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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 at 4:24 PM.

  1. Diesel8873ne

    Diesel8873ne Registered User

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    Okay so title pretty much sais it all, I just recently purchased a 88 f250 7.3 with zf5. I noticed people seem to be fine with starting in second when not on a hill and I'm just curious of everyone thought, it sais right in the owners manual not to start in 2nd.

    Other question is floating gears I'd like to get some feedback on that, what are your opinions and what do you guys do ? I drive a international 4900 for work alot and was taught from the get go to float gears and have been doing it for years with no negative side effects that I can tell.

    Thanks ahead of time for any help.
     
  2. jaluhn83

    jaluhn83 Full Access Member

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    Pretty common to start in 2nd. Harder on the clutch, but IMHO if you're not an idiot about it there's no real ill effect.

    Floating gears doesn't work as well with a synco trans and can quickly kill the synchros. Works better with the heavier closer ratio trannies in MDT too.
     
  3. Diesel8873ne

    Diesel8873ne Registered User

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    Okay good to know about 2nd. I was just curious because of what the manual said.

    Regarding shifting in general when I shift if I don't match the rpm just right it makes a noise wich is worse the further I am odd in rpm and less so the closer it is. Wondering if that is something to worry about.

    Radio doesn't work I truck so I hear everything. Sorry if that's stupid question new to this truck and the zf5. Used to bigger trucks with manual transmissions
     
  4. Clb

    Clb Another old truck Supporting Member

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    Proofread man.
     
  5. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    Not a stupid question at all. From your description, it sounds, to me, like you have a synchronizer going out. If it does this in all gears, you may have other issues.
     
  6. Diesel8873ne

    Diesel8873ne Registered User

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    Seems to be in all gears from what I can tell. Wasn't sure if it meant synchros or something to do with clutch possibly
     
  7. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    It may be the clutch if it does it in all gears. That would be MUCH cheaper than a transmission rebuild.
     
  8. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    If it's hard to get the transmission into gear at a stop, check the fluid in your clutch master cylinder. It could be as simple as low fluid.
     
  9. austin92

    austin92 Full Access Member

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    Mine has such a slow leak I have to top off maybe twice a year. Pedal feels different, grabs low, and is hard to get in gear at a stop. Top it off and all is well


    Sent from my iPhone using Tapatalk
     
  10. pelky350

    pelky350 Full Access Member

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    The noise your hearing is the synchros trying to match the gears speed but since the clutch isn’t depressed it’s just burning them up, they will last quite a while like that if your good at matching the Rpms but eventually it’s gonna start grinding when you try to float the gears.
     
  11. compressionignitionrules

    compressionignitionrules Full Access Member

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    "floating gears" by your description means not using the clutch? if you have been doing this with a ZF 5 , you have already destroyed it!

    clutchless shifts are for non synchronized trans , even spicer 6 and 7 speeds and eaton single countershaft 5 and 6 speeds will be destroyed by it.

    get ready to put all the syncros in your ZF5.

    hey ignorance is bliss.:fan:
     
    Macrobb, Thewespaul and 79jasper like this.
  12. Diesel8873ne

    Diesel8873ne Registered User

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    I have attempted it, but have not been driving around "floating gears" consistently. The noise i hear happens when using the clutch and happens in all gears, also has been making this noise since I purchased the truck before I ever even thought to try floating them. Perhaps p.o. had been doing it as well or just tired tranny.

    I will check clutch master fluid level today, if it is low what fluid do I top it off with?

    Also say that the transmission needs synchros what is a rough cost to "rebuild " a zf5
     
  13. Diesel8873ne

    Diesel8873ne Registered User

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    Also forgot to mention it is very easy to get into gear from a stop, any way the noise could be the clutch?
     
  14. Diesel8873ne

    Diesel8873ne Registered User

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    Last thing I forgot I should have said is the noise reminds me of the noise you get when letting the clutch out too slowly from a start not sure if that helps
     
  15. The_Josh_Bear

    The_Josh_Bear Full Access Member

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    This has come up at work lately.
    We have an International 4300 at work I drive all the time with the gawd-awful Eaton 6-speed and while I've heard of floating gears, rarely tried it. It's too slow for one thing.

    Anywho we only have 3 drivers and the other two are new guys who both started in class-A trucks and asked the same thing.
    Sounds like you are pretty sure about this style of shifting ruining synchros?
    Can you expand a little? When "floated" correctly I would imagine there being very little worry or wear. But if you're pushing too hard before the shaft speeds match then yeah I can see how that would burn them up. Thoughts?

    OP: it just occured to me that if you're getting chatter in most gears and it isnt a clutch issue, you've got the wrong oil in the transmission. I personally use Redline MTL which is a synthetic Manual Transmission Lubricant. I've heard great things about the Synchromesh(I think it's a GM product), and many good reports about synthetic ATF. These are all approved by ZF. But beware ZF also approves of dino 75w-90 and that performs like absolute crap in these things.
     

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