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

Transmission/T-case Swap

Discussion in 'Early CJ5 and CJ6 Tech' started by Peter Harman, Apr 29, 2018.

  1. Apr 29, 2018
    Peter Harman

    Peter Harman New Member

    Fountain CO
    Joined:
    Feb 4, 2018
    Messages:
    29
    I've got to pull the t-case and trans cause of a terrible clutch job on my cj5. I have a SM465 and a Dana18 twin stick (with bellhousing flywheel etc)

    Should I bother switching them out or just stick with factory?
     
  2. Apr 29, 2018
    colojeepguy

    colojeepguy Colorado Springs Sponsor 2019 Sponsor

    At the foot of...
    Joined:
    Apr 4, 2010
    Messages:
    4,386
    An SM465 is a very stout truck type 4 speed that should be virtually indestructible.
    Realize that this swap won't be a bolt in...you'll have to modify crossmember, clutch linkage, driveshafts, floorpan...

    Your other option is to sell it cheap to a local Jeep aficionado :whistle:
     
    Last edited: Apr 30, 2018
    Peter Harman, ITLKSEZ and Twin2 like this.
  3. Apr 30, 2018
    ITLKSEZ

    ITLKSEZ Volvophilic

    Post Falls, ID
    Joined:
    Aug 13, 2015
    Messages:
    3,468
    ....and totally worth it if you've got the time, money and knowhow.
     
    fhoehle likes this.
  4. Apr 30, 2018
    Sierra Bum

    Sierra Bum Member

    The High Sierra
    Joined:
    Oct 23, 2017
    Messages:
    145
    Yep, if you're wheeling it, a truck granny gear 4 speed is one of the best upgrades on a trail jeep. It will be involved. Novak makes a 1" long adapter for the SM465 to your model 18:

    SM465 Information

    1" Adapter
     
    Biggyniner and jzeber like this.
  5. Apr 30, 2018
    Glenn

    Glenn Kinda grumpy old man Staff Member Sponsor

    Apopka, Fl
    Joined:
    Sep 21, 2002
    Messages:
    9,220
    Answer depends on what kind of off-roading you plan on doing with the Jeep.
     
  6. Apr 30, 2018
    47v6

    47v6 junk wrecker! Sponsor

    Washington DC.
    Joined:
    Oct 25, 2006
    Messages:
    4,629
    I swapped in a SM420 because I needed a full rebuild on the T-90. After the cost of everything factored in, including the adapter, it turned to to be similar.. So I got an indestructible 4 speed with granny gear for similar effort... I did need new driveshaft too, but mine was wore out anyway.

    Its just money and time.
     
  7. Apr 30, 2018
    Peter Harman

    Peter Harman New Member

    Fountain CO
    Joined:
    Feb 4, 2018
    Messages:
    29
    All in all, it sounds like a winter project!
     
  8. May 2, 2018
    Warloch

    Warloch Did you say Flattie??? Staff Member Sponsor

    Falcon, CO
    Joined:
    Mar 4, 2003
    Messages:
    4,482
    Yes it is - and if you want to drive about 30 - 45 mins, I can show you what it looks like.
     
    Biggyniner likes this.
  9. May 2, 2018
    jzeber

    jzeber Well-Known Member Sponsor 2019 Sponsor

    Morgan Hill, Ca
    Joined:
    Nov 15, 2003
    Messages:
    2,408
    The SM 465 swap was my 2nd best mod ever. #1 being dumping the trash lock and installing a Detroit. It was indeed a winter project. I ended up going through the D18 (it was out anyway), new motor mounts and an oil pan gasket. Definitely not a "cheap" upgrade but worth every penny for the wheeling I do.
     
  10. May 3, 2018
    71CJ54WD

    71CJ54WD Sponsor Sponsor

    DC
    Joined:
    May 3, 2018
    Messages:
    238
    Could anyone tell me what the size difference between the stock transmission and the SM did to your floor pan and clearance under the Jeep? The T14 I have in my 1971 is tiny and has a 1st gear that leaves a lot to be desired. I planned on swapping in either an SM420 or a T18 Ford. Both of these with adapters are longer which is fine - but also tall and wider which worries me. Any information as to the handling of the added bulk would be much appreciated.
     
  11. May 3, 2018
    sterlclan

    sterlclan Member Sponsor

    exploring the...
    Joined:
    Feb 21, 2009
    Messages:
    3,041
    i changed a t14 to a np435 the tunnel in the jeep was the only thing that isnt a jeep part,the cross member fit the new mount and lined up with existing holes. the rear shaft needed to be shortened the front needed to be longer.[​IMG] here is the tunnel prior to welding and paint
     
  12. May 3, 2018
    '74Renegade

    '74Renegade Active Member Sponsor 2019 Sponsor

    Fair Oaks, CA
    Joined:
    Sep 1, 2005
    Messages:
    1,096
    I don't know how well this will apply to your jeep, but when I swapped a t15 for a t18 in my 74, I was able to reuse the original floor pieces and crossmember with only slight modifications.
     
  13. May 3, 2018
    71CJ54WD

    71CJ54WD Sponsor Sponsor

    DC
    Joined:
    May 3, 2018
    Messages:
    238
    Thanks to both of you. Looks like if the NP435 fits any should fit as I believe that is a hair bigger. No problem making a floor but just didnt want it a ton taller than stock and it looks like it won't have to be.

    EDIT: what did you use to adapt the Dana 18 to your new transmissions?
     
  14. May 3, 2018
    Daryl

    Daryl Sponsor Sponsor

    Bonney Lake, WA
    Joined:
    May 25, 2006
    Messages:
    2,800
    Richard at Washougal Classic Jeepss has an original very rare 1971 t18, 18 setup from a CJ5.
     
  15. May 3, 2018
    71CJ54WD

    71CJ54WD Sponsor Sponsor

    DC
    Joined:
    May 3, 2018
    Messages:
    238
    Thanks. I doubt thats in the budget lol. Most likely a truck Ford T18 and the current Dana 18 I own would have to do the trick. Or an NP435. Just curious what adapters are being used between the transmissions and the Dana 18.
     
  16. May 3, 2018
    Sierra Bum

    Sierra Bum Member

    The High Sierra
    Joined:
    Oct 23, 2017
    Messages:
    145
    Both Advanced Adapters and Novak make adapters for all the truck 4 speeds to the Model 18 case. And they both make a quality product. I have the SM420 in my current rig and have put this tranny in two jeeps. You will enjoy a 7:1 first gear with the SM420, the lowest 1st gear of all the truck 4 speeds. It will bolt directly to the 225 V6 but will require front drive line clearance work between the tranny and front drive line yoke. It will also require a little sheet metal work on the floor but not as much as say, the SM465, which is also awesome but quite a bit bigger case. Any of the granny gear four speeds are a good choice but each has their quirks in terms of their installation challenges. Check out the research links on the Novak site for a ton of useful info on all the different swaps including clutch info and total drive train length.
     
    Last edited: May 3, 2018
  17. May 3, 2018
    Muzikp

    Muzikp Sponsor Sponsor

    Sacramento Ca.
    Joined:
    Sep 27, 2016
    Messages:
    896
    This is my SM420 in mine. I actually lifted it up into the cab a bit more than needed to gain some ground clearance and gain a bit more clearance between the valve cover and the firewall.

    [​IMG]

    I made a cover for it like this

    [​IMG]
     
  18. May 3, 2018
    Sierra Bum

    Sierra Bum Member

    The High Sierra
    Joined:
    Oct 23, 2017
    Messages:
    145
    Just thought I'd add that if you decide to go T18, you should know that the T18 4 speed has many different versions, bell housing bolt patterns, input shafts and even ratios. I've learned that the early CJ T18's are mostly close ratio, non-granny low (4:1) gear boxes. I think the early Ford T18 has the 6.32:1 first gear as is desirable and adaptable to the V6. The GM granny boxes are all the same for the given model. BUT, the SM465 will require a bell housing with larger input shaft bearing retainer than the SM420. Too much info, I know.

    Edit, sounds like you know about the ford T18 deal
     
    beninboston likes this.
  19. May 3, 2018
    71CJ54WD

    71CJ54WD Sponsor Sponsor

    DC
    Joined:
    May 3, 2018
    Messages:
    238
    Thanks. I do believe ill be going with the ford T18. What clearance issue did you have on the front yoke and what was your solution?
     
  20. May 3, 2018
    Sierra Bum

    Sierra Bum Member

    The High Sierra
    Joined:
    Oct 23, 2017
    Messages:
    145
    I cannot speak for the T18 in terms of actually installing one against a V6, other than its a great tranny and a common swap. The SM420: The passenger side of the sm420 case is very close to the front drive shaft yoke. So close that you need to grind down the side of the case to create clearance for the shaft to be able to turn. There are a few threads that have talked about this. I have about 1/4" or so of clearance between the front driveshaft yoke at the t-case and the Sm420 gear box.
     
    Last edited: May 3, 2018

Share This Page

New Posts