So I tore the inner mount loose from the frame that holds the front sway bar. I was using the 25.5 mm hollow bar with delrin bushings on the inners, rubber on the outers.

Basically, it pulled the nuts that were welded inside the frame through the frame, leaving the sway bar with only 3 attachment points, the drivers side inner bracket left dangling. The bracket itself appears unharmed to the naked eye, just the bolts attached to it pulled themselves through the frame.

Ive got some ideas on how to fix it, but I was wondering if any listers have ever had a similar problem. Would those brackets that attach to the frame and the inner bracket at a 45 degree angle (making a right triangle) have prevented this? Whats the best documented fix?

Ok, thinks for the help everyone!!

 

Wow, it takes some serious force to pull those nuts through the frame. You did it with a 25.5mm bar on there?... This wasn't in a crash or running over a curb or anything was it?

Those angled brackets do help to take some of the load of the sway bar mount when it is pushing front-to-back (by that I mean _THE_ load, because the normal bracket does nothing for this) so I would assume they take some of the load off in the vertical direction as well. Would it have prevented this? Who knows. I've never even seen it happen before.

 

I dont think it was a single brute force impact that failed it, but rather a fatigue failure. 1000's of times loading that small 1X2 inch footprint of that bracket finally failed the frame. On second inspection, it looks like its been repaired before by welding a saddle to the frame to spread the load, and cover the old hole where it tore through. Looks like they used 16 guage to make the saddle, welded the bolts to the back of it, and then slipped it in place over the frame. If would have worked, but it appears to have been unable to distribute the load across the saddle and just tore through it. Im going to do a hardness test on the steel they used tomorrow, but im guessing its just 1014 or something.

Anyone ever had to fix this before?

 

Nope. I think the damage that caused the first repair is the root cause of your problem.

 

Agreed. Somebody has done something bad to that swaybar mounting point!
I mean, they are nuts welded inside the frame of the car...

One more thought, somebody could have stripped out / broken the nuts free of the frame, that would require the type of surgery you have seen to correct it as well.

Sounds like you have the repair procedure down, more a matter of fixing their mistake than repairing the nuts.

 

Um, I beg to differ. This happened to my car as well, and a friend's car at a DE. The sway bar bracket just tore off the frame rail and took a chunk of the rail with it. I haven't had time to fix it yet but I was going to MIG weld a thick piece of steel to repair the hole, with holes drilled and nuts welded on the inside before welding the plate to the frame. I think TIG welding the nuts would be better than MIG.

 

Running larger than stock sway bars on those cars?

 

My '84 was running a standard 23mm hollow bar. My friend was running a thicker bar, I forget but I want to say 26.8...?

 

26.8 is the factory turbo bar.