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Old 08-18-2018, 12:37 PM   #1
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Going down steep hill

Might be a dumb question. How do u reduce RPM’S when going down a steep hill.?
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Old 08-18-2018, 12:42 PM   #2
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Might be a dumb question. How do u reduce RPM’S when going down a steep hill.?
If you can start in low gear then it is best to do so. If you find yourself going a bit too fast then step on the brake firmly and watch the rpms then downshift when the rpms drop, one gear at a time. If you have an Allison transmission then just step on the brake and the trans will down shift automatically. Never ride the brake and NEVER put it in neutral. I was surprised to see that some drivers actually do this.
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Old 08-18-2018, 01:06 PM   #3
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If you have a DP with a jake / engine brake, use that instead of the wheel brakes.
I just got an electric foot pedal to augment the dash switch to apply the jake during twisty roads. The jake / allison will downshift for you.

Best is to put your RV in your signature so we can be more helpful.

BTW, when one downshifts ideally before the downhill gets steep, the RPMs go UP, not down. In any given gear, as you slow MPH the RPM will then also drop.

If you have a Gas RV, downshift manually before the hill gets steep and allow the engine / transmission to do most of the decel. Use the brakes when needed but try not to continually ride the brakes down the length of the hill so they have a chance to cool off inbetween applications.

The key is to not let the RV get going too fast. Keep it managed the whole way from the "It's going to get Steep" sign, to the base of the hill.
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Old 08-18-2018, 06:20 PM   #4
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Starting out at a low speed is you best approach but if you have to brake to get the speed/RPM down intermittent hard braking is better than light to moderate long braking. You need to be proactive and down shift early at the top of the hill. Hung the right lane, activate the four way flashers and keep your speed manageable. Engine braking by down shifting works, be it a gas or diesel engine.

I've found on my gas coach that I can easily hold 35 mph in second gear on 8% grades with the RPM up around 4200 RPM. The electronic rev limiter for the Ford V10 is around 5250 RPM so I'm well within safe engine limits. If I find the coach picking up speed too fast or I have to brake too often I'll drop to first gear.
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Old 08-18-2018, 09:19 PM   #5
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Starting out at a low speed is you best approach but if you have to brake to get the speed/RPM down intermittent hard braking is better than light to moderate long braking. You need to be proactive and down shift early at the top of the hill. Hung the right lane, activate the four way flashers and keep your speed manageable. Engine braking by down shifting works, be it a gas or diesel engine.

I've found on my gas coach that I can easily hold 35 mph in second gear on 8% grades with the RPM up around 4200 RPM. The electronic rev limiter for the Ford V10 is around 5250 RPM so I'm well within safe engine limits. If I find the coach picking up speed too fast or I have to brake too often I'll drop to first gear.
Sound advice! Fawndale has a Winnebago Vista, 27'.
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Old 08-19-2018, 05:11 AM   #6
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Lots of good advice. Just remember...NEVER ride the brakes but rather intermittent "hard" breaking. Riding the breaks will make them fail and have the fire extinguisher ready at the bottom of the hill (I have seen brake fires at the bottom the hill before)
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Old 08-19-2018, 05:12 AM   #7
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I should add.. NOT my coach on fire
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Old 08-19-2018, 06:49 AM   #8
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Quote:
Might be a dumb question. How do u reduce RPM’S when going down a steep hill.?
On my gasser, V10 and 4 spd transmission... When descending a long steep grade, I use the engine as a brake. The higher the rpms, the more braking action, but I like to keep the rpms below about 4,500.

In order to do this, I'll slow down, and manually downshift. If the MH continues to pick up speed, I'll slow down more and downshift to a lower gear..

Usually long descents I can usually do 45 mph, 2nd gear, 4,000 rpm. I've descended a few grades in 1st gear and 25 mph (4,000 rpm)
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Old 08-19-2018, 10:28 AM   #9
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Actually, you don't want to reduce RPMs in most cases. You want the engine to help with speed reduction, whether its a gas engine or a diesel with exhaust or engine brake. In either case higher rpms means more braking and you actually downshift to keep the rpms up higher.


If your engine is in danger of exceeding it safe rpm limit, it will probably upshift all by itself, but you could manually up shift if you want. But then you will need to use the brake pedal more, and that's probably not a good thing.
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Old 08-19-2018, 05:10 PM   #10
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My 2010 Vista, 27' gas V10 has a button on the shifter called 'Tow'. Press that and the transmission pretty much keeps the speed constant down hill. Seldom have to brake.
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Old 08-19-2018, 05:15 PM   #11
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Stab braking. As your speed picks up apply the brakes hard to scrub of about 10mph - as you gain speed again - repeat. Don't ride the brakes - you will overheat them.
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Old 08-19-2018, 05:22 PM   #12
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When you brake on a twisty hill do it on the straight sections. You want the wheels to track the turn so better with the speed already down and the brakes off. On the straight sections tracking is not so much of a problem as you just keep going straight.
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Old 08-19-2018, 05:56 PM   #13
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I don't know why you want to reduce RPMs going down hill. Your question isn't very clear. However, the advice given is good. I live near mountains and travel on many a steep grade. I see out of towners ride their brakes down the mountain passes and smell the burning brakes and occasionally see wheels on fire (or entire vehicles). DON"T RIDE YOUR BRAKES! Give them a rest to cool in between applications as has been said. They get very hot.
Use the engine exhaust brake if you have a DP, it works great and really slows the coach without using service brakes. On a gasser, Down shift to use the gas engine to slow the coach (this will increase RPM though which is opposite of your question). For V10 motorhomes have a tow haul mode button on the end of the shifter that will indeed downshift and slow the motorhome as you tap the brakes.
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