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.

OD or D ???

Discussion in 'The Garage' started by George_Pimpdaddy, Jul 16, 2005.

  1. George_Pimpdaddy

    George_Pimpdaddy 1/2 ton status

    Joined:
    Oct 17, 2002
    Posts:
    1,306
    Likes Received:
    1
    Location:
    Edmonton Alberta Canada
    Just a quick question that came up about gas milage is it safe to dd my 350/700r4 combo in od or should i be in d all the time till about 80km/h ish? thanks for any input im just trying to cut the beast back a bit :eek1:
     
  2. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

    Joined:
    Jan 21, 2001
    Posts:
    20,716
    Likes Received:
    2
    Location:
    Undisclosed Location
    Drive up to about 45-50 mph and then OD unless you are towing. I ain't converting it over to that there KmPH thingy though :D
     
  3. BrianDamage

    BrianDamage 1/2 ton status

    Joined:
    May 14, 2001
    Posts:
    753
    Likes Received:
    0
    Location:
    Alabama
    OD all the time unless you are towing, or just want a harder shift (when you want to "get on it")

    If you will notice, newer vehicles did away with the the OD on the gear shift...it's now D, 3,2,1....but it's the same gears (d=OD, 3=D). I guess they just got tired of having folks not knowing whether to use OD or not :confused: .
     
  4. pauly383

    pauly383 Daddy383 Staff Member Moderator

    Joined:
    Jul 22, 2001
    Posts:
    16,217
    Likes Received:
    1
    Location:
    Mesa , Arizona USA
    My 83 doesn't say OD , just d 321 , I have seen a newer second gen say OD , so they went BACK to it on the newer ones like you said:D
     
  5. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

    Joined:
    Jan 21, 2001
    Posts:
    20,716
    Likes Received:
    2
    Location:
    Undisclosed Location
    :whistle: :whistle: :whistle:
     
  6. George_Pimpdaddy

    George_Pimpdaddy 1/2 ton status

    Joined:
    Oct 17, 2002
    Posts:
    1,306
    Likes Received:
    1
    Location:
    Edmonton Alberta Canada
    thanks for the tip
     
  7. Eric M.

    Eric M. 1/2 ton status

    Joined:
    Dec 10, 2001
    Posts:
    2,118
    Likes Received:
    0
    Location:
    Oakland, CA
    I do OD all the time, unless towing. The trans will shift from 3rd to Overdrive on it's own, when necessary, no sense in you shifting. The trans. may not go into overdrive when you shift to OD anyways. It's an automatic, let it do it's thing.

    Eric M.
     
    Last edited: Jul 16, 2005
  8. MOBK5

    MOBK5 1/2 ton status

    Joined:
    Apr 5, 2005
    Posts:
    180
    Likes Received:
    0
    Location:
    MCAS Cherry Point, NC
    My 82 (first year 700s came out) says D 321.
     
  9. TravisO

    TravisO 1/2 ton status

    Joined:
    Apr 17, 2003
    Posts:
    143
    Likes Received:
    0
    Location:
    Aloha, OR
    I've got a reverse manual valvebody in my 700R4. I get to pick when to use OD. Shift up and down every gear on my own. :D
    Travis
     
  10. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

    Joined:
    Dec 24, 2003
    Posts:
    4,395
    Likes Received:
    50
    Location:
    VA
    I've used OD all the time for the last 7 years and 160,000 miles on my '91 that I've owned it! No problems.
     
  11. 78Suburban

    78Suburban 1/2 ton status

    Joined:
    Jul 4, 2005
    Posts:
    2,609
    Likes Received:
    0
    Location:
    Georgia
    just out of curiosity PIMPDADDY, what size tires are you running and what gears are you running?
     
  12. PsychoticDeadGuy

    PsychoticDeadGuy 1/2 ton status

    Joined:
    Jan 8, 2005
    Posts:
    753
    Likes Received:
    0
    Location:
    Fairfield, California
    so you get harder shifts when not in OD? i dont understand how that would matter. could someone explain?
     
  13. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

    Joined:
    Dec 24, 2003
    Posts:
    4,395
    Likes Received:
    50
    Location:
    VA
    I don't know why but it certainly does! Not neck snapping shift kit style shifts but thet're definately firmer in D.
     
  14. R72K5

    R72K5 Banned

    Joined:
    Mar 5, 2001
    Posts:
    8,905
    Likes Received:
    0
    Location:
    central IL
    the tranny is not going to go into OD before its already been through 1 and 2 and 3rd, it will not skip and go from 1 or 2 and then into OD or from 1 to OD

    OD = fourth gear, which is the final gear in the 700r4 and 2004r trannies and 4l60's and 4l80s and whatever other AOD trannies are out there

    if you arent going fast enough to get to top of 3rd gear and ready for 4th then ti wil not have touched OD regardless of whether oyu hasve the thing ni D or OD

    it wont go into 4th til its been through 1 and 2 and 3

    lol

    or do you already know this

    alot of ppl have no clue so im just informing you, and maybe others can learn something today

    and you dont want to be pulling up hill in OD/4th- if you are even going fast enough for it to need to go to 4th yet, cuz its not going to go to 4th til its done with 3rd and at the top of that gear,


    leave it in D/3rd when pulling uphill at speeds faster than 3rd gear lasts before hitting 4th

    when you run around in D and not in OD and are going as fast as to have hit top of 3rd gear and RPN of engine is calling for 4th gear then it will nnot go to 4th since oyu have prevented it by holding it in D position(3rd) by hand/manually with the shifter

    this is as baisc of an explanation of AOD gears and shifting as i think you can find really in a message board forum reply anyways

    google search about this if you want to try and learn anything more about this one,



    hope i helped somehow
    good luck and happy hauling :D
     
  15. Jonny-K5

    Jonny-K5 1/2 ton status

    Joined:
    May 27, 2003
    Posts:
    1,654
    Likes Received:
    0
    Location:
    SoCal
    i run around in D, switch to OD when on the freeway. i feel its better for the tranny when driving at not quite freeway speeds to keep it in third so its not constantly hunting from 4 to third and locking/unlocking the torque converter. you also keep the engine in its torqueband by leaving it in D when OD is not needed, which means more power with less throttle.
     
  16. George_Pimpdaddy

    George_Pimpdaddy 1/2 ton status

    Joined:
    Oct 17, 2002
    Posts:
    1,306
    Likes Received:
    1
    Location:
    Edmonton Alberta Canada
    by the way its a rebuilt 355 with 31" bfg all terrains
     
  17. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,977
    Likes Received:
    189
    Location:
    Roy WA
    Not sure about the 700, but pretty sure the 2004R changes line pressure based on what gear is *selected* manually, not by what gear the tranny is specifically in. You can probably check this with an ATSG manual that shows line pressure based on gear selected, since those are part of some tranny testing.

    The key to the 700 is not to lug the engine in 4th gear. That builds up tranny heat, along with constantly shifting gears/locking/unlocking the torque converter,and is what kills them. If the vehicle is constantly hunting for a gear, then manually put it in 3rd and leave it there until vehicle speed and load are low enough that it will stay in OD without losing engine speed.

    Newer trannies can handle all of the shifting much better than the older TV controlled ones, and the later the 700, the "stronger" it is in the first place.

    My '83 shifted into OD much too fast, (probably 35MPH) but as I started to pay attention to what the engine and tranny were doing, 50MPH on flat ground became OD territory. Earlier than that it spent way to much time shifting while the load on the engine changed just slightly.
     
  18. stockk5

    stockk5 1/2 ton status Premium Member

    Joined:
    Apr 13, 2004
    Posts:
    2,033
    Likes Received:
    71
    Location:
    Cromwell, CT
    when i am in OD.. and my truck is on a slight uphill its like it has NOOO power, so i have to drive in D,, unless im on the highway i wont use OD.. this is w/ a k5 w/ a 305, and 342 gears and 33" tires
     
  19. 6.2Blazer

    6.2Blazer 1/2 ton status

    Joined:
    Feb 24, 2000
    Posts:
    4,675
    Likes Received:
    26
    Location:
    Ohio
    It should shift the exact same. There is no reason why it would shift harder when driving in "D" vs. "OD"......................
     
  20. 6.2Blazer

    6.2Blazer 1/2 ton status

    Joined:
    Feb 24, 2000
    Posts:
    4,675
    Likes Received:
    26
    Location:
    Ohio
    If you apply more throttle it should downshift from OD to D on it's own.

    The problem with older trucks that have OD (early to late-80's, maybe even into early '90's) is that:
    1. in stock form they had relatively low power (compared to today's standards)
    2. they typically had higher gears (lower numerically)
    3. the trans were completely hydraullically controlled

    The combination of 1 and 2 simply meant the truck didn't have enough grunt to sustain speeds up hills in OD. Add some larger tires with the stock gears and it was even worse. The 3rd item caused issues because it was difficult to calibrate the transmissions to know what gear they should be in under certain conditions. The result was certain uphill climbs that put the powerband right between D (3rd) and OD (4th) gears........it would start lugging and losing speed in OD so the driver kept giving it more gas, it would then downshift into 3rd and the driver could then let up on the gas, which caused it to try to upshift into OD again (classic "shift-hunt" scenario which causes heat build up and wear). My '90 K5 was bad about this with larger tires and stock gears, but my '03 2500HD shows absolutely no signs of this issue even while pulling a heavy trailer.
     

Share This Page