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Gearing too high need ideas

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by J.C.Staley, Dec 11, 2001.

  1. J.C.Staley

    J.C.Staley Registered Member

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    Ok you gear heads I need your unbiased opinions. The 84 K5 is geared way too high. I think I have 2 options, 1 is to replace the gearing in the current axels. 2 is to replace the axels with a pair already geared lower. I'm looking to go with 3.73s. I'm not a hard core rock crawler or mud bogger. I do get in the back country a lot and pull a decent sized boat. Let me know what you have done, costs, and possible other options.
    Thanks
     
  2. SlyDog

    SlyDog 1/2 ton status

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    What size tires do you have? And what kind of axles? If you have 1/2 ton axles now is a good excuse to upgrade them to 3/4 or 1 ton and get 4.11 gears or 3.73 like you said! If you have 33" tires I would go with the 4.11's and 31" tires get the 3.73's.

    <font color=green>[​IMG]1977 K5 GETTIN IT AWN[​IMG]</font color=green>
    BUILT NOT BOUGHT
     
  3. BLUESMAN

    BLUESMAN 1/2 ton status

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    You should have 10 bolt diffs frt. and rear.Okay for tires under 33" and not hard wheelin.I would and am go to a stronger diff. with the gears you want.That way you can still sell your 10 bolts while they are still intacted.Maybe just go for a 12 bolt rear, but you would need matching frt. gears.Start looking and you are sure to find something.Good luck! the problem with going w/ 3/4 ton diffs is that you would need new wheels that are 8 lugs.
     
  4. 2Dogs

    2Dogs 1/2 ton status Premium Member

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    Yup. The step to 8 lug wheels is a big one. If you can find the wheels you can't go wrong with a 14FF. And they are cheap(er) in the 3.73s you are looking for.

    Dave

    Horn Broken... Watch For Finger.
    <a target="_blank" href=http://coloradok5.com/gallery/Daves-Pics>http://coloradok5.com/gallery/Daves-Pics</a>
     
  5. BLUESMAN

    BLUESMAN 1/2 ton status

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    You can get the wheels (new) in stell for around$35 to $60 each.If you want to know PM me and I'll tell ya.I went to the 3/4 ton diffs(I bought the whole truck for $300),and bought the wheeels for $160(4),and I am very glad that i did.Oh the diffs are geared either 4.10's or 4.56's!!!!
     
  6. BigTex

    BigTex 1/2 ton status

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    You can get 8 lug black rockcrawlers (my favorite rim of all time) for about 28.00 bucks at Discount Tire.

    <font color=red>"SETTING OFF ALARMS IN A CITY NEAR YOU!"</font color=red>

    <a target="_blank" href=http://coloradok5.com/gallery/BigTex-Mean-Machine>http://coloradok5.com/gallery/BigTex-Mean-Machine</a>
     
  7. Hossbaby50

    Hossbaby50 3/4 ton status

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    If you have an excuse upgrade.

    My Chevy isn't broken, its just out of gas.
     
  8. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Fill us in here. What gears have you got now? What size tires? What Tranny?
    with a 700R4 and 33's I would say 4.10's to keep the load off the tranny. The OD should have you at about 2500 or so in OD at 70mph. I turn 3100 on my 32's with no OD. with 35's I would say you need to be at 4.56. You don't want to get that tranny where it starts hunting gears. That will fry them for sure. If you had 4.88's and 33's yeah I would say to regear down to 4.10 or buy bigger tires.

    Women dig dents and flat paint!
    coloradok5.com/gallery/Grim
    75 Jimmy, Dollar
    Grim-Reaper
     
  9. J.C.Staley

    J.C.Staley Registered Member

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    Thanks Grim. I'll give you some details. My back country tires are 33x9.5x15, my highway tires are 31x10.5x15. The tranny is a 700R4 just rebuilt. Right now, the best guess for the current gears is 2.73 or maybe the next step lower. It's an 84 K5 that came with a 305. The parts identification page under the hood says the rear axle option # is a 1GQ1 Rear Axel-Standard. I think for the type of driving I do the 3.73s would be just the ticket. What I'm wondering is would it be easier/better/cheaper/stronger to go with a new set of axels already geared 3.73 or to change the gears in the current axel. Along the same lines I'm thinking posi trac for the rear end while I'm at it. Any advise on that. So far none of my 4x4 since 1977 have had it but I think it might be a good idea.
     
  10. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Ohhhhhh 273...YUCK!
    Yeah you need gears. Well like I said about what I'm turning. Yeah 3.73 would be and improvment but you might want to go to 4.10 since your on 33's and have over drive. That will reduce the load on the tranny a lot and make it live much longer. That will also give you the optiong of going bigger on the tires if you want to. Now I notice a millage improvemnt going from 3.08's to 4.10. I Mean I picked up a good 2mpg. There are folks here running 4.56 without OD running 35's. I'd say 4.10 would be the better gear.
    I would not put a dime in that rear 10bolt. for what it would cost you to gear it you could buy a 14. I'd seriously think about that. Several people have the parts for sale for the front. Heck give me $450 and I'll sell you my 12 bolt with a detroit and 4.10 and I'll go to a 14 :)

    Women dig dents and flat paint!
    coloradok5.com/gallery/Grim
    75 Jimmy, Dollar
    Grim-Reaper
     
  11. J.C.Staley

    J.C.Staley Registered Member

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    Thanks from the info Grim. If you're serious I just might take you up on that offer next spring. My lovely bride has taken my check book away until then. Seems I've been spending a little more than I make. I told her is was the American way but since she is incharge of paying the bills I need to keep a low profile for a couple of months. The new gears, one way or another is definitely on for next summer.
     
  12. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    The 2.73 might be why your tranny went out. My friend had 3.08 gears on 39's and he'd eat a tranny every year. The trans just couldn't lug those tires around with that gearing. I'd say go 4.10 for extra power on 31's and perfect power on 33's.

    Red 1989 GMC Suburban SLE V1500 - TBI 350, 700R4 w/ shift kit, Quad-shock front, 31/10.50/15 Pro Comp MT, 4.10 gears, Duals off cat
     
  13. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    Oops, it was $139 for the gears, $90 for the installation kit, $370 to install. You can go to www.drivetrainwarehouse.com and when you buy two sets of R&amp;P sets for certain axles. If you buy two 10 bolt axle R&amp;P sets, they'll give you free installation kits. THe discout code, if needed, is 810. Hope this helps!

    Red 1989 GMC Suburban SLE V1500 - TBI 350, 700R4 w/ shift kit, Quad-shock front, 31/10.50/15 Pro Comp MT, 4.10 gears, Duals off cat
     
  14. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    I might be game about that time. I got a line on a Van 14 for cheap. Will need to do some work on it. Will need to convert my tront to 8 lug and probably won't be ready to install till about that time.
    There is one other person that has expressed intrest in my axle so I need to give them first shot at them. Just have to figure out who it was. Will be a while so WHEN I'm ready to sell if ever I'll post.

    Women dig dents and flat paint!
    coloradok5.com/gallery/Grim
    75 Jimmy, Dollar
    Grim-Reaper
     

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