New driver with shifting issues

Discussion in 'The Welcome Wagon' started by Chrisdw, May 25, 2017.

  1. Chrisdw

    Chrisdw Bobtail Member

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    May 25, 2017
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    I have a 1991peterbilt with a C15 caterpillar engine. The truck is a dirt hauler enddump and pup trailer I am a new driver what RPM range is this engine best shifted at. I do notice that this engine in the lower gears 1 2 3 4 does not pick up speed very quickly shifting between 1100 and 1500 RPMs I was told shift between 1200 and 1700 RPMs or between 1500 and 1700 RPMs and to start off in 3rd gear unloaded. Anyone that is familiar with this C15 Caterpillar engine and its power band for shifting gears please respond.
     
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  3. swaggerjacker

    swaggerjacker Medium Load Member

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    Be loose and relaxed. If you're using the clutch, don't push it past the brake pedal when coming out of gear, even less when going into gear. The clutch is not there to help you shift. It is the shifter's enemy. We shift the FLD's at 17 and 14. But they are 60 series Detroits with Eaton Fuller trannies.
     
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  4. Brandt

    Brandt Road Train Member

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    It's a truck so their not very fast but have lots of torque.

    I would say shift low rang gears at 1,000 RPMs or less. That way you don't have to worry about matching the next gear. It very smooth shift so you not tearing up the truck.

    Then when get ready to flip switch to high rang you shift at 1,500 or 1,600 RPMs.

    You will wear the clutch out if you shift and ride the clutch like a car. That why you shift low rang at 1,000 rpm your using the engine torque not the clutch to get rolling. You can also just slide the gears with more practice.
     
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  5. swaggerjacker

    swaggerjacker Medium Load Member

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    Out at 1700 in at 1400. Place the shifter in the hole so all you have to do is slip her in at 1400.
    Watch the tach until you can shift by ear.
     
  6. swaggerjacker

    swaggerjacker Medium Load Member

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    Going uphill the shift will be slower. Wait for it to fall into gear, don't force it. Downhill will shift faster. Be quicker. It's all timing. Slight incline and downshifting, you can get away with 11 and 14. Otherwise, out at 11 throttle to 16 -17 back into the next gear. You will get differing opinions. Experiment.
     
  7. Bean Jr.

    Bean Jr. Road Train Member

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    All the engine manufacturers recommend progressive shifting. As you go into higher gears, you wind it higher. Unless you are going uphill, even with a heavy load, there is no reason to ever wind up to 1,700 in the low range. I have owned 5 trucks and been driving for a living for 17 years, and had my license for another 18 years. Loaded, start in 2nd gear, or in a 13 speed, 1st, not low. Wind it up to about 1,000, and it will fall right in, next shift, about 1,050, and so on until you get in high range. Your first shift in high range should be coming close to as high as you need to wind it. If you have a 13 speed, then 1,500 will be ok. 10 speed then you will need to take it to 1,600. Big block Cats and Cummins pull pretty good at 1,200. With a Detroit, like the other poster said, you got to wind them a little tighter ad they don't pull well at 1,200.

    An aside, is the year correct, or the engine? A 1991 would have a 3406b in it, and from what I've heard from the Cat guys, they wouldn't trade a "b" for anything!
     
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  8. swaggerjacker

    swaggerjacker Medium Load Member

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    He said he's new. revving to 17 gives him time to catch his gears. Once he's consistent he won't need to. I'm talking about starting in fourth and up unloaded.
     
  9. x1Heavy

    x1Heavy Road Train Member

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    You can buy time with a very quick stab of the fuel in between gears as the RPMs fall quickly. Done right that engine will sort of snort and rev just a hair, maybe 200 rpm or so and then continue to fall off. By then you should have the time needed to move towards the next gear up.

    Its a truck, the word "Fast" does not compute. Slow and steady is smooth and fast. My old Mack super 500 with the 15 double under is somewhat fun. allow her to lumber down to 900 rpm with a little fuel and even less then downshift. Come out of the double under and then start using whole gears. click click click until the hill is topped. Check jacobs braking switches and set up for the downgrade in whatever gear you used to top the hill. (Go down the gear you climbed in.. make sense?)

    The reason the low end seems faster is because there is a great mechanical strength to keep the engine's work in the low range. The higher gears move towards a direct drive one to one and even into a touch of overdrive where the engine turns less than the final drive.
     
  10. Diesel Dave

    Diesel Dave Last Few of the OUTLAWS

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    1991 with a C15 ? You sure it ain't a B model ? If it really has a C15, someone must of love that truck to go to the trouble to drop all the electronics to make it run.
     
  11. BigTennOTR

    BigTennOTR Medium Load Member

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    You mean its not a racekar Ricky Bobby :(
     
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