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Mountain climbing
When climbing a steep grade on 4lane roads I usually leave it in Cruise, The tranny knows better than me when to shift, Note I am talking about east coast mtns 5-6000′. I was coming home from a trip to carolina and decided to take another route up the mountain 4miles 8% grade, the problem a lot of switch backs, I started off in 4th gear had to eventtualy shift down to second gear to keep my RPM above 2000 and the heat below 200 degrees, the roads were so curvey you could not do more than 25mph, everything was fine no heat issues, just slow I guess this normal on such a incline with switchbacks? Gary
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5 Replies
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While I believe the cruise control produces more HP than your foot, and I use it on long climbs, I am not so sure I want it engaged where there are sharp turns.
When I have had to climb very steep grades with turns I have used my foot on the gas pedal and have ended all efforts to climb as fast as possible, preferring to manually select the gear so the transmission isn’t hunting and the revs are high enough to control temps. If I let the transmission downshift by itself if it is in a gear in which it can gain speed at some point it downshifts, increases speed, upshifts, loses speed, downshifts, increases speed, upshifts, etc. etc. That is why I just pick a gear in which it can accelerate and just maintain a decent speed rather than the up and down shifting that occurs when I let the transmission pick the gear.
If the engine isn’t lugging in a particular gear it is unlikely the temps will climb because if the right gear is selected the engine is not unduly stressed.
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I will find the gear that I can maintain at least 1800 RPMs and sort of accelerate,I will not be fast but it seems to help temperatures.A old Detroit Diesel tech told me that the series 60 has just enough water flow to stay cool as long as the RPMs are kept well above 1500.I usually find that I am in 3rd or 4th and the throddle is 60-80% when I am going up the east coast mountains at 1800+rpm.
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I do the same thing Jack, keep the rpm’s up and not need full throttle.
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Ditto what others said about avoiding cruise in the steep and twisty, plus keep in mind that the cruise will disengage at a certain low speed. I learned the hard way on an 8% climb in my old 8-v92 when I got to particularly steep spot with cruise on. The cruise disengaged at 25mph and I was do instantlhy down to 10mph, which was the best I could do for the rest of the climb. The Series 60 is better about building speed, but those 8Vs would not build speed up a hill if a hornet was in the tail pipe. Sure did sound great coming down though, with the jake in high.
I made a 12 mile 8% climb this weekend in my car. Eventually caught up with a semi pulling double (empty) flat beds. He was able to maintain 30MPH on a very twisty road. I was impressed with that.
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I am also amazed how those pickups can haul some of those big 5th wheeled motorhomes. They just cruise by me like I am pulling doubles.
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