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.

Differential ID please

Discussion in 'The Garage' started by jim85K5, Nov 27, 2005.

  1. jim85K5

    jim85K5 Newbie

    Joined:
    May 22, 2005
    Posts:
    2
    Likes Received:
    0
    Location:
    Portland, Oregon
    Ok Boys and Girls a newbie needs some help in ID'ing this rearend set up. It is on an '85 4x4 Suburban, 6.2L Diesel, 208. What I know (or think that I know) is that it is a GM Corp. 14 bolt, 9 1/2". When both rear tires off the ground one rev of the right rear tire gives me 1.75 revs of the drive shaft (+/-). Sometimes the tires will turn and the driveshaft does not. Guress I should say that when you rotate one tire the other turns with it. This is in Neutral with the Emergancy brake off.
    If you do know what this rearend is I am interested hearing what you have to say as far as how good or bad it is.

    Thanks to one and all,

    Jim

    P1010148.JPG
     
  2. 1977k5

    1977k5 3/4 ton status Vendor

    Joined:
    May 26, 2003
    Posts:
    9,991
    Likes Received:
    130
    Yeah, its a SF 14 bolt. You should also learn to resize pictures. My guess for gear ratio is either 3.42 or 3.73.
     
  3. 74757685k5

    74757685k5 1/2 ton status

    Joined:
    Nov 13, 2004
    Posts:
    258
    Likes Received:
    0
    Location:
    montana
    0pen diff . if you want to find your gear ratio spin only one tire 2 times and count D shaft revs.
     
  4. neverendingproject

    neverendingproject 1/2 ton status

    Joined:
    Jul 24, 2005
    Posts:
    1,637
    Likes Received:
    0
    Location:
    Tulsa, OK
    or find two first two numbers you see on the ring gear. take the second one, divide by your first one, and you have your ratio.
     
  5. jim85K5

    jim85K5 Newbie

    Joined:
    May 22, 2005
    Posts:
    2
    Likes Received:
    0
    Location:
    Portland, Oregon
    The numbers on the gear are 11 and 47. Looks to me like I have a 4.27. If this is an open diff. is it correct that both wheels will spin together when jacked up??

    Once more THANKS for all the help!

    Jim
     
  6. 74757685k5

    74757685k5 1/2 ton status

    Joined:
    Nov 13, 2004
    Posts:
    258
    Likes Received:
    0
    Location:
    montana
    one will spin forward and one reverse.
     
  7. atho

    atho 1/2 ton status

    Joined:
    May 14, 2003
    Posts:
    1,115
    Likes Received:
    0
    Location:
    Wayne County, Ohio
    I'm betting its 11 and 41, which is 3.73.
    the only vehicles i've heard of using 4.27 are old jeep cj's and scout 80/800s.
     
  8. neverendingproject

    neverendingproject 1/2 ton status

    Joined:
    Jul 24, 2005
    Posts:
    1,637
    Likes Received:
    0
    Location:
    Tulsa, OK
    Doesnt look like an open diff.
     
  9. bablazer73

    bablazer73 1/2 ton status

    Joined:
    Apr 4, 2000
    Posts:
    3,363
    Likes Received:
    0
    Location:
    upstate ny
    From this side it looks like a "gov-loc" type posi unit. the ring gear on the inside Is the give away. I bet there is a set of weights on the other sidetahts geared to that ring gear. Gov-locs are not known to be strong. They are made to "wind-up" before engagement. Very often will act like an open diff until the centrifical force and weights activate the locking mechanisms.
     
  10. neverendingproject

    neverendingproject 1/2 ton status

    Joined:
    Jul 24, 2005
    Posts:
    1,637
    Likes Received:
    0
    Location:
    Tulsa, OK
    Well i just got a gov lock (look for "is this a posi or gov-lock in my 14sf" in the garage section) and it turn freely. you have to yank it pretty good to lock it by hand, but otherwise, one shaft this way, the other shaft, that way.

    here http://coloradok5.com/forums/showthread.php?t=156697
     
  11. thatK30guy

    thatK30guy 1 ton status Premium Member

    Joined:
    Jan 12, 2001
    Posts:
    32,076
    Likes Received:
    55
    Location:
    .
    Thats definitely NOT an open dif. Thats the Gov-bomb. At least on the 10 and 12 bolts they are known as GB's. 14 SF and FF's GB's are stronger than the smaller axles and will live longer than them, too.
     

Share This Page