Mountain Driving

[wstalker]

So, tomorrow we will be doing our first drive through some mountain ranges for a trip from Tucson, Az. to Lake Roosevelt, AZ. I have been doing a lot of reading and I have traveled extensively in the US, but not in a big motorhome. I have towed a 40 foot fifth wheel through the mountains. My rig has an engine brake, with low, high, or off settings. I have a 400 HP Cummins with six speed Allison transmission. Any hints from people would be greatly appreciated.

[Selah]

When aproching a steep ascent gain a little speed to help keep your momentum up. Once you lose that momentum it is hard to get it back.
Start steep down grades at a lower speed. I start with my Jake Brake in low and that us usually sufficient, especially if you started at a slow speed. I'll switch to Hi if needed.
Use the Jake on low in towns and traffic.
Everything else is going to,be just like pulling the 5 er.

[Sandy Swede]

Saleh has given good advice. Just don't let your RPM's get over 2,000 when going downgrade. You may have to use the service brakes, but don't ride 'em.

You said that you plan to drive your MH from Tuscon to Roosevelt Lake. Just be sure not to take the Apache Trail (Hwy 88) from there to Phoenix. Have fun!

[jerichorick]

Originally Posted by wstalker

So, tomorrow we will be doing our first drive through some mountain ranges for a trip from Tucson, Az. to Lake Roosevelt, AZ. I have been doing a lot of reading and I have traveled extensively in the US, but not in a big motorhome. I have towed a 40 foot fifth wheel through the mountains. My rig has an engine brake, with low, high, or off settings. I have a 400 HP Cummins with six speed Allison transmission. Any hints from people would be greatly appreciated.

I had a '05 Vectra FD. No problems in the mountains. I always left the engine break switch on. That engine has a 2 stage if I recall correctly. Worked very well on steep down grades and was a great asset when stopping.

Watch your RPM and don't over rev on the down grade when coasting. Manually downshift on the upgrades before you loose too much momentum and don't have the transmission in the econo mode. Again, keep an eye on the RPM.

This Meridian has a Cummins 380hp with the DEF system. We went over the Grand Teton highway, a 10% grade up and down. The speed limit was 25mph. Did it on the up side with the cruse control engaged. My engine break is not as strong as yours and, with the AF1 helping on the car, the down grade did not overheat the breaks. I must admit that I was too busy to sight see while driving, but it was a fun driving trip.

Bottom line: Be wise, alert and enjoy your trip. It is a beauty!

Happy trails,
Rick Y

[OLYLEN]

Look over engine owners manual, the red line for compression braking is higher than under load. Your motor will protect itself and do an up shift if RPM goes too high. As above use stab braking 5-10 MPH then if speed increases again stab again. Play with high low and gear select to set the speed you wish. Up hill you may want to select a gear to make the motor happy, best cooling or torque.

LEN

[wstalker]

So we made the trip and the coach did fantastic. There were times when we revved over 2k on the downhills with the engine brake, but according to the manual it would upshift if necessary. I had more of an issue not knowing the mode of the transmission. The mode button will light up in a certain position, but I am not sure when I am in economy or what the different modes are. The Allison book was no help with that issue. There is supposed to be an indicator light that tells you what mode you are in, but apparently mine is not working. I did have times when I probably should have been in a lower gear when climbing and there were also times when I shut off the engine brake as the coach did better without it. I never used the high position on the engine brake. The worst incline was 8%. Any errors were mine. I'm still learning, but very impressed with the capabilities of the rig. Thanks for all that chimed in.

[Jim_HiTek]

Truck drivers would give you this advice, go down the hill no faster than you went up.

Me, I creep up to the tops of hills...I'm retired, no need to be in a hurry. Use the exhaust brake all the way down and the brakes to stay at a reasonable speed. Again, why hurry? This is a 28,000 pound vehicle and I'd never forgive myself for plowing into some family car because I was heading downhill too fast.

[TonyDi]

On a long uphill be aware of traffic around you, and who might be overtaking you. There's nothing worse hen overtaking a slow moving vehicle and just as you start to pass someone passes you. You take you foot off the accelerator or have to brake. The resulting deceleration will kill all the momentum you had, and then you will just wind up lugging it up the rest of the grade.

[jerichorick]

Originally Posted by wstalker

So we made the trip and the coach did fantastic. There were times when we revved over 2k on the downhills with the engine brake, but according to the manual it would upshift if necessary. I had more of an issue not knowing the mode of the transmission. The mode button will light up in a certain position, but I am not sure when I am in economy or what the different modes are. The Allison book was no help with that issue. There is supposed to be an indicator light that tells you what mode you are in, but apparently mine is not working. I did have times when I probably should have been in a lower gear when climbing and there were also times when I shut off the engine brake as the coach did better without it. I never used the high position on the engine brake. The worst incline was 8%. Any errors were mine. I'm still learning, but very impressed with the capabilities of the rig. Thanks for all that chimed in.

Congratulations Will! You did good on your first run.

The little red light in the upper right hand corner of the "Mode" button can be hard to see in bright light. When it is on you are in Econo mode. Off is power mode. Your Freightliner manual has this information (if I recall correctly). I wonder if the light my be dirty. Try cleaning it with a q-tip.

Did you enjoy your adventure? Hope so!

Rick Y

[Saber77]

Rule of thumb is to descend using the same gear you used on the ascent and engage the engine brake for a slow, but controlled descent. Do not allow the speed to build up! Use the truck lane with flashers on.


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