sm465 vs sm420 gear ratios

Discussion in '40- & 55-Series Tech' started by yoda-g3, Oct 19, 2004.

  1. yoda-g3

    yoda-g3

    Messages:
    765
    Location:
    Spokane, WA
    I'm more curious how the granny gear ratios compare between these two. It looks like the 465 would be a much easier swap into my '70 and I have a friend with one I may be able to pick up for cheap. But I want a crawler so I want to make sure there isn't a huge difference between the two.


    Thanks!
  2. woody

    woody the internet is just a fad... Staff Member

    Messages:
    9,641
    Location:
    Wisconsin
    7.01 for the SM420
    6.55 for the SM465

    age favors the 465, but both will have rebuild needs at some point...
  3. fj40charles

    fj40charles GOLD Star

    Messages:
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    Location:
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    Some people say the 420 shifts better than the 465.
  4. bsilva132

    bsilva132

    Messages:
    962
    Location:
    Elk Grove, Ca
    the 420 is an easy swap if you have the original toyota 3spd. you just need a bearing retainer sleeve, pilot bearing, indexing ring, chevy 10" clutch disk, and the plate adaptor. It is not the smoothest or quickest shifting trany, but it is great on the trail. Also, I would rebuild the trany before you install it. I didn't and not the 3rd gear syncro is bad and I have to double clutch to keep it from ginding. Pin Head's write up in the tech section is great.
  5. Pin_Head

    Pin_Head

    Messages:
    11,641
    Location:
    OC, CA
    I wouldn't say that the 465 swap is easier, but they may be easier to find in some parts. The 465 output shaft needs to be drilled and tapped to use a plate adaptor. This is best accomplished with the shaft out of the tranny. Other than that, the swaps are pretty comparable in terms of difficulty or effort and in the outcome.
  6. mr_manny

    mr_manny

    Messages:
    1,606
    Location:
    san pancho, ca
    I would second the 465

    Don't forget the front Drive-shaft clearance issues, the tranny housing requires some GRINDING.

    Current config:
    Toyota 1F motor
    Toyota 3spd bell-housing
    special pilot bearing to accommodate the 465 to 1F motor - Custom Cruisers
    Chevy 88 V6 1/2 ton 11" clutch disc
    Toyota 3spd pressure plate
    Toyota 3spd throw-out bearing
    Chevy sleave to accommodate Toyota TB
    You will also have to reduce the OD on the sm465 front bearing holder.
    Chevy sm465 plate adapter - Custom Cruisers
    Transfer case cross-member brace - Proffits Cruisers


    NO synchro 1st is a big CON. for me (read DD), you will get tired of this (trust me) :D

    manny 72fj40
  7. Without setting myself up to be massacred, why spend so much time and effort swapping trannies. Why not just regear the diffs? All in all your just changing the gear ratio of the driveline right?
  8. woody

    woody the internet is just a fad... Staff Member

    Messages:
    9,641
    Location:
    Wisconsin
    crawl ratio options:

    6.55 x 2.313 x 4.11 = 62:1 crawl ratio with a SM465 and 3-speed t-case....adequate for most (90%+)wheelin, but "ideal" manual crawl is in the 90-120:1 range, depending on where you are....

    3.555 x 1.999 x 4.88 = 35:1 crawl (stock 4-speed, stock t-case, deeper gears, tho 5.29's available)
    2.757 x 2.313 x 4.88 = 31:1 crawl (stock 3-speed, stock t-case, etc...)

    30-35:1 is marginally better offroad, but not significant enough over the 29:1 stock ratio to be worth the expense...if your goal is ROAD manners with larger tires, then yes, gearing at the diffs can keep your powerband in the same or better range....
  9. FJBen

    FJBen

    Messages:
    2,634
    Location:
    Greeley, Colorado
    Highway ratio...and crawler gear...

    Lower diff gears will REALLY slow you down on the highway...at least with the 4.11's you can get a decent granny gear, and still make it to the trail going above 55 unless your tires are HUGE...

    4.88's tend to work better with OD trannys, but if you don't care about highway...go for it.
  10. yoda-g3

    yoda-g3

    Messages:
    765
    Location:
    Spokane, WA

    So the 465 DOES have synchros? That would be really nice for those quick shifts in the sand dunes. Are all these parts/mods required for the sm420 as well? Or is does the 420 have less fabrication needed? Did you have to re-lenghthen your drivelines as well?

    Overall what was your cost for all this, assuming you have all the 3spd components like I do?
  11. woody

    woody the internet is just a fad... Staff Member

    Messages:
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    Location:
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    465 estimate, adapters are now cheaper tho...
    http://www.ih8mud.com/tech/woody/sm465.html

    IMO, costs are similar...it will all depend on your own fab skills and the deals you find. The big previous price difference was in the plate adapter itself, but that's no longer true.

  12. Interesting. I changed my bronco from 3.73 to 4.88s and i could still go highway speeds with no dfficulty. Made a HUGE difference in the wheeling ablity as well. I guess i just dont like going that freeking slow.

    Good info though. Thanks woody
  13. woody

    woody the internet is just a fad... Staff Member

    Messages:
    9,641
    Location:
    Wisconsin
    3.73 to 4.88 is a 30% drop...
    4.11 to 4.88 is a 18% drop...
    3.55 to 6.55 is a 85% drop...

    30% is noticeable, 18% for gearing or 16% if you do a simple early t-case swap is minor...85% is WAY noticable, and I've yet to have any issue running 70mph with my TBI V-8, 38.5 tires, and 4.11 stock gears.

    One advantage to 4.11 stockers is availability....kill a set of 4.88's (RARE, I know, but possible) and you are stuck with new...kill 4.11's and used "get you by" replacements are easy to find.
  14. CruisinGA

    CruisinGA

    Messages:
    6,152
    Location:
    Georgia Tech
    IMO non-synchro first gear is not a big deal. I've driven my 40 every day for 2 years with the factory 3 spd and very rarely has the non-synchro 1st presented an issue. Once you get used to the trans you can get it into first with minimal to no grinding at speeds between 5-10mph.

    The SM420 has synchros for everything but 1st. The only difference is first gear. I wouldn't think the lack of a synchro'ed first would hold you back much in the dunes.
  15. Maybe ill start a new thread so i dont steal his thunder. But im pretty sure i have an early transfer. Seeing as its a oct of 72.
  16. I agree with GA. Ive gotten very used to my non synchro 1st gear. Its not even something i think about anymore. Dont let the little stuff scare ya.
  17. Ian Rogers

    Ian Rogers

    Messages:
    1,403
    Location:
    Mill Valley, CA
    i would agree as well, i have a 3 on the tree and after few days on the trail you get use to it, in fact i like the 3 on the tree better then the 5 speed in my ford ranger. Granted its a FORD.
  18. bsilva132

    bsilva132

    Messages:
    962
    Location:
    Elk Grove, Ca
    I never use first on my 420 unless I am in 4lo and doing somethin technical. the granny is made for take offs under heavy loads not everyday driving. 2-4 are syncro'd so it is esentially a 3 spd with a granny for the slow technical stuff. 1st is just too slow most of the time.
  19. Cruiserdrew

    Cruiserdrew SILVER Star

    Messages:
    11,952
    Location:
    Sacramento, CA
    We'll all sound like a bunch of echos here but:

    The non-syncro first gear is a non-issue
    The SM420 shifts fine and is strong as h*ll
    The drive line mods are minor, but necessary (lengthen rear, shorten front drive shaft)
    3rd and 4th ratios are a little too far apart on the SM420-not sure about the 465
    Match the gear in your diffs to your tires-I run 4.56 and 35s, works well
    60:1 or more crawl ratio is what you need for technically challenging trails
    SM420 is a pretty simple swap but you need a 3 speed transfer case
    I agree-rebuild the tranny prior to install in your Cruiser
    The SM420 is noisier than the SM465 by just a bit

    I ran the Rubicon with stock gearing 4 years ago-stock 4 speed first gear is WAY TOO HIGH. The SM420 effectively doubles your crawl ratio. The next year with SM420 my gearing was perfect. I tend to do hard sections in 1st gear/low range, and normal trail in 2nd gear low range.
  20. timbercruiser

    timbercruiser

    Messages:
    780
    Location:
    Below Da Bridge
    Why not regear the t/c?
    How about a doubler ?

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