I live in Denver. Westbound on I-70 there are two 11000+ ft passes. Grade is slightly steeper eastbound than westbound. Westbound I can climb to the top in our 99FG in 4th gear (we're around 12klbs) Eastbound, the grades are just steeper enough that in 4th gear I start slowing down. I might be able to continue climbing around 40mph and 2000rpm's but I don't like that. I suspect, despite the fact that I lack a pyrometer, that the EGT's are probably climbing with my foot to the floor at those rpm's. So I drop down to 3rd gear but at 3200 rpm's I'm around 30 mph. The truck is happier with the higher rpm's and more air. I on the other hand, with diesel pickups passing me at 70mph pulling 36' Fifth Wheel campers, feel a combination of fear and jealousy. There's no gearing possibility to utilize the speeds between 30-40mph. I yearn for a 3.5 gear. (of course all this is a result of a warped psychology since climbing at 30mph instead of 38 mph likely doesn't even add 10 minutes to the trip). How do other people drive in these circumstances?
Driving habits on steep highway inclines
- Thread starter kerry
- Start date
alanymarce
Well-known member
We live at 2600m (8530 ft) and have multiple passes in all directions - the two we use most frequently reach 3265m (10,712 ft) and 3679m (12,070 ft) and we can take an alternative route to one of our frequent destinations, with the pass at 4126m (13,537 ft). We let the engine tell us what's comfortable; most of the time on the steep ascents we're in 3rd or 4th, and on very steep sections drop to 2nd (of the 5 available). The rev/min are usually therefore around 2500-3000 and this seems fine. The roads are tortuous and have very short sections (50-100m or so) which are remotely "straight" so we can't drive at much more than 40-70Km/h anyway. If we find ourselves on a section where the gear options mean either maintaining more than 3000 rev/min or "lugging" in a lower gear (in our case this means a very steep section where the choice is between 2nd and 3rd) we'll drop to 2nd and keep the speed down to keep the rev/min below 3000.
Not sure this helps much however hope it does a little.
Not sure this helps much however hope it does a little.
yabanja
Explorer
Peak torque on these engines is about 2000 rpm so that is their happy place. I don't shift down to third until 35 mph and the truck usually holds in the 40 mph range pretty well on most hills(we are 10k lbs.) That having been said I often run at 80 mph(actual not indicated) at redline for hours on end with no real detriment other than economy.
Allan
SkiFreak
Crazy Person
The only way my truck would ever get to 80 mph is if I drove it off a cliff and gravity took charge of the acceleration...
What year is your truck? 80mph??? Maybe I can get 70 out of mine approaching redline. Do you have a link to the torque curve? My truck is happier at around 2300 or 2400 rpm's. I have the 4D34 engine.
The FG is not a modern car. There's a big leap between 3rd and 4th gears.
yabanja
Explorer
Ours is a 2000 model FG39-completely stock mechanically 4D34. It will drive all day on the flat at redline at 81 mph GPS verified(and witnessed by traveling companions). Maybe we just got lucky and got one of the good ones! We are light at 10k pounds and have very little frontal area with the dropping camper roof. The truck has 5.7 gearing and 37" tires. The Torque curve is listed in the factory service manual or owners manual. Can't remember which. There is a PDF copy floating around here somewhere.
Allan
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yabanja
Explorer
Is yours up and running then? Congrats!The only way my truck would ever get to 80 mph is if I drove it off a cliff and gravity took charge of the acceleration...
SkiFreak
Crazy Person
Truck has always been driveable, but the camper is still a work in progress. Sadly, there is still no end date in sight.
yabanja
Explorer
Sorry to hear that. Hopefully things improve!
Ahh. The tires explain it.
yabanja
Explorer
I am on my second set of all terrains. The first were BFG A/T KO2's which were 3/4 inch out of round and always vibrated horribly. Replaced them after 10k miles with the cheapest tires money could buy which are PRO-COMP A/T. 25K hard hard miles later and they still have 30 percent left.I did the math on your tires compared to mine. It works. I could keep up with you on a downhill run.
86scotty
Cynic
OP, I own and drive a tractor trailer. We do that pass, and every pass at 80,000 lbs. and sometimes more. More people should do what big trucks do, because we (well, most of us) are professionals at work with a lot at stake. So, get in the right lane, put your flashers on as you climb/descend slowly and don't over-drive your machine. I don't like dropping 7 gears and creeping up passes at 25 but I like getting to my destination at the end of the day.