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Factory gear ratio's and what tire size...

Discussion in '80-Series Tech' started by Lars, Oct 18, 2003.

  1. Lars

    Lars

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    Do all zj80's have the same gear ratio from the factory? If so, what is it?

    Also, what size tire is the largest you can run without a gear change before everyday driving performance is unnacceptable?
     
  2. cruiserman

    cruiserman

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    4.1

    IMO 33" is acceptable.
     
  3. landtank

    landtank SILVER Star

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    Factory ratio is 4.10, tire size is subjective. I ran with 35" tires for a while and that included towing a 3500 lb trailer through the white mountains with factory gears. It was what I expected and I dealt with it. I now run 4.88s and am much happier.
     
  4. cruiserdan

    cruiserdan SupportingVendor Emeritus Moderator

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    Agreed,

    even 33 is a bit much unless forced induction is also used. 4.3 gears return the ratio to Stock with 33 inch tires. 4.56 gears return to stock with 35 inch tires.
     
  5. the shed guy

    the shed guy

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    But 4.88 is the best swap to do because no one ever goes smaller tyres, so may as well fit the 4.88 and then when you go 36 or 37, they will still be ok :D
     
  6. DanKunz

    DanKunz SILVER Star

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    of if you are running a 3FE you will be able to actually move your vehicle with oversize tires :D
     
  7. Riley

    Riley

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    So since I'm thinking of moving to 33" tires - what's the ballpark cost to move to 4.33 gearing?

    Assuming that I'm having this done at a shop.

    Any ideas how much this would set me back?

    Is it hard to regear yourself?


    Riley
     
  8. cruiserman

    cruiserman

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    Not worth the effort and expense unless you are 100% sure you will never go back to stock tires and never get larger tires. Just go 4.56 or lower or don't bother. Setting up a diff typically costs around $250 plus bearing kit. You will save some dough if you bring the 3rd member to the shop.

    Edit: it's 4.3:1, not 4.33.
     
  9. CruisinGA

    CruisinGA

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    [quote author=Riley link=board=2;threadid=6479;start=msg52460#msg52460 date=1066539680]

    Is it hard to regear yourself?


    [/quote]
    Yes, setting up new R&P's is very difficult to get correct, and requires special tools, and is one of those things that's best left to those that do it on a regular basis.
     
  10. landtank

    landtank SILVER Star

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    As I stated I now have 35" tires with 4.88 gearing. This gives me a slightly lower than stock total ratio for the truck. The driveablity of the truck this way is far better than the stock ratio. If you are going to go with 33" tires and regearing also I'd go with 4.56 gears. This will put you about where I am now at a slightly lower total ratio and give you some room if you want to go with 35" tires later which would return you back to stock.

    I got my gears from Randy's R&P. Both sets with bearing sets where about $800.00, about the price of a single set of factory gears w/no bearings. Install would be about $1000.00, I chose to have my front axle overhauled at the same time and the labor was $1400.00.

    A lot of us are running 35" tires and 4.88s. I personally think this is the ideal setup. The rub issues aren't that prevelant and the driveability is fantastic.
     
  11. T Y L E R

    T Y L E R

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    Rick ,

    I'm curious how your Truspeed™ recallibrator manifests itself within your setup . Might be a good tidbit to differentiate for us how the T.R. changes things ; if you even have it setup still . I know you can set it up for gear size and tire size (both) . And if you have kept it online , wouldn't the driveability seem enhanced (over stock) from 2 gear up only ? IOW's won't your 80 fly off the line , but then settle back into thinking it's running stock gearing ??

    Cheers ,

    Tyler -- still trying to twist my head around gears and computers *L*
     
  12. landtank

    landtank SILVER Star

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    Tyler,
    I still have the truespeed installed but now setup for the 8% total change of both the tires and the gears. As the truck's computer reads rpm and speed to chose an ideal shift point, unlike the favorable response of holding shifts longer when you don't regear there is no adverse effect when you do because the regear shifts the torque band down in the rpm range so when the truck shifts sooner the torque is available there mechanically.

    Hope this helps. You've got the 35s and the truespeed already, treat yourself to a set of 4.88s, YOU WILL NOT BE DISAPOINTED!!!!
     
  13. T Y L E R

    T Y L E R

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    You know ... I think I almost understand that *L* . Seriously , if I ever crawl from under this debt load long enough ( and I don't blow a wad on a chopper ) I will treat myself to some gears ... and a set of Slee bumpers . Oh and a snorkle and umm .. :eek: ::) :-X :-\ :'(

    Cheers Rick ,

    Tyler