Range Shifts

Discussion in 'Trucks [ Eighteen Wheelers ]' started by dieselcow, Apr 5, 2007.

  1. dieselcow

    dieselcow Bobtail Member

    Apr 5, 2007
    Do you preselect your range shifts or shift ranges only when neutral and why? I have heard people argue both ways.
  2. Joethemechanic

    Joethemechanic Medium Load Member

    Mar 22, 2006
    Phila Pa
    There is a valve on the top cover of the trans that only lets the air through for range shifts when the stick is in neutral. So you can preselect range shifts without hurting anything. Now the splits are a different story. As soon as you move the split switch the air pressure goes right to the air cylinder in the trans and the trans is trying to shift. This puts pressure on the shift fork and the whole syncro assembly. This is bad.

    So to answer your question. It is ok to preselect your ranges, but bad to preselect your splits.
  3. dieselcow

    dieselcow Bobtail Member

    Apr 5, 2007
    I was wondering because if you look in like a Roadranger manual they say "Never move the range lever in neutral while the vehicle is moving" and the say to "preselect all shifts". I don't really get that because it is not going to shift ranges until it hits neutral anyway. I know people who don't preselect, they just change ranges in neutral as they are going for the next gear and say it is easier on the transmission.
  4. PackRatTDI

    PackRatTDI Licensed to Ill

    Jul 15, 2006
    El Chuco, Tejas
    I would defer to what Eaton/Roadranger says about range changing since they more than likely know what they are talking about.:yes2557:
  5. Joethemechanic

    Joethemechanic Medium Load Member

    Mar 22, 2006
    Phila Pa
    Personally I preselect my range shifts. And it's my truck and if it breaks I have to fix it. And I have built a whole lot of roadrangers so I know what is going on inside of them when you shift. Those guys that try to tell you not to preselect ranges don't understand how the trans operates. I think somebody told them not to preselect the splits and they probably got that confused with ranges. Lots of truck drivers are clueless about how a truck works mechanically. Not that anyone of them will admit it though.
  6. buck and a half

    buck and a half <strong>Mr. Miles & Miles with Many Smiles</strong

    Aug 11, 2006
    I always thought that either the eaton or rockwell,one says ok to preshift and one says no,but not sure which one. i just drive them all, smooth as silk most of the time, like an auto if you ride with me,never one to like breaking down or breaking anything. Joe you are way up on this from what I know.
  7. jorlee

    jorlee Light Load Member

    Feb 17, 2007
    Preselect all the time, PERIOD. Those that don't are playing the thin line of working ok, and needing repair. These transmissions have a valve body on the top driver side (if I remember college correctly). This valve only allows range shifts over neutral. It's there for a reason. You can drive in 5th for a long time with it preselected high before you actually shift to high.

    Out instructor told us when he used to work in shop, he had a truck come in. Had to rebuild the range synchronizer. The driver complained of it making noise when he range shifted. When it was fixed they went for a drive. He sat in the passenger seat, the whole time, watching him range shift in neutral. After the trip he told the driver what he was doing wrong.

    That valve has a part called a preselection pin, for a darn good reason. Preselect those ranges, cuz it's all in timing. As soon as the stick is moved to neutral it's shifting, and should be shifted before you get into the next gear.

    Remeber, Preselect those ranges!!!
  8. smittybilt

    smittybilt Bobtail Member

    Apr 26, 2007
    i have a problem when splitting the high side with my 18 speed, sometimes when i let off the pedal to grab the next gear when i get back into it it just grinds and the gears arent engaging, if i let back out of it and get back in it then it will shift, any ideas
  9. CenutryClass

    CenutryClass Road Train Member

    Feb 15, 2006
    i think you have to watch the tach. According to Eaton, of you get back on the throttle before the RPMS drop by the specified amount, misshsifts are possible.

    I saw this guy @ CDL school the other day. Said he bought an 05 shaker.

    He shifts to neutral then range changes. i wanted to tell him that was bad, but i kept my mouth shut.
  10. Brickman

    Brickman Trucker Forum STAFF Staff Member

    Sep 17, 2006

    Preselect only works with the newer idiot proof trans. The new local job I just started has a bunch of old trucks (80s) with 13 spds. You cannot preselect any thing in those old trans. Same thing with all the other old trucks I've driven. You HAVE TO range shift in neutral. Some of the trucks you cannot even split from hi to low while making a gear shift.
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