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sm465 or 420?

Discussion in 'Early CJ5 and CJ6 Tech' started by 57cj5, Jul 20, 2010.

  1. Jul 20, 2010
    57cj5

    57cj5 Member

    North Carolina
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    looking at eventually putting a 4 speed in the Jeep (stronger than the T90A currently installed and recently rebuilt). Any advantage to a 420 over a 465? I understand the 420 has a lower first gear, older, and harder to find parts. I don't plan on doing any rock crawling. I also read the 4th gear is a 1:1 for both. I have a warn overdrive so I don't think that is an issue for highway driving. I would be using my original D18 T-case. Fitment might be an issue in the 57.
    1) which fits better?
    2) Which is more suited for more use on road than off?
    3) Engine is a 283 so no adapter needed.

    Thanks.. By the way, I know there are a lot of opinions on 420 versus 465 and they are all welcome. (I also did a search here and used the knowledge base of Novak).

    (Jeep is a 1957 CJ5, 283 engine, Powerlocks installed in the D25 and D44, tires are 32x11.5x15)
     
  2. Jul 20, 2010
    colojeepguy

    colojeepguy Colorado Springs

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    If you don't plan on rock crawling, why bother with the trans swap? A good T90 should stand up to a 283 in a lightweight CJ, unless you drive it like mad max.
     
  3. Jul 20, 2010
    Corveeper

    Corveeper Member

    Chanute, Kansas
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    The SM465 has more front drive shaft clearance, is lighter than the SM420 and AA has an adapter to mate your Dana 18 to an SM465 that makes it the shorter of the two drive-lines by several inches.
     
  4. Jul 20, 2010
    colojeepguy

    colojeepguy Colorado Springs

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    ^SM465 is lighter? It's pretty big, I thought it was heavier than a 420??
     
  5. Jul 20, 2010
    Corveeper

    Corveeper Member

    Chanute, Kansas
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    I don’t see how. The 420 is huge with a thick cast case.
    I haven’t had them side by side to compare but I have had to pick them both up at one time or another and my impression was the 420 was heavier.
     
  6. Jul 20, 2010
    duffer

    duffer Rodent Power

    Bozeman, MT
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    Actually, I think the 465 is the heavier trans (about 20 lbs?) but that is a minor issue. I would still use it for no other reason than it will give you at least 2" more rear driveshaft.
     
  7. Jul 20, 2010
    54cj3b

    54cj3b Member

    evergreen colorado
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    The sm465 is about 50 lbs heavier than the sm420 I learned the hard way having it drop on my chest . I thought I could save time not using a jack to remove it myself by just pressing it down to the ground .boy I thought I was a goner.

    KIDS DON'T TRY THIS AT HOME
     
    Last edited: Jul 20, 2010
  8. Jul 20, 2010
    dvader

    dvader Member

    Northern Nevada
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    From th Novak website: SM420 = 135lbs. Length w/adaptor = 15.2 inches
    SM465 = 175lbs. Length w/adaptor = 13 inches
     
  9. Jul 20, 2010
    scott milliner

    scott milliner Master Fabricator

    Seattle Wa.
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    SM465. Best swap I ever did.

    If you need pictures, to help with the swap let me know.
     
  10. Jul 20, 2010
    Corveeper

    Corveeper Member

    Chanute, Kansas
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    My memory must be wrong then. The size of the thing must’ve added to how heavy it felt.
    Apologies for misleading information.
     
  11. Jul 20, 2010
    AKCJ

    AKCJ Active Member

    Fairbanks, Alaska
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    I put in the sm420 and it is great.

    sm420 is lighter but the sm465 is newer. Perhaps your decision would be based on what you find first/cheapest. Also research the T18.

    Note that the swap turned out to be more difficult than I expected so be prepared to spend some time & money.
     
  12. Jul 20, 2010
    Corveeper

    Corveeper Member

    Chanute, Kansas
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    Good point. A buddy and I wound up having to fabricate a new cross member because the SM420 to Dana 18 adapter holds the transfer case at a different angle than the T-10 to Dana 18 adapter did. The transfer case is actually clocked down a bit further than it was before.
     
  13. Jul 20, 2010
    sparky

    sparky Sandgroper Staff Member Founder

    Perth, WA
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  14. Jul 20, 2010
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    So how many of you guys have put a Ford transmission behind a GM bell? From the Novak article http://www.novak-adapt.com/knowledge/ford_to_gm.htm it sounds like a straightforward process. If you can adapt as shown, you add the T18, T19 and NP435 to your list of suitable swaps.
     
  15. Jul 20, 2010
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    We modify the transmission case of T-18's/ T-19's, Rug, Ran, etc. Toploaders to bolt directly to the GM bellhousing with no mods. We do this for customers ease of install though. No reason the Novak info shouldn't work just fine though.
     
  16. Jul 20, 2010
    jzeber

    jzeber Well-Known Member 2022 Sponsor

    Morgan Hill, Ca
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    I used a SM465 because I was able to purchase it for $50. I had to change some internals due to rust and parts were readily available at a local trans shop.
    One thing lead to another and the above quote is very true. It cost me a lot more than expected.....still worth every penny!
     
  17. Jul 21, 2010
    Mjragan

    Mjragan Member

    socal-Simi Valley
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    Don't rule out a T18, look for one out of a jeep with the t-case adapter still attached. The T18 with adapter is 13" same as the 465 with adapter, Chorokees and Wagoneers are good donors, you will have to change the input shaft and bearing retainer but its cheeper than having to buy a T-case adapter for the 420 or 465 and it's narrower than the 420 and 465. Just my two cents good luck.
     
  18. Jul 21, 2010
    jpflat2a

    jpflat2a what's that noise?

    Hermosa, SD
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    I've got a rebuilt 420 with a Novak adapter waiting on the floor of the garage to go in this winter.
    I've spent 1K just to get to this point.
    yes, it will be costly to swap.
     
  19. Jul 21, 2010
    Patrick

    Patrick Super Moderator Staff Member

    Los Alamos, NM
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    While my T18 only has the 4.02:1 1st. gear, I paid $600 for a running factory 4 speed V6 '71 CJ5 to swap into my Jeep. I hadn't found a cheaper way to get a 4 speed.
     
  20. Jul 21, 2010
    windyhill

    windyhill Sponsor

    PA
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    I've Installed the T-18 ford 4speed ( adapted to the Buick v6 and original dan18.) The SM465 with :v6: and dana18, and also have a sm420 w :v6: combo in my shop. After doing all three I'd go with the T-18 again with novaks 1" adapter, easier to work on, lighter and parts are easy found. The SM465 is HUGE and you need a press to change the shaft.
     
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