Cast iron or aluminum drums?

[Guest buschj]

The JTR manual says that replacing the aluminum drums with cast iron drums and installing a proportioning valve will decrease stopping distances. They also admit that the cast iron drums will not cool as efficiently as the original aluminum drums. My dilemma began this morning when I was watching a 1960’s race at Sebring and the Triumph engineers replaced the cast iron drums with aluminum drums for the 12-hour race. Can anybody confirm that the best choice without converting to disk is the cast iron drums?

[johnc]

Look at what the racers use: aluminum.

[Mike C]

The aluminum are lighter and finned for cooling, but the cast iron will give you better braking and a firmer pedal. I would definitely suggest this as a budget alternative to rear discs. If you are racing you may need the aluminums ability to shed extra heat, but for the streets the iron is best IMO.

[Dan Baldwin]

I'm convinced that the "iron drums are stiffer and give better pedal feel" effort is a myth invented by 510 drivers who want our aluminum drums. I can't imagine there's any benefit, and there's definitely increased unsprung mass and reduced heat dissipation. Plus, the finned aluminum looks cool (for drums). When I swapped in ZX disks at the rear, a 510 racer snapped up my drums in a heartbeat. No complaints from him:) I never had any pedal feel/firmness issues at the track with the aluminum drums myself, either.

[johnc]

The stock braking system on an early Z is not the limiting factor in braking distances. The biggest limiting factor is tires. From pretty much any speed you can lock all 4 wheels on a Z if you press hard enough on the brakes. And that's even true with super sticky 225 Hoosier R3S03s.