Wilsometer@aol.com wrote:
. The problem with surge brakes is that they do not like long sustained downgrades. What happens is that as soon as you start downhill and the vehicle brakes are applied (or even compression braking of engine/downshifting), the weight of the trailer shifts forward and activates the surge activator's piston/master cylinder. At this point, the trailer brakes are essentially locked on, and the only way to disengage them is to accelerate the vehicle forward (which isn't going to happen going downhill). Invariably, the vehicle brakes are then released as the trailer brakes are engaged, and the trailer brakes are now doing most, if not all, the work for both vehicle and trailer. The net result is often superheating of the trailer brakes (usually accompanied by pronounced brake fade), and in worst case, damage to linings/pads/drums, or rotors. An electric/accelerometer controlled system allows an (adjustable) balancing of vehicle and trailer braking. Also, Disc trailer brakes require almost twice the hydraulic pressure as drums, and there are very few surge couplers (at present) that can produce enough pressure for panic stops.
Scott, I modified the surge brake on M23 Sadhana's trailer by making an adjustable hold off T bar under the sliding hitch using a pair of Z-80 valve springs which delayed trailer brake application until some 200 lbs of pressure was encountered. Worked just fine hauling back and forth over the Siskayous for 10 yrs and allowed descents in drive 3 or 4 with cold brakes for any emergency stop. Shortly after buying the M23 I descended Spooner summit from Lake Tahoe to Nevada and could smell the trailer brakes so stopped at the end of the downgrade and emptied 2 gals of water on the brake drums, instant flash boiling scalding my arm and the rubber wheel cylinder cups and shoes were all cooked. Missed you at the NW cruise, mixed weather, great company and some fine sailing. Regards, Dick, NS 26 Swoose