A343F vs. A750F Transmission Gears

Discussion in '100-Series Cruisers' started by hoser, Sep 22, 2005.

  1. hoser

    hoser SILVER Star

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    I believe these are the gear ratios of both transmission available for U.S. UZJ100's. I got the numbers online.

    Not surprising, 1st gear of the 5-speed is lower and the top gear is higher. Reverse is lower as well. The 5-speed looks pretty sweet in terms of gearing.

    A343F "4-sp Auto" (Effective Ratio=Gear X Diff gear)
    - 1st Gear 2.804 (12.06)
    - 2nd Gear 1.531 (6.58)
    - 3rd Gear 1.000 (4.3)
    - 4th Gear 0.753 (3.24)
    - Reverse 2.393 (10.29)
    Diff Ratio 4.3

    A750F "5-sp Auto" (Effective Ratio)
    - 1st Gear 3.520 (14.43)
    - 2nd Gear 2.042 (8.372)
    - 3rd Gear 1.40 (5.74)
    - 4th Gear 1.00 (4.1)
    - 5th Gear 0.716 (2.936)
    - Reverse Gear 3.244 (13.3)
    Diff Ratio 4.1

    I have the A343F. What's interesting is if I install 4.88's, my effective 1st gear will be 13.68 versus the A750F/4.1 combination of 14.43
    Last edited: Aug 22, 2006
  2. e9999

    e9999 You want to do what...? Moderator

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    750 gears rule! I knew it! :)
    and man, is that thing sweet to drive with! You 4 spd dudes will be amazed when you try it out!


    and if somebody double checks these numbers, I'll put them in the FAQ!
  3. bjowett

    bjowett Supporting Vendor

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    You should try the Touareg Aisin 6 speed automatic w/ 4.15 first gear, 2.66 t-case, and 4.56 gears. Lexus has a 6 speed auto in their cars, probably the same family.
  4. macneill

    macneill Rollin’ on 33s

    :confused: Uhhh... man that is some complicated terminology, my brain hurts...
  5. So how long is the A750F transmission compared to the A343F? Are they the same size? Is there any way to run the newer transmission instead of the older one? Would the old ECU work with the new transmission or is the transmission controlled separately?

    Sorry, this is my first automatic:doh: I'm a manual sort of person.
  6. Greg B

    Greg B

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    For you guys running the 5 speed transmission, you could re-gear to 4.30 diff gears. These are definitely available and would take your 1st gear effective ratio to 15.136 vs. 14.43. I don't know if the 5% increase is worth the price of re-gearing, but it is an option. Also, it should be pretty easy to source some used 4.30's at a pretty low price. If you were already going to install ARB's, it might not be that expensive to add 4.30's at the same time. Just a thought.
  7. Jim_Chow

    Jim_Chow

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    An alternative is to replace the entire front/rear diff w/ the 4.3's rather than sourcing the R&P's, especially if you can find a junk yard w/ a rolled '98-'02 100.

    --Jim
  8. hoser

    hoser SILVER Star

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    Preferably the 4-pinion front (00-02)
  9. hoser

    hoser SILVER Star

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    I thought I would update this chart. The main reason I'd 'upgrade' to a newer 100 would be for the 5sp. The lower gearing advantage is obvious. But top gear cruising is a concern. Turns out, going from 35/4.88's/4sp vs 35/5.29/5sp would only raise my top gear rpm by 100rpm (@ 70 mph). I think that would be fine.

    Crawl ratio would also be 36% higher with 35's/5sp/5.29s! 1:45 vs 1:33

    Add in Marks t-case gear and the crawl ratio would be 74% higher. 1:58 vs 1:33

    Attached Files:

  10. spressomon

    spressomon glutton

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    Never know 'till you know...:D Often thought about 5.29's on mine instead of the 4.88's. But the big potential downside has to do with drivetrain RPMs...and how that, more than likely given what I've experienced with the 4.88 convert, might translate to more driveline noise and vibes.

    I think you should test this hypothesis Les :D

    Good 411 BTW...Thanks!

  11. bluecruiser

    bluecruiser

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    I believe Marlins gears are Marks gears. Same with different name.
  12. hoser

    hoser SILVER Star

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    I'd love to test it… it's just the cost of the experiment ($$$) is holding me back. It requires I buy a whole new 100 :)

    Also, interesting to note, the 4sp/5.29 combination has very similar gearing to the 1st through 4th gears of a stock 5sp/4.1 set-up.

    When I get to my home computer I can share the file. But tire size is not factored into the "crawl ratio"… though we know it is a factor.

    I could not decide where to fit the tire sizes in the spreadsheet. But with the given numbers, your tire size and using one of the online RPM calculators, you find engine RPM's at XX speed. The only one I am worried about is highway cruising RPM. I ran 4sp/4.88's/33's for awhile and thought it was too buzzy for the freeways around me.

    Like blue said, Marks and Marlin have the same ratio of 3.116 which was rounded off on the spreadsheet as 3.12 (I don't know if they are actually the same manufacturer though).

    Stock LOW range gear ratio is 2.488:1

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