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4.10's or 4.56 gears?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 85scottsdale, Feb 25, 2004.

  1. 85scottsdale

    85scottsdale 1/2 ton status

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    4.10\'s or 4.56 gears?

    I have a 85 K10 shortbed with 4" of lift, 350 with headers and dual 2 1/4" exhaust with 800cfm Q-Jet, aluminum intake (soon to be a Weiand) and will also have a cam in it to match the gears. Also has a 700r4 and 33x12.5" tires.

    I'm thinking going with 4.10s would be good and that would put my cruise at 70mph right around 2k and my cruise rpm in 3rd around 2900-3000 for towing. I use this truck for towing a single axle trailer with 4 motorcycles, 1 4-wheeler, and some other small stuff and sometimes a lawn mower. I figure the 3k rpm cruise speed while towing would be good rpm and i'll get a cam that gives good power for that rpm also. And sometime in the future it will be getting a 406, so torque will be of no concern by then.

    It also tows a 18' tri-hull boat with a Chevy 250 I6 in it.
     
  2. MTBLAZER89

    MTBLAZER89 3/4 ton status GMOTM Winner

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    Re: 4.10\'s or 4.56 gears?

    Yeah 4.10's sound ok for 33's, but if you plan on even maybe going to 35's and still towing I would say just opt for the 4.56's. /forums/images/graemlins/thumb.gif
     
  3. 85scottsdale

    85scottsdale 1/2 ton status

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    Re: 4.10\'s or 4.56 gears?

    For now, I have no plans on going with 35s unless I go with 2 more inches of lift, then it won't be any good for towing. As it is now i'm going to need a pretty big drop hitch.
     
  4. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    Re: 4.10\'s or 4.56 gears?

    I would go with 4.10's and not worry much if 35's eventually become in the works because with a 406, you will have so much low end torque you will have no problem cruising at 1,500-1,800 in OD and 2,500RPMs towing. I have a 406 and am probably going to 4.88's but I am not to excited about my RPM's in direct drive. It is close to 3K RPM which is too high for my motor because it delivers plenty of torque at it's current 2,500 pulling a load in direct drive. I wan't 4.88's for better acceleration and they will probably let me run in 4hi in the sand.
     
  5. beater_k20

    beater_k20 Banned

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    Re: 4.10\'s or 4.56 gears?

    i'm assuming since you said you have a K10, that its got 10 bolts front and rear. if so, do yourself a favor and dont waste a dime on the 10 bolt rear, put a 14FF in it and call it good. same with the front, just get a 4.10 3/4 ton front axle. shoudl be able to pick them up in the $100-250 range all day long. assume $250 for the axles, and another $250 for a set of 8 lug rims. when you talk about putting new gears in both axles, the labor alone will probably eat up the $500 you would've spent on the 3/4 axles and new rims.
     
  6. Hossbaby50

    Hossbaby50 3/4 ton status

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    Re: 4.10\'s or 4.56 gears?

    This one is borderline. I ran 4.56's and 32's (really 31") and loved it. I also run a 700R4. OD had plenty of power for cruise and D had plenty of power for towing. If your motor is pretty stout or is going to be stout then 4.10's might be a good option if you don't plan on 35's at all.

    I am running 35's and 4.56s right now and I was dissapointed. I hated it at first, but I have since added TPI fuel injection in place of the carb so it is alot better then the carb was. I don't mind 4.56's and 35's now.

    Harley
     
  7. rcpilot

    rcpilot 1/2 ton status

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    Re: 4.10\'s or 4.56 gears?

    I currently run 3.73's, 35" MTR's, 350/TH350/NP203 and I have PLENTY of power. To keep from spending the cash on new gears I'm considering going to 465/205 combo... awesome granny gear for climbing and great engine breaking on the down hill side /forums/images/graemlins/woot.gif
     
  8. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: 4.10\'s or 4.56 gears?

    [ QUOTE ]
    I currently run 3.73's, 35" MTR's, 350/TH350/NP203 and I have PLENTY of power. To keep from spending the cash on new gears I'm considering going to 465/205 combo... awesome granny gear for climbing and great engine breaking on the down hill side /forums/images/graemlins/woot.gif

    [/ QUOTE ]

    That's exactly what I did, but it's not for everybody.

    In your instance I would go to 4.56s. With the 33" tires it will be much better for towing.

    My tow rig has 4.10s and 31.5" tall tires with no O/D.
     
  9. 85scottsdale

    85scottsdale 1/2 ton status

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    Re: 4.10\'s or 4.56 gears?

    [ QUOTE ]
    i'm assuming since you said you have a K10, that its got 10 bolts front and rear. if so, do yourself a favor and dont waste a dime on the 10 bolt rear, put a 14FF in it and call it good. same with the front, just get a 4.10 3/4 ton front axle. shoudl be able to pick them up in the $100-250 range all day long. assume $250 for the axles, and another $250 for a set of 8 lug rims. when you talk about putting new gears in both axles, the labor alone will probably eat up the $500 you would've spent on the 3/4 axles and new rims.

    [/ QUOTE ]

    I have a 12 bolt in the rear from an older truck and a 10 bolt front. I don't really want to swap to 3/4 ton axles because of the extra weight and clearance issues. I can do all the work myself, so I won't be paying for labor. But it is an option, but the only problem is i'll need to grind down the 14 bolt to get the same ground clearance I have with my 33's. Plus I just bought brand new rims and tires which with the 8 lugs would then be useless unless I can fit 15" rims on a 3/4 ton 10 bolt and 14bolt? It is an option though but I don't wanna have to get rid of my brand new timberline M/Ts.
     
  10. Beast388

    Beast388 1/2 ton status

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    Re: 4.10\'s or 4.56 gears?

    [ QUOTE ]
    unless I can fit 15" rims on a 3/4 ton 10 bolt and 14bolt? It is an option though but I don't wanna have to get rid of my brand new timberline M/Ts.

    [/ QUOTE ]

    I can easily be done. I am running 15 X 10 rims with my 8-lug D44 and 14BFF. Rims are cheap too.....around $40-50 each. /forums/images/graemlins/waytogo.gif
     
  11. 6.2Blazer

    6.2Blazer 1/2 ton status

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    Re: 4.10\'s or 4.56 gears?

    My vote would be for the 4.56's. My last two daily drivers had 4.10's and stock tires (current one has the tiny stock LT245/75R16s) with decent running V-8's and I thought it worked out good. Therefore with the much larger 33's I think 4.56 would be the way to go.
     
  12. Jonny-K5

    Jonny-K5 1/2 ton status

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    Re: 4.10\'s or 4.56 gears?

    4.56 all the way, if you didnt have overdrive, i'd say 4.10, but your 700 is gonna be lugging in OD with 4.10.

    i went from 3.73 to 4.56 and im very happy.i think if i went to 4.10 it wouldnt be enough .
     
  13. 85scottsdale

    85scottsdale 1/2 ton status

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    Re: 4.10\'s or 4.56 gears?

    What if I were to go with a SM465/np205 setup? It has crossed my mind since I like manuals and it would be a lot stronger than my 700r4. I know they don't have Overdrive so I would be looking at higher cruise rpm but am concerned about gas mileage also.
     
  14. 1989blazer

    1989blazer Registered Member

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    Re: 4.10\'s or 4.56 gears?

    I've got 4.10's and 33's. Can't use OD unless doing 60 or faster. OD around town is a non-starter. OTOH, D seems to revving pretty high at 70. Got 18mpg driving 190 miles on the freeway (no mountains) yesterday, though. I'm happy with the set-up, although I want to adjust my transmission's TV cable to downshift out of OD sooner and upshift later. If you want to tow, I'd recommend 4.56's or forget using OD.
     
  15. 85scottsdale

    85scottsdale 1/2 ton status

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    Re: 4.10\'s or 4.56 gears?

    I won't be running OD while towing, so I don't want gears that i'm going to be turning too many rpm on the highway in 3rd. But I would say 3k rpm would be ok for pulling down the highway.
     

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