best disc brakes for sbp
I received the Centric K-H rotors. The photos below show some issues involved in installing them on a 10" drum car. The rotor is shown where I think it would sit relative to the spindle. I don't have a spare hub to fit.
On a hub (drum installed), I measure/estimate 2.15" from hub face to spindle face. The K-H rotor is 1.96" from hub face to inner rotor face, putting the rotor 0.19" off the spindle face. That is ample thickness for a caliper bracket plate to bolt to the spindle face. Indeed, as the photos show, the bracket could turn inward and be enclosed within the rotor and thus be even thicker. But, for comparison the drum backing plate is 0.15" thick, so 0.19" seems fine.
The caliper shown is a '95 Camry (10.825"D rotor). The bracket bolts to the front of the spindle, which would have better fit the Lebaron/Acclaim/Voyager rotor (14" wheels) I was considering. However, for the K-H rotor's taller hat, a caliper that bolts to the rear of the spindle might fit better (90's Mopars and others). I might return the Toyota calipers and try those. If lucky, a simple flat plate could serve as the caliper bracket, though I noticed Scarebird has complicated designs for other cars that bend to pickup bolts on both front and rear of the spindle, so he could design most anything.
There is much more to the problem than axial positions. The inner face of the K-H rotor is shown. While the rotor hat ID clears the drum hub's 5.50" OD, there is a machined counterbore 0.1" deep that is only 5.188"D. I don't know if just on the Centric rotors. I thought the only thing that touches the inner side on the disc cars is the lug bolt heads. The only way to deal with this is to machine a matching face on the drum hub or make a spacer. A thin plate could kill other birds like provide a hub register. While seemingly simple, we know what wheel adapters cost. One couldn't bolt the rotor as is since the gap would cause the rotor to warp and perhaps lug nuts loosen.
In the background of the above photo is a mockup showing why the Voyager 5x100 mm rotors won't work. The hat is too low, causing the caliper to hit the wheel. Some wheels bow outward to clear the caliper, but my 14" Cragars only bow 3/8" out from the hub face. My dream caliper is the Wilwood 120-8729, a 4-pot aluminum body for 0.81" th rotors to 11"D. It needs only 12.32"D for the wheel to clear. It sticks out 1.46" from the rotor face, but the K-H rotor hat is 1.47", and most wheels bow out a bit more, so should work fine. Cost $139 ea (free shipping).
BTW, ignore earlier comments about the rotor axial position affecting how braking tries to turn the wheel. I should have drawn a diagram. Since the caliper also attaches to the spindle, all moments are reacted out in the wheel bearings. The only thing that affects the tendancy to turn the wheel is where the tire's contact point on the road is relative to the spindle axis (line thru ball joints). They always angle the spindle axis so it goes thru the contact point on the road, which is why the upper ball joint is more inward than the lower one (see photo). Where the rotor sit does affect bearing loads, but I would think braking forces are minor compared with vertical loads like road bumps. I don't know why disc brake cars had stouter lower ball joints (not just Mopar). Probably a performance idea. On a related note, did V8's really require bigger hubs and drums than Slant Six's? The later were definitely under-sized, probably due to cost targets (both hubs failed on my Slant).
I received the Centric K-H rotors. The photos below show some issues involved in installing them on a 10" drum car. The rotor is shown where I think it would sit relative to the spindle. I don't have a spare hub to fit.
On a hub (drum installed), I measure/estimate 2.15" from hub face to spindle face. The K-H rotor is 1.96" from hub face to inner rotor face, putting the rotor 0.19" off the spindle face. That is ample thickness for a caliper bracket plate to bolt to the spindle face. Indeed, as the photos show, the bracket could turn inward and be enclosed within the rotor and thus be even thicker. But, for comparison the drum backing plate is 0.15" thick, so 0.19" seems fine.
The caliper shown is a '95 Camry (10.825"D rotor). The bracket bolts to the front of the spindle, which would have better fit the Lebaron/Acclaim/Voyager rotor (14" wheels) I was considering. However, for the K-H rotor's taller hat, a caliper that bolts to the rear of the spindle might fit better (90's Mopars and others). I might return the Toyota calipers and try those. If lucky, a simple flat plate could serve as the caliper bracket, though I noticed Scarebird has complicated designs for other cars that bend to pickup bolts on both front and rear of the spindle, so he could design most anything.
There is much more to the problem than axial positions. The inner face of the K-H rotor is shown. While the rotor hat ID clears the drum hub's 5.50" OD, there is a machined counterbore 0.1" deep that is only 5.188"D. I don't know if just on the Centric rotors. I thought the only thing that touches the inner side on the disc cars is the lug bolt heads. The only way to deal with this is to machine a matching face on the drum hub or make a spacer. A thin plate could kill other birds like provide a hub register. While seemingly simple, we know what wheel adapters cost. One couldn't bolt the rotor as is since the gap would cause the rotor to warp and perhaps lug nuts loosen.
In the background of the above photo is a mockup showing why the Voyager 5x100 mm rotors won't work. The hat is too low, causing the caliper to hit the wheel. Some wheels bow outward to clear the caliper, but my 14" Cragars only bow 3/8" out from the hub face. My dream caliper is the Wilwood 120-8729, a 4-pot aluminum body for 0.81" th rotors to 11"D. It needs only 12.32"D for the wheel to clear. It sticks out 1.46" from the rotor face, but the K-H rotor hat is 1.47", and most wheels bow out a bit more, so should work fine. Cost $139 ea (free shipping).
BTW, ignore earlier comments about the rotor axial position affecting how braking tries to turn the wheel. I should have drawn a diagram. Since the caliper also attaches to the spindle, all moments are reacted out in the wheel bearings. The only thing that affects the tendancy to turn the wheel is where the tire's contact point on the road is relative to the spindle axis (line thru ball joints). They always angle the spindle axis so it goes thru the contact point on the road, which is why the upper ball joint is more inward than the lower one (see photo). Where the rotor sit does affect bearing loads, but I would think braking forces are minor compared with vertical loads like road bumps. I don't know why disc brake cars had stouter lower ball joints (not just Mopar). Probably a performance idea. On a related note, did V8's really require bigger hubs and drums than Slant Six's? The later were definitely under-sized, probably due to cost targets (both hubs failed on my Slant).
