Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

gears for 10 bolts

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by blackwidowk5, Aug 6, 2002.

  1. blackwidowk5

    blackwidowk5 1/2 ton status

    Joined:
    Dec 1, 2000
    Posts:
    107
    Likes Received:
    0
    Location:
    Richmond, Virginia
    I'm looking ofr 3.73 gears for my front 10 bolt axle, and was wondering if all the ring and pinions fit from the same size 10 bolt whether it's front or rear. ie, could i pull gears out of a rear 8.5 10 bolt.
    Also i'm stepping up from 3.08 gears, did they by any chance use the same pinion gear for both the 3.08 and the 3.73? i figure it's a long shot but why change both gears if you don't have to.
    thanks
     
  2. Rebel88

    Rebel88 1/2 ton status

    Joined:
    Sep 7, 2000
    Posts:
    1,855
    Likes Received:
    0
    Location:
    Richmond, VA
    dont know about using the gears from a rear axle

    but i do know that the pinion gear has to be changed with the ring gear since they come in matched sets...

    as far as the carrier...the cutoff for the carrier in a 10 bolt is 2.73 and numerically lower so your carrier would work with 3.73s

    Later
     
  3. bigmack

    bigmack 1/2 ton status

    Joined:
    Jan 3, 2002
    Posts:
    478
    Likes Received:
    0
    Location:
    Tennessee
    The ring and pinion gears are the same in front and rear 8.5 10 bolts. The pinion gears are not the same for different ratio's, and yes you could pull the gears out of a rear end and install them into the front end but they might make some noise as they will allready have a wear pattern in them from being in the rear.
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,980
    Likes Received:
    189
    Location:
    Roy WA
    If I were you I'd just wait until you find a matched pair of 10 bolts, and swap the whole things over. Unless you break them, (or have a gov-lock heh) a stock setup will go hundreds of thousands of miles with just diff fluid changes.
     
  5. Blue85

    Blue85 Troll Premium Member

    Joined:
    Jul 26, 2000
    Posts:
    9,084
    Likes Received:
    486
    Location:
    Grand Rapids area
    Yes, front and rear 10-bolt diffs are the same (carrier, spiders, cross shaft, ring and pinon). The only difference is that the C-clips are not installed on the front. They turn in the same direction whether they are installed in the front or the rear, since the pinion is on the left of the ring up front and on the right of it in back. The effect of the wear pattern when swapping from front to rear
    is no different than using any used ring and pinion.

    You can't use a ring and pinion originally from different ratio gearsets. In fact, you shouldn't even interchange from gearsets of the same ratio. They have to be matched at the factory and intalled together.

    Start educating yourself now as to what it takes to install new gears (much more than unbolt the old, bolt in the new), start kissing up to a buddy who has experience with the process or save up $300-$500 for a shop to do the install.

    Swapping the entire axle can be cheaper and easier, if you score the right deal.
     
  6. wrathORC

    wrathORC 1/2 ton status

    Joined:
    Apr 27, 2002
    Posts:
    908
    Likes Received:
    0
    Location:
    Hancock, MI
    Everything is the same in front and rear Corporate 8.5" 10 bolts except the C-clips aren't used in the front because the axles are held in by those nifty things at the end of the axle tube.

    I, myself, would try to find 3.73s out of a front axle. It's just about guaranteed to have fewer miles on it than the rear.

    You couldn't use the same pinion gear because the teeth wouldn't mesh correctly even if they had the same number of teeth.

    2.73 = 41/15
    3.08 = 40/13 (if I remember correctly)
    3.73 = 41/11
     
  7. blackwidowk5

    blackwidowk5 1/2 ton status

    Joined:
    Dec 1, 2000
    Posts:
    107
    Likes Received:
    0
    Location:
    Richmond, Virginia
    Thanks for the input. Does anyone have any idea what models had 3.73 ratios from the factory? Did any cars use the 8.5" 10 bolt? Thanks again
     
  8. Blue85

    Blue85 Troll Premium Member

    Joined:
    Jul 26, 2000
    Posts:
    9,084
    Likes Received:
    486
    Location:
    Grand Rapids area
    I don't think there is any sure fire model to find 3.73 in. A Blazer is probably not your best bet. 3.73 and 4.10 were often used in 1/2-ton towing packages. You may have to check the glove box stickers in junkyards if they don't know what they have.

    Cars mostly used the smaller 10-bolt. It has a 7.5 or 7.75" ring gear diameter (I forget) with the 5-lug pattern. I have heard that a few larger cars got 8.5"'s, but I think you are more likely to find a 3.73 ratio in a truck. Maybe it was offered as a performance gear in Camaro's at some point?
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,980
    Likes Received:
    189
    Location:
    Roy WA
    Some big cars (Caprice, Full Size wagons, etc)used the 8.5", and for sure the 85-87 442's used 8.5's with 3.73, as did the same year Grand National. (but 3.42') As you can imagine, good luck finding those cheap. "Normal" cars would not have received anything near 3.73, more 3.23 as the "performance" ratio.

    Suburbans are great donors of 3.42's, but a Sub. with towing package is probably likely to have 3.73's. Make it real easy on yourself, and just look for ones that have the tag still in the glovebox. Not 100% accurate, but at least its quick, then you can crawl under and check the gears to make sure. I've seen more than a couple of K5's with 3.73's, but it appears later ones ('87-up) had them more commonly than say early 80's ones.
     
  10. blackwidowk5

    blackwidowk5 1/2 ton status

    Joined:
    Dec 1, 2000
    Posts:
    107
    Likes Received:
    0
    Location:
    Richmond, Virginia
    Thanks, I'll keep an eye out for them.
     
  11. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,980
    Likes Received:
    189
    Location:
    Roy WA
    If you wanted to get real technical, you can actually tell if the K5 could even have 3.73's based on tranny, engine and whether CA or not, but its just easier to ask people or check the sticker, at worst pull the cover. Most everyone trying to sell them will (should) let you pull the cover and check the count stamped into the gears.
     
  12. 88jimmyoungowner

    88jimmyoungowner 1/2 ton status

    Joined:
    Nov 20, 2001
    Posts:
    425
    Likes Received:
    0
    Location:
    georgia-rome
    how does one tell whta gear ration they have by the glove box sticker? i looked at ine yesterday for a while, and even pulled out the owners manual. i still cant figure all the crap my car has from that sticker. is there a web site that tels you how to figure this out or somethin for me?
     
  13. BJarvis354

    BJarvis354 Registered Member

    Joined:
    Jun 17, 2002
    Posts:
    58
    Likes Received:
    0
    Location:
    New York City
    Here is a good site someone pointed me to: GM RPO CODES

    Here are some codes I pulled off to find out what I had:
    GU2 = 2.73 (what I have! /forums/images/icons/frown.gif )
    GU4 = 3.08
    GU6 = 3.42
    GT4 = 3.73
    GT5 or GT8 = 4.10
    G80 = Gov-lock

    Brady
     

Share This Page