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Stepping down to 33s

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by DesertDueler, Dec 5, 2001.

  1. DesertDueler

    DesertDueler 1/2 ton status

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    I decided to go down to 33s on my Burb so it will tow better and get better gas milage. That and I am getting 4 brand new 33 BFG MT KMs for my wore out 35" BFG MTs. Anyways what gears to you guys think would be best for this setup? Keep in mind I wont use OD while towing. I was thinkink 3.73s or 3.90s.

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

    BigTex 1/2 ton status

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    I would highly recommend 4.10s. That gives you better low end torque for towing. Besides, 4.10s are good gears with 33s.

    <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>
     
  3. DesertDueler

    DesertDueler 1/2 ton status

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    Well the motor is being built for low end torque. It will have edelbrock intake, throttle body spacer, 454 throttle body, ported heads with 2.02s and 1.60 valves and 1.6 roller rockers, roller cam(206 at .050 intake and 214 at .050 exhaust), MSD ignition, and a custom burned chip. It should put out between 325 and 350 hp no problem.

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

    muddysub 1 ton suburban status Staff Member Moderator GMOTM Winner

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    dang you're gonna have a sweet motor!! i would go with 4.10s, if your motor is for low end torque, get gears for low end torque.

    people that get good mileage aren't having any fun!
    scott,
    1989 GMC suburban 3/4t 4" lift finally rollin on 36" swampers, tbi350, th350, np241
     
  5. Hossbaby50

    Hossbaby50 3/4 ton status

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    3.73's aren't bad. I have them in my Jimmy. I have a supposed 300HP crate motor, and in drive is turn plenty of RPM's to tow on the highway. Hell, my truck will even accelerate going up Sunset point. That is with all my tools, parts, huntin gear, and fat friends. Usually 500-600 pounds worth (of friends). Plus me at 280. 3.73's ought to handle your needs ok with that motor, and you will get better gas mileage.

    My Chevy isn't broken, its just out of gas.
     
  6. EDdaTREE

    EDdaTREE 1/2 ton status

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    I agree with Hoss on the 3.73's...I never ran a tach, but seemed to be running pretty high R's with 33's and 3.73's.

    9/11/01..Never forget...Never forgive
     
  7. ChevyCaGal

    ChevyCaGal 3/4 ton status

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    IMHO say 3.91's would be good for the gas mileage with 33's....

    &lt;&gt;&lt;<a target="_blank" href=http://www.chevycagal.homestead.com/steph.html>Steph's Webpage</a>&gt;&lt;&gt;
    Suck Fumes Ford Boy
    I keep trying to lose weight, but it always finds me!
     
  8. Rebel88

    Rebel88 1/2 ton status

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    3.73s

    Later

    Have you driven OVER a Ford lately?
     
  9. Pugsley

    Pugsley 1/2 ton status

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    3.73's are good if you don't plan on doing much towing outside the valley, like US60 or SR77 - My Blazer drags it's ass with 3.73's and 33's pulling an 18' bass boat through Queen Creek canyon from Superior up to Top of the World, or any other 6% plus grade. On flat or shorter grades it kicks ass though[​IMG] - Go with 4.10 if you ever head north or east.

    ......And knowing is half the battle
    <a target="_blank" href=http://pugsley.alloffroad.com>pugsley.alloffroad.com</a>
     
  10. greg83k5

    greg83k5 1/2 ton status

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    towing and gas mileage, in a gas motor???

    4.10 gears are the least i'd have with 33 inch tires on a suburban, towing something...

    a vortec 350 with 3.73's and weenie stockers feels sluggish towing a car, add the weight of a sub.....

    you're not gonna get any mileage out of it anyway, so why have a sluggish setup, let that baby sing....

    greg ( 10 years of towin' with about 5 different pickups- that's what i base my opinion on... )
     
  11. HarryH3

    HarryH3 1 ton status Author

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    What axle and gears do you have now?

    <font color=black>HarryH3 - '75 K5</font color=black>
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  12. muddin4fun

    muddin4fun 3/4 ton status

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    I've got 3.73's with 33's and a TH350 and it's a little on the high side for me. I'd recomend you go with 4.10's with your OD.

    Don't hit me, Mr. Moderator... I'll go back on topic... I swear![​IMG]

    <a target="_blank" href=http://www.geocities.com/muddin4fun79blazer>www.geocities.com/muddin4fun79blazer</a>
     
  13. 87GMCJimmy

    87GMCJimmy 1/2 ton status

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    I have 3.73, no lift and 32 inch tires. I like the combination. I have a 19 ft 3000# + ski boat and can pull at 55mph in second going upto sunset point and out of camp verde on the the way back. . If you go with deeper gears running in second gear with reasonable rpms 3000-4000 will bring you speed down around 45-50. Just something to thing about.
     
  14. dyeager535

    dyeager535 1 ton status Premium Member

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    I would say 3.73 at a minimum. Even without OD, 3.42's, 33's, I'm turning a bit low RPM to tow in. I bet 4.10's would be the most satisfying for you. 'Course it depends if you are towing a 12' boat or a 5000lb trailer...either way, 4.10's aren't too much for a motor with 1:1 tranny ratio, and when not towing, it would still be "economical" when you put it in OD.

    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?
     
  15. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    3.42 with my 31" would make my burb drag its ass up hills in OD. I had to leave it in D when it got hilly. I think 4.10 would be perfect. 3.73 is perfect for a truck on 33's, but 4.10 would give you more pull. Actually, that 3.91 that steph mentioned would be a good one to try, too. My 31's have no problem going up hills with a head wind in OD right now with the 4.10 gears. We also have a 67 Chevy C10 with a 350/TH400/12 bolt with 4.10 on 235/75/15 tires, and the RPM's aren't too bad. We get 15 MPG out of it. Just to let you know, I get about 11 MPG with my 4.10 and OD when empty.

    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
     
  16. DesertDueler

    DesertDueler 1/2 ton status

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    My old combo was 35s and 3.42s. It towed great even there as long as I was going 75 plus. Under that it put too much of a load on the tranny. Anyways I put the 33s on it today and it has more get up and go, but looks kinda funny with a 4" lift in front and 6" in the rear. I dont want to go in the 4 gear range, either 3.73s or 3.90s. It will have plenty of power and I like being able to tow above 75, so 4.10s are too much rpms.

    86Jimmy 4"&35"MTRs,87 burb 4"&35"MT,69Firebird w/525 hp,and 70GTO live in PHX,AZ<a target="_blank" href=http://www.geocities.com/modifierperformance>My vehicles</a>
     
  17. Hossbaby50

    Hossbaby50 3/4 ton status

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    I was just on 4 Lo.com and ran your numbers with 3.73's and 3.90's. There is only about a 100-125 RPM difference between the two from 55-75. With the motor your going to use I don't think the 100RPM is a real big deal. 3.73 would give you a little better mileage. (not noticable, but a little $avings) I am just partial to 3.73's because thats what I got, and I like them alot.



    My Chevy isn't broken, its just out of gas.
     
  18. DesertDueler

    DesertDueler 1/2 ton status

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    Like I said I like the high 3 series gears, just dont want to step up to the 4 series unless I really need them. I wont have a problem switching gears if needed since I can set them up.

    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>
     
  19. Emmettology 101

    Emmettology 101 3/4 ton status

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    I fyou are worried about mileage go with the 3.73's. If you aren't worried about mileage go with the 3.90's or 4.10's....

    Mike

    <font color=green>"1024x768x256... Sounds like one mean woman."</font color=green>

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  20. MudFrog

    MudFrog 1/2 ton status

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    4.10's all the way.

    89 K5 Silverado, 4", 33's, 3/4 ton axles
    <a target="_blank" href=http://mudfrog.rockcrawler.com>http://mudfrog.rockcrawler.com</a>
     

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