Montana Owners Club - Keystone Montana 5th Wheel Forum - View Single Post

Bob Pasternak · 11-10-2004, 02:41 AM

Glenn: From what I've read on D/max, as soon as your foot is off the brake it will go back to OD or whatever it was in.(Somebody tell me if I'm wrong.) You must manually shift to a lower gear. The big ones use Jakes in conjunction with gearing down. We also had switches on the dash to use 2, 4 or 6 cylinder retarding. You DO NOT start down a severe grade (south bound I-15 Cajon, 22 miles of 3 to 9%, east bound I-40 from Barstow to Needles, northbound I-5 Grapevine and others too numerous to mention.) in high gear and rely solely on the Jake to hold it back. Read my other post again. Start down the grade in a gear you're sure will hold it. Then you can shift up...maybe. With a 4 or 5 speed automatic you'll not have quite the braking effort of a tranny with more gears. The newer Jakes will give about 90%+ of the engine horsepower to braking effort. And you do not use exhaust brakes or Jakes on slippery roads. Instant jack-knife because all the braking effort is applied to the drive wheels. My experience has been with engines of 300 to 500+ HP, transmissions with 9 to 18 speeds, and gross weights up to 80,000+ lbs. The premise is the same regardless of size and weight.

11-10-2004, 02:41 AM	#12
Bob Pasternak Montana Master Join Date: Jan 2004 Location: St. John Posts: 591 M.O.C. #800	Glenn: From what I've read on D/max, as soon as your foot is off the brake it will go back to OD or whatever it was in.(Somebody tell me if I'm wrong.) You must manually shift to a lower gear. The big ones use Jakes in conjunction with gearing down. We also had switches on the dash to use 2, 4 or 6 cylinder retarding. You DO NOT start down a severe grade (south bound I-15 Cajon, 22 miles of 3 to 9%, east bound I-40 from Barstow to Needles, northbound I-5 Grapevine and others too numerous to mention.) in high gear and rely solely on the Jake to hold it back. Read my other post again. Start down the grade in a gear you're sure will hold it. Then you can shift up...maybe. With a 4 or 5 speed automatic you'll not have quite the braking effort of a tranny with more gears. The newer Jakes will give about 90%+ of the engine horsepower to braking effort. And you do not use exhaust brakes or Jakes on slippery roads. Instant jack-knife because all the braking effort is applied to the drive wheels. My experience has been with engines of 300 to 500+ HP, transmissions with 9 to 18 speeds, and gross weights up to 80,000+ lbs. The premise is the same regardless of size and weight.