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Cracked Vette Brakes Products control arms.... Ideas wanted
While chassis disassembly goes on with my 70 coupe project, I discovered one of the lower control arms was cracked near the ball joint. I am pretty sure I am not going to try to repair this since I have no good way to realign it before welding. Besides, this appears to be a weak point in the design and probably should be reinforced.
*** Potential safety issue: I would recommend that all owners with these control arms make a point to inspect this area for cracks every oil change.***
I am thinking about getting a set of Van Steel tubular lower control arms and stock springs to replace the VBP lower arms and monoleaf. This assumes the upper A arms pass inspection.
Any other good solutions? This is repair /replace damaged parts project.... A full front end system would be out of scope.
Matt, thanks for posting the picture of the cracked lower control arm. Unfortunately, not being familiar with this particular VB&P system, I'm having a bit of a problem orienting myself to your picture. If you could post another picture of the complete control arm that will orient us to the picture of the cracked portion, I would appreciate it.
I bought a lot of things from VB&P over the years and was generally very satisfied with their products and customer service. Especially so in the early years - for me, the early 90's. I certainly did not wish to see them close down but realize it was for a variety of reasons and not specifically related to the quality of their products. However I was never a fan of their front mono-leaf system despite the fact that it has been used extensively in later generation Corvettes.
My primary concern was that it reduced ground clearance (not insignificantly since I like to autocross my cars) and it made no real provision for protecting such a critical portion of the front suspension. From the C4 on, the front mono-spring was encased in the front crossmember providing excellent protection without reducing ground clearance. It may have seemed a simple solution to add adjust ability to the front suspension at the time, but for me not worth the risk.
Agreed that spring cushion cup looks like it is in a flat area that is not heavily vertically reinforced like the factory arms spring pocket. Thus it would flex more, as also evidenced by the stress crack. Combined with the loss of ground clearance that Gusto mentioned, their front monoleaf retrofit kit does not look like a very well engineered & durable design to me.
Might I ask how many miles you have on yours?
So that other monoleaf retro-fit owners would have a data point?
The Global West delrin bushing system is hard to beat, if you autocross or road race your car. At street speeds it is not really necessary. My autocross car was so capable I could triple interstate on-ramp speeds with utter confidence with those bushings up to like 90 on a tight 30mph cloverleaf ramp. They are really not needed at anything approaching sane speeds on the street. Car pulled 1.3 G and had terrific laser like steering feel even at the limit. Easy to drive,. A lot of that feel was due to those bushings. .
My c3 will be a hot-rod street car and I will be using rubber bushings there. I won't use poly anywhere, too many bad experiences. 27 yrs of it in racing.
It is a bit of a PITA to adjust ride height with a coil spring, but really you only have to go thru it once, and then you have factory durability.
So sorry for your trouble and so glad you have a "keen eye". My son's car had a lower ball joint failure just yesterday, lots of damage but fortunately he is OK. No cotter pin in the castle nut. REALLY mad at his mechanic.
I'm having a bit of a problem orienting myself to your picture. If you could post another picture of the complete control arm that will orient us to the picture of the cracked portion, I would appreciate it.
I really should have known better. Ill have to get some better orientation photos this weekend.
Agreed that spring cushion cup looks like it is in a flat area that is not heavily vertically reinforced like the factory arms spring pocket. Thus it would flex more, as also evidenced by the stress crack. Combined with the loss of ground clearance that Gusto mentioned, their front monoleaf retrofit kit does not look like a very well engineered & durable design to me.
Might I ask how many miles you have on yours?
So that other monoleaf retro-fit owners would have a data point?
The Global West delrin bushing system is hard to beat, if you autocross or road race your car. At street speeds it is not really necessary. My autocross car was so capable I could triple interstate on-ramp speeds with utter confidence with those bushings up to like 90 on a tight 30mph cloverleaf ramp. They are really not needed at anything approaching sane speeds on the street. Car pulled 1.3 G and had terrific laser like steering feel even at the limit. Easy to drive,. A lot of that feel was due to those bushings. .
My c3 will be a hot-rod street car and I will be using rubber bushings there. I won't use poly anywhere, too many bad experiences. 27 yrs of it in racing.
It is a bit of a PITA to adjust ride height with a coil spring, but really you only have to go thru it once, and then you have factory durability.
So sorry for your trouble and so glad you have a "keen eye". My son's car had a lower ball joint failure just yesterday, lots of damage but fortunately he is OK. No cotter pin in the castle nut. REALLY mad at his mechanic.
The crack initiated just outside of the weld in a high stress area. They should have made the outer part of slightly thicker material and carried it up the arm tube some more to get the weld further away from the stress concentration. The area around the weld are where the weak spots can live and they put that in the highest stress area of the arm.... according to my analysis anyway.
Unfortunately, I cannot offer and information on how much time or mileage is on these parts. I bought the car off a guy I used to work with years ago with no motor in it and I have lost touch with him so I can't ask. I assume they went in the car in the mid 90s.
"REALLY mad at his mechanic"....... I always say, never trust a professional. The quality of work I see people get these days is abysmal.
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.
I too would appreciate a better picture of the control arm to know where the crack is, and to know if it is a coil spring or mono spring arm. I too have VB&P control arms, the mono spring type.
I too would appreciate a better picture of the control arm to know where the crack is, and to know if it is a coil spring or mono spring arm. I too have VB&P control arms, the mono spring type.
Here are a couple pics of mine while the car was still up in the air. You can see that this is on a monoleaf system and that the crack is right inline with the hole for the spring bolt.
I don't have any photos from after we fixed them, but I might lift it up tomorrow and take some.
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
To the OP I agree this would be your least expensive solution. It should hold up well with double the steel. It also sounds like it was VBPs solution on the 2nd generation of these.
07-02-2020, 01:22 PM
Cracked Vette Brakes Products control arms.... Ideas wanted
REALLY mad at his mechanic.
