Mountain Driving

[srappleby]

We are taking our first big road trip this summer! Our route will take us through the Smoky's, up to the Dakotas and down the eastern side of the Rockies, through Denver and Colorado Springs. In Florida, our elevation doesn't change more than about 300 feet so, mountain driving in a MotorHome has me thinking.......

Any suggestions from those experienced with driving these rigs on these kinds of roads? The Legacy has an Allison 6-speed trans. We'll be flat towing a CR-V (another new adventure) on a Blue Ox bar. I'm particularly interested in advice about manually shifting the transmission for safety and efficiency while climbing and descending.

Thanks

[dalford]

I can’t help you with driving since I pull a 5th wheel with a diesel engine. Not sure if you are diesel or gas and if you have exaust brakes. Others will chime in.

All that being said I still worry about mountains and climbing them and more importantly descending them. Want to be able to control speed. I use the Mountain Directory. This directory gives critical information for all mountain roads so you can be prepared for what you are going to encounter or even decide to alter your route to avoid a white knuckle drive.

It is not free and you buy regions based on what you need. The graphics could use some improvements but I find it to be invaluable.

Check it out... Mountain Directory for Truckers, RV, and Motorhome Drivers

[mwdilday]

I also do not have a motorhome - I am towing a 18,000 lb fifth wheel. I use the Garmin™ RV 760LMT GPS. It has elevation charts that are updated along the route in real time. It also alerts to turns ahead. I is a big help driving thru the mountains. I control my speed on descents and have engine braking on my F-350 Diesel. Works great.

[HangDiver]

If it helps at all the front range of the Rockies is relatively flat.

[rskeans]

I've traveled many steep grades both up and down. Keep your exhaust brake on maximum braking. Drop down a couple gears for going up or down. Use your head. Keep control of the vehicle.

[Cypressloser]

I don't drive a motorhome, but I have (believe to have) experience driving heavy trucks with 10 speed and 13 speed standard transmission and we pull our 5th wheel over the continental divide regularly.

Make yourself familiar with the terrain before the trip.
Keep your eyes on the road and on the gauges.
With the Allison transmission lock out 6th gear, lock out 5th and 4th gear as well if necessary and turn the engine brake on medium or high.
Going uphill find a gear that the engine is comfortable maintaining, constant shifting is hard on the transmission and can easily cause it to overheat.
Keep your foot off the brakes, use the engine and the transmission to control the speed and to slow down. Using the air brakes to much can deplete your air reservoir and smoke the drums, especially on long descends.
Make sure you approach curves at slower speeds than normal, slowing down on down grades takes twice (or is it 4 x?) the effort.
Use common sense and enjoy the drive.

[KRedburn]

Just came over the rockies. The DX3 was a dream to drive. Traveled from Ogden, Utah to Cheyanne, Wy then down to Denver.

Use your engine/jake brake drop a gear or two going up the long steep roads drop one gear and the engine brake on hi for the down side.
Pay attention to the curves. Most were marked well when there was a slower recommended speed. I traveled in the "sweat" spot that the MH seemed to like = right around 66 mph. I watch what the OTR drivers are doing when approaching curvy areas that I haven't traveled before.

Take your time and pay attention to your temp gauges. If they start climbing fast then back off a bit and enjoy the ride.

[formerFR]

your exhaust brake is perfectly designed to provide slowing while descending mountains, with a little help with the pedal brake periodically... you don't 'have' to do ANY manual shifting - I never have, and we've taken the same routes, Alaska, Colorado, Idaho, and yes, the 'Smokies' between Cherokee NC and Gatlinburg TN... we LIVE in the western NC mountains, and believe me, they can be just as 'fun' here as anywhere.... just try the mountain drive between Helen GA and Hiawassee GA(just south of here), or the Hwy64 drive between Franklin NC and Hendersonville NC!

you coach and ours are almost twins : )

for the exhaust brake, you can also override it's slowing by adding just a slight push(feathering) on the fuel pedal, when desired. I drive with mine seldom 'ON', though, except when descending mountains or when interstate driving on cruise, as it will kick in to help limit the downhill speed pickups above your stated cruise range. The exhaust brake is designed to help keep you at the same speed as when you 'engaged' it by coming off the fuel pedal, so topping a mountain pass or hill at 45 and engaging the exhaust brake will continue to try to keep you at that similar speed on the way down, with you helping manually with the brake pedal if needed.

use 'MODE' to get the best economy, take it off when ascending the mountains, and just let the engine and trans take over, even when you have your foot firmly all the way to the 'floor'...

fun! you'll enjoy, don't fret, it's designed for just where you want to go!

[sleepybadger]

I'd detach the toad and drive it independently to take that extra load off the rv if you are still concerned when you get there. Less to pull up and less to slow down that way.

We did the bighorns last summer in a class c gasser. Going up wasn't an issue, dropped gears and pulled over at a couple overlooks on the way up so wife could take pictures. Going down, don't worry about the vehicles behind you. Take it slow and if you do use your brakes, take yourself below the speed you want by 5-10mph so you have more coasting time to let them cool back off.

-Sleepy

[srappleby]

Thanks FormerFR, I was hoping you would weigh in as I know your Pallazo is essentially the same machine as my Legacy. Also, if I'm not mistaken you "porter" a lot of different rigs around the country, right?

Love driving the Hiawassee/Cherokee area.....in a car!! Been up to Nantahala a couple of times and Blue Ridge, GA was a regular cabin rental place for us before we bought the coach.

I've driven stick-shift cars all my life and am familiar with down-shifting when climbing and for slowing. And when driving the family in the mountains in the mini-van, I use the automatic transmission, manually a lot! Just trying to anticipate what to expect with 30,000 lbs of fun.

So, you don't ever find yourself running in anything other that "D" when climbing or descending? The tranny seems to find the right gears most of the time?

Lastly, we budgeted to set up a Corolla to drag behind and since its only 2,300 lbs, I was going to skip the aux brake unit for now. We changed our plans and are setting up the CR-V to flat tow and it's about 3,300 lbs. looks like braking system would be required in pretty much all but a few states but I also see a lot of folks on here who run without and don't have problems. Your thoughts and experience?

[srappleby]

Originally Posted by sleepybadger

I'd detach the toad and drive it independently to take that extra load off the rv if you are still concerned when you get there. Less to pull up and less to slow down that way.



We did the bighorns last summer in a class c gasser. Going up wasn't an issue, dropped gears and pulled over at a couple overlooks on the way up so wife could take pictures. Going down, don't worry about the vehicles behind you. Take it slow and if you do use your brakes, take yourself below the speed you want by 5-10mph so you have more coasting time to let them cool back off.



-Sleepy

Thank you sleepy, I'm keeping the "drive the toad separate" as a Plan B.

[srappleby]

Originally Posted by Cypressloser

I don't drive a motorhome, but I have (believe to have) experience driving heavy trucks with 10 speed and 13 speed standard transmission and we pull our 5th wheel over the continental divide regularly.

Make yourself familiar with the terrain before the trip.
Keep your eyes on the road and on the gauges.
With the Allison transmission lock out 6th gear, lock out 5th and 4th gear as well if necessary and turn the engine brake on medium or high.
Going uphill find a gear that the engine is comfortable maintaining, constant shifting is hard on the transmission and can easily cause it to overheat.
Keep your foot off the brakes, use the engine and the transmission to control the speed and to slow down. Using the air brakes to much can deplete your air reservoir and smoke the drums, especially on long descends.
Make sure you approach curves at slower speeds than normal, slowing down on down grades takes twice (or is it 4 x?) the effort.
Use common sense and enjoy the drive.

It's been a while since I read through the Allison Operators Manual (yes, I'm one of THOSE people lol) and plan to glance at it again before our trip. By "lock out 6th gear", do you mean press the arrow down button on the shifter (mine's digital) so that the left digit is a 5? My understanding of that process is that the tranny will operate as normal except that it wound go higher the 5th. Set it to 4 and the tranny will use only 1st, 2nd, 3rd, and 4th gears shifting as it sees fit. Is than correct?

[formerFR]

yes, but the exhaust brake will already do that for you... don't over complicate it.

[tmartin]

I have a 2015 Legacy and live in the mountains of Colorado. I tow a Jeep or a 22 foot enclosed trailer when we travel. Most of the highways are 65 mph in Colorado. When climbing a mountain, I keep the transmission in automatic, it will downshift on its own when needed. I can hold 50-60 mph on most climbs unless traffic causes me to slow down. If I lose my momentum, I can’t get it back up to speed on the climb so I move into the right lane with the big trucks and wait for a downhill to get it back up to speed. Acceleration is very poor when towing and climbing. On the downhills I engage the engine brake at the top of the hill, the best gear for most descents is 4th. When engaging the engine brake it will also start downshifting the transmission, most of the time if I’m not going too fast when I engage the engine brake it will go to 4th gear. For it to go into 3rd, the bus needs to be slowed down into the 40s range. Like climbing, I don’t manually override the transmission as the engine brake will put it in the lowest gear based on the speed. The engine brake does not work when the cruse control is on. Also the cruse control will not downshift itself to control speed on a descent like most cars. It will quickly gain speed when rolling downhill so the engine brake is your best way to control speed with the cruse control off. When the engine brake switch is on, the brake only engages when your foot if off the accelerator, if you give it some gas, the brake turns off and you can drive normal but when you let up again, the brake comes back on. I have never seen a temperature increase in the transmission or engine beyond a few degrees when climbing and towing so overheating is not an issue. Last thing, do not drag the air brakes all the way down a descent. If you need to brake, use them to slow down to allow the transmission to downshift and then get off them to allow them to cool. Holding the brakes on all the way down a mountain will cause them to overheat. The big descents are marked for the trucks so you can be prepared to move over into the slower lanes and get your engine brake on. Have fun.

[67L48]

When going up the grades in the Rockies, you'll be in the 8,000 - 11,000 foot range. Power loss is going to be ~3% per 1,000 feet over some nominal value for your engine (usually 500 - 1,500 feet). That adds up fast (e.g., at 10K, you're losing ~27% of your rated power ... 320 hp engine delivers 230 hp). Turbos in diesels and some gasoline engines help to overcome this, but it is still limited by the scarce oxygen in the air.

The other issue is that the roads are often two lanes with heavy truck traffic. That means that the speeds range between 80 MPH for unencumbered passenger cars to 20 MPH for big rigs. This can be really dangerous due to these massive speed differences and can make lane changes and passing tricky.

Be careful and don't worry one bit about crawling up the passes in the 35-50 MPH range.

I think the Smokies (apostrophe withheld) are an order of magnitude smaller and probably not as difficult to traverse.

Good luck.

[srappleby]

Thanks to all for the info. I think I got this, now. Lol

[TKN 516]

Originally Posted by formerFR

your exhaust brake is perfectly designed to provide slowing while descending mountains, with a little help with the pedal brake periodically... you don't 'have' to do ANY manual shifting - I never have, and we've taken the same routes, Alaska, Colorado, Idaho, and yes, the 'Smokies' between Cherokee NC and Gatlinburg TN... we LIVE in the western NC mountains, and believe me, they can be just as 'fun' here as anywhere.... just try the mountain drive between Helen GA and Hiawassee GA(just south of here), or the Hwy64 drive between Franklin NC and Hendersonville NC!

you coach and ours are almost twins : )

for the exhaust brake, you can also override it's slowing by adding just a slight push(feathering) on the fuel pedal, when desired. I drive with mine seldom 'ON', though, except when descending mountains or when interstate driving on cruise, as it will kick in to help limit the downhill speed pickups above your stated cruise range. The exhaust brake is designed to help keep you at the same speed as when you 'engaged' it by coming off the fuel pedal, so topping a mountain pass or hill at 45 and engaging the exhaust brake will continue to try to keep you at that similar speed on the way down, with you helping manually with the brake pedal if needed.

use 'MODE' to get the best economy, take it off when ascending the mountains, and just let the engine and trans take over, even when you have your foot firmly all the way to the 'floor'...

fun! you'll enjoy, don't fret, it's designed for just where you want to go!

Came here to say exactly this... Excellent response formerFR!

[elchilero53]

The best advice out west is take it easy on those long steep grades both up and down. I don't push hard going up hill on a long climb and really take it easy going down a long grade. I use the engine to brake the truck/trailer combo. Works every time without fail. And as stated before, stay off of your brakes except to maintain your speed and then use them sparingly to avoid overheating.

[cgpalmer]

Originally Posted by tmartin

I have a 2015 Legacy and live in the mountains of Colorado. I tow a Jeep or a 22 foot enclosed trailer when we travel. Most of the highways are 65 mph in Colorado. When climbing a mountain, I keep the transmission in automatic, it will downshift on its own when needed. I can hold 50-60 mph on most climbs unless traffic causes me to slow down. If I lose my momentum, I can’t get it back up to speed on the climb so I move into the right lane with the big trucks and wait for a downhill to get it back up to speed. Acceleration is very poor when towing and climbing. On the downhills I engage the engine brake at the top of the hill, the best gear for most descents is 4th. When engaging the engine brake it will also start downshifting the transmission, most of the time if I’m not going too fast when I engage the engine brake it will go to 4th gear. For it to go into 3rd, the bus needs to be slowed down into the 40s range. Like climbing, I don’t manually override the transmission as the engine brake will put it in the lowest gear based on the speed. The engine brake does not work when the cruse control is on. Also the cruse control will not downshift itself to control speed on a descent like most cars. It will quickly gain speed when rolling downhill so the engine brake is your best way to control speed with the cruse control off. When the engine brake switch is on, the brake only engages when your foot if off the accelerator, if you give it some gas, the brake turns off and you can drive normal but when you let up again, the brake comes back on. I have never seen a temperature increase in the transmission or engine beyond a few degrees when climbing and towing so overheating is not an issue. Last thing, do not drag the air brakes all the way down a descent. If you need to brake, use them to slow down to allow the transmission to downshift and then get off them to allow them to cool. Holding the brakes on all the way down a mountain will cause them to overheat. The big descents are marked for the trucks so you can be prepared to move over into the slower lanes and get your engine brake on. Have fun.

Great advice! I read this as we were traveling west towards Yellowstone. Followed your advice and also Former FR and it worked out great and relatively stress free. The transmission and exhaust brake really did a great job and I was surprised how little I used the air breaks in ascending and descending 9,600 feet. And we did have fun!

[linchat]

Drove the Rockies last year, your going to love the 7% grades over 2-3 miles lol. I am used to the southern flat lands and hills. So the Rockies was a bit wild.

Likes others said, keep your speed down, be patient and like a car do not ride you breaks. Your are better off with a good hard 2-3 second break to drop your speed 10-15 mph then riding the breaks down 10-15 mph. Then let breaks cool and let the tran help maintain / engine break speed down.

In those 7% declines, I do not think my engine break did much of anything. lol.

Like someone else said, if you loose you speed going up, your are not going to get the speed back up (esp if your towing). So ride up the mountain slowly and enjoy.