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06-08-2016, 11:49 AM
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#15
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Senior Member
Join Date: Sep 2013
Posts: 4,121
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Last summer we did I 70 East from Utah thru Colorado. Had no issues up hill, however I really was uncomfortable with the downhill.
I left the transmission to manage it,,, as said for the up hills. When we started down we were in 6th, jake on high, and we went faster than I like, and had high engine RPM's.
If I were to do it over, I might at the top force a shift down, maybe even to 4th gear???,,, and come down the pass at a lower speed, in a lower gear, which I hope would keep the RPM's down?
L.
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RVing since 1974!
Lots of Motorcycles
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06-08-2016, 11:54 AM
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#16
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Senior Member
Entegra Owners Club
Join Date: Jun 2012
Location: The Villages FL/Traverse City MI
Posts: 875
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One "rule of thumb" I heard somewhere about downhills was to top the hill at the same speed you wanted to be at on the downhill at the bottom. Makes sense, you want to start the downhill at the proper slow speed and use the engine brake and "Snub" braking to keep the speed and rpm in line.
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Ron & Glenda (The Good Witch!)
2015 Entegra Anthem 42DEQ Classic
2020 Chevrolet Traverse toad
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06-08-2016, 12:47 PM
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#17
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Senior Member
Join Date: Oct 2012
Location: Louisiana
Posts: 11,531
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Here is another adage. "Whatever gear your coach needed to be in as you approach the uphill crest (let's say fourth or third on a steep climb) is the same gear you want to be in as you begin the descent." Do that by maintaining speed as you crest, kick on the low jake and see what the coach does. I would never start downhill after a mountain pass in 6th. Most likely I am in 4th, where tranny was as we created.
My left hand moves to the Jake control. With the jake on and in 4th lets say, I see what the speed does. If it climbs lets say to 50, I move the jake to high. That should slow the coach along with any automatic Allison downshift to let's say 40. If not, then I snub brake down to 40, then move the jake to low and see how we do. When we get back to 50, back to high jake, and or snub, and repeat. My left hand stays on the Jake shift switch until I see the bottom of the mountain. If I am too slow, I turn off the jake until I get back up to an appropriate speed, turn on the jake and follow the same logic. VERY steep descents, I use the same process but maybe between 30 and 40.
I really obsessed with how to do steep downhills in an automatic transmission, asked a lot of questions, and got a lot of good pointers and was referred to lots of stuff on the Internet. It IS quite different from a car so it is a new learning process for everyone. What I am describing has worked very well for me and is my SOP. No white knuckles.
Gary
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06-08-2016, 01:09 PM
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#18
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Senior Member
Join Date: Sep 2012
Location: SW Georgia
Posts: 147
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An old semi driver taught me when descending a hill that most all unsafe problems occurred at the crest of the hill...starting off too fast. " Always start off 1 gear lower than than the one needed to crest the hill". Of course, this will require up-shifting as the grade decreases. As noted in previous posts, let the engine brake work and assist it as needed by "stabbing" the air brakes to maintain a safe speed and not overheat the brake pads, since it will decrease braking to nothing should they get hot enough (they will crystallize, thus requiring a complete replacement of pads).
I never used the cruise control when climbing. I watch the engine temp, if it starts increasing, I downshift to increase RPMs to the engine cool.
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Paul & Eugenia
2015 Aspire 39E
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06-08-2016, 02:10 PM
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#19
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Senior Member
Join Date: Jan 2016
Location: Raleigh, NC
Posts: 332
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Thanks guys, good info for me.
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06-08-2016, 04:14 PM
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#20
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Senior Member
Join Date: Oct 2012
Location: Louisiana
Posts: 11,531
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Have fun!! You will feel completely in control following all those suggestions. All if them are good advice, and all of them are fundamentally consistent.
I am always amazed that I just came down a 6 or 7 mile long constant 7% grade and probably never touched the service brakes. Just amazing. And no period of concern the entire way down. I have heard owners of Cornerstones say that they virtually never use the third (highest) Jake level....the bottom 2 are enough to do the job.
Gary
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Gary and Dee, Zowie and Bowie (traveling cat sibs)
2019 Cornerstone 45B, X15-605hp, Imperial, Spartan K3,
2013 Honda CR-V toad, Demco Excali-Bar II,
Demco Baseplate, Demco Toad Light system, 73 de W5FI
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06-08-2016, 05:42 PM
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#21
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Senior Member
Join Date: Jun 2010
Location: Sun City Center, FL
Posts: 1,847
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There is no reason to avoid downshifting to a lower gear at the crest. I never do a 5% downgrade in 6th gear.by the same token, I rarely go up a challenging grade in 6th gear.
Pat Bauer, President
Entegra Coach Owners Association
www.entegraowners.com
2017 Anthem DEQ/Ford Edge
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Pat & Medarda Bauer; Tess and Tighe (our fur kids)
2017 Entegra Anthem/FL/Allison/Grand Cherokee
Entegra Coach Owners Association, President
Sun City Center, FL
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06-09-2016, 07:44 PM
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#22
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Senior Member
Entegra Owners Club
Join Date: Nov 2012
Posts: 8,107
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You do not need to fear overspeeding the engine because the Allison transmission won't allow it. The transmission will automatically upshift to protect the engine if RPMs get too high. In my previous coach which had a comparatively ineffective exhaust brake, I descended many a hill with the RPMs at 2400 and had zero problems in ten years. Occasionally the transmission would shift up a gear in order to lower the rpms, whereupon I needed to use my service brakes in the "stab" fashion described above to keep the spred under control.
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Marc and Jill, Wellington FL
2013 Entegra Anthem 44SL
2018 Lincoln MKX
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06-09-2016, 08:00 PM
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#23
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Senior Member
Damon Owners Club Freightliner Owners Club
Join Date: Mar 2006
Location: North East Texas
Posts: 4,946
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Quote:
Originally Posted by Mike&Chris
When pulling a long grade and the speed drops down to around 50 mph do you keep the petal to the floor until you reach the top and start to regain speed? This is my only diesel experience with the exception of a Ford 6.0 and we know what that was like.
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what do you mean about the 6.0
mine was oustanding....
but for hills and climbs
water temps and tranny temps
if its getting hot, back off
otherwise use common sense
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USN Retired, Life time member of the DAV.
Enjoying the 2008 Damon Tuscany 4056, #3998 no your eyes are fine, there are really 6 slides
2022 F150 King Ranch or 2012 Edge toads
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