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Diff Gears for 100 series

Discussion in '100-Series Cruisers' started by cruiser99, Jul 31, 2003.

  1. cruiser99

    cruiser99

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    Hello everybody,

    I am looking into re-gearing the diffs on my 100 series (IFS UZJ100). I am planning on going from 4.30 t0 4.88 ratio.

    Few questions:
    Did anybody perform this mod yet?
    Does the 100 series (IFS) uses the same gear set as the 80 series?
    I not, does anybody knows a source for these gear sets?

    Thanks,
    Doron.
     
  2. cruiserdan

    cruiserdan SupportingVendor Emeritus Moderator

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    The 100 series IFS front diff is all by it's self. Incidently, the '03 100 has gone to a 4.10 ratio.
     
  3. cruiserdan

    cruiserdan SupportingVendor Emeritus Moderator

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    Doron,

    I just discovered something whist I was snooping through the catalog. I seems that the 4.10 gearset used in the '03 100 front is the same part number as the 4.10 gearset used in the 80's. The IFS diff is of course not the same but it appears that one could use a 4.88 gearset intended for an 80 front diff in a 100..... :D

    Dan.
     
  4. cruiser99

    cruiser99

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    Dan,

    Thanks for the info. I assume that gear-set refers to both ring and pinion. Also, do you think that it is safe to assume that the 03 model has the same diff as the 99?

    What about the rear? Is it the same as the 80 as well?

    Thanks, Doron.
     
  5. cruiser99

    cruiser99

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    Dan,

    I forgot to mention that my 99 has a factory locker in the back.

    Sorry. :-[

    Doron.
     
  6. cruiserdan

    cruiserdan SupportingVendor Emeritus Moderator

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    The front diff case and related parts are common 98-03.

    As far as the rear, I can't say for sure. The gearsets (ring and pinion) are different part numbers. They could possibly be swapped out. One way to find out would be to get them (ring and pinions) side-by-side and compare the dimensions.
     
  7. montocr

    montocr

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    Gear change done

    I just installed 4.88 gears into my 99 100 w/ factory locker. I had to use the carrier case half from an 80 series in order to run the available gears. It is certainly possible to change your 100's gears, just costs a little more $$$.
     
  8. Jukelemon

    Jukelemon

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    Monto:

    A Faq write up would be highly applauded ( :
     
  9. Greg B

    Greg B

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    Great News! :beer: I have a couple of questions though. Was Dan correct in that the gear set for the front is the same on an 80 and a 100? Was it a direct drop in replacement? On the rear, I'm not clear what you mean when you say "using a carrier case half from an 80 series". Are you talking about swapping out part of the axle housing or just part of third member? I don't know a lot about this particular vehicle's axle setup. Any more info you have would be greatly appreciated. :cheers:

    Greg
    '01 UZJ100
     
  10. Greg B

    Greg B

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    Also, if you used part of an 80 to add 4.88's in the rear, do you need to go with an ARB for an 80 too? When I regear, I'd like to change out diffs at the same time to save money on install and get it all done at one time.
     
  11. cruiser99

    cruiser99

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    Come On montocr. More info please...
     
  12. montocr

    montocr

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    100 gear swap

    Christo,
    I did 4.88's in my 100. All that I had to use to make std aftermarket gears work was the ring gear side carrier case half. The ID on this side is large enough for 100 series axle. I retained the small hat from the 100 diff. Note: the side-gear thrust washers are slightly larger OD on the 100, and interfered in the 80 series case half. We also have some different gears, these ones set up smoother than any I have set up prior, and are silent even in the 100.
     
  13. cruiser99

    cruiser99

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    montocr,
    Which gears did you use?

    Thanks,
    Doron
     
  14. Jukelemon

    Jukelemon

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    More info please. Not following you on the cases issue.
     
  15. ShottsUZJ100

    ShottsUZJ100

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    Doron: Front 80 gears are the same as front 100 gears. Nobody makes a rear gear set for the 100 yet.
    Christo did the pumpkin swap on his LX. He took an 80 rear end and 100 ARB diff. Along with other corrections, the trick worked, though I'll wait for a proper gear. The 100 is stronger, more splines, etc. I won't take a chance (myself).
     
  16. montocr

    montocr

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    gears in 100

    Actually the 100 gears are not larger. The ring gear is thicker to accomodate the different carrier case deck hieght, but not in areas that make it stronger (not the teeth). It is not likely that 100 series specific gears will be made anytime in the near future. So, to change the gears in a 100 is deffinately possible, just costs a little more because you need to use the carrier case out of an 80 in order to bolt the gears on. It is necessary in many other differentials to change the carrier case when doing a ratio change. It is just part of the cost to do it.
    Carl
     
  17. cruiser99

    cruiser99

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    Carl,

    Could you some up the custom work you had to do on the rear, above and beyond the work necessary for a usual gear swap.

    Also what gears did you use. You mentioned they run smoother then usual.

    Once I understand what it takes, I am right behind you. Been waiting for a long time.

    Thanks,
    Doron.
     
  18. ShottsUZJ100

    ShottsUZJ100

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    I hear ya, though I think I side on my locker installer's opinion (no offense) combined with the fact the 100's powertrain is notably upsized in torque compared to the 80. My installer said that because the gear was thicker (more area and mass the better) and it had more splines (another plus), and the fact they had 80 gears there to compare, that their opinion was the 100 gear was notably stronger. Who's correct? Who knows.

    Why did Toyota make the change? Who knows for sure, but they had to have a reason to make new parts. Was it because:

    100 weighs more?
    100 is much more powerful? (I think this is the main reason)
    Rear axle shafts are larger in diameter and stronger than the previous model?

    Toyota wanted that new gearset in there for a reason. I'll stick with that. Too much invested and I use this thing hard off-road. I can wait for my old crawl ratio. If it never comes, not a big loss.
     
  19. ShottsUZJ100

    ShottsUZJ100

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    Doron: Have you changed your mind on this? Last we spoke I thought you said you didn't want to go backwards by installing 80 gears? I might remember wrong? I do know though you need them more than anybody in the US as your 100 is Expo'd Out (sweet truck!) and you use it! I could see how you'd try the 80-gear swap because you wor on your truck. Gonna do it?
     
  20. expeditionswest

    expeditionswest

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    Great news Doron! That is the last piece of the puzzle...