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Fc-150 Rough Shifting Until Warmed Up

Discussion in 'Jeep Truck and FC Tech' started by jeepstar, Mar 31, 2021.

  1. Mar 31, 2021
    jeepstar

    jeepstar Well-Known Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Sheboygan
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    hello all.

    I recently had a shop rebuild my FC-150 trans/T-case. it was leaking a lot, and I figure get it professionally done so it right, just for peace of mind.
    since I got it back (almost a year now) it hasn't leaked a drop. HOWEVER....now its really rough to slide into gears until everything is warmed up, like 5 miles down the road, give or take. once its warmed up it shifts into 1-2-3 just fine. if i push the clutch in, i cant really downshift until the RPMS are matching, otherwise it grinds.

    what causes this, and how do i fix this?
     
  2. Mar 31, 2021
    ITLKSEZ

    ITLKSEZ Hope for the best, prepare for the worst

    Spokane Valley, WA
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    They might’ve put some insanely thick gear lube in there to help keep the leaks at bay. I’d drain it and fill with the recommended stuff. Let it drain overnight.
     
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  3. Mar 31, 2021
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Hills of NH
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    2x
     
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  4. Mar 31, 2021
    Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

    Tantallon, Nova...
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    Classic vehicle transmission issue.

    Classic vehicle transmission fix.


    [​IMG]
     
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  5. Mar 31, 2021
    Twin2

    Twin2 not him 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Virginia Beach, VA
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    reminds me of used car lots in the 60's and 70's . noise stopper :whistle:
     
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  6. Mar 31, 2021
    jeepstar

    jeepstar Well-Known Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Sheboygan
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    Is that sawdust?
     
  7. Mar 31, 2021
    Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

    Tantallon, Nova...
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    Could be :whistle:
     
  8. Mar 31, 2021
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Hills of NH
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    Using sawdust would be wrong, wrong, I say!

    s-l1600-4.jpg
     
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  9. Apr 1, 2021
    Twin2

    Twin2 not him 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Virginia Beach, VA
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    pete sure that ones out of date , 1.35 :D
     
  10. Apr 1, 2021
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Hills of NH
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    I know. Last time I used it! It was a big deal when I was a kid but I never see it anymore.

    Is STP even still made? :D
     
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  11. Apr 1, 2021
    Mr Vaughan

    Mr Vaughan

    one of my uncles has a truck like that, but it's got a 10 speed from a large truck, so to be expected.
     
  12. Apr 1, 2021
    duffer

    duffer Rodent Power

    Bozeman, MT
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    Refill with synthetic gear lube. If it doesn't leak the stuff does wonders. Available in both 75-90 and 75-140. I have not tried the latter but it is what will be going in the current D18 project.
     
  13. Apr 7, 2021
    Keys5a

    Keys5a Sponsor

    Florida Keys
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    I went to full synthetic gear lube in my Syncro VW years back. It started leaking in about 5 places. 3 months later, I drained it out and put GL4 back in. All the leaks stopped a week or two later.
    I can't imagine the leaks in an old Jeep with full synthetic gear lube.
    My Tux recieved some sawdust in the trans many years before I started driving it. Probably why the trans/TC need a rebuild a couple years later. That was a common "trick".
    -Donny
     
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  14. Apr 8, 2021
    duffer

    duffer Rodent Power

    Bozeman, MT
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    You will note my caveat. Yes, the seals need to be perfect and the shim pack coated. And you still may get a little seep from the ends of the intermediate shaft. But I'll bet the shifting issue will go away with the stuff.
     
  15. May 9, 2022
    jeepstar

    jeepstar Well-Known Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Sheboygan
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    All right, follow up time. It's been over a year since I first posted about my issue, but life happens. I dealt with the awful shifting on weekends when I'd be up at the cabin. Then it was in storage from October until 2 weeks ago. brought it home and just looked at it.
    Today was gonna take it fishing. Transmission was not shifting so enough is enough. Drove it around a few blocks to warm it up, drained it, put in the recommended 80w90, and blamo. Problem solved. Thanks guys
     
    Last edited: May 9, 2022
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  16. May 11, 2022
    Keys5a

    Keys5a Sponsor

    Florida Keys
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    Lets hope it doesn’t start leaking again now that you have liquid gear oil in it!
    The remote shift linkage in FCs leaves a lot to be desired.
    -Donny
     
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  17. May 11, 2022
    Daryl

    Daryl Sponsor

    Bonney Lake, WA
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    I have seen full synthetic do this. Most overdrives will not shift at all with synthetic 90 wt.
     
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