Pirate Jacks disc brake conversion kits

BillGrissom said
When you throw in a random requirement like that, your choices shrink to almost nothing. True, many kits (Dr. Diff, etc) are based on 1973+ factory disk parts, including its spindle, but I doubt an earlier drum hub with 4" bolt pattern can fit that spindle. Maybe if you found proper-sized wheel bearings, but never heard of that. The 1973+ hubs are integral with the rotors. Perhaps you could re-drill a rotor for 4" bolt pattern, but never read of such.

What scares you about a drum spindle? They are forged, and never heard of one failing. Definitely prefer the 10" drum spindle since beefier and its hub uses larger wheel bearings (SET2 & SET 6). The small bearings in the 9" drum hub can fail (SET 1 & SET4). Indeed, you are better with a drum spindle than the rare disk spindle since most kits bolt to a drum spindle. The SSBC W153 kit bolts to a 10" drum spindle. I wouldn't chose that since it uses the now-rare K-H calipers and rotors. Your best choices to keep your 4" bolt wheels are Scarebird and Wilwood. Scarebird is only ~$120 for brackets and you can source calipers and rotors cheap locally (Toyota & Chevy parts).

The PirateJack kit is just a ‘73+ mopar disk kit. It uses ‘73+ spindles, rotors, calipers, caliper brackets, wheel bearings etc.

The only difference is that the rotors are drilled for the 5x4” bolt pattern, and the outside of the hub registers are turned down slightly so they’re smaller than the original 73+ hubs. It is important to note, however, that they are still a larger diameter than the SBP drum brake hub registers so original SBP drum rims won’t fit.

The only part of the PirateJack kit that isn’t an exact reproduction of ‘73+ original BBP disk brake parts is the finished rotor itself.

The things to consider with that kit are that it does increase the front track width the exact same amount as a 73+ BBP disk conversion. So if your current wheels can’t be pushed out close to a 1/2” without hitting the fenders you’d need new wheels anyway. And the hub registers are still a larger diameter. They’re smaller than the 73+ hubs, but still larger than SBP drum hubs. So if your wheels hub bores fit tight to SBP drum hubs, they won’t fit the PirateJack kit.

On the plus side, if you do ever decide to go BBP, all you need is an off the shelf 73+ rotor.

DoctorDiff, last I heard, was having rotors made that matched the PirateJack kit. So, you can do the same thing and get much better customer service if you call DoctorDiff.