JetAonly wrote:
Very interesting! The two Duramax I owned had grade braking, and later models have an exhaust brake. You don't mention what year engine/transmission your used. You might find those features useful.
My engine and transmission are from a 2006 GMC Sierra. GM insituted those features later. However, Banks has a unit called a Speedbrake that enables the variable vane turbo in my unit to be an exhaust brake. Tow/haul mode engages the torque converter clutch and changes the shift points to a higher point which is the grade brake feature. I have been able very easily control downhill speeds by simply engaging tow/haul mode and easily shifting down using the electronic shifting capability of the 6 speed Allison. In 3rd gear I desend 6% grades at 50-55 mph and 3300-3500 rpm. The engine red lines.at about 4800 rpm. First gear will bring me down very steep grades like 11-12% without using the brakes.
I had all the wheel bearings (which includes the rear wheels due to the swing axel independent suspension in the rear) packed and the brakes inspected while on this trip. The shoes still look almost new even though they were installed 15 years and 65,000 miles ago when I first bought the coach. While still a gas coach I used the engine for grade decent. I cringe when people talk about brakes heating up on grades. All coaches can and should be coming down with the engine as the brake, not the foot pedal. Brakes are for stopping, not speed control. If you need use the brakes coming down a grade, you are in too high of a gear.
Sorry for the speech, but proper, safe grade decent is a sore subject with me based on living a number years at the base of a 15 mile grade, driven light and medium trucks from time to time and having seen the results of improper decending.
Thanks for the question as you identified an important point.
