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

ronnilu · 07-28-2006, 01:12 PM

Hi Don & Annie, & welcome to the forum.
Your question reminds me that I still don't know if an exhaust brake would help me or not. My tow vehicle is an '03 GMC Duramx diesel with 5 speed transmission. We first towed a 2950 RK Montana & now tow a larger 3295RK. With both rigs I experienced a steady acceleration when going down steep grades, & when I brake the transmission downshifts as designed, but usually the rpm 's are quite high and then begin increasing as we progress down the hill. The holding back ability of the diesel just doesn't seem to hold back on the steeper grades. I dont feel I wait until speed is too much (usually somewhere in the 55mph range) before beginning to brake. The problem is that even then the vehicle continues to pick up speed downhill with a resultant increasing rpm's going up into the red. To solve the problem I found that by clicking out of the "Tow/Haul" mode and then braking down to around 50 or less before going back into Tow/Haul places the rpm's at a more reasonable rate. I still continue to accelerate and have to repeat this process if the grade is very long. In June we came down Wolf Creek Pass in Colorado, a 7% grade for nine miles, and I had to slow it way down every time we got up to about 35 mph because we were in the lower gears and the rpm's & speed kept increasing. Our travel companion was driving a big block 2000 year Ford diesel with a lighter 5th wheel, and no comparable Allison-type transmission, and he reported having no problems with increasing speed/rpm's. So far my experience has not convinced me that I would do better with an exhaust brake, but for now I will leave everything stock and just keep it slow and continue to manage speed/rpm as I've been doing. As said above, plan ahead & slow down going over the crest & there shouldn't be a problem.

07-28-2006, 01:12 PM	#6
ronnilu Montana Fan Join Date: Jun 2005 Location: Bakersfield Posts: 214 M.O.C. #3933	Hi Don & Annie, & welcome to the forum. Your question reminds me that I still don't know if an exhaust brake would help me or not. My tow vehicle is an '03 GMC Duramx diesel with 5 speed transmission. We first towed a 2950 RK Montana & now tow a larger 3295RK. With both rigs I experienced a steady acceleration when going down steep grades, & when I brake the transmission downshifts as designed, but usually the rpm 's are quite high and then begin increasing as we progress down the hill. The holding back ability of the diesel just doesn't seem to hold back on the steeper grades. I dont feel I wait until speed is too much (usually somewhere in the 55mph range) before beginning to brake. The problem is that even then the vehicle continues to pick up speed downhill with a resultant increasing rpm's going up into the red. To solve the problem I found that by clicking out of the "Tow/Haul" mode and then braking down to around 50 or less before going back into Tow/Haul places the rpm's at a more reasonable rate. I still continue to accelerate and have to repeat this process if the grade is very long. In June we came down Wolf Creek Pass in Colorado, a 7% grade for nine miles, and I had to slow it way down every time we got up to about 35 mph because we were in the lower gears and the rpm's & speed kept increasing. Our travel companion was driving a big block 2000 year Ford diesel with a lighter 5th wheel, and no comparable Allison-type transmission, and he reported having no problems with increasing speed/rpm's. So far my experience has not convinced me that I would do better with an exhaust brake, but for now I will leave everything stock and just keep it slow and continue to manage speed/rpm as I've been doing. As said above, plan ahead & slow down going over the crest & there shouldn't be a problem.