Pls help. Rpm rev up while gaining low speed

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Smstrucker22, Oct 6, 2022.

  1. Smstrucker22

    Smstrucker22 Bobtail Member

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    Sep 26, 2022
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    I just purchase this truck which the seller is not been honest. From 6th gear to 7 to 8 and 9, the rpm rev up and I'm going little speed. At 23mph I have to shift to 8th gear, 33pm I have to shift to 9 and 40mph I have to shift to 10. It's d60 series 14L with 342 rear. Driving on 63mph, my rpm will be on 1900. Pls any advice
     
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  3. baha

    baha Road Train Member

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    What year and make is your truck? Ck the clutch Adjustment!
     
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  4. uncleal13

    uncleal13 Road Train Member

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    If you’re lucky it just needed adjustment, but the more you drive it like it is now, the sooner you’ll need to replace the clutch. Assuming it’s not worn out to begin with.
     
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  5. skallagrime

    skallagrime Road Train Member

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    Given what you said you have completely bald low pro 22.5 tires (38.1 diameter) and your transmission is direct drive in 10th to be going that speed for 3.42 rears...

    Im not so certain thats correct.

    If we call it 3.55 rears, thats not dangerously bald tires, but still low pro 22.5s and a direct drive 10th gear

    If you can post your tire size, we can try to figure out what actual rears you have. But a transmission tag might be helpful to establish that too

    (Though if your clutch is partially engaged that could explain things, id be surprised if you didnt blow the clutch up in the first 500 miles of driving it, it should be impossible to climb a hill with any weight if clutch is partially engaged)
     
    Last edited: Oct 9, 2022
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