PM does a great job as an alternative to the Banana Caliper ... So does GMA ... Of course a drum is very capable of stopping the rear wheel too ... One of the biggest complaints with the Banana Caliper is that is can become quite noisy as the mounting pins and bushings wear ...Ask me how I know :>)

 

^^ This is a Problem certainly
The later "Y" bracket and an 11" rotor should suit everyone I would think!! I am just Not convinced it is "better"..
Like the Drum... long as it is maintained... it works fine..

On Rattling... Rebuilding of the caliper and Pins is a Maintenance item.... I have even made my own bushings... gotta do what ya gotta do..

 

I ran the "Y" bracket with the banana caliper for a lot of years on my Shovel until I fabbed up this early 2000 Softail caliper.

 

JUST 2 CENTS
=========================
Also for brakes the Pads are an important consideration. Stainless steels are hard and allow for use of harder sintered pads that contain metals. This lowers the pads thermal resistance and allows more heat to be dissipated to the pads. Also sintered pads last longer and are less prone to fade than organic pads. They are also better in wet and muddy conditions making them ideal.

Stainless really is a great material for this application not even considering the corrosion resistance it provides. It is not a gimmick.

ISR Brakes use CRSS as it disiaptes heat faster than cast iron and does not crack or shatter. Yamaha were using cast iron discs back in the 1980's before Carbon was used (Yamaha were the first 500cc GP team to use carbon) the discs used to crack every race. But they put up with it as Iron gave the best properties for friction and the strongest brakes. ISR spoke to Yamaha about CRSS discs and Yamaha just dismissed it say all discs crack and it was just one of those things and were happy with the supplier (sponsorship means they were getting them for free... ISR would be selling them to Yamaha so why pay when Brembo were giving them free discs??) So ISR took a rotor and folded it in half and stuck a business card in between the fold with a simple "Our discs do not crack!" written on it.... After that ISR supplied discs until the advent of Carbon brakes.

The brake track itself is kept clean & rust free by the pads, the rest of the rotor, well, that's a bit of a problem. In a car or other motor vehicle it's not a big deal since the disc itself is over an inch thick, it's going to take quite a few years for the rotor to rust to the point where its strength is compromised. On a bike where the rotor is only 2mm thick at most, it doesn't take much rust before the rotor gets weakened to the point where it's unsafe.

Because stainless works just fine, and doesnt rust. The decision was definitely made from an engineering perspective, carbon steel would be a terrible choice.

A carbon steel rotor would rust. I dont know about you, but I dont want to be wire brushing my rotors after every ride to keep rust off. Regular carbon steel rotors will rust from moisture in the air. The rusting is removing material from an already very thin rotor. You'd be replacing rotors often, and we'd see people breaking rotors off the hub frequently.

It's not just the absolute performance. Larger rotors need less pad pressure to achieve the same stopping force. That means less force on the lever as well. That is probably felt as greater control too.

obvious improvement with the larger rotors... taking 5 ft off the stoping distance. 5 feet in a car can be the difference between a minor hit if any, and wearing someone's bumper as braces.

Real world results for the OP instead of scientific argle-bargle above. I weigh 240 lbs, and ride a hardtail. Started with 160's and moved up to 185's. Much better stopping power. Less fade. Can run 5-6 mile downhill grades with far less fade.

Because a large rotor requires less input from the lever to lock up, the modulation is reduced. You start to brake by pulling the lever, initially there's just some slack. You increase pressure on the lever to pad contact -> slight braking. Add pressure -> more braking. Finally, lock up. If you have a large rotor, the lock up will happen sooner (at a lower pressure on the lever) compared to a small rotor.

Basic physics.
Larger rotors act a larger lever arm.
The wheel radius is one lever, the disc radius is the 2nd lever
The axle is the is fulcrum.
Therefore a larger rotor will have more leverage = more power from the longer lever .
And as a byproduct of greater surface area it stays cooler =less brake fade.

Velocity has very little effect on the coefficient of friction. Temperature, on the other hand, has a rather large effect. The coefficient of sliding friction between the brake pads and rotor decreases as temperature increases, which contributes to the dreaded brake fade. The pressure applied to the rotor by the brakes pads will be the same regardless of the size of the rotor, assuming both are operating at the same temperature. The larger rotor, however, will generate more braking torque than a smaller rotor when applying the same pressure to the brake lever.

The single biggest advantage is improved resistance to heat. For two reasons. One, the larger rotor will have more area to cool, so it's more resistant to fade. Two, the larger diameter will allow for a greater mechanical advantage after fade sets in, so it performs better under fade.

Vented, slotted, and drilled will improve cooling. Vented the single best for that. Slotted and drilled will improve resistance to fade. Fade is usually accompanied by gas pressure from the pads heating up making a lubricating bufffer between the pad and the rotor. The slots and drill holes give the gas a place to go, so for the same temperature, the fade will be less with slotted and drilled rotors.

 

^^ that"s more than 2c there...
We are still talking about Shovelheads tho right???
or are we building Competition Bikes from scratch?? using a Shovel for power????
.

 

Hi, I just joined today and was reading your discussion about the banana brakes, I just dragged an '81 NOS caliper and mount out of my stash today and noticed it's a real tight fit, I think it's due to the addition of the anti-rattle clip and that high tech plastic seal, feels really solid

 

the seal was pretty hi-tech for HD in 1981 it seems

 

seal