Quote:
Originally Posted by bobsmanstuff
good video
|
Well,
NOT so good video. I like Wilwood products, but their explanation of a drum residual is
total BS!
Why in the hell would you want the shoes to float inside a drum, with only .020"-.030" or so
total drum-to-shoe clearance?? Drum shoe return springs do just that-return the shoes to their anchors, as they were designed to do.
I didn't recommend looking for residual info because there are still so many who don't know how or why they work, including some brake suppliers that should know!
Drum residuals are necessary in older drum systems because of the strong shoe return springs that can cause air to enter past the cylinder cups when releasing the brakes quickly. Production residual "check" valves ranged in pressure, but the aftermarket uses 10 lbs for drums. Wheel cylinder cup expanders made residuals obsolete by the mid '70s along with front discs.
Modern disc brakes never used residuals because the masters have all been mounted higher than the calipers, preventing any fluid transfer back to the master reservoir. However, if the master is located lower than the calipers, an aftermarket 2 lb residual will prevent any fluid transfer.