Floating gears in non synchronized transmission? (5 speed)

Discussion in 'Questions From New Drivers' started by Zonno, Jul 1, 2022.

  1. Zonno

    Zonno Light Load Member

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    Earlier this week I had to drive a truck that only had a 5 speed, not a 10 speed like the other trucks we have. It’s 89 model International, and I believe it’s either a 4700 or 4900 model. I wondered if if I could float the gears, or if I should try and shift like a non commercial vehicle. And turns out, that was the correct decision. Clutch all the way to the floor, bring it out of gear and into the next gear, then release the clutch. No grinding, and didn’t have to worry about the RPMs matching.

    Had I tried floating the gears, would/could I have torn the transmission up?
     
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  3. tscottme

    tscottme Road Train Member

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    Floating means not using the clutch except to start moving. All other shifts do not use the clutch. Smaller transmissions usually have RPMs drop so quickly it is hard to float. Floating doesn't hurt the transmission, it's the not quite being able to get in gear when trying to float that causes damage.
     
  4. tscottme

    tscottme Road Train Member

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    If the transmission is synchronised you can always get into gear using the clutch. If the transmission is not synchronized you can only get into a gear if the RPMs, roadspeed are within the correct operating range. Floating just takes the clutch mechanism out of the equation, not change if the gears are harmed.
     
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  5. Zonno

    Zonno Light Load Member

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    Ok I had it backwards. 4-wheel cars it’s stick-shift are synchronized, whereas most commercial vehicles are not.

    And I know what floating the gears is; I do it all the time in the 10 speed dumptruck I drive. :D
     
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  6. kranky1

    kranky1 Road Train Member

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    Depends. You first have to figure out if the transmission is synchro-mesh or constant mesh. Shifting a synchro transmission without the clutch will eventually tear the synchronizers up. You’re moving a gear into another gear with a synchro box. A constant mesh you’re only moving a collar that locks an already engaged gear to the main shaft.
     
  7. SmallPackage

    SmallPackage Road Train Member

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    Put over 1 million miles on a syncro’d spicer 6 speed in a ‘99 FL 60. Used the clutch in first and reverse only. Never had issues with trans. It’s still solid. Only replaced the clutch twice in that time around 500,000 miles at each engine overhaul and I don’t think they were ready for replacement yet.
     
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  8. Zonno

    Zonno Light Load Member

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    Not sure which one this truck was. But as I said, I was able to shift perfectly by pushing the clutch to the floor, to upshift and downshift. Wouldn’t work in the 10 speed. Even if you double clutch like you’re required to do in school, you only push the clutch down about 2 or 3 inches when shifting. (You do go all the way to the floor to put it in gear when you’re parked, but that’s the only time).
     
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  9. SmallPackage

    SmallPackage Road Train Member

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    The truck is 23 years old and the clutch peddle pad still looks factory fresh. Lol!
     
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  10. SmallPackage

    SmallPackage Road Train Member

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    Rule of thumb on medium duty syncro’d trans is if no clutch brake it has synchro’s. Unless it is an older main for a two stick setup. Those were non syncro and non brake.
     
  11. kranky1

    kranky1 Road Train Member

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    You just reminded me of something. I’ve got an ‘89 KW that just recently started to show the pedal through the pad. I need to invest in one for it.
     
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