George_Pimpdaddy
1/2 ton status
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 
CK5
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OD or D ???
- Thread starter George_Pimpdaddy
- Start date
Bubba Ray Boudreaux
1 ton status
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 
BrianDamage
1/2 ton status
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
.
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
.
pauly383
Daddy383
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
Bubba Ray Boudreaux
1 ton status
BrianDamage said:
George_Pimpdaddy
1/2 ton status
thanks for the tip
Eric M.
1/2 ton status
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.
Eric M.
Last edited:
My 82 (first year 700s came out) says D 321.
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.
78Suburban
1/2 ton status
just out of curiosity PIMPDADDY, what size tires are you running and what gears are you running?
PsychoticDeadGuy
1/2 ton status
so you get harder shifts when not in OD? i dont understand how that would matter. could someone explain?
I don't know why but it certainly does! Not neck snapping shift kit style shifts but thet're definately firmer in D.PsychoticDeadGuy said:
R72K5
Banned
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
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
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.
George_Pimpdaddy
1/2 ton status
by the way its a rebuilt 355 with 31" bfg all terrains
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.
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.
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
stockk5 said:
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.
