Basic Re-gearing question

Discussion in '80-Series Tech' started by Romer, Oct 24, 2005.

  1. Romer

    Romer fatherofdaughterofromer Moderator

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    Did a search and found a lot on what the proper gears are for 35's some say 4.56 others 4.88.

    I could not find anything on HOW to re-gear and that is the point of my question.

    Whats the basic install and how much needs to be torn down.? I am gussing the Tcase needs to be removed and dis-assembled.

    Can a 2 bannana mechanic do it?

    How expensive are the gears?

    And all the other questions I couldn't think of because I am unclear on the procedure.

    Thanks

    Probably a simple question for some. Probable answer is to take it to a shop and pay $1000 to have it done.
     
  2. beno

    beno Gihee Arakawa Moderator Supporting Vendor GOLD Star

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    Ken...From my understanding, I believe that you actually regear the differential gears and not the xfer case gearing.

    So you would need a set for the front and a set for the back.

    I could be wrong though.
     
  3. MTNRAT

    MTNRAT

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    Romer, you have to chage the ring and pinion gears in the diffs. It is more than a 2 banana job and uses some special tools and know how to get the proper backlash set. Try searching ring and pinion R&R. That was one job I thought was better to leave to my mech.
    Cheers,
    Sean
     
  4. Cruiserdrew

    Cruiserdrew On the way there SILVER Star

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    Romer-You can't regear the T-case, unfortunately. Regearing means to replace the ring and pinion with ones of a higher ration. You need to disassemble the axles in order to pull out the diffs. I would do that yourself. For the actual install of the new gears and bearings, take it to a differential speciality shop. Then re-install the diffs on your truck yourself and reassemble the axles. You will save a minimum of $500 this way and possibly more.

    As to level of difficulty-not hard-maybe 2 :banana: . I've had the diffs out and on the ground by myself in about 4 hours. The rear is super simple on the 80, pull the axle shafts, unbolt the diff and pull it out. On the front you need to pull the spindles to get to the axle shafts so it is more work.
     
  5. Romer

    Romer fatherofdaughterofromer Moderator

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    Thanks Guys, I appreciate it.

    Was debating on going with 35's and putting the 285's on daughterofromers 4runner. I don't think I would want to do that without regearing because its a dog enough on mountain passes.

    So I am guessing $2000-$2500 to go from 285's to 315's with the tires, regearing, bump stops, etc. From the search, doesn't look like 35's will buy me that much (1 inch clearance)over my 285's, since I am fully armored and a little scraping won't hurt. Is that a fair conclusion? I know its subjective, want to know if I missed anything I should consider.
     
  6. Tools R Us

    Tools R Us

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  7. Arya Ebrahimi

    Arya Ebrahimi

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    Romer, one option, if $$ is an issue, is to remove the diffs yourself and take them to a competent mechanic to regear. Many mechanics will only charge $50-100 labor if you hand them the diff. Where as if they have to tear down the axles to get the diffs out, that figure can go up to $2-400. This means you must have an alternate means of transportation, but I would imagine DOR wouldn't mind giving up her 4runner for a few hours here and there to facilitate new tires on her rig ;) (I know you have the 40, but you gotta make her earn it somehow! :D )

    Edit: Wasn't very clear above. Those labor figures are per diff. So it could net you a savings of up to $700 total! This would also be an opportune time to do any brake/bearing/seal work in your axles that you have on the to-do list.

    Ary
     
  8. cruiserdan

    cruiserdan SupportingVendor Emeritus Moderator

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    You do need a re-gear for 35's. Even forced induction 80's do not like 35's with stock gears. 4.56 gears will get you "back to stock" as far as effective ratio goes but the vehicle still has to spin heavier tires. It is widely held that 4.88 is better as you get a bit of mechanical advantage but you can still run down the hiway without the engine trying to claw its way thru the radiator....:D

    A trip to 4.88 effectivelty prevents you from running stock height tires as the high speed hiway RPM's go up there a bit. Not a problem if you do not swap tires back and forth.


    D-
     
  9. powderpig

    powderpig SILVER Star

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    If you have toyota electric lockers the rear is more difficult then the front or unlocked version. This is due tothe shims toyota has chosen to use to adjust the back lash with instead of with the adjusters of old. Others in the Rising sun club may be able to tell you how difficult it has been for them, or loan you the tools(bill morgan, chief, steve r) to name a few. doing it your self may take several days to get stuff done right, patientce is the key here. later robbie
     
  10. Biff

    Biff

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    I regeared to 4.56's and added ff/rr arbs to my 80. Pulled the 3rds and took them to a shop, total install cost for lockers and gears was $350. Used Precision gears, and since I do not plan to go bigger than 33's and choose 4.56's.
     
  11. cruiserdan

    cruiserdan SupportingVendor Emeritus Moderator

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    4.56 with 33's is much like 4.88 with 35's.

    Victor did you notice a difference in drivability with that change?
     
  12. Biff

    Biff

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    I did notice a diffrence, the new gears brought the rig back to stock performance, which is good considering all the armour I've loaded on.
     
  13. alia176

    alia176

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    Ken,

    I did my own 4.56 R&P and wouldn't want to do that ever again! I finished the front and was halfway done with the rear when I simply took it to a shop and he finished it for me. Besides needing special tool like Inch-lb torque meter (not wrench) and a dial indicator, you need to know the "feel" of many aspects of this job. This job is NOTHING like simply installing a locker. Locker installation is a cake walk as compared to having to crush a crush sleeve just right and setting pinion bearing preload w/o having a inch-lb torque meter.

    As someone stated earlier, drop out the 3rd and take it to a competent shop. It's worth the $100 labor they charge and you won't have to worry about possibly ruining a set of R&Ps and wasting your time once again on dropping out the 3rd!

    My .02 cents worth!

    Ali
     
  14. Romer

    Romer fatherofdaughterofromer Moderator

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    So it seems that you guys are saying 35's with 4.88's are worth the effort (I know - I am asking the guys who already have it)

    So if I can gfind a compotent mechanic (I might know of one) who can help, the gears are not that expensive.

    So 4.88's and 35's would make it better on the mountain passes. What do you lose when you do this. Currently stock gears and 285's. There is a lot of varied opinions in the different threads I searched, but I don't recall this question being answered.

    Thanks
     
  15. landtank

    landtank SILVER Star

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    Actually you will need 35" + 4.88s + truespeed calibrator + another spot for your spare. I lost nothing as the higher rpms is ofset with less throttle so MPG remains the same. Gears and bearing sets are like 800.00 for non OEM from what I remember. You will not regret doing this mod.
     
  16. MoJ

    MoJ Moderator

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    For what it's worth...
    It seems like everyone focuses in on acceleration when considering larger tires / regearing. There's very little discussion about the impact it has on diminishing the crawl ratio. To climb a 45 degree (100 percent) slope with perfect traction a vehicle weighing 5500 lbs, with 200 lb/ft torque, and 30 inch tires needs a crawl ratio of approx. 80. If going to 35 inch tires the ratio needed is increased to almost 100 so the need for lower gearing increases.
     
  17. cruiserdan

    cruiserdan SupportingVendor Emeritus Moderator

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    That is cool info, where did you find that out?
     
  18. MoJ

    MoJ Moderator

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    Pure plagiarism. "4-Wheeler's Bible" by Jim Allen, p 139. If I had a scanner I'd add the graph showing torque on the y-axis, crawl ratio on the x-axis, and several curves representing various vehicle weight/tire combos all under the assumption of a 45 degree slope with perfect traction.

    (engine torque) (crawl ratio) (.85) (1200)
    __________________________________ = % grade able to climb

    (tire radius) (loaded weight)



    The .85 is to represent a 15% loss due to drivetrain friction. Not sure where the 1200 comes from - maybe someone smart can explain. Note it's tire radius not diameter. He says to reduce the torque figure by 10% or so because you're unlikely to hit peak torque RPM's during most climbs, more reduction if peak is above 3500 rpms.

    There's a Cruiser on the cover so the info's gotta be right. ;)
     
  19. landtank

    landtank SILVER Star

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    So 4.88s are right or wrong for a 35" tire? And are they an improvement or need to be even lower?
     
  20. cruiserman

    cruiserman

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