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Gearing Questions

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by raptordriver, Aug 2, 2001.

  1. raptordriver

    raptordriver Registered Member

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    I've got a couple questions for the experts out there.

    I definately want to change the gearing in my 90 Jimmy. I finally got some 35's for it, and I'm just not happy with it on the highway. I didn't even use overdrive with 32's...now drive is getting a little doggy.

    I guess my question is what ratio's are some of your running? I have the stock 10 bolt diff's that'd I'd like to stick with. I do a lot of commuting on the street and would like it to pull pretty good from the 70 - 85 mph range...be it a down shift from OD. What I'm looking for I guess is to have OD to be geared lower (higher revs) than regular drive was stock...but not too much. Are 4.56's or 4.88's what I should be looking at?

    Anybody have any for sale?

    Is there a pretty good resource on the net for changing gears? Anything else I need to be concerned with? Does the locking assembly or anti slip or whatever that's on the current stock stuff work with different gears?

    Many many thanks for any input here.

    The village idiot,
    Larry
     
  2. Rockjunkies

    Rockjunkies 1/2 ton status

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    4.56's should satisfy ya I think!

    Keep it simple!
     
  3. gokartergo

    gokartergo 3/4 ton status Staff Member Moderator

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    Check out <a target="_blank" href=http://www.ring-pinion.com/>http://www.ring-pinion.com/</a>.......I run 4.56 with 33 in tires I love the combo........Dan

    If it ain't broke.......Don't fix it....
     
  4. SWAMPRNR

    SWAMPRNR 1/2 ton status

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    I Run 4.56s With 35 Inch TSL SXs And No Overdrive.
     
  5. raptordriver

    raptordriver Registered Member

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    No overdrive as in you don't have one...or you just don't use it?
     
  6. solowookie

    solowookie 1/2 ton status

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    I'm running 4.10's with my 35's and the sm465 (work's out just right with no OD), and 4.10's with 33's and an 700r4 (love the combo)

    [​IMG] <font color=blue> Jeff </font color=blue> [​IMG]
     
  7. raptordriver

    raptordriver Registered Member

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    Here's the deal...one valuable lesson I learned from roadracing is to utilize your gearing. To get the best use, of the best part of your power band, you need to use all your gears. I'm sick of wasting OD.

    OD seems pretty worthless in my opinion in the stock setup. I would bet it actually decreases gas mileage. But if you gear OD to act like regular drive, you should have a sweet passing gear that you don't normally get with the standard setup. That's what I'm hoping for anyway.

    &lt;***********************&gt;
    Larry Needham
    LBN@satx.rr.com
    www.teamneedham.d2g.com
    &lt;***********************&gt;
     
  8. gokartergo

    gokartergo 3/4 ton status Staff Member Moderator

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    Yep that's it. That is what I went for also............Dan

    If it ain't broke.......Don't fix it....
     
  9. mudhog

    mudhog THEGAME Staff Member Super Moderator

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    with that setup i would go with 4:56's

    77blazer see it at<a target="_blank" href=http://community.webshots.com/user/ssmith6333>http://community.webshots.com/user/ssmith6333</a>
     
  10. CaptCrunch

    CaptCrunch 1/2 ton status

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    I currently have 4.10's and 35's... it isn't bad but am gonna step up to 4.56's I think for the OD

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
    <a target="_blank" href=http://www.geocities.com/milnerlives_2000/blazer.htm>http://www.geocities.com/milnerlives_2000/blazer.htm</a>
     
  11. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Dan what are you running for a tranny (your profile does not state)? Also what are your approx. RPMs at 65 and 75? Just curious. Thanks.

    If you didn't build it yourself, how can you call it yours.......?
     
  12. muddin4fun

    muddin4fun 3/4 ton status

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    Hey solo! I like your orange name! [​IMG]

    I've got a mind like a . . . a . . . what's that thing called?

    <a target="_blank" href=http://www.geocities.com/muddin4fun79blazer/>http://www.geocities.com/muddin4fun79blazer/</a>
     
  13. for 35's and 36's I'd run 4.56 if your gonna be driving on the street 50/50

    Damn I need to learn how to use my welder!![​IMG]
    (90 Jimmy 350 TBI, 14 FF/10 bolt, 4.56, tires ??
    (ftn96)
     
  14. 6.2Blazer

    6.2Blazer 1/2 ton status

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    If you really want to lower the axle gears so o/d gives the same overall ratio as drive w/ the stock gears did, here's some numbers (since I don't know what your stock ratio is).

    The o/d in the 700r4 is about 0.70:1, so you times the axle ratio by .7 to give you the equivalent ratio.

    For example, if you had 3.08 axle gears and shift into o/d, it would then be equivalent to having 2.15 gears with a non-overdrive trans. Of course this is only true when the trans is running in o/d since it doesn't effect the other gears.....

    Anyway, if you did have 3.08 gears stock and wanted to re-gear the axles so the effective ratio while in o/d was still 3.08, you would need around 4.56 gears (4.56 x .7 = 3.2). Plus, you still have to accomodate for the 35" tires so that puts you around 4.88 axle gears.

    Concerning the use of o/d, I think people got a bad impression of it when it first became readily available back in the mid 80's. Manufacturers put the o/d trans in the vehicles but still kept super high axle ratios like 2.73 and 3.08. If you look nowadays, it's not uncommon to see stock trucks with 31" tires with 4.10 gears (offered as an option in the new Silverado's and the Dodge Off-Road package). My dad has a '00 Chevy with the stock 265/75 tires and the 4.10's, quite frankly it's a pretty nice gearing package.
     

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