1. Registration trouble? Please use the "Contact Us" link at the bottom right corner of the page and your issue will be resolved.
    Dismiss Notice

3.15 Low D-18 Transfer Case

Discussion in 'Early CJ5 and CJ6 Tech' started by LSwanson448, Dec 7, 2023.

  1. LSwanson448

    LSwanson448 New Member

    Is there a way to determine if a D-18 transfer case has the 3-15 low gear installed?
    Can I tell by opening the output cover or the bottom cover?
    I have a FrankenJeep that has the low range speed I want for my CJ5.
     
  2. Jw60

    Jw60 That guy 2024 Sponsor 2023 Sponsor 2022 Sponsor

    You'll know quickly with either cover removed.
    I don't think they are cast but milled from round stock.

    Spin the gears and note any numbers. Or count teeth. The Tera low set also has a much larger intermediate gear on the helical side.
     
  3. dnb71R2

    dnb71R2 SuperDave 2023 Sponsor

  4. duffer

    duffer Rodent Power

    Just pull the PTO cover-no need to drain case. A TeraLow gear will be marked "TL20A". It will be 26 tooth, but way different than the Dana/Spicer 2.43:1 gear set 26 tooth gear. Top is the Dana gear, bottom TeraLow.
    [​IMG]
     
    Danefraz, vtxtasy and Jw60 like this.
  5. danielbuck

    danielbuck Uncle Buck

    I'd pull the inspection cover like John said, but if it's an unknown t-case, might be a good idea to change the oil anyway :)
     
    vtxtasy likes this.
  6. Oldpappy

    Oldpappy A.C. Fults - Curmudgeon at large 2022 Sponsor

    I am thinking your "FrankenJeep" probably has lower ratio axles.

    You didn't mention what your "FrankenJeep" is, just that you want that low speed for your CJ5, nor did you provide any details for your CJ5.

    It is a large jump of imagination to assume your "FrankenJeep" has a lower geared transfer case, and just wishful thinking that it has Tera Low gears. I think that is unlikely.

    Most early Jeeps had 5:38 axles standard, as did early CJ5 Jeeps up through early 60s, then things started to change.
     
    Twin2 and vtxtasy like this.
  7. LSwanson448

    LSwanson448 New Member

    You get a gold star. Uncovered the diff. Tag that had 5.38 stamped on it.
    The frankenjeep has no jeep bodywork at all. The frame is cut off just behind where the front of the rear springs attached. The rear axle is now solidly mounted. Much like a tractor. It has a F134 engine and a T90 transmission. I use it to move firewood.
     
  8. Oldpappy

    Oldpappy A.C. Fults - Curmudgeon at large 2022 Sponsor

    My older Jeeps with the 5:38 axles are like driving a tractor in many ways.
     
    Jw60 likes this.