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Time for a driving lesson


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So I have put on about 2500 miles on our "new to us" Kenworth, 1600 miles bobtail brining it home from Texas, and a couple in state trips of about 450 miles round trip pulling our 40 ft toyhauler. What a ride!! so much more comfortable than the 3500 dually. But now the real trip is about to begin, in about 10 days we head for the Bighorn Mts. in Wyo. From the last town up to the top is about 20 miles, the first 10 miles is between 8 and 10% grade with numerous switchbacks that limit speed to about 25 mph max on the short stretches between the corners. This is US Hwy 14 west of Dayton Wy. So what do I need to know about driving "the Big Truck" up and more importantly coming back down? I'm guessing on the way up just let the 3 pedal auto shift do the thinking and the work? But I'm not exactly sure on proper protocol for the descent. I've been up and down this mountain numerous times with the 3500 and camper (it was about all the duramax could handle!) So what's your advice?

As always Thanks for the help.

 

2000 Kenworth T2000, 500hp cat with eaton 10 spd autoshift

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My guess is 9th will not be low enough. I usually gear down until the engine is in the 1500 rpm range. A little higher for more hold and a little lower to speed up. About the same gear used to climb or 1 lower. Engage the jake and let it work. If the service brakes are needed use the stab method. Brake hard enough to bring the speed about 5 mph below the desired speed. Release and allow the truck to speed up. Repeat as necessary. Go slow until you get a feel. Use hold to keep the gear locked but be aware if the engine reaches red line it will upshift to protect the engine.

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I have the same truck but with a Cummins. When I descend long grades, I place the transmission in "L" - low and turn the Jake on all six cylinders. Low keeps the transmission from up-shifting and in combination with the Jake will slow the truck and allow it to downshift as needed. Sometimes I actually have to push the gas pedal periodically to keep the truck from slowing down too much. When you push the gas pedal, it stops the Jake. I will feather the gas pedal to keep my Jake from slowing me down too much without actually speeding up - if that makes sense. I only apply the service brake as needed to get me to the speed I want and then let the Jake and the transmission do their work.

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The main thing is to find the speed you wish to descend at. Once there place it out of the automated mode. Sounds like you need the press the "L" on your gear selector. Once you do this the transmission should hold the gear you are currently in until you go back in to automated mode or press the up/down gear selector. The computer will prevent you from being able to up/down shift if you current speed will not allow you to safely make the shift. Mine will beep at me loudly to tell me it is not going to make the shift I told it to do. As already mentioned you should have your engine brake fully engaged. If you feel you need more braking power then use the service bakes to slow down more and then downshift. Personally I then just the engine/jake brake switch to control my speed. Basically if I slow down too much I just use less engine/jake brake. Then apply more engine/jake brake as my speed increases. Ideally you will make the entire descend with out touching the service brake pedal.

 

Remember your engine/jake brake works best with more engine speed. So ideally you should be on the upper end of your torque band.

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The only problem with relying on cruise, is the speeds he wants to maintain. A lot of times, cruise is programmed to turn off below about 30 mph. Depending on your shifter style, (keypad or lever) you want to lock the trans in manual. If you let the truck stay in auto, it will try to upshift at the worst time, and will be a pain to force back down. Pay attention to any signage at the top of the hill, if you see signs for a brake check, take advantage of them to pull in, let traffic pass you, and start down the hill in a lower gear than you think you might need. It's easier to upshift than down. Be aware the Jake is controlled by your right foot, as well. A feathers' weight on the throttle is enough to turn it off, with a foot completely off the pedal, it's back in effect. We use this method all the time, as the switch on the dash is in the "On" position all the time. If you have a multi-stage Jake, you can also switch between stages to maintain the speed you want.

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That is a beautiful drive. I have had the pleasure of driving on it. I also lived in WV when I had my HDT, so have been on many back windy roads with similar grades.

My past HDT was a manual Super 10, so can't comment on specific gearing.

However, as with any HDT, you have superior brakes and at lower speeds you will enjoy that safety factor.

Regardless of transmission, choose a gear that keeps you in the ~1500 RPM range, as stated above and let the Jake do it's job going down hill. Up hill will be a piece of cake.

If you have a three stage Jake, you can switch from 4 to 6 cylinders and be pretty comfortable.

Lastly, you will probably get some tailgaters on your butt that will be rude or/and anxious.

Ignore them and don't be in a hurry. Just travel your speed and enjoy. (Especially with your new found reality of what a pleasure it is to tow with an HDT) :)

Cheers,

Bob

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I have the twin of your truck. Do not use cruise going down those hills. Put it in d going up. Let the computer do its job. As you hit the crest slip it in h for hold. This will keep it in the gear it is in. Turn on Jake before you start going up. Turn the other switch on 6. If your Jake doesn't work in all 3 setting your switch is bad. When in h you control the shifting with your up and down buttons on the shifter. Do not let it over rev. Use the breaks to keep it at the speed you want.

 

By the way if you are on the flat and come to a stop, slip it into h when in 4th. Then you can start in 4th. After you get moving slip it into d or you can hit the up button twice to skip shift.

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Watch your air pressure. Depending on how often you have to use the brakes, you can use air faster than the compressor can rebuild it. Not likely with a Jake, but watch anyway. If your pressure starts dropping, find a pull out and stop until it rebuilds.

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In the old days, whatever gear you'd use climbing the hill was the gear to use descending the hill (with Jake Brake on, or equivalent). Nowadays, today's more aerodynamic trucks can climb the hills in a higher gear because of the lowered air drag, and as a result they also get less air resistance on the descent. Whatever gear you climb with should be 1-2 gears higher than you descend with.

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Watch your air pressure. Depending on how often you have to use the brakes, you can use air faster than the compressor can rebuild it. Not likely with a Jake, but watch anyway. If your pressure starts dropping, find a pull out and stop until it rebuilds.

Jeff-CIL;

 

Sounds like you have a bad air leak! The compressor should keep up with your braking! You only "rest" the brakes if their overheating. With leaking that you describe you wouldn't make it out west with all the hills and mountains around here! I would truly check out the problem.

 

Curt

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Put it in cruise , jakes/engine brake enabled , just sit back and listen to the music.

Thats all I ever do,it has always held the speed selected.

If a change in velocity is required (up or down) tap the cruise button up or down.

I don't think my cruise would activate at that slow a speed.
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That is a beautiful drive. I have had the pleasure of driving on it. I also lived in WV when I had my HDT, so have been on many back windy roads with similar grades.

My past HDT was a manual Super 10, so can't comment on specific gearing.

However, as with any HDT, you have superior brakes and at lower speeds and you will enjoy that safety factor.

Regardless of transmission, choose a gear that keeps you in the ~1500 RPM range, as stated above and let the Jake do it's job going down hill. Up hill will be a piece of cake.

If you have a three stage Jake, you can switch from 4 to 6 cylinders and be pretty comfortable.

Lastly, you will probably get some tailgaters on your butt that will be rude or/and anxious.

Ignore them and don't be in a hurry. Just travel your speed and enjoy. (Especially with your new found reality of what a pleasure it is to tow with an HDT) :)

Cheers,

Bob

Yep I know too ignore the tailgaters, there really not that bad on this stretch, pretty slow road for everyone except motorcycles, and sportier cars. Course the locals do pretty good in there pickups!
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I have the twin of your truck. Do not use cruise going down those hills. Put it in d going up. Let the computer do its job. As you hit the crest slip it in h for hold. This will keep it in the gear it is in. Turn on Jake before you start going up. Turn the other switch on 6. If your Jake doesn't work in all 3 setting your switch is bad. When in h you control the shifting with your up and down buttons on the shifter. Do not let it over rev. Use the breaks to keep it at the speed you want.

 

By the way if you are on the flat and come to a stop, slip it into h when in 4th. Then you can start in 4th. After you get moving slip it into d or you can hit the up button twice to skip shift.

I don't think I have an on/off switch well not an on switch anyway. I have 4 buttons on the steering wheel spoke, one button each for 2, 4, 6 cylnders and other button to shut it off. Am I missing something??

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In the old days, whatever gear you'd use climbing the hill was the gear to use descending the hill (with Jake Brake on, or equivalent). Nowadays, today's more aerodynamic trucks can climb the hills in a higher gear because of the lowered air drag, and as a result they also get less air resistance on the descent. Whatever gear you climb with should be 1-2 gears higher than you descend with.

Wow Peety3, first I find something to agree with Big5er about and then I read your post and totally agree! Scarey huh? Lol

 

For the folks trying to figure which gear to run, it doesn't need to be a mystery. If you look in the manual for your transmission you should be able to find info with a speed range for any given gear. After you drive your truck a while, you will know what gear you need for a given speed.

 

A couple of general rules I always follow:

1. Don't start down a hill without a number for the max speed I want to travel at.

2. NEVER drive faster than the caution/advisory speeds you see posted on a hill or curve.

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I don't think I have an on/off switch well not an on switch anyway. I have 4 buttons on the steering wheel spoke, one button each for 2, 4, 6 cylnders and other button to shut it off. Am I missing something??

No, you're not missing anything. Your truck has a SmartWheel, but Ronbo's does not. He would have two switches above the B Panel for his Jake, while we have the steering wheel controls.

 

It sounds like you've got it all figured out. You have no on/off switch, just buttons for 0, 2, 4, or 6 cylinders. Any setting greater than zero is "on", as the yellow engine brake light to the left of the A Panel will indicate.

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So I have put on about 2500 miles on our "new to us" Kenworth, 1600 miles bobtail brining it home from Texas, and a couple in state trips of about 450 miles round trip pulling our 40 ft toyhauler. What a ride!! so much more comfortable than the 3500 dually. But now the real trip is about to begin, in about 10 days we head for the Bighorn Mts. in Wyo. From the last town up to the top is about 20 miles, the first 10 miles is between 8 and 10% grade with numerous switchbacks that limit speed to about 25 mph max on the short stretches between the corners. This is US Hwy 14 west of Dayton Wy. So what do I need to know about driving "the Big Truck" up and more importantly coming back down? I'm guessing on the way up just let the 3 pedal auto shift do the thinking and the work? But I'm not exactly sure on proper protocol for the descent. I've been up and down this mountain numerous times with the 3500 and camper (it was about all the duramax could handle!) So what's your advice?

As always Thanks for the help.

 

2000 Kenworth T2000, 500hp cat with eaton 10 spd autoshift

Are you planning on going through a Driver Training Course?

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