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Who Is Running A SM420 Behind A Dauntless ?

Discussion in 'Early CJ5 and CJ6 Tech' started by masscj2a, Jun 16, 2017.

  1. Jun 16, 2017
    masscj2a

    masscj2a Member 2023 Sponsor

    Ware, Mass
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    I just picked up a Dauntless with a SM420 and Novak adapter, connected to a Dana 18, 1 1/4 inch shaft. I'm wondering who has run this combo and how did you like it. This will be going into an early CJ5 . Its a running motor, but I'm going to take it down and rebuild it. The tranny is nice and clean inside and it looks to be rebuilt as does the transfer case. I have a pair of 62's and going to build at least one good one out of both. If you have run this combo before or presently, I'm wondering what you think the pros and cons are. Thanks
     
  2. Jun 16, 2017
    ITLKSEZ

    ITLKSEZ Hope for the best, prepare for the worst

    Liberty Lake, WA
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  3. Jun 16, 2017
    47v6

    47v6 junk wrecker! 2023 Sponsor 2022 Sponsor

    USA
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    I run that same setup. It works fine. Synchros have been problematic. I run a 1st generation sm420. Parts are available but not so much for gears etc. Rebuild is easy, transmission s tough. Its great if it works well. Shifts slow. I like it.
     
  4. Jun 16, 2017
    jpflat2a

    jpflat2a what's that noise?

    Hermosa, SD
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    I did the swap almost 3 years ago.
    For rocky or slow trails, you can't beat it.
    As mentioned, the slower shifting between shifts takes a little getting used to.
    420/V6 will crawl and idle so slow it's a snail race.
     
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  5. Jun 16, 2017
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    Slower than the other truck 4-speeds?
     
  6. Jun 16, 2017
    Muzikp

    Muzikp Active Member

    Sacramento Ca.
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    I run that setup with 3:73 gears and 31" tires. The crawl ratio in granny low is really nice, I calc'd the ratio at one point but forget what it was, I wanna say close to 90:1 crawl. Like others said, it shifts really slow and takes some getting used to (if you are in a hurry you probably shouldn't be in a CJ anyway). I did have a bit of trouble getting the throw-out bearing adjusted perfectly but works good now. I use the clutch adapter that has the chain, can't remember what it's called. Overall I'm really happy with it, no desire to change it. I think it may stick up through the floor a bit higher than the stock tranny, mine has a different floor panel that the rubber shift boot sits on, it's a bit taller than stock.

    [​IMG]
     
  7. Jun 16, 2017
    masscj2a

    masscj2a Member 2023 Sponsor

    Ware, Mass
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    My SM420 is also a first generation. One good thing for me is, both the tranny and TC have just been rebuilt. The PO stated that to me, but I took the covers off and confirmed it when I got home. The Novak adapter goes for over 500 on their site alone. I paid $500 for it complete, motor, tranny, adapter, TC. To me, this means after the engine is done, I will have a complete drop in driveline. I'm not interested in going fast with this Jeep. Normal back roads and some medium trails, maybe some rocks now and then. But I was thinking what better to put it in than a early 5. I'm pretty good at slow double clutching. Drove a few big trucks that required that and that only. So that's not a big deal. I think if I had a choice, a SM465 would have made more sense, but not at this price for being rebuilt. I'd be crazy not to use it.
     
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  8. Jun 17, 2017
    47v6

    47v6 junk wrecker! 2023 Sponsor 2022 Sponsor

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    The SM420 better honestly basically be free(less than 100 bucks) because of the price of the adapter. The adapter is a nicely made part, but there are 2 pieces to adapt to the big hole D18. When I replaced my 1947 D18 with a big hole one, the second piece to adapt the adapter to the big hole D18 was very tight tolerances. It needed more than the .002 clearance to fit together easily.

    I don't think it would be an issue on a bench, but I did that under the jeep It could have been more fun than it was because of the almost interference fit.

    Sounds like you got a pretty good deal. I got mine for 75 bucks and I ran it as is for a while. Had to double clutch into 4th. I fixed that issue, but after installing new synchros 3rd does not slow down enough during a shift to not grind occasionally. Oh well should have broken the glaze on the cup part of the assembly.

    To do again I would also have selected an sm465 just because parts are easier to source and no other reason. I think you will be happy.
     
  9. Jun 17, 2017
    jzeber

    jzeber Well-Known Member 2022 Sponsor

    Morgan Hill, Ca
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    I am running a SM 465 and it was one of the absolute best upgrades ever for what I use my Jeep for. As others have said great for slow crawling on the rocks.
    I have heard from a good friend that he had some clearance issues on his SM420 with larger u-joints on the T-case side.
     
  10. Jun 18, 2017
    masscj2a

    masscj2a Member 2023 Sponsor

    Ware, Mass
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    The sm465 is much more common and replacement parts are more readily available. Other than that, nothing. I like the fact that I will have a little over 7 to 1 first gear. Makes my axles gearing options a little more varied.


    jzeber, this one already came out of a cj2a, so the u-joints are correct for my early five. And seeing as its going into a little longer wheel base, I think the fact i'm planning on angles, it should be fine.
     
  11. Jun 18, 2017
    ITLKSEZ

    ITLKSEZ Hope for the best, prepare for the worst

    Liberty Lake, WA
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    If every inch is critical, the adapter for the 465 is shorter.
    From Novak:
    "The SM420 with adapter to Dana 18 is 15.2", while the SM465 with the Dana 18 adapter is only 13"."
     
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  12. Jun 18, 2017
    47v6

    47v6 junk wrecker! 2023 Sponsor 2022 Sponsor

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    Its to make clearance for the full sized U joint.
     
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  13. Jun 20, 2017
    SierraCJ5

    SierraCJ5 New Member

    Bakersfield CA
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    I'm running a Dauntless, SM420 with a Novak adapter, 1.25" model 18 t-case, 3.73 gears and 31" tires. I absolutely love it. SM420 was a craigslist find, it's a late model unit with the webbing on the passenger side bulge. I run the large u-joints on the front drive shaft and after slightly grinding the webs for clearance everything fits fine. I rebuilt the transmission with the Novak rebuild kit and it performs flawlessly; nice shifting (for a heavy truck tranny) and no grinding at all. The best thing is that I can get down the highway at 2300 rpm at decent speed and still have plenty of gearing in low for serious rocky trails. It is so satisfying to drop it into the straight cut granny gear once the trail gets rough. The SM465 is an option, but I like the 420 for it smaller physical size and decreased bulk (it's still huge compared to a T86). Both are bulletproof behind a V6 and offer real performance and piece-of-mind when far off the beaten path. I also like the connection to the past with the 420, it's the way things used to be and I enjoy that. I run a GL4 80-90 fluid in mine; supposedly helps synchro life. If I had to do it over again I wouldn't change a thing. The swap was one of the best mods I've made with power steering and disc brakes close seconds.
    20170401_124540.jpg
     
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  14. Jun 20, 2017
    masscj2a

    masscj2a Member 2023 Sponsor

    Ware, Mass
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    Sierra, what model Jeep do you have it mounted in? Year, etc ?
     
  15. Jun 20, 2017
    SierraCJ5

    SierraCJ5 New Member

    Bakersfield CA
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    It's a 1967 CJ5. Stock engine, Dana 30 front and 2 piece 44 rear. Powerlock in both. Has disc brakes I took off a narrow track Dana 30. Added Saginaw power steering a few years ago. The whole package works really well off road.
     
    Last edited: Jun 20, 2017
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  16. Jun 21, 2017
    masscj2a

    masscj2a Member 2023 Sponsor

    Ware, Mass
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    Thanks for the info. For some reason the shift tower on my 420 is locked in place. I have not had the time to mess with it yet, been bust trying to finish up the 47 build, so time is limited. But that will be next on my list.
     
  17. Jun 21, 2017
    AKCJ

    AKCJ Active Member

    Fairbanks, Alaska
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    The SM420 is a great upgrade. It's such a heavy duty unit there's no need to worry about it - pretty sure mine will outlast the rest of the Jeep.
    The guy I got it from said it was from a 67 Suburban.
    Gearing: 7.05 x 2.46 x 4.1 = 71.10 to 1 It crawls pretty well. With the more common 3.73 rear end it would be 64.68 to 1.
    I used the Novak adapter.
    I often shift 3 to 4 or 4 to 3 without using the clutch.
     
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  18. Jun 21, 2017
    Warloch

    Warloch Did you say Flattie??? Staff Member

    Falcon, CO
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    Have fun with that - I'm running the SM465, stock D18 and 4.88s down to the 80:1 crawl ratio... I'd think about not doing the TeraLow as you really shouldn't need it. I've rarely seen anyone crawling with more than about 80 be useful. I also have the OD and wouldn't trade it for the world.

    Just food for thought.
     
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  19. Jun 21, 2017
    ITLKSEZ

    ITLKSEZ Hope for the best, prepare for the worst

    Liberty Lake, WA
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    ^+1
    I ran a T-18, D18, and 5.38s for a ~85:1 crawl ratio on 33s. I did some serious rock crawling with that setup, and I never once wished it could go lower.
     
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  20. Jun 21, 2017
    47v6

    47v6 junk wrecker! 2023 Sponsor 2022 Sponsor

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    I don't have an OD. Since almost all of my driving is under 55MPH, I don't need it. Still would be nice to have. Just need to make sure your T/C oil level is on the full side all the time to not wreck it.

    I am not sure about case size of the SM465 as I do not have one.
     
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