Wanting to run the 4-1/2" bolt pattern rotor on my straight axle A. There are some kits out there but it seems the newer kits use a dual pattern g.m. rotor. If it's one thing I hate on a driver it's custom parts. If I break down I like being able to go to local parts store and get what I need. So after crunching numbers I think I figured it out. Using the bearing adapter on the 37-48 round spindles I'm looking at 74 challenger rotors, the inner bearing is .002 bigger but I don't see that as a problem. Next the seal, the national seal is a 472439#, it's .001 bigger on outside bore diameter again no problem and the shaft size is .005 smaller so again no problem that I can see. BTW the seal is a jeep transmission seal. Next I'll get a rotor and mock it up to check caliper placement but I think I've got it beat
Yo do know that the commercial kits that have a 5-on-4-1/2" pattern use a 1975-1981 Volare rotor, right? It is not a custom, or GM part. It has all already been done.
The kit is this: https://www.speedwaymotors.com/Basi...aliper-to-Ford-Spindle-5-on-4-1-2In,7675.html If you already have everything else, then you would still need this (2x): https://www.speedwaymotors.com/Repl...ing-Adapter-for-Early-Ford-Spindle,26936.html This is charted territory.
I used the Speedway kit on my 34 also. Before I mounted everything though I took my stamp set and stamped every part with what it came from the factory as because I always lose paperwork on what parts I use.
Thanks gimpy, yeah I've seen those kits. With the challenger rotors I can use stock challenger bearings. Also I'm using forged bolt on arms with that kit you use flat arms. Also most kits use a special grease seal, this way I won't have to use their seal, it will be a standard OTC part and who knows that might be their "special" seal. Thank you gents for the feedback though.
Special seal? Not in my experience. I have Aspen rotors and the bearing adapters for early Ford spindles. The seals are SKF 19768, readily available.
I've been selling the basic disc brake kit from So-Cal Pomona for several years. It does not use the press on adapters like most kits. Comes with either 4.5 or 4.75 BP. I have no ides what the rotors are? I like it because some of my chassis customers are intimidated by the press on adapter. It may not be for everyone but it works for me.
Yeah it's no problem, mopar used that rotor on just about every big car up into the 80`s and probably many others.
Ok an update, just a quick note on what I'm doing. First off I'm using bolt on steering arms, second, I want over the counter parts and three, I want 4 1/2" bolt pattern. Well 1 above limits me a lot so I tried some other options. Also at one point you could buy a conversion kit for either gm or dodge rotors depending on which bolt pattern you wanted from different vendors well I've noticed lately that's been narrowing down as now many of the kits that allow bolt on arms are using the gm kit with the gm rotor being drilled for both which goes against point 2 above. So then I ordered a set of cheap helix bearing adapters as they are different sized then the ones speed way sales and those fit the gm rotor. Well as I expected the fit is terrible, they are .003 too big on the spindle But they fit the mopar seal and the offset for the rotor to caliber is perfect. IF the internal diameter was .003 smaller it would be perfect for the mopar rotor. Next step, I ordered the speedway adapter and as expected they are set up for a gm rotor and the rotor to caliper offset is .090 different, doesn't sound like a lot but there isn't much play in rotor to caliper pad clearance and the seal area is bigger for the gm seal. Which btw gm and mopar outside seal diameter and inside diameter share nothing in common. Mopar is bigger. So I downloaded the national seal book and found a seal that fits the mopar rotor and the gm inside seal diameter within .005, seal 472439, which is a jeep manual transmission driveshaft seal and it fits perfectly. At this point the only thing left to do is I need to machine .090 off of the back of the speedway adapter and it will place my rotor perfectly centered between the brake pads. So now I have a kit put together that will allow bolt on arms, over the counter rotors, bearings, seals etc with perfect alignment of the rotor to pad. Factory 1974 charger rotors, bearings and cups, jeep trans seals and factory gm caliper and pads, only custom piece is the speedway adapter I had to machine to make everything fit perfect, and it's basically a non wear item.
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