Mountain driving

May 10, 2015, 03:38:32 am

1st time RV'er Getting ready for our first long trip. Headed north. We have not yet had the opportunity to drive on mountain roads so looking for advice.

We have a 2004 40' country coach 350 cummins, with a 6 speed allison 3000 transmission

I know climbing and descending mountains with our coach is going to take some practice. i am hoping to learn from your experience at least as a starting point. What RPS's do others with similar coachs like to climb at? What gear do you choose to start with?

Now same questions on the way down, and when you see a grade sign, say 6%.... what gear do you start with?

Re: Mountain driving

Reply #1 – May 10, 2015, 11:20:24 am

Yahoo Message Number: 100676

Unknown, give us a call, maybe I can give some advice......Skip 2002 Intrigue #11329 166,000 miles.
239-349-0119

Re: Mountain driving

Reply #2 – May 10, 2015, 12:11:21 pm

Yahoo Message Number: 100677

At the bottom of the climb have the cruise off and econo mode on.
Try to be at 60 mph or so if conditions allow. Hold the accelerator position steady as is and avoid mashing it to floor which only consumes diesel without benefit.
Monitor the transmission gearing as you climb and slow. Note the gear the transmission has downshifted to as you crest.
Manually downshift to that gear and ride that down. Use the Jake brake in steps to control acceleration. Be cautious and use the Jake sooner than later . . . best to be safe than sorry.

Re: Mountain driving

Reply #3 – May 10, 2015, 01:39:21 pm

Yahoo Message Number: 100683

For both climbs and descent I keep the gear selector in 5th gear and ready to downshift to 4th as needed. When descending I hardly ever use 6th gear because doing so eliminates any braking action of the transmission and the freewheeling speed can get uncomfortably high.

For 5% downhill grade, and definitely for 6% grade, have the transmission in 4th gear and watch the tach to prevent RPM from climbing above 2500, and preferably hold RPM at about 2200 or less. Understand your engine brake always operates in 4th gear anyway, and so if you manually select 4th gear at the start of your descent, you can then utilize your engine brake most effectively. Also, in case you aren't aware already (at least with my coach) there is a 2stage engine brake that selects either 3 or 6 cylinder braking action.

My engine manual describes the engine brake as designed for use at 2200 or lower RPM, and that only short duration use between 2300-2500 RPM is OK, and that damage can occur above 2500 RPM. SO... If you start your descent into a 5% or 6% grade having already selected 4th gear you can monitor RPM to not exceed 2200 and then alternate between no engine brake or stage 1 or stage 2 braking depending on need. I found that if I descended steep grades in 5th gear and then utilized the engine brake as needed to limit speed, it would too often cause an uncomfortable spike in RPM above the recommended 2200 limit. Each time the engine brake is activated the transmission downshifts to 4th gear and if the tach was already at higher numbers the downshift would run the RPM too high.

My first drive in a motor home was just 18 months ago but I've been from Denver to Oregon and Washington and back twice now and over many mountain passes. Before my first trip I had sleepless nights pondering the possibilities but learned quickly, and downhill isn't a concern any more. You'll get the hang of it. I find I just stay concentrated on the road signs and the degree of descent. Always seems that trucks go downhill faster than I do but that's OK with me. I figure they have many more wheels than I do for braking action, and I'm never in a hurry.

John Coleman
'02 Intrigue

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