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Saturn Overdrive Woes

Discussion in 'Early CJ5 and CJ6 Tech' started by kenb, Dec 29, 2019.

  1. Dec 29, 2019
    kenb

    kenb Cleverly disguised as a responsible adult

    Detroit
    Joined:
    Jan 22, 2019
    Messages:
    670
    Hello,
    I finally made the leap and ordered a Saturn overdrive for my Willys. Here are the particulars:

    1954 M38A1
    4F engine, T90, Dana 18. I think the D18 may be original to the vehicle, it has the 26 tooth gear. Transmission and transfer case work well, smooth shifting, no unusual noises, no popping out of gear.

    Install of the overdrive went smoothly. The linkage was the unit from Advanced Adapters for the T90. I had to do a bit of trimming to the linkage at the point where it attaches to the overdrive. This was to ensure there was no binding. I have the linkage adjusted to where there is unobstructed throw in both directions. Sitting stationary with the engine off it shifts smoothly and easily both in and out of overdrive.

    Took it for a test drive. Transmission cover still removed from the tub so no clearance issues from that factor in. Sometimes it will shift easily in and out of overdrive. Other times it will not want to engage or will pop out of (overdrive) gear when I release the clutch. Apparently there is a neutral position between overdrive and direct drive? Sometimes when this happens I need to pull over and work with the shifters a bit to get it back in or out of overdrive. Sometimes these difficulties are accompanied with a bit of gear clash.

    Needless to say this is all very frustrating. When it works it's great. Going 55MPH with less than 2500RPM is exhilarating. I would like to find a way to make this work. Does anyone have suggestions or ideas?

    Thanks,
    Ken
     
    jeepstar likes this.
  2. Dec 29, 2019
    scott milliner

    scott milliner Master Fabricator

    Seattle Wa.
    Joined:
    Dec 17, 2002
    Messages:
    2,361
    Do you mean, pops out of direct drive. If the Overdrive is engaged. It's in direct drive. I had the same issue. I tried two different Overdrive units both kept popping out. I assumed it was from my SM465. I removed it and never used it again.

    Wonder if it is a design problem. After study. It looks like it should have a 1/4" more engagement. (Yes. I had the gear measurement per instructions.)
     
  3. Dec 29, 2019
    kenb

    kenb Cleverly disguised as a responsible adult

    Detroit
    Joined:
    Jan 22, 2019
    Messages:
    670
    Thanks for the reply. Sometimes when shifting from no overdrive to overdrive engaged it will pop back to a sort of neutral position. Also sometimes when shifting from overdrive engaged to no overdrive it will pop back into that middle neutral position.

    Note I did also check the gear protrusion from the transfer case prior to mounting the overdrive unit.
     
  4. Dec 29, 2019
    Jw60

    Jw60 Sitting up n buckled down. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Sedalia MO.
    Joined:
    Apr 8, 2008
    Messages:
    4,716
    How much shift rod travel do you get at the Overdrive? It sounds like you're not getting it shifted fully. Yes there is a neutral between gear positions so you might think you are in drive or Overdrive but really it's in neutral going in and out of one or the other.
     
  5. Dec 30, 2019
    kenb

    kenb Cleverly disguised as a responsible adult

    Detroit
    Joined:
    Jan 22, 2019
    Messages:
    670
    I'll have to measure how much travel I'm getting at the overdrive. The stick in the cab is not obstructed. I'm able to push it as far as it will travel forward and rearward. I'm pushing as hard as I can. When it won't shift for me it feels like something won't mesh or seat in the unit.
     
  6. Dec 30, 2019
    PeteL

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

    Hills of NH
    Joined:
    Aug 3, 2003
    Messages:
    9,754
    I wonder if it is mounted perfectly aligned and concentric etetera?

    I had issues with a pto unit. I found that slightly loosening the mount bolts allowed it to operate smoothly. What fixed it was "working" the unit as I gradually retightened them.
     
    Last edited: Dec 30, 2019
  7. Dec 30, 2019
    65CJ5 SRD

    65CJ5 SRD Member

    NM
    Joined:
    Aug 12, 2019
    Messages:
    103
    I never could get mine installed, had to take it to a shop. Been working well ever since. It can be a little tricky to get into gear from time to time due (I think) to rotational speed of the gearbox. But nothing that keeps it from working. I hope you can get it sorted.
     
  8. Feb 22, 2020
    kenb

    kenb Cleverly disguised as a responsible adult

    Detroit
    Joined:
    Jan 22, 2019
    Messages:
    670
    I finally have an update. I returned the unit to Advance Adapters. They sat on it for a while due to a system issue for them checking in my return and getting it into the service queue. Upon inspection they found the internal synchronizer ring (the one at the rear of the unit, not the one you see when you install it) was out of place. It's running well now for the 40 or so miles I have on it. I just need to cut the floor pan and get a shifter boot installed.

    During test driving with the floor pan removed I gained a new appreciation for how much energy must be involved spinning the front drive train. I had installed original hub flanges for looks but I think I'll be going back to lockout hubs.
     
    65CJ5 SRD likes this.
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