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Old 03-24-2023, 03:06 AM   #1
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THOR #28437
Driving in mountains

Have a 17' Thor Miramar 35.2. I am a novice and looking for advice on going up and down hills/mountains. I am pulling a Ford Escape. While going up do I keep the cruise control on? Do I drop to a lower gear on steep inclines.
What about going down hill, same questions.
Thanks!

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Old 03-24-2023, 03:28 AM   #2
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Originally Posted by gofishbass View Post
Have a 17' Thor Miramar 35.2. I am a novice and looking for advice on going up and down hills/mountains. I am pulling a Ford Escape. While going up do I keep the cruise control on? Do I drop to a lower gear on steep inclines.
What about going down hill, same questions.
Thanks!
not 100% as i have diesel but your rig looks like 3,900 rpm for max torque and HP having your rv close to that as you are starting the climb that is where you want to be. With diesel we downshift prior to the load to make sure we are at the top of the torque curve. If we loose momentum all is lost.
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Old 03-24-2023, 03:29 AM   #3
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Seat time and experiment.
No one can tell you so it fits you.
Do the speed limit and pullover for traffic every chance you can.
Try all ways until you find your right way.
There is no standard way.
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Old 03-24-2023, 03:59 AM   #4
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Biggest thing I would suggest is using the tow haul mode. Going up it will help to hold in gear longer. And going down will help keep you at a controlled speed. If you tap the brakes it will automatically downshift for you. Don’t ride your brakes down the hill.
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Old 03-24-2023, 09:45 AM   #5
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Go down carefully and don't exceed a comfortable speed

Absolutely tow/haul and never ride brakes

Watch temperature climbing
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Old 03-24-2023, 11:09 AM   #6
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I only use tow/haul when in mountains. This helps especially with descents using gearing to hold speed down instead of brakes. I turn cruise control off both up and down hills. Going up Iíll find a comfortable rpm, get in RH lane, and enjoy the scenery at 35 mph. I agree with Duck, youíll figure it out with experience.
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Old 03-24-2023, 01:21 PM   #7
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Originally Posted by Elite Washington View Post
Biggest thing I would suggest is using the tow haul mode. Going up it will help to hold in gear longer. And going down will help keep you at a controlled speed. If you tap the brakes it will automatically downshift for you. Donít ride your brakes down the hill.
Exactly what we have done for 25k miles.
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Old 03-24-2023, 02:08 PM   #8
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Gear down .. Go Up slow & Go Down slower..
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Old 03-24-2023, 03:25 PM   #9
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Thanks for the advice. Just a few more questions. When I am going down a mountain the rpm tend to race high, in the 4500 range.
Also when in cruise control going up hill the engine also runs high. Is this normal?
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Old 03-24-2023, 03:48 PM   #10
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AS rpm builds, the engine computer will control shifting, you control braking. To slow, brake firmly to get a cushion below desired speed/rpm. Then get off the brakes to let them cool.

The old rule to come downhill in the same gear you needed uphill is a little harder with automatic trans but the idea is the same. Get the tranny to help you. You'll get the hang of it.
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Old 03-24-2023, 04:15 PM   #11
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Thanks for the advice. Just a few more questions. When I am going down a mountain the rpm tend to race high, in the 4500 range.
Also when in cruise control going up hill the engine also runs high. Is this normal?
Yes - on the V10 engine.
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Old 03-24-2023, 05:09 PM   #12
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I would suggest you use the interstate system while learning to drive n the mountains. There is more room, no switchbacks and plenty of trucks to follow. Once you get the hang of it, then you can switch to US highways and state roads.
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Old 03-24-2023, 10:58 PM   #13
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Originally Posted by gofishbass View Post
Have a 17' Thor Miramar 35.2. I am a novice and looking for advice on going up and down hills/mountains. I am pulling a Ford Escape. While going up do I keep the cruise control on? Do I drop to a lower gear on steep inclines.
What about going down hill, same questions.
Thanks!
Just finished a 5000-mile trip out west to Las Vegas Phoenix and south Texas. The ACE 30.3 is my second motorhome, the first was a 1996 Tiffin Allegro on a Chevy P30 chassis with a fuel injected 454 V8. Compared to the Allegro the ACE performed much better. On hills that would slow the Allegro down to 35, the ACE just marched up the hill at 60 or 65 even passing trucks, something I could never do with the Allegro. Downhill was much better as well. Tow haul mode saved me from ever having to manually downshift. all I had to do as tap the brakes and the transmission would downshift allowing me to keep full attention on the road. Having to manually downshift while driving just absolutely terrified the hell out of me because I could not do it by feel I had to look at the selector and take my attension off the road to see what gear I was selecting. Tow Hall is much better. so here is my advice.

1. Remember your tires are rated for 75mph. So, when you see that 80mph sign keep it below 75 no matter what. I generally draw the line at 70mph and that is only when the wind is < 12mph. When the wind gets above 15mph be prepared to slow down so you have time to keep up with course corrections forced by the wind.

2. Since you will likely want to touch the brakes when you begin your descent that will make the choice about whether or not to cancel the cruise control for you. Touching the brakes will cancel cruise control.

3. Use tow Haul mode all the time. One of the other posters said he only used Tow Haul in the mountains. However, remember this, Tow Haul will also help you slow down just as much on flat roads as on hilly roads.

4. In the mountains you will often find curves that are not banked or banked the wrong way. Be prepared for this. Also pay attention to the yellow recommended speed signs. Cars can navigate such curves at the full posted speed limit, but motorhomes and trucks cannot. To prove my point, next time you see a recommended speed on a curve with concrete barriers, notice all the black tire marks on the outside barrier.

5. Finally remember that you are driving unfamiliar roads. This means that you do not have a "muscle memory" to anticipate how your motorhome will behave taking curves on these unfamiliar roads. In Short SLOW DOWN!
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Old 03-25-2023, 03:22 AM   #14
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You are getting some good advice from our members. Somewhere in that rig of yours is a Ford F53 owner's manual. Lot's of good info in there, including how the tow/haul mode works. We put our ACE in tow/haul mode and leave it there.
You are towing roughly 3500 + pounds of dead weight. In the event you need to get everything stopped in a hurry the tow/haul transmission braking will help get that done.
Last summer we were tooling down I 94 in Michigan at 63 mph in fairly heavy traffic when everyone in front of me lit up their brakes and started to jump lanes. When the last car in front of us dove into the emergency lane a little POS sedan had stopped mid lane as the kayak they were hauling on the roof fell off. The transmission braking feature of the tow/haul helped me get our ACE and 4300 lb toad safely slowed and into the emergency lane.
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Old 03-25-2023, 02:10 PM   #15
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Originally Posted by Hooligan2 View Post
ÖThe old rule to come downhill in the same gear you needed uphill is a little harder with automatic trans but the idea is the sameÖ
This is an old wives tale that is not appropriate for interstate highways. If the speed limit is 65+ and I am struggling up a grade at 45 mph, Iím certainly not going to come back down that same interstate grade at 45! Iím going to let the coach come back up to the speed limit on the downhill side. Our motor homes and RVs are heavy, to be sure, but they donít weight 80,000 pounds like a fully loaded semi. There is no need to come down interstate grades below the speed limit.

On the US or state routes, the situation is different because they were built long before sensible limits were placed on the steepness of grades. Interstate grades max out at 7%, but Iíve seen grades of 15% to 20% on off-interstate routes. A 15% grade is a serious hill that demands all your attention. A 6% or 7% grade, not so much.
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Old 03-25-2023, 03:13 PM   #16
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This is an old wives tale that is not appropriate for interstate highways. If the speed limit is 65+ and I am struggling up a grade at 45 mph, Iím certainly not going to come back down that same interstate grade at 45! Iím going to let the coach come back up to the speed limit on the downhill side. Our motor homes and RVs are heavy, to be sure, but they donít weight 80,000 pounds like a fully loaded semi. There is no need to come down interstate grades below the speed limit.

On the US or state routes, the situation is different because they were built long before sensible limits were placed on the steepness of grades. Interstate grades max out at 7%, but Iíve seen grades of 15% to 20% on off-interstate routes. A 15% grade is a serious hill that demands all your attention. A 6% or 7% grade, not so much.
If you come down Black Mountain, on I40 in NC at the posted speed limit, youíll soon be testing the runaway truck ramps.
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Old 03-25-2023, 03:19 PM   #17
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If you come down Black Mountain, on I40 in NC at the posted speed limit, youíll soon be testing the runaway truck ramps.
Been there and done that, several times, most recently just a month ago. With the Jake Brake on high and a downshift to fifth gear, I have no problem coming down that hill at 65 mph and I never have to touch the service brakes.
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Old 03-25-2023, 04:30 PM   #18
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Been there and done that, several times, most recently just a month ago. With the Jake Brake on high and a downshift to fifth gear, I have no problem coming down that hill at 65 mph and I never have to touch the service brakes.
How's that "jake brake" work in the gas MH the OP has?

For OP:

Tow/Haul
Tap the brake pedal to force a downshift early
If you need to use wheel brakes - brake early and brake hard intermittently. Do NOT ride the brakes.
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Old 03-25-2023, 05:40 PM   #19
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How's that "jake brake" work in the gas MH the OP has?

For OP:

Tow/Haul
Tap the brake pedal to force a downshift early
If you need to use wheel brakes - brake early and brake hard intermittently. Do NOT ride the brakes.
Our diesel has the exhaust brake and used the same way. Next RV will have the real jake which deals with valve timing. Newmar.
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Old 03-25-2023, 06:00 PM   #20
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Sensible people always err on the side of caution.
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