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SM420 Practical Experience....Testimonials...

Discussion in '40- & 55-Series Tech' started by JGM, Mar 3, 2007.

  1. JGM

    JGM

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    Searching has lead to a bunch of different opinions, so I thought I would throw this out there and see what these are all together.

    I plan on putting an SM420 in my 71 FJ40. I like the 3 spd, but as my skill has increased, my desire for lower gearing finally reared its head. :grinpimp: I use this truck mostly for trail driving, but sometimes running around town on the weekend and the occasional drive to work, which includes some highway time.

    I do not trailer this truck, nor do I plan to. I will be putting on 35's on a 4+" SUA lift.

    Question: With my intended use of the truck, if it is similar to your experiences, how would you compare the 3 spd with the SM420? Pluses? Minuses? Regrets?

    :beer: :beer: :beer:
     
  2. rsc71

    rsc71

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    4th gear is still 1-1.around town you just dont use 1st
     
  3. Degnol

    Degnol

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    Like rsc71 said it is essentially a three speed around town. 1st is not synchro'd, but I think an SM465 is...................:confused:


    Ed
     
  4. Poser

    Poser Oh...Durka Durka Durka. s-Moderator Supporting Vendor

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    Night and fing day.


    7.05 vs. 2.7?


    Install the 420. You will love it.
     
  5. 73fj

    73fj Tho at sumbitch in ayer!

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    A 465 has no synchro in 1st.
     
  6. projektdotnet

    projektdotnet

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    Sorry to hijack but when you say 1st do you mean L or the "1st" gear according to the shift knob :confused:
     
  7. bandy rooster

    bandy rooster

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    1st gear in the trans man...


    i have a 465, sweet low gearing only complaints are just how hard the shifts are, not really that smooth compared to the toyota transmission but the gains are more then the loss's for me.
     
  8. G_Stratton

    G_Stratton

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    An SM420 is a 4 speed with a granny low. Depending on the shifter knob it will be marked as L or 1.

    When I installed my SM420 I switched back in the stick from my LC 3 speed.

    As for how it handles around town. I've done 70 on the freeway.

    It cruises at 60 all day long.

    On the trail the granny low is great when I need it. I believe my crawl ratio is around 70 to 1.
     
  9. Pin_Head

    Pin_Head

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    Think of it as a synchronized 3sp tranny that has an extra low first or low gear that you only use off road. Since you already have a 3sp, this will be very familiar, except for the new low gear that is twice as low as what you have now.
     
  10. 66fj40x2

    66fj40x2

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    Do it, you'll love it.

    and if you don't have an sm420 nearby I have one for sell :hillbilly:
     
  11. Cruiserdrew

    Cruiserdrew SILVER Star

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    The best low buck mod for an FJ40. Any crawling at all, and you need it. If you just buzz around town, then no need.

    The low gearing takes much of the stress out of trail work.

    Others complain about the clunky shifts-mine seems just fine.

    There is a big split between 3rd and 4th that is not well suited to the power band of a 2F. Long steep hills in 3rd at 35 mph are painful.

    An SM420 is probably 10 times stronger than an H42 if that matters to you. It really is "heavy duty"

    It makes more gear noise than a Toyota tranny.
     
  12. 65swb45

    65swb45 Supporting Vendor

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    Based on this scenario, I'd say go for it! My buddy JB has his truck set up the same way, uses it about the same, and is very happy with it.

    :cheers:
     
  13. ArmyFJ

    ArmyFJ

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    I have a SM465 (very similar) and mine is also my daily driver (40 miles a day at 60+ mph) no problems. With 35s you will be at about 2300-2400 RPMs. No issues.

    Matthew
     
  14. Tigerstripe40

    Tigerstripe40

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    I am a die hard toyota nut.
    I personally don't believe in V8 swaps.

    So I had a hard time with the idea of putting in an SM420.
    But I did it.
    And it's been one of THE BEST mod's I have done to my FJ40.
    I'd do it again all over again.

    When I did mine, no drive shaft or tranny hump mod's were necessary.
    I had the stock H42 shifter modified. and looking in the cabin of my FJ40, you wouldn't be able to identify that the trany wasn't stock.

    Frakking awesome on the trail.
     
  15. e rock

    e rock

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    Just a note: this will not be the case for swapping out a 3-speed.


    As far as driveability, I don't recall a very big difference between the upper 3 gears in my sm420 and the 3-speed that it replaced. Shifts are a bit slower to avoid grinding, but the ratios are relatively close. Then there's your newfound crawler gear - [voice=Tony the Tiger] It's Grreat! [/voice]



    For some reason, my 420 doesn't like to stay in 2nd gear... I rebuilt the whole thing prior to installing it, and I thought everything was fine but it's finally bugging me enough that I may be tracking down a NOS tranny in the next few months.
     
  16. KingBeeIII

    KingBeeIII

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    :cheers: Sounds like yours will pretty much mirror mine and I have no regrets. The smile on your face will be huge when you creep up an obstacle instead of having to bump and bounce over it in the 3 speed. It changed the way I wheel.
     
  17. JGM

    JGM

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    Thanks, folks. Looking at the gear ratios side by side, it seemed that I will be using the upper 3 gears like my OE 3 -sp. I know some folks wished the shifting was a little smoother, but that shouldn't bother me too much...its not like I think the truck is a celica or something....

    I was following some trucks on a trail a few weeks ago and I had to stop, wait for space to build up, get going, and when I caught up, had to do it all over again. I need to go slower!!!!!:mad:

    Sweet - I am excited. :cheers:
     
  18. Cruiserdrew

    Cruiserdrew SILVER Star

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    A couple more things.

    Since you want to go slower in your 40 you don't have too many choices. I have seen working SM420s sold here for $50. Add the plate adapter $250 and a bit of work and you are done. You probably should re-size your driveshafts-$75 each. THis will net you a crawl ratio about double stock, somewhere in the 60-70 range which is fine for most things. You already have the right bellhousing and t-case.

    Your alternative is a Toyota 4 speed (these can also be had pretty cheap) and an Orion. This is a preferable set up in my view, but the hardware will cost somewhere in the $2000 range, and you need a bellhousing, new shafts, etc.

    With the SM420, just remember it does not shift silky smooth like a Honda. It's big, burley and clunky. Mine locked itself in 3rd once when it was first installed-it resolved on it's own and has not done it since in 5 years, but I have heard of the same problem with others. It has never popped out of gear.

    Call Poser and get one of his transfercase savers. All that extra torque can damage the t-case.
     
  19. treerootCO

    treerootCO Where are my keys?! SILVER Star

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  20. Josie'sLandCruiser

    Josie'sLandCruiser Stop calling it a "FJ."

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    Hi All:

    Do it! The "granny low" of the SM420 on the trail will be well worth the effort! Besides, the "effort" is really not that much, as far as tranny swaps go.

    For a 4 inch SUA lift, consider the "Hell For Stout" springs from CCOT. I know three guys running this lift kit on their '40s and all are happy with it. Two are running 35 inch radials, the other 33s.

    Good luck with your rig!

    Regards,

    Alan