I remember once readng that GM designed their cars to have an expected lifetime of 10 years. I don't know if this is true, and more importantly, I don't know if there were some qualifications associated with the putative 10 year rule. Look at this part and the dimpled surface salt corrosion. I suspect this part has exceeded it's design life.
I decided to repair the VBP arms instead of buying new ones. I ended up having to do a repair to both of them since they were both bent out of shape. The repair consisted of cutting the cracked/deflected area, bending the arm back to it's original angle, welding the cuts closed then adding a doubler over the stressed area. I ended beefing up both the front and rear of the arm much like VBP did on their later design.
07-11-2020, 05:19 AM
