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.

86 K5 4spd what gears would i have

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 84CUCV, Jun 17, 2006.

  1. 84CUCV

    84CUCV 3/4 ton status Premium Member

    Joined:
    Jul 1, 2002
    Posts:
    7,115
    Likes Received:
    2
    Location:
    NJ for now
    I was told 3.08s, but i dont see how that could be. My cucv has a 400 and 3.08s. So what would i have? Should i stop being lazy and go pull the cover? Just need to know. I would like to run 35" bfgs for now with stock gears.

    As always thanks for the help
     
  2. 84CUCV

    84CUCV 3/4 ton status Premium Member

    Joined:
    Jul 1, 2002
    Posts:
    7,115
    Likes Received:
    2
    Location:
    NJ for now
    anyone
     
  3. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

    Joined:
    Jul 23, 2000
    Posts:
    36,178
    Likes Received:
    1,387
    Location:
    E-town baby!
    My '81 was a factory 465/208 truck and it came with 2.73's...so yeah, I'd pull those covers and find out for sure before slapping some 35's on it.

    Rene
     
  4. 84CUCV

    84CUCV 3/4 ton status Premium Member

    Joined:
    Jul 1, 2002
    Posts:
    7,115
    Likes Received:
    2
    Location:
    NJ for now
    so if it is 2.73s what will happen if i do put on 35s? to much rpms? thx rusty
     
  5. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

    Joined:
    Jun 13, 2003
    Posts:
    29,624
    Likes Received:
    1,380
    Location:
    Jersey Shore
  6. 84CUCV

    84CUCV 3/4 ton status Premium Member

    Joined:
    Jul 1, 2002
    Posts:
    7,115
    Likes Received:
    2
    Location:
    NJ for now
    not to sure i get you, dont know much about gearing yet. Could i get away with 33s? thx
     
  7. berserker

    berserker 1/2 ton status

    Joined:
    Nov 19, 2005
    Posts:
    127
    Likes Received:
    0
    Location:
    columbus,ohio
    old school

    jack up the rear end so both wheels are off the ground then turn one wheel by hand one full rotation and count how many times the driveshaft spins that will give u a rough estimate
    if the drive shaft spins 3 times you probably have 3.08 gears if its just under 3 times its probably 2.73

    youll should be fine with 35's with 10 bolt axles you will wany some gears though
     
  8. BowtieBlazer

    BowtieBlazer 1/2 ton status

    Joined:
    Jul 15, 2001
    Posts:
    2,462
    Likes Received:
    0
    Location:
    Baton Rouge, Louisiana
    for what its worth my stock 84 w/4spd had 3.73's i was suprised felt like 3.08's
     
  9. 84CUCV

    84CUCV 3/4 ton status Premium Member

    Joined:
    Jul 1, 2002
    Posts:
    7,115
    Likes Received:
    2
    Location:
    NJ for now
    OK so 3.73s, 2.73s and 3.08s are all highway gears? so i think the truck would be real slow with the 35s. am i thinking right or way off? thx for the help
     
  10. BowtieBlazer

    BowtieBlazer 1/2 ton status

    Joined:
    Jul 15, 2001
    Posts:
    2,462
    Likes Received:
    0
    Location:
    Baton Rouge, Louisiana
    I ran mine with 3.73's and 35's and it wasn't bad. 4.11's woke it up some. Just don't go too deep in the gearing if you plan on running much interstate
     
  11. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

    Joined:
    Jul 23, 2000
    Posts:
    36,178
    Likes Received:
    1,387
    Location:
    E-town baby!
    With 2.73's and 33's I used to have to use granny low gear as a regular first gear to get the truck moving. The only upside was it was pretty good on fuel mileage on the highway...was only turning 1750 rpm on the highway. When I swapped to 3/4 ton diffs they had 3.73's which was much better. I ran 35's with the 3.73's and it was fine with the 4 speed.

    Rene
     
  12. 84CUCV

    84CUCV 3/4 ton status Premium Member

    Joined:
    Jul 1, 2002
    Posts:
    7,115
    Likes Received:
    2
    Location:
    NJ for now
    Ok thx for the replys, i think i got it.
     
  13. Creek

    Creek Registered Member

    Joined:
    Mar 17, 2006
    Posts:
    36
    Likes Received:
    0
    Location:
    Mint Hill, NC
    Check the inside of the glove box lid for RPO codes.

    RPO FY LY DIVISIONAL RPO DESCRIPTION
    GS4 85 86 AXLE,RR 3.70 RATIO
    GT4 76 88 AXLE,RR 3.73 RATIO
    GT5 76 88 AXLE,RR 4.10 RATIO
    GT8 76 88 AXLE,H.D. RR 4.10 RATIO
    GU1 76 87 AXLE,RR 2.41 RATIO
    GU2 76 88 AXLE,RR 2.73 RATIO
    GU3 82 85 AXLE.AR 2.93 RATIO
    GU4 76 88 AXLE,RR 3.08 RATIO
    GU5 76 88 AXLE,RR 3.23 RATIO
    GU6 76 88 AXLE,RR 3.42 RATIO
    GV4 82 87 AXLE,RR 3.36 RATIO
    GV8 82 85 AXLE,RR 2.72 RATIO
    GW4 84 85 AXLE,RR 3.31 RATIO
    GW6 85 88 AXLE,RR 3.27 RATIO
    GW9 76 88 AXLE,RR 2.93 RATIO
    G80 76 88 AXLE,RR LOCKING TYPE
    G83 82 83 GEAR,RING 8.75 IN
    G87 76 87 GEAR,RING 8.50 IN
    G88 76 83 GEAR,RING 8,875 IN
    G89 76 87 GEAR,RING 7.50 IN
    G92 76 88 AXLE,PERFORMANCE RATIO
    G95 85 88 AXLE,ECONOMY RATIO
     
  14. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,980
    Likes Received:
    189
    Location:
    Roy WA
    Go check dremu's brochure pages. I'll bet money that there probably aren't more than 4 possibilities that year:
    2.73 maybe, 3.08, 3.42, 3.73

    It seems that later years didn't even bother with 2.73's, but they did hang on for awhile. Nowhere near as common as 3.08's.

    As an edit, I don't see that available gear ratio's are shown in the brochures for '85 or '86, at least. ('81 looks like the last year that gear ratios were important enough for owners to know:()
     
    Last edited: Jun 23, 2006
  15. 84CUCV

    84CUCV 3/4 ton status Premium Member

    Joined:
    Jul 1, 2002
    Posts:
    7,115
    Likes Received:
    2
    Location:
    NJ for now
    thx guys i will find out.
     
  16. 84CUCV

    84CUCV 3/4 ton status Premium Member

    Joined:
    Jul 1, 2002
    Posts:
    7,115
    Likes Received:
    2
    Location:
    NJ for now
    damn they are 2.73s thx for the help
     
  17. BKinzey

    BKinzey 1/2 ton status

    Joined:
    Jan 13, 2006
    Posts:
    3,145
    Likes Received:
    0
    Location:
    Hollywierd, CA
    Hmmmm. My 87 w/ 700r4 has 4.10s
     
  18. 84CUCV

    84CUCV 3/4 ton status Premium Member

    Joined:
    Jul 1, 2002
    Posts:
    7,115
    Likes Received:
    2
    Location:
    NJ for now
    4.10s from GM? never knew that one for a k5
     
  19. BKinzey

    BKinzey 1/2 ton status

    Joined:
    Jan 13, 2006
    Posts:
    3,145
    Likes Received:
    0
    Location:
    Hollywierd, CA
    OOPS! I'm lying:o The RPO code says 3.42. Previous owner said 4.10:rolleyes:

    What does the FY & LY stand for?
     
  20. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

    Joined:
    Jul 23, 2000
    Posts:
    36,178
    Likes Received:
    1,387
    Location:
    E-town baby!
    First year, Last year

    Rene
     

Share This Page