Newly installed LS1 brakes scraping...

[rp0029]

Just installed Ls1 brakes on the front of my 68 camaro. When I installed the brakes, I thought I shimmed them out with washers to where the rotor was square with the caliper. The spindles were drum spindles with the upper boss machined down, but I don't know if the machine shop made the spindle true. I only eyeballed it. I did my best with washers to align the whole thing but no matter what, whenever I tightened the bracket bolts, the rotor got super tight. I did my best and put it all back together, but at first test drive (5 mph) it scrapes from the front driver brake. The scrape is there whether I apply pedal pressure or not, and is not one giant grinding noise, but pulses with the frequency of the wheels.
Where do I begin?

[Apogee]

I would remove the wheel, reinstall a couple of nuts to retain the rotor on the hub, then remove the caliper body with the (2) M8x1.25 x 20 HHCS fasteners and take a good look at your pad abutment brackets (PABs) with respect to how it is aligned over the rotor. The fact that the noise is pulsing and not steady implies to me that you have some sort of axial runnout issue. If you spin the rotor and the clearance between the PAB and rotor changes, that's a problem. The rotor should spin freely at all times, possibly with very slight pad drag when fully assembled, but that's it. If it is getting in a bind when you tighten down the brackets, then something is wrong. You should be able to see exactly where the rotor is being scraped, so determing where the interference is occurring should be the easy part...why is the slightly more involved part.

It could very well be that the spindles were not machined properly. It could also be that the rotors are not fully seating on the hubs which I assume you had machined as well to fit inside the rotor hats. You can get creative with straight edges and digital calipers to determine offsets and flatness if you don't have a magnetic base indicator or something along those lines. If you're limited to a tape measure, it might be time to add some decent measuring tools to your toolbox.

Tobin
KORE3