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Dana 18 upgrade...need opinions

Discussion in 'Flat Fender Tech' started by RandyYJ, Jun 15, 2010.

  1. Jun 15, 2010
    RandyYJ

    RandyYJ Member

    Davenport, FL
    Joined:
    May 23, 2008
    Messages:
    83
    I had the old/new flatty out this weekend and found my first weak point. I'd like to know if you all think this might be a fluke or something I'm gonna be doing all the time. I've ordered the new replacement gear and I'm planning on having the whole case Cryogenically treated. They boast a 30% improvement on tensile strength and 100 percent on wear. I read a few old threads on here about the D18 surviving 400 horsepower and small V-8's, and I'm nowhere near that realm. Did I just have a bad day with this one?

    [​IMG]

    [​IMG]
     
  2. Jun 15, 2010
    RandyYJ

    RandyYJ Member

    Davenport, FL
    Joined:
    May 23, 2008
    Messages:
    83
    Also, this is the Dana 18 with the 39 tooth (broken) gear behind an SM465 and a TBI 4.3.
     
  3. Jun 15, 2010
    jpflat2a

    jpflat2a what's that noise?

    Riverside CA
    Joined:
    Jul 30, 2003
    Messages:
    7,818
    just depends on your driving, more or less.
    anything can be broken, at any time or place, given the right circumstances.
     
  4. Jun 15, 2010
    Corveeper

    Corveeper Member

    Chanute, Kansas
    Joined:
    Jul 29, 2005
    Messages:
    817
    I’ve been pretty mean to mine and it’s survived well so far.
     
  5. Jun 15, 2010
    Extreem

    Extreem Member

    Massachusetts
    Joined:
    Apr 10, 2006
    Messages:
    87
    I'm running a Dana 18 behind an SM465 with a 283 SBC. I've got 60's f/r and 36" tires with no problems yet. I'd call it a fluke and rebuild it.

    Extreem
     
  6. Jun 15, 2010
    Mike S

    Mike S Sponsor Sponsor

    Cameron Park Ca.
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    Oct 6, 2009
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    Nickmil has one for sale right now, IIRC.
     
  7. Jun 15, 2010
    RandyYJ

    RandyYJ Member

    Davenport, FL
    Joined:
    May 23, 2008
    Messages:
    83
    I have another out there rusting away as a spare. Not that I'm turning something down, I just don't think I need it yet. Keep the opinions coming, though. I'd like to hear them all. I'm feeling better about my 18 already.
     
  8. Jun 15, 2010
    neptco19

    neptco19 That guy.... Sponsor

    Athens, GA
    Joined:
    Sep 26, 2003
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    1,381
    I stripped two sets of gears just like you have pictured behind a stock 360 and t18 fwiw. Although both times it happened I was romping on it, one was a quick 1-2 shift and the other I bounced and didnt let out of the gas. The third set was still working well the day I sold it.
     
  9. Jun 15, 2010
    duffer

    duffer Rodent Power Sponsor 2019 Sponsor

    Bozeman, MT
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    Sep 17, 2009
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    2,521
    Yep, mine surviving just fine behind not too mild 381 sbc. That said, I drive off-road like the old man I am and am only running 33's. I would suggest that you rebuild using a case from a D20-substantially more iron, and put in a set of terra low gears. I really like the terra lows-they were well worth the expense.
     
  10. Jun 16, 2010
    RandyYJ

    RandyYJ Member

    Davenport, FL
    Joined:
    May 23, 2008
    Messages:
    83
    I'm thinking I'll disassemble it, check everything over good including the intermediate shaft, install new gear, have it cryoed, and then maybe install the Dana 18 girdle and go from there. If that doesn't work, I'll have to find a D20 box and start from there. I like the Terra low gears, especially the crawl ratio, but pretty pricey. That's plan C.
     
  11. Jun 16, 2010
    jeep2003

    jeep2003 Active Member

    Vestal NY
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    May 30, 2006
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    1,460
    yeah make sure everything is tight and the intermediate shaft isnt worn. A loose mesh might have put more stress on the outside of the teeth
     
  12. Jun 19, 2010
    ncs

    ncs New Member

    Joined:
    Apr 2, 2007
    Messages:
    24
    A friend of my broke his dana 18 once. I had a 20 case, upgraded rear output shaft and a lower gear set(not sure if it was terra). It was behind an sm435 behind a stock ford 302 in an fj-40.

    I'm not sure if it was unstucking a 7000 lbs ford from a snowdrift, or the 10 people that rode on it back up the hill, but the gears gave up the ghost on the way off the trail.

    A strong transfercase that still has an offset rear output would be an fj-55 case. I've seen one survive in a rig that broke the input shaft on it's sm420.
     
  13. Jun 19, 2010
    Jeepenstein

    Jeepenstein Me like Jeep.. Sponsor

    Middle TN
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    Jun 15, 2003
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    I used a dana 20 caseand put all the dana 18 guts and stuff in it. The dana 20 has a thicker casting than most of the 18's.. Not that it will help your broken gear situation but it is an overall improvement.
     
  14. Jun 20, 2010
    RandyYJ

    RandyYJ Member

    Davenport, FL
    Joined:
    May 23, 2008
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    83
    I'll have to look up that FJ55 case. I'm not familiar with it. The path I'm leaning towards now is buying a buddy's Dana 20 for 150 bucks, and ordering Herm's Terra low kit, swapping all my 18 stuff into it and then cryo dipping the whole thing. That would run about 1000 bucks. In the mean time, I think I'm still gonna replace that one broken gear and take it out again and see what happens. This is still too much money for a 63 year old transfer case, but I'm not sure where to go from here.
     
  15. Jun 26, 2010
    RandyYJ

    RandyYJ Member

    Davenport, FL
    Joined:
    May 23, 2008
    Messages:
    83
    Herm's Tera-low kit and rebuild kit ordered. I decided against the new Dana 20 case only for money reasons. I'm sure I have plenty of questions coming soon.
     
  16. Jun 26, 2010
    aallison

    aallison 74 cj6, 76 cj5. Has anyone seen my screwdriver?

    Green Cove...
    Joined:
    Nov 24, 2006
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    1,773
    I thought the D18 and the D20 transfer cases were about the same strength. And the D18 has a lower low gear.

    But a D20 with a Tarra Low kit is way cool. Or just go all the way and get an Atlas or Stak...........
     
  17. Jun 26, 2010
    Jeepenstein

    Jeepenstein Me like Jeep.. Sponsor

    Middle TN
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    the early 18's had a thinner case.. the later ones had the same thickness as the 20 but the later 20's had better castings.

    BUBBA
     
  18. Jun 27, 2010
    nickmil

    nickmil In mothballs. Sponsor

    Happy Valley, OR
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    Sep 23, 2002
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    Yup, I agree.
    One thing you want to watch out for on the 20 cases is the location of the fill plug if running the stock parking brake and make sure it has the casting boss for the clutch pivot. Not all of them do and many of the 20 cases have the fill plug on the back instead of the passenger side. Most can be drilled and tapped but something to watch for.
     
  19. Jun 27, 2010
    scott milliner

    scott milliner Master Fabricator

    Seattle Wa.
    Joined:
    Dec 17, 2002
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    2,011
    Here's mine. V-6 SM465 and 17year old popping the clutch at 3000rpms in low range.

    [​IMG][/IMG]
     
  20. Jul 11, 2010
    Sandjeeper4

    Sandjeeper4 New Member

    Joined:
    Jun 9, 2010
    Messages:
    3
    Here is a griddle I had a friend made for me. He made two other for other friends.
    [​IMG]

    [​IMG]
    My transfer case held up after I dumped the clutch @ 6000rmp.
    I blew up my Muncie M21 transmission instead.
     

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