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Is Driving In Overdrive Most Of The Time With A 700r4 Transmission Good Or Bad?

Huh? I mean its an overdrive trans. Its the fourth gear and designed to be used as so. The only time using OD it bad is if you lift a truck, put bigger tires on and dont regear it and it constantly shifts between 3rd and 4th on the highway.
 
Stomis said:
Huh? I mean its an overdrive trans. Its the fourth gear and designed to be used as so. The only time using OD it bad is if you lift a truck, put bigger tires on and dont regear it and it constantly shifts between 3rd and 4th on the highway.
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So how do you regear it?also i was in a debate with my uncle that due to what happened to the last tranmsission he claims because i had thw transmission in overdrive on the highway which made the transmission go out amd no reverse
 
replace the ratio in the differentials to a lower numerically higher ratio.

Use 4th all you want, it is easier on the trans if you down shift to 3rd on a hill with or without a load. Having the correct gear ratio with a larger then factory tire will help the trans live a longer life.
 
Flatland overdrive is fine, in the hills or pulling stay out of it. High speeds will kill it to if its shifting alot.

We smoked many transmissions in Caprices before we changed our ways.
 
70jimmy said:
Flatland overdrive is fine, in the hills or pulling stay out of it. High speeds will kill it to if its shifting alot.

We smoked many transmissions in Caprices before we changed our ways.
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Even not bad driving in overdrive through the stop amd go city amd interstate ? Mixed city driving
 
Look in glove compartment at the RPO codes and see what the gear ratio is. If not re geared will more than likely 3.08 gears. 35" tire and 3.08 = toasted 700R4 trans.
 
blackandgold51 said:
Even not bad driving in overdrive through the stop amd go city amd interstate ? Mixed city driving
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Like I said the only time you shouldnt use OD is if you're on the highway and its switching between 3rd and 4th constantly aka hunting gears. Overdrive is not like some afterburner mode you're only suppose to use sometimes or something like that. Not using OD on the highway is simply an issue caused by not properly addressing all systems when you lift the truck, aka you should have regeared it.
 
blackandgold51 said:
The tires i have are about size 15s that are 33s to 35s and thats it.

Vehicle is 1990 Suburban V1500
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Find out exactly what size of tires you have before digging too far. If this is the same stock truck you've been referencing for so long, 35" tires are not an easy thing to fit.
 
For heavy towing, it can be beneficial to keep it in 3rd, since 700's don't cool as well in 4th. However, you should have 3rd gear lockup working if you will run in "3" and not "D". You also shouldn't really use 4th gear if the 700 has no lockup working. Too much heat.

Other than that, for normal driving with a working setup, no reason not to just drop it in "D" everyday. They're called "automatic" for a reason.
 
My understanding is if the 700r4 isn't locked up it's making a bunch of heat. So I don't think there's going to be a problem as much driving in 3rd as much as you want that torque converter locked.
 
As said in several of the above posts there is really no reason to not run in overdrive all of the time in a stock vehicle. There are theories that running in 3rd most of the time helps, and I did that for years when daily driving my K5, but there is no concrete evidence that running in 3rd helps the longevity of the trans. I would also say that the vast majority of vehicles with 700r4's over the years were always driving in the regular D (OD) position there entire life. You can get into trouble after adding larger tires without regearing in which the trans will want to constantly hunt between 3rd and OD at certain speeds and driving conditions. It's just not the added shifting between gears but the unlocking of the torque converter that causes extra heat build-up.
 
It's the heat from the shuttling from gear to gear and the Tc locking and unlocking. There's two issues at play, when the converter is unlocked the pump does not provide full flow to the cooler circuit because the converter is unlocked.. So you heat it up and cannot remove that excess heat, and the only way to combat this is to get it into lockup. So even shifting into 3rd won't always do the trick, the clutch is still unlocked.. The PO on my truck believes this was the best thing for it.. Same argument your uncle claims. Totally Bs mine toasted 3rd instead of Od.. So regardless of the gear used the Trans should be kept under 225-230 if possible and if overheated change the oil asap.
But most won't gear the rear end low enough to allow a normal truck to lockup 3rd gear with a decent load.
Meaning the problem still exists..
 
The higher the gears (lower number), the more torque the engine is delivering to maintain the same speed, and the higher the torque during the shift, the more wear on the clutches and the greater the shock load. Shifting is the greatest short-term source of heat, especially for towing or high throttle, but in the long-term the torque converter slip creates most of the heat because it's always there (unless lock-up is engaged, of course). So staying in 3 can save wear on band but shouldn't do anything for the 3-4 clutch since that should be engaged (and not slipping) all the time on the highway.

The converter stall speed makes a big difference, as heat is basically the speed difference x torque.

But would anybody really put 35's on with 3.08s and pull a trailer? Would they really let it shift constantly and not think that's bad? Would they tow without a trans temp gauge? Yeah, I suppose these all happen.
 
JoshHefnerX said:
My understanding is if the 700r4 isn't locked up it's making a bunch of heat. So I don't think there's going to be a problem as much driving in 3rd as much as you want that torque converter locked.
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GM OD transmissions will run cooler if you allow them to lock up. Gears and clutches -since clutches do not slip -don't make any substantial heat.

It's the torque converter that makes heat, whipping the fluid hard!

"Shuttle shifting" all the time is a lot of wear to the shifting components, so if you get that happening, after the unit drops to third gear, THEN pull it into 3rd manually. That keeps the shock to the drive train to a minimum.

Some units will lose the heat protection that the ECM provides via a fluid sensor in the pan that will apply lockup if the driver hasn't disabled it by manually pulling it into a lower gear.

So, typically leaving the unit in 4th or OD is the way to drive it all the time with the aforementioned exception.

In the olden days oF automatic transmissions .... and current Dodge stuff.... the OD was not an integrated design, something that was added on as an afterthought.

Since I built transmissions and owned a couple of transmission shops in SoCal, I've seen a lot of misunderstanding and wive's tales concerning transmissions. The incorrect use of the OD function was one of the hardest to debunk...... that along with people manually shifting an automatic unit thinking it helps the unit live longer or better and get better performance.
 
302000 miles minor towing otherwise in OD. Od usually doesn't come in till 45 mph, unless you screw with it. Install a Trans cooler with a thermostatically controlled electric fan set to on at 245 of at 210. When towing or mountain climbing use 3rd. Some will feel the torque converter lock up in third in slow steady state driving and think its in OD.

Keep it cool and don't screw with it
 
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