Front upper control arm knurled bolt to control arm shaft

[83hurstguy]

17-4 PH isn't cheap... not saying it's $48 worth, but it's definitely more than $10, especially with the flange head shown. If you want carbon steel, yeah you can do it for $10.

I drilled mine to 1/2" and used standard Grade 8 bolts and nylocks, but I have the SPC adjustable uppers so it's easy to access both sides of the bolt/nut.

If you want something that's removable but easily loosened and tightened without having to put a socket or wrench under the control arm, the other option is to grind a flat on a bolt head side, weld a block to the frame next to the bolt head... this way, the bolt can't spin when it's seated, but once the nut is loose you can slip the bolt back for downpipe clearance. Stude engines use that principle on their rear crank to flywheel bolts.

 

[charlief1]

You reminded me of something we did years ago and I had forgotten about. Don't weld the bolts to the frame, weld them to a bar so both bolts are held together on the bar and it just slips in. No knurl to deal with and no bolt head to hold either. The great thing about doing this is you can back the bolts out if you need the clearence to take the control arm out and you never have to worry about them coming loose ever again.