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.

gear ratios

Discussion in 'The Garage' started by 1983Blazerkid, Feb 6, 2007.

  1. 1983Blazerkid

    1983Blazerkid Registered Member

    Joined:
    Nov 12, 2005
    Posts:
    98
    Likes Received:
    0
    Location:
    brownsburg, in
    i know i know ive looked it up but the charts say for a manual trans or whatever. well i have a 700r4 so i know its going to change things. but which way i want to run 38s for now but ill prolly back it down to 35s or somewhere in that range. just want to know what gears i should be looking for. ive got a 350/ 700r4/208 thanks for the help cody
     
  2. NEK5

    NEK5 3/4 ton status Premium Member

    Joined:
    Oct 25, 2005
    Posts:
    9,843
    Likes Received:
    37
    Location:
    Ipswich MA
    I think you could get away with 4.88s in the 35-38" range....
     
  3. CB77GMC

    CB77GMC 1/2 ton status GMOTM Winner

    Joined:
    May 6, 2005
    Posts:
    771
    Likes Received:
    0
    Location:
    Heath Springs, SC
    4.88 or better for 35's to keep from killing tranny.
     
  4. Leper

    Leper 1/2 ton status

    Joined:
    Feb 18, 2005
    Posts:
    4,437
    Likes Received:
    0
    Location:
    Dallas Baby!!!!
    4.56 for the 35"
    5.13 for the 38"
    4.88 in the middle
    What do you do with the truck?
     
  5. loafer

    loafer 1/2 ton status

    Joined:
    Aug 19, 2003
    Posts:
    634
    Likes Received:
    0
    Location:
    Lyman, Maine
    Take the RPM # off the manual charts you were looking at (I assume a 1:1 transmission ratio) and multiply by 0.7, which is the OD ratio of the 700. In OD the torque converter is locked, so you don't have to consider any slippage in the calculation. You can also calculate your RPMs"

    Engine RPM = [((miles/hr) x 336) / (tire diamer) ] x axle ratio x transmission ratio

    Example: [(65 x 336)/35] x 4.56 x 0.7 = 1992 RPM

    There are calculators on the web to do this, but it's handy to know how and do it yourself.


     
  6. Chrisblazzer89

    Chrisblazzer89 1/2 ton status

    Joined:
    Oct 12, 2006
    Posts:
    1,966
    Likes Received:
    0
    Location:
    Massachusetts 02301
    I will sonn have 38x14.50R16.5 super swampers TSLs And I will only have 4.10s I will let you know how it feels.
     
  7. 1983Blazerkid

    1983Blazerkid Registered Member

    Joined:
    Nov 12, 2005
    Posts:
    98
    Likes Received:
    0
    Location:
    brownsburg, in
    thanks for all the info guys cody
     
  8. 1983Blazerkid

    1983Blazerkid Registered Member

    Joined:
    Nov 12, 2005
    Posts:
    98
    Likes Received:
    0
    Location:
    brownsburg, in
    i mostly just play with it. dont know if im going to ever drive it on the street again. but i have 35s now and the gears suck. so im going to fix that. then maybe if it helps alot i might start driving it again
     
  9. Avery4jc

    Avery4jc 1 ton status Premium Member GMOTM Winner

    Joined:
    Oct 24, 2005
    Posts:
    10,760
    Likes Received:
    75
    Location:
    Fresno, Ca.
    I've got 4.10's with 38.5's that measure out to 37....it feels fine and thats even with a slipping tranny. We have the same exact setup too...sb350/700r4/np208...
    Something else to keep in mind is the 700r4 has a pretty low 1st...but again it depends on what you do with it...If you aren't going to keep it on the street just go 5.13's and be done with it...if you might keep it on the street go 4.56/4.88 (probably won't see a huge difference between the two).
     

Share This Page