Oddly enough ElP, the gusset you suggest is the ONLY piece that would need to be custom fitted if it were included with a "kit" front end. If it were included and NOT custom fitted for frame variance, it might cause the novice installer to misalign the whole front crossmember. Thats not acceptable, so the easy answer(?)...just leave it out completely! It doesn't even matter if this was the actual cause of the roll or not...because it was a failure waiting to happen anyway. You don't need to be an Engineer to see what the issues are with that poorly braced design!!!
One possibility is that with the car sitting so low the a arms would be at a steep angle and the ball joint just didnt have enough rotation left to absorb a hard jounce which would cause it to twist and pull out of its socket . I do agree the wide a arm on the narrow mount is a lousy design and shouldnt have left the shop . The original mustang II configuration used a heavy strut rod on the lower a arm that ran back at an angle to a very solid mount and had plenty of rubber to aborb shock loads . Suspensions should be designed to fit the car they are on ! They are not a one size fits all application and the aftermarket co's that sell them that way are just begging to get nailed with a monster lawsuit someday when a family gets killed because of thier product . And with designs like this one they deserve what they get . As a side note OEM designers build suspensions to handle shock loads as high as 40 times the total wt. of the car . and thats on a econobox not a 400 hp streetrod with huge brakes and wide tires .
I have seen and repaired the same problem that ElPolako is describing on several IFS set ups. Another problem I have seen with some of the fabricated spring pocket-upper control arm mounts is the top plate to the outer band on the inside corner wasn't fully welded. The outer corner was fully welded (without good penatration) and the weld ground off. This allowed the plate the top of the coil spring rests on to tear away from the side band that gives it the strength. I have had the upper coil spring mounts on a new IFS kit where one side would be fully welded on the inside and the other side would have two or three half inch long welds on the inside. I have repaired two vehicles that this happened to after a few thousand miles leaving the car with the cross member sitting on the ground. This could have been prevented from the begining if the installer had examined the parts a little closer. Just because a large company manufactured the product doesn't mean it is perfect or that a weld area couldn't get overlooked during production. I will post some photos of a duece roadster that dropped the front wheel off the edge of the pavement and high sided the axle. It had a chromed tube axle that the welds had been excessivly ground smooth where the cast end welds to the tube. It instantly ripped the cast end off the axle and caused a lot of damage to the car but didn't hurt the driver. This more than likely wouldn't have happend if a beam axle had been used or if the weld was left intact Some of these problems could also be prevented be doing a thorough look over of a car at least once a year. Kind of like an annual on a airplane.
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