Community Forums

Waiter21 · 02-18-2018, 06:53 PM

I keep my foot on the gas as its slowing down and downshifting. I find a speed that I can maintain while running 4,000 rpm. I have a 4 speed (4R100) so I know the speeds and rpms.. I manually shift the transmission to the lower gear then hold a speed and rpm while making the climb. Keep the rpms up.

1st gear, 25 mph at 4k rpm
2nd gear, 45 mph at 4k rpm

micd · 02-18-2018, 07:27 PM

We live in Colorado and never had a problem with the big hills. We let the automatic transmission do its thing on the way up. Sometimes we turn off the dash air as that does help. On the way down you want to use engine braking so as not to overheat the brakes.

You'll probably do better than the semis and not as well as the cars. Getting some momentum going before the hill helps.

530ktm · 02-18-2018, 07:35 PM

On previous gas coaches I usually let the tranny down shift on it's own but then I also will manually shift it down to match what gear it was in so it stays in that lower gear so as to not upshift if I let off the accelerator a bit. I was never concerned much about what was happening going up the hills but more so coming down. My 97 P30 Adventurer had crappy brakes and the tranny did nothing to help slow down. You could put it in first gear and it would pick up speed until you had to use the brakes and hope not to fry them.

twinboat · 02-18-2018, 07:42 PM

You really don't want to compare the V10, 415 cubic inch RPM numbers with a V8, 460 cubic inch engine.

Because the V8 is a " big block " engine, its power will be at lower RPMs. The larger V8 will also have a lower rear end gear ratio, to keep the RPMs lower at highway speed.

The V10 has a smaller bore and stroke so it can spin higher RPMs without coming apart.

Bahamaniac · 02-18-2018, 09:43 PM

Put a K&N air filter on it. It will help with the hills.

OLYLEN · 02-19-2018, 08:21 AM

Good old motor. You should have a tack and a red line, on most you cannot go over redline as the trans will shift up automatically. you can shift with a little experience manually to a lower gear before the hill to setup the climb RPM before the need. If your not comfortable with the high end of the red line just stay a few 100 R's lower than red line and at a gear you can hold speed, it will be lower than the limit. As others have said 4000 seems to be a good RPM for the 460 v-8 and 2-3 gear which ever will hold a speed and not reduce any further. At the high altitudes you will find 25 mph is as fast or as much power as you have(the higher the you go the less O2 you have for the motor).

LEN

Roy1 · 02-19-2018, 11:36 AM

My previous coach was a classic GMC (1976) with a 455 olds engine and 3 speed hydromatic. I would not run it as high as 4K 3.5 k was what I ran it up to and then held it there on steep climbs . With the toad in tow it made for a tougher climb here in the high Sierra . I always selected the correct gear manually on steep climbs to keep the trans from violently shifting up or down it is easier on the nerves and equipment not to mention perspiration . Select a lower gear going down also to preserve your brakes and don’t let it over rev. My current rig is a diesel and I operate it the same way but going down is easier with the pack brake.

TonyMac · 02-19-2018, 11:54 AM

I manually downshift if the rig can't make up her mind. If she downshifts, begins to accelerate and upshifts, only to lose speed again and downshift, I drop the shifter into the gear she's in, settle for a comfortable rpm, and wait for the hill to disappear in the rear view. And as pointed out by a wise person, the gear you use to go up is the gear you use to go down, so you gotta move the shifter anyway.

Wbonsell · 02-19-2018, 12:02 PM

Have found in our previous 454 as well as our current 8.1 with Allison tranny that its best to manually downshift rather than allowing the tranny to automatically do its thing as often too much momentum is lost. Then I just hold the RPM's steady and enjoy the climb.

As comparison, my 454 was 2nd gear around 30mph on 6% grades. My Workhouse 3rd gear around 50-52mph with rpm's 3800-4000. But they both get you to the top.

Gpsmith620 · 02-19-2018, 05:36 PM

I have a 08 Dolphin with a 8.1 and a Allison six speed , can climb 7% grades at 60 mph ,towing a Jeep Liberty. The reason is the six speed trans, makes a world of diff over my other Dolphin with the 5 speed. All the torque for a 8.1 is achieved at 3200 rpm , more than that and your not getting anymore power than the engine can provide, also getting 8mph!