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Skykingtcb

Steep hills pac brake

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Hello I am a two year newbie. I have a trip coming up that I am thinking about because of two long steep hills. the two hills I am thinking about is CA hwy 223 from hwy 58 down to Arvin, CA. and then hwy 166 from hwy 99 over to hwy 101. I am driving a 2003 Diplomat 300 cummins Allison pac brake. pulling a 2016 Jeep with air supplement braking. I have learned to turn on pac brake slow it down to let it shift. on these long steep hills how low of gear to u want to go? or how low on speed? or r these  crazy hills stay away from. I have serviced brakes. Thank u for your help. on 166 from 101 to 99 it has two runaway ramps in a short distance so it is got thinking I need to ask someone gas been there done that.

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I had a similar set up on my last coach and I have driven most of those hills including the Grapvine several times. My technique would be to slow before you head down. Some hills require trucks to slow to 30 mph. I usually start around 45-50 (or the speed and gear I came up in) and let it down shift to 4th gear. If it wants to speed up you can use the service breaks to slow it down by braking fairly hard then releasing the brakes once you have slowed to the speed and rpm you want to maintain so they don't overheat. If it wants to pick up speed you can always slow till it drops in to 3rd gear. I could go down a 35 degree hill and it wouldn't pick up the pace once I hit 3 ed gear. I would have to give it throttle to keep it from slowing more than needed. 

Bill

 

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Gear down until you hardly need your service brakes.

As you learn your coach you will know the gear you need.

If in not sure go lower gear and then go up as it is easier than over speed and heating your brakes.

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On 6/4/2020 at 6:14 PM, Skykingtcb said:

Hello I am a two year newbie. I have a trip coming up that I am thinking about because of two long steep hills. the two hills I am thinking about is CA hwy 223 from hwy 58 down to Arvin, CA. and then hwy 166 from hwy 99 over to hwy 101. I am driving a 2003 Diplomat 300 cummins Allison pac brake. pulling a 2016 Jeep with air supplement braking. I have learned to turn on pac brake slow it down to let it shift. on these long steep hills how low of gear to u want to go? or how low on speed? or r these  crazy hills stay away from. I have serviced brakes. Thank u for your help. on 166 from 101 to 99 it has two runaway ramps in a short distance so it is got thinking I need to ask someone gas been there done that.

Hwy 223 going west from Hwy 58 does not have much of a grade...nothing to worry about. CA-166 across the valley is flat. Once you go thru Maricopa you will encounter a 6 -7 % climb for 3+ miles. Once you level off CA-166 is pretty much level then you will have an easy downhill ride to Hwy 101. The climb out of Maricopa is the only grade and it's uphill. Take your time & you'll not have any problems. 166 intersects 101 just north of Santa Maria, going south you will pass thru Buellton & then on to Santa Barbara. Going north on 101 you will be just a few minutes south of Pismo Beach. From there it's 40 some miles to the wine country around Paso Robles. Going north on 101 out of San Luis Obispo you will climb up Cuesta Grade, a 6 -7 %   3 mile climb. Going up is slow & easy.....be careful coming down, gear down to 3rd probably & use your exhaust brake but your service brake only as necessary. I used to have a 39 ft Safari with a 300 hp Cummins......40 - 45 mph, exhaust brake on as I crested the top...let it come down in 3rd gear watching the tach closely. North of Cuesta it's basically flat traveling until you get north of Ukiah.

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I have taken 101 in both directions, from  Olympia to LA and back.  I jumped off before Big Sur & the Russian River to do Napa.  Some areas are not compatible for a 47+ foot coach & toad. Found that out last time.  Campgrounds was also a big issue!  My mind was stuck on old memory of a 24' gas coach in 1976. LOL. 

As for your route, take Brad's word...my rule has always been to follow the slowest 18 wheeler down hill.  The last thing you ever want to do in a coach, is to use a "Runaway Ramp!"  If your real lucky, all you'll do is total the coach!  Ramps look smooth, but the first thing to happen in a coach is sink to the frame, take the front end totally off along with generator and front axle, after that is a moth point. 

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