Broken shock mount.... Weird. Any ideas?

[NovaSF]

Sooo.... It appears my rear lower shock mount broke the other night when I was out having some spirited driving. 70 Nova LS3 TKO 600 3.91s. ****ty old BFGs that are just about dead and can’t hook for crap. Rear suspension is older style lift bars (kinda like slapper bars but they also secure to the front of the leaf spring).

The area that broke was about 1/4 inch steel.

IT has me wondering why? .. crappy steel that had had some fatigue and was bound to go? The car wasn’t hooking at all on old tires though even it if was, would that potentially cause this failure?

Any thoughts? Seems weird.

[Josh@Ridetech]

The leaf is taking almost all of the load of the suspension so it would almost have to be that the shocks are either bottoming or topping out at some point. If the bracket keeps getting a hard hit it'll just keep bending until it breaks (and if it is some cheap/bad metal, that'd make the problem show up sooner).

[kimosabi]

Shock mounts see load every time the suspension travel, and even harder loads with fast travel. According to this pic it started with a small crack, then just broke. Fatigue.

How hard are your shock settings btw? That ear for the shock mount seem underdimensioned to me. I wouldn't be surprised if someone else with that kit also had similar problems.

[Josh@Ridetech]

How hard are your shock settings btw? That ear for the shock mount seem underdimensioned to me. I wouldn't be surprised if someone else with that kit also had similar problems.

This also crossed my mind. A very aggressive shock setting could cause some issues on a single-shear mount of that size.

[NovaSF]

I checked the shock. All good, full travel, not topping or bottoming out. I’m thinking tiny crack grew with time. True shock was a Calvert adjustable On the softest setting..

The replacement lift bar I put on just now has an even smaller mounting tab/area.

lets see how long this one lasts...

[Twentyover]

Being an apparent unsupported overhung load probably didn't help either

[TheJDMan]

That mount looks too light weight for the application. Weld the tab back on then reinforce it with a second layer of material. A double shear mount would be best.

[raustinss]

Zooming in on the pic it looks like a tiny crack and then rust formed , reweld it and if you can reinforce it

[pitts64]

Was it cold out, that makes things brake..

[NovaSF]

Thanks everyone.. A welder is next on my wish list.

- - - Updated - - -

Not too cold.. SF Bay Area cold is sissy stuff

[David Pozzi]

Go with new 3/8" thick 1045 "Plow" steel. It's stronger and tougher. Weld it with gas shielded Mig or Low hydrogen stick arc, something like E7018. Make sure the bracket is parallel to the shock angle so the shock is not twisting the stud so much. A gusset on the nut side inboard edge of the shock plate would help if you can get enough clearance to the nut. A more ideal mounting would be to add a good support on the other end so the shock eye is in double shear.