Community Forums

pflightnut · 05-06-2021, 09:51 PM

Sometime this summer we will probably make a trip from Atlanta to Syracuse. Up I-85 to I-77 to I-81. Our 2008 Monaco Knight will weigh close to its limit of 33k lbs, with a 5k lb toad. We have a 360hp Cummins, and I'm concerned about the grades. RV Trip Wizard doesn't show anything over 2%... but I'm still worried. I don't want to be lumbering uphill at 25 mph. I will gear down and use the exhaust brake downhill. Is there any possibility that I'd just slow to a crawl uphill? Other than engine and tranny temps, what should I be monitoring?

Any and all advice will be greatly appreciated.

Best regards,
Steve P

Hurricane-TX · 05-06-2021, 09:54 PM

Don't worry, you really wont be doing any mountain driving on that route.

TGAWLAK · 05-07-2021, 06:39 AM

you should not have a trouble I do that route every spring coming back from winter fun there are some hills and valleys but nothing to worry about I do have 400 HP towing a toad but no problem

wolfe10 · 05-07-2021, 06:55 AM

No worries uphill. You will be faster than all the loaded 18 wheelers (straight physics--power to weight ratio).

Keep RPM near higher end of your engine's RPM range. If LONG grade and your coolant temperature starts to climb, same higher RPM and throttle just less than WOT.

Downhill the secret is to maintain what I call "equilibrium speed". That is neither speeding up nor slowing down WITHOUT USING THE SERVICE BRAKES. If you are speeding up, use the service brakes firmly and long enough to drop a gear. Again, your speed will be faster than the loaded 18 wheelers who are at their "equilibrium speed" (more weight= lower speed).

Been all over N America (Canada, U.S. and Mexico) on some outrageous grades with a 250 HP 36' DP.

You will be fine-- just use your gears and your brain.

okcnewbie · 05-07-2021, 07:00 AM

On a side note....
We just drove through Atlanta yesterday. Wowsa last time we saw that much traffic we were driving our little mini through Paris. In one area I think we counted 12 or more lanes.

Rustygold · 05-07-2021, 07:07 AM

Quote:

Originally Posted by pflightnut

Sometime this summer we will probably make a trip from Atlanta to Syracuse. Up I-85 to I-77 to I-81. Our 2008 Monaco Knight will weigh close to its limit of 33k lbs, with a 5k lb toad. We have a 360hp Cummins, and I'm concerned about the grades. RV Trip Wizard doesn't show anything over 2%... but I'm still worried. I don't want to be lumbering uphill at 25 mph. I will gear down and use the exhaust brake downhill. Is there any possibility that I'd just slow to a crawl uphill? Other than engine and tranny temps, what should I be monitoring?

Any and all advice will be greatly appreciated.

Best regards,
Steve P

Rt 77 at Fancy Gap entering VA will probably your steepest climb. Gear down and stay right and you will be fine. Probably slow down a bit, but you will make it.
Dave

campnrace · 05-07-2021, 10:39 AM

if I remember correctly, Fancy Gap is around a 5% grade, a Hurricane with a v10 pulling a 26' enclosed had no trouble, slowed up a bit but we certainly weren't in the way. It is a beautiful drive too.

RustyTools · 05-07-2021, 02:25 PM

Brett-
Excellent explanation about 'Equilibrium Speed" and how to do it. I hope a lot more mountain-drivers see it.

twinboat · 05-07-2021, 02:34 PM

Fancy Gap is 6% grade.

My 1999 245 HP 30 ft class C made it up towing a car at 50 MPH, with it to the floor.

You'll be fine on that and the rest of the much smaller grades.

Equilibrium speed ???? Is that why there are runaway ramps on down steep grades ?
YOU need to control your speed on any downgrade, there is no magic equal speed. Engine brakingis your friend.

wolfe10 · 05-07-2021, 02:51 PM

Quote:

Originally Posted by twinboat

Fancy Gap is 6% grade.

Equilibrium speed ???? Is that why there are runaway ramps on down steep grades ?
YOU need to control your speed on any downgrade, there is no magic equal speed. Engine brakingis your friend.

Perhaps I didn't explain it properly:

Equilibrium speed (not equal speed) is when you are neither speeding up nor slowing down by using your engine braking and gears, but NOT your service brakes (except, perhaps for very brief applications).

Have been on some VERY steep grades. On one in Vermont, I was in 2nd gear, exhaust brake on and just "toddling" down the very steep grade-- 11% if I recall correctly. Dianne asked if I wasn't concerned about someone running into us-- we were going 22 MPH. Before I could reply we rounded a corner and rolled up on a loaded logging truck doing under 10 MPH-- his equilibrium speed.

If there is a better way to describe-- descend safely without using the service brakes, would be pleased to see it.

JerryLook · 05-09-2021, 06:22 AM

We just made the trip from St Augustine to just north of Syracuse (Pulaski area) a few weeks ago. I have a little less power than you, and about the same weight. It wasn’t bad on the hills. I got stuck in some fog and rain towards the end, which slowed me down a little. I manually shifted the Allison on most of the bigger hills. It seemed to help keep the RPMs up and stay in the gear I wanted.

I drive my coach easy, and try to keep it in the sweet spot. Coolant temps stayed around 180 through the hills.

pflightnut · 05-09-2021, 06:50 AM

Thanks everyone... your perspective, experience, and explanations are a huge help. I'm still apprehensive about 6% grades and don't even want to think about steeper. I will read my owner's manual again with a focus on RPM's, coolant and transmission temps and make sure of which gauges and Aladdin screens to pay attention to. Thanks again, and if you think of anything else, I'm listening.

mlh2013 · 05-10-2021, 10:21 AM

Quote:

Originally Posted by pflightnut

Thanks everyone... your perspective, experience, and explanations are a huge help. I'm still apprehensive about 6% grades and don't even want to think about steeper. I will read my owner's manual again with a focus on RPM's, coolant and transmission temps and make sure of which gauges and Aladdin screens to pay attention to. Thanks again, and if you think of anything else, I'm listening.

Steve don't sweat a 6% grade...we have close to the same setup as you, my toad is a bit lighter than yours. We are in the southwest now and recently climbed a 8% so what we were only doing 39 mph. You will be fine just enjoy the ride but remember you can come down a lot faster than you went up... use your exhaust break and gear down as needed to keep speed under control and jab on those service breaks if you get going faster than you want .Have a great trip!

pflightnut · 06-04-2021, 07:54 PM

Okay, I was climbing a long grade for about 10 minutes today, doing about 50mph, and the longer it got the steeper. Coolant temp climbed to 208, tranny temp to 195 in my Cummins 360 ISL/Allison 3000. I was in 4th gear at about 2000rpm. Boost was about 35psi.

I slowed to about 45mph, and that seemed to help a couple of degrees. The grade came to an end before I had to make further changes.

What should I have done? 3rd gear? Slower speed? Same speed @ higher rpms?

Still learning and much appreciate any helpful advice!

Thanks,
Steve

2008 Monaco Knight 40DFT
2014 CR-V toad
Demco tow bar
Brake Buddy