Shackle Bolts.

[chevydan3]

Okay guys. In the past month I have busted 2 grade 8 7/16" shackle bolts, they break right at the nut and slide out. I lost half the bushing last time and had to stick a 1/2" drive 3/4 socket in there to drive around on until I could drive down to Summit Racing and buy some new bushings. I think it is the combo of pinchlock nuts, too tight of tolerances on the shackle bolt holes, and crappy 8" Superlift springs. I have new grade 8 7/16" bolts with nylock nuts that I am going to run, and I am going to ream out the holes in the shackles a little bit, but then I got to thinking. Should I just upgrade to a 1/2 inch bolt or will my 7/16" work? I am switching to the much better BDS 8" springs next winter and never buying another Superlift product again, those springs have been nothing but problems. Anybody else have a problem with shackle bolts breaking? I bought my 1 inch lift shackles from ORU, maybe that is the problem. Should I go bigger or stay the same?

 

[diesel4me]

..."under sized and over stressed" parts!

I've always been amazed I've never broken one of those 7/16" front shackle bolts on any of my GM trucks..I've had 8' monster plows on them,with 454 motors,and when I take them apart to junk them 20 years later,the bolts were nearly worn in half by the shackle just under the head!..GM must use some pretty dam good bolts!.. ..and how come a huge 5/8 bolt on the front "eye" of the spring?..it never "swings",so why use a huge bolt there,then put a puny 7/16" bolt on the rear eye,WITH a shackle,that swings on it and eventually cuts into it ??

I also can't figure out how only 6 little studs on the stub axle of a Dana 44 or 10 bolt hold up the weight of an entire truck and plow either..my 74 K20 had a 454 in it,and I plowed 3 seasons before I discovered only 4 of those cheesy 3/8" bolts were holding the drivers side on,when I had to put axle U joints in it!..

I guess some things are just like that..like the "nails" that hold your drum brake shoes on with!..your LIFE is riding on those "nails"..couldn't they have used BOLTS instead??..I hate the way many critical parts are held on by cotter pins,snap rings,and clips that rust away too--

(like the infamous wheel cylinder clips that rot off here,and let the wheel cylinder rip out of the backing plate..GM shoulda been sued over that design!..and forced to fix ALL the vehicles that had that setup and convert them back to bolt in wheel cylinders!..)

but I guess GM did lots of research and engineers felt the parts were adequate,so they used the cheapest size they could to maximize profit..so what if a few people die because the parts rusted, or failed under extreme duress..

I always say bigger is better..just like in engines,no substitute for cubic inches..those bolts in the shackle SHOULD have been bigger,in my opinion,and the shackles(stock GM) should have had a bar welded across them to stiffen them (so they look like an "H")..or been made of thicker stock!..it might be difficult to find bushings with the right O.D. and let bigger bolts fit though,unless someone makes them already..

 

[divorced]

..and how come a huge 5/8 bolt on the front "eye" of the spring?..it never "swings",so why use a huge bolt there,then put a puny 7/16" bolt on the rear eye,WITH a shackle,that swings on it and eventually cuts into it ??

The big bolt takes all of the force from acceleration, braking, and hitting big bumps or running into curbs, as well as suporting the vehicle. And I always though the 7/16" shackle bolts were supposed to stay tight against the shackles and not twist inside?