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What’s the largest size rotors I can put on my 72 Cutlass with stock 15 rallys? I came across some 14 inch rotors disc brakes. Will they fit?
No, 14" rotors will not fit inside a 15" wheel (unless you do not plan to use calipers). Here are my 14" rotors on the front of my vista cruiser. With an 18" wheel there is only a little over 1/8" between the caliper and the wheel. When I had the tires balanced, the shop used 2 layers of stick-on wheel weights in a couple spots. After a revolution, those areas were down to 1 layer of weights. You might get away with a 12" rotor, but in most cases even they require at least a 16" wheel.
Last edited by Loaded68W34; Aug 17, 2024 at 08:22 PM.
No, 14" rotors will not fit inside a 15" wheel (unless you do not plan to use calipers). Here are my 14" rotors on the front of my vista cruiser. With an 18" wheel there is only a little over 1/8" between the caliper and the wheel. When I had the tires balanced, the shop used 2 layers of stick-on wheel weights in a couple spots. After a revolution, those areas were down to 1 layer of weights. You might get away with a 12" rotor, but in most cases even they require at least a 16" wheel.
Damn that’s a tight fit! But you’re tellin me there’s a chance if I put my 18s on huh? I have the same wheels. Boss 338. But I like riden my rallys too.
First of all, clearance depends on BOTH the rotor diameter AND the caliper configuration. Wilwood has templates of their calipers that can be used to check clearance.
Second, the factory 15x7 SuperStock ("Rally" is a Chevy wheel) uses the same center stamping as does the 14" SuperStock wheel. That means that 15" versions use a special rim that has a greater amount of "drop" in the center to mate up with that center stamping. The result is that the Olds SuperStock wheels DO NOT clear the same calipers as will other 15" wheels. Diameter isn't the only thing that matters. I would expect that the factory 15x7 SuperStock wheels won't clear anything larger than the OEM 10.75" rotors and D52 calipers.
First of all, clearance depends on BOTH the rotor diameter AND the caliper configuration. Wilwood has templates of their calipers that can be used to check clearance.
Second, the factory 15x7 SuperStock ("Rally" is a Chevy wheel) uses the same center stamping as does the 14" SuperStock wheel. That means that 15" versions use a special rim that has a greater amount of "drop" in the center to mate up with that center stamping. The result is that the Olds SuperStock wheels DO NOT clear the same calipers as will other 15" wheels. Diameter isn't the only thing that matters. I would expect that the factory 15x7 SuperStock wheels won't clear anything larger than the OEM 10.75" rotors and D52 calipers.
On my 73 cutlass supreme,
Wilwood D52 calipers wouldn't even clear my 15" SSII's. I have the powerstop rotors
I'd have to modify the caliper or use a wheel spacer
Let's all keep in mind that the SS II/III wheels use the same center disc for both 14" and 15" versions. The 15" wheels have a special hoop that has a dropped center section to match the ID of the 14" hoop. The result is even less caliper clearance than for a normal 15" steel wheel.
Here's an illustration of why SS II/III wheels do not provide the same clearance for disc brakes that other 15" wheels provide. The use of the same center as on the 14" wheels results in less room for the calipers.
