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3:08 to 3:73???

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by k5'er, Jan 4, 2002.

  1. k5'er

    k5'er Registered Member

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    hey guys, do you think it would be worth it to go from 3:08's to 3:73's??? would i tell that much of a diff??? your help would be great!!

    When i die,bury me upside down so the world can kiss my a@# goodbye! lol thought that was a hoot!
     
  2. k5'er

    k5'er Registered Member

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    Anyone? :(

    When i die,bury me upside down so the world can kiss my a@# goodbye! lol thought that was a hoot!
     
  3. K5DRAGER

    K5DRAGER 1/2 ton status

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    What do you have? Do you have an auto, an auto with OD, a manual? What size tires are you running ? Hard to answer that ? without this information
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    3.08 to 3.73 would be a huge jump in acceleration/felt power no matter what you are running now, but depending on tire size and transmission, it raises highway RPM's quite a bit, and lowers highway MPG by a bit. But with 32 or 33" tires and a 700R4, I wouldn't hesitate to do the swap. Any bigger tires and I'd probably go with 4.10's or 4.56's.

    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     
  5. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    Better be worth it, because I've redone a 12-bolt 3.73 rear to replace my 10-bolt 3.08. I still have to clean up my Dana 44. They're going in after I get my paint done. I've got 31"s, soon to be 32"s.

    <a target="_blank" href=http://www.geocities.com/bigkern76>The Blazer Boy Page</a>
     
  6. k5'er

    k5'er Registered Member

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    its an 88 k5 with 700 trans (auto) with 35" thornbirds.think its worth it?

    When i die,bury me upside down so the world can kiss my a@# goodbye! lol thought that was a hoot!
     
  7. K5DRAGER

    K5DRAGER 1/2 ton status

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    If you have a 700r4 and 35's I'd go with 4.10's or 4.56's. I have a 90 with a 700r4 and 35's and am running 4.56's. But when it comes down to it, it's always personal preference as far as mpg and rpm's on the highway compared to trail and off road performance.
     
  8. shawnboy

    shawnboy 1/2 ton status

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    I went from 3.08 to 3.73 and am running 33" tires . 350 cid, 700r4 tranny. Noticable change in fuel consumption, 450k on a tank to 550k. I am also running with a few other goodies, the gear swap alone didn't do this. You will feel the change in accelleration as well. Do it!!!!!!!!
    Shawnboy.

    <font color=red>If you are having too much fun it's probably illegal.</font color=red>
     
  9. Mreetz

    Mreetz 1/2 ton status

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    I'm running 3:73s with 35" tires.
    Goes great down the highway and offroad.

    1984 K-5
    4" lift
    35x12.5 MTs
    buildin a 400 for it, any info greatly appreciated
     
  10. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Hey K5drager, tell me how you like the 700R4, 35's, 4.56's. I am getting ready to do the same setup on my 1989 blazer. I am installing a corp 14 FF rear also. I really want to know what the milage is like, how's the torque? My guess is that the torque is really good with that combo. I used to have a 76 blazer with the same gears and tires but without OD. that was real good too.
     
  11. k5'er

    k5'er Registered Member

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    ok good! you guys helped me out alot!! i bought 3/4 ton front and rears w/ 3:73's with the brakes and everything for 300$!! and was debating wif i should put bigger gears in it. so i think ill keep the 3:73's and spend that extra money for something else!!! thanks for the help guys!!!

    When i die,bury me upside down so the world can kiss my a@# goodbye! lol thought that was a hoot!
     
  12. horsepit

    horsepit Registered Member

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    K5'er
    Where did you find it? Wrecking yard? What year is the best to look for?

    1987 Blazer, Rancho 4"
     
  13. POWERMAD

    POWERMAD 1/2 ton status

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    If you get a weekly paper likke the Nicle ads, check them out.
    We get it for free here in the Portland area.
    I always see good finds in there.
    I would have the money set aside and be ready to jump when you do see a good deal.
    I saw a 10 bolt 3/4 ton front for $75. I called Shannon to let him know and when he called it was being loaded up.
    One day earlier and he coluld have had it.
    People parting rigs out will get you a better deal than any salvage yard. You might have to remove the parts yourself but oh well.
    Most times you can get a whole rig for a few hundred dollars.
    Gut it and haul what ya don't want to the salvage yard.

    <font color=green> Too bad ignorance isn't painful </font color=green>
     
  14. k5'er

    k5'er Registered Member

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    75 bucks?? dang, now i think i got ripped!!

    Mud! Its cool!
     
  15. Neil

    Neil 1/2 ton status

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    Good thing you got the whole deal. I do believe the 1988 model 3:08 carrier is a different size than the one for 3:23 and up and will not accept factory 3:73 gears. 2:73,3:08 is series 1 and 3:23,3:42,3:73 and up is series 2.
    I think that's right anyways. I know on the cars/light trucks it is.

    Neil H. Alabama.. "It's a full size thang, Jeep owners don't understand!!" '78 K5 400ci 4x4 AT,AC,PW Cheyenne., '74 C10 4x2
     
  16. DesertDueler

    DesertDueler 1/2 ton status

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    I use to run 3.73 and 35s with the 700r4. It gor great gas milage down the freeway and moved pretty good still. Now that I have gone to 4.56s it wheels alot better because the crawl ratio is lower, and it gets up and goes alot better, but I am not sure about the freeway milage though because its not street legal at the moment.

    86Jimmy 4"&35"MTRs,87 burb 4"&33"MT,69Firebird w/525 hp,and 70GTO live in PHX,AZ<a target="_blank" href=http://www.geocities.com/modifierperformance>My vehicles</a>
     
  17. 6.2Blazer

    6.2Blazer 1/2 ton status

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    While 3.73's are not the ideal ratio for 35" tires, I do think you will notice a substantial difference as compared to the 3.08's. If you were actually installing new gears into the axles then I would say go lower, but if the axles already have the 3.73's then it shouldn't hurt anything to try them out......besides, you can't get much worse than 3.08's.

    A couple of other points:
    - Fuel consumption - lower gears do not always mean lower mileage. In your case (35" tires), going from the 3.08 to 3.73 could actually improve the mileage because it will allow the engine to operate in a more efficient rpm range rather than lugging at a low rpm all of the time. I don't think most people take into account the error in the speedometer/odometer when changing tire size or gear ratios and then calculating fuel economy, thus giving the false readings. For example, going from 31" to 35" tires will make the odometer show about 11-12% less miles than actually travelled which can easily change the fuel consumption readings 1-2 mpg.
     
  18. TXsizeK5

    TXsizeK5 1/2 ton status

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    Yeha thats true... i went from 3.08-4.56 with my 35" tires. Let me tell you i will never regret what i did (except when it comes summer and i need to drive highway to the beach).. i rev quite high for medium speeds such as at 55mph im at over 2k in my top gear of 1:1
    I get alot of power too... putting it in 4 lo i can crawl over things my friends cant even hauss their way over in 4 hi and alot of speed


    87 Custom Deluxe
    305/Sm465/ NP208
    4.56 , 35" BFG Muds, Series 40 delta flow 3" tips
    Coming Soon: All springs, shocks, and body work
     
  19. TXsizeK5

    TXsizeK5 1/2 ton status

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    Ohh and then the speedometer diff i used to read 5-10mph under with my 3.08's now with 4.56 i read about 5mph over

    87 Custom Deluxe
    305/Sm465/ NP208
    4.56 , 35" BFG Muds, Series 40 delta flow 3" tips
    Coming Soon: All springs, shocks, and body work
     
  20. txbartman

    txbartman 1/2 ton status

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    I had 3.73s, 700R4, 305 with 35s. The weakness of the 305 engine became rudely apparent. Those gears were great for 32s, but not for 35s. I installed 4.56s and have never looked back. It actually gave me some "power" from a stop and such. I am installing a new 350 with about 300HP in a couple of weeks and can't wait to see how fun that is with those gears!

    Brian
    Check out <a target="_blank" href=http://tx85gmcguy.alloffroad.com>My Jimmy</a> with all her projects!
     

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