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Stock Gears

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by InSearchofAk5, Aug 23, 2001.

  1. InSearchofAk5

    InSearchofAk5 Registered Member

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    What are stock gears on a 87 blazer? can you keep these gears and run 35's alright?
     
  2. Derf00

    Derf00 1/2 ton status

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    Maybe. You need to fill out you profile with a little more info.

    Derf00

    "A WISE MONKEY NEVER MONKEYS WITH ANOTHER MONKEY'S MONKEY."
     
  3. MOABDADC22

    MOABDADC22 1/2 ton status

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    Check the tag on your diff, if it is still there. There were quite a few different gears offered, so you might have to tear off the diff covers and count the teeth on the pinion and ring gear to be absolutely sure.

    <a target="_blank" href=http://www.moabdadc22.alloffroad.com/>http://www.moabdadc22.alloffroad.com/</a>Real four wheelers don't need tools to remove body panels, paint, tail lights..etc.
     
  4. bigblue

    bigblue 1/2 ton status

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    Mine WERE 3.42 stock. WERE....

    It ran pretty good till i blew out my 10 bolt ring gear.

    Surfing is Life...<P ID="edit"><FONT class="small">Edited by bigblue on 08/23/01 05:59 PM.</FONT></P>
     
  5. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Look in your glovebox for the following code:

    GU4- 3.08
    GU6- 3.42
    GT4(or5X1)- 3.73
    GT5(or GT8)- 4.10
    G80- Limited Slip Diff



    <font color=red>PHOTO ALBUM-</font color=red> <a target="_blank" href=http://albums.photopoint.com/j/AlbumList?u=1289798>http://albums.photopoint.com/j/AlbumList?u=1289798</a>.......<font color=blue>TRUCK & HIKING PICS</font color=blue>
     
  6. txbartman

    txbartman 1/2 ton status

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    There were many different sizes from the factory. The only way to now FOR SURE is to take of the cover and count the teeth. The ratio is the ring gear teeth divided by the pinion teeth. And, if you haven't had the cover off, it wouldn't hurt doing this and replacing the fluid. RTV for the seal and a few pints of gear lube are pretty cheap, you know.

    Now I refuse to answer any more of your questions until you fill out your profile.

    Brian
    Click to see <a target="_blank" href=http://tx85gmcguy.alloffroad.com> My 85 Jimmy </a>
    Who put a stop payment on my reality check?!?
     
  7. Seventy4Blazer

    Seventy4Blazer 3/4 ton status

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    unless you are the first owner and only owner of the K5 how do you know they are stock?
    Grant

    1974 Chevy Blazer Cheyanne. but it is on 33's now, with saggy old springs. i am in Yuma Arizona if ya got any parts for me.
     
  8. Seventy4Blazer

    Seventy4Blazer 3/4 ton status

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    unless you are the first owner and only owner of the K5 how do you know they are stock?
    Grant
    You need to count them IMO

    1974 Chevy Blazer Cheyanne. but it is on 33's now, with saggy old springs. i am in Yuma Arizona if ya got any parts for me.
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    No reason to count teeth, the tooth count is stamped on the outside edge of the ring gear. Regardless, good idea to open it up to inspect the internals/change fluid anyway.


    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</a>
    No anti-theft measures on your truck? No pity when its stolen
     
  10. tom

    tom 1/2 ton status

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    If you don't wnat to remove the diff. cover, jack up one rear wheel. Put a mark on the driveshaft or tape one end of a long piece of string to the driveshaft. Turn one rear wheel two complete revolutions exactly and count the number of turns the driveshaft makes. The number of driveshaft turns is equal to the gear ratio. A tad over 3 turns is 3.08 gears; nearly 3 and 1/2 turns is 3.43; 3 and 3/4 turns is 3.73; a little over 4 turns is 4.11gears.
     
  11. Executioner

    Executioner 1/2 ton status

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    This is on of those wife's tales, becuase it does not work all of the time.
    Where did you pick this up Tom ?
    Give it back, it is not worth posting !
    TGIF
     
  12. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    In reply to the original post, it all depends on what the stock gears are and what tranny you are running.
    I just want to preface by saying the best way to check what gear ratio you have is to pull the cover and A.) count the ring gear teeth and divide by the pinion gear tooth count, and/or B.) check the stamping on the gears themselves. This also gives you a chance to inspect the condition of the components.
    As for Executioner, I have agreed with some things you have said in the past, but this time no, and to tell Tom to "Give it back" was a little too rude even for you. Tom was just trying to help by giving a proper suggestion (more than you do) rather than just saying "WRONG!!!".
    I know there is bad advice given from time to time, and people who say "well my friend did this, that, and the other thing....." without knowing first hand if something works or not, but for the most part the advice is good.
    If there is bad advice, don't just say it's wrong, but explain why it is wrong and what is correct.
    As for what Tom said being a wives tail, you might want to put your skirt back on for this because it is not. The only time it won't work, is if the rearend is equipped with a Locker, in which case if one wheel was on the ground, and one wheel was up in the air, he would not be able to turn it, then the person would know to try another way (True this is ASSuming the locker is functioning properly). In this case you would only need to rotate the wheel once (ASSuming the other wheel spun freely).
    As for a open differential or true limited slip. Holding one wheel (say on the ground), and rotating the other 2 full revolutions while counting the driveshaft revolutions will give you the gear ratio (human error comes into play when trying to count partial revolutions, but the ACTUAL revolutions is true none-the-less). The reason for this is because the way a differential is set-up, we will use a 3.73 ring and pinion ratio for example, you get a finite number of axle revolutions per input/driveshaft revolutions. In a "Locked" rear end, for EVERY 3.73 revolutions, the axles (which the tires are bolted to for all practical purposes) rotate 1 time each. Each axle/wheel rotates 1 full revolution, that times 2 axles equals 2 axle revolutions. In an open differential, the axles are allowed bias (one to rotate more than the other) but total revolutions never changes. As you know, in a straight line an open differential will rotate both axles the same amount (ASSuming again you do not break traction as in a burnout). For every 3.73 driveshaft revolutions each axle with rotate once (2 axles * 1 revolution = 2). In a cornering situation, the spider gears allow bias. The inside tire does not cover as much ground as the outer tire, so the outer tire spins faster and covers more ground, but the same ratio (every 3.73 driveshaft revoltions:2 axle revolutions) holds true. For every 3.73 driveshaft revolutions in cornering situation, the inside axle may only turn .5 times, but that means the outside axle must turn 1.5 times (.5 + 1.5 = 2).
    The same hold true for a true limited slip differential, but it has clutches that limit the amount of bias. When the clutches are disengages such as low rpm of a person turning a tire by hand, it acts just like an open differential.
    This is the reason that when someone keeps the engine at steady rpm and both wheels are spinning at the same rate, but one catches traction and slows down/stops, the other tire will actually speed up if the engine rpm stays constant (also ASSuming no change in transmission gears). So the 2 revolution test is not a wives tail.
    Tom I hope you weren't offended here.

    There is a Right way, a Wrong way, and then there is My way. The latter is usually the most fun! [​IMG]
     
  13. DesertDueler

    DesertDueler 1/2 ton status

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    I have 3.08 gears in my 86 Jimmy and run 35 Goodyear MTRs. I have the 700r4 tranny. If you were to do this make sure you dont drive in overdrive. Also make sure you have a tranny cooler. either the stock one or an aftermarket one. Ive put 30,000 miles on it this way with no problem. My friend has 2.73 gears and 35s on his 89 Jimmy. He has put 50,000 miles on it tis way. You just have to keep the rpms above your stall rpm.

    86 Jimmy 4"lift 35"MTRs locked front.Other cars 69 Firebird w/525 hp,and 70 GTO <a target="_blank" href=http://www.geocities.com/modifierperformance>MY vehicles</a>
     
  14. 6.2Blazer

    6.2Blazer 1/2 ton status

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    Hey, you beat me to it!

    Just to re-state what Leadfoot already explained, you can estimate the gear ratio by spinning the tire and counting the driveshaft revolutions. Executioner is right in a certain way that it does not always work, but that is only because people don't take into account the variables that Leadfoot described.
     
  15. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Boy, I once had 3.08 gears. I really feel sorry for you guys.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  16. pcorssmit

    pcorssmit 1/2 ton status

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    Executioner, care to explain yourself (since you're wrong)?


    Posted by: DesertDueler:

    "I have 3.08 gears in my 86 Jimmy and run 35 Goodyear MTRs. I have the 700r4 tranny."

    I'm sorry. :D

    Pete


    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  17. bigjbear

    bigjbear 1 ton status Staff Member Moderator

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    Leadfoot, well stated. But, for the most part, Ex is right on this one. The only way that will work is with an open diff or a worn out L/S and its still not 100%. Will not work with a Gov-Lock or Detroit/Lock-Rite. If you want to do the spin thing, spin the drive shaft instead. As far as attitude, I think he is relater to blazerbabe (I know that was a cheap shot, but if you had some tact you would't get bashed.)

    Jim '80 GMC & '73 Blazer
    Tread Lightly!
    <a target="_blank" href=http://www.tellicok5.rockcrawler.com>www.tellicok5.rockcrawler.com</a>
     
  18. pcorssmit

    pcorssmit 1/2 ton status

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    It will work w/a posi or a locker, yes it is a little trickier, and the 2:1 thing doesn't apply.

    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  19. DesertDueler

    DesertDueler 1/2 ton status

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    Thats why I still have my 208 in it. The low makes up for not having a bigger gear. I am getting 4.56s or 4.88s in it now since I cant drive it on the street. I still have no windsheild since the rollover. I also have a strong motor which helps.

    86 Jimmy 4"lift 35"MTRs Other cars 69Firebird w/525 hp,and 70GTO live in PHX,AZ<a target="_blank" href=http://www.geocities.com/modifierperformance>My vehicles</a>
     
  20. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    If you read what I wrote, you will see that I said it will not work with a locker (and you could tell this by not being able to spin the tire if one was on the ground and the other was off the ground) and yes it (not being able to turn one wheel if the other is on the ground if the locker works correctly) applies to loc-rights (which I have), detroits, gov-locs, etc. But then again it's easy to tell if one of those is installed. Besides if you do the two spin test on a broken locker equipped differential, a 3.73 will look as if its a 7.46. Even the low 2.73 will look like a 5.46 which was NEVER stock.
    So to say Ex is right on this one, I will again have to disagree. I stated he is correct on one occasion (the locker) but I explain why (he does not), as well as he implies the 2 spin test doesn't work at all (which it does). And yes a true L/S will work with the two spin version unless the clutches are stuck in the locked position (usually centrifical force is what locks the two by sensing one axle rotating much faster than the other), in which case it will seem as if it's a locker when trying to spin one wheel (see comment about locker above).
    By saying he is right only feeds his ego, please update your post appropriately. Thanks

    There is a Right way, a Wrong way, and then there is My way. The latter is usually the most fun! [​IMG]
     

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