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Zf5 starting in 2nd/floating gears

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Diesel8873ne, Jan 10, 2019.

  1. compressionignitionrules

    compressionignitionrules Full Access Member

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    dual countershaft trans don't have synchros, they have sliding collars . there is no friction material as in a synchronized trans, thats why its called a synchronized trans. anything other than ATF or synthetic atf in a ZF 5spd will eat up synchros.

    I'm not a truck driver but am a truck/coach mechanic. personally I find it easier and faster to shift a dual countershaft (non synchronised) trans without the clutch. but only if I drive the truck for more than a few minutes.

    one big problem with medium duty synchronised truck trans is people putting them into gear initially before the vehicle is stopped. have replaced many ZF 5 and eaton 6 speed 2nd gear synchros from impatient drivers. there is a reason why so many truck come with auto transmissions now.
     
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  2. Diesel8873ne

    Diesel8873ne Registered User

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    Alright great info won't be floating any gears in the future just to be safe know some people do it but id rather be safe . I think that I'll change the fluid with the redline from what I've gathered, any tips when I go to change it, anything I need to know or also need to replace while doing it. Truck has 200k miles don't really know maintenance.
     
  3. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    The last time I refreshed my Eaton 6 speed I bought a faceplated gear set. Now I use the clutch to start and clunk gears on everything else. It’s really satisfying when I get to drive the truck, but you wouldn’t want to shift that way in any other transmission that hasn’t been built specifically for that.
     
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  4. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    It uses brake fluid.
    Mine does that too. It may not even be that often. I usually forget about it until it gets low the next time.
    This makes sense. I don't have this issue though. I used to have a car that had a four speed with what I call "the standard H pattern" for shifting. Reverse was all the way to the left and forward. It had a dentent to keep it from going far enough to the left to engage reverse unless you pushed down on the top of the shifter. the problem started when the detent decided to quit working. My solution was to drop back to second gear and then forward into first. I still keep that habit today even if I'm at a complete stop in neutral. It never grinds using this method, whether stopped on still rolling slowly. If also helps if you don't force the shifter, just let it go into gear when the transmission wants to.
     
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  5. compressionignitionrules

    compressionignitionrules Full Access Member

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  6. Runningaford

    Runningaford Registered User

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    Sometimes, you just gotta float it into gear. I've read several folks on here who've had Master/slave cylinder issues, meaning no clutch to use at the time. You'll also read some folks, myself included, with no clutch at the time, have limped these trucks home by shutting the engine down at a light, starting it while in 1st gear to go.

    I think the biggest thing with any manual transmission is really knowing it, and not abusing it. My dad shifted his 1970 FJ40 for as long as I can remember, hardly using the clutch as the 2nd to 3rd syncro would grind; no significant difference even today with that rig.
     
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  7. 79jasper

    79jasper Chickenhawk

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    These trans have weak synchros in the first place.....

    Sent from my SM-N960U using Tapatalk
     
  8. Kevin 007

    Kevin 007 Full-floater

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    Im one to never float a syncro trans. Im a truck driver and float transmissions plenty, when its a transmission designed to do so. But not a ZF. I also always start in 1st even with 4.10 gearing, unless the truck is rolling slightly or starting off downhill. Why put extra strain on the clutch just to save a simple shift. That's just being lazy IMHO. I like to get the most service life out of everything, not because im cheap, just why not get the most out of something. As Jasper said, these transmissions have weak synchros as it is.

    Yes there are times when you might have to float it like when your master or slave fails and you need to get home or whatever, but im talking about not floating during regular driving, when its not necessary to do so.
     

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