Driving in OD

[tcaron]

What is the best way to drive around town- with overdrive or without? What is the best speed to kick in with OD?

 

[Joe G.]

I lock out the OD on the streets. Otherwise I leave it unlocked and let the trans decide when the conditions are right for OD. Of course, my DTT VB is a bit better than stock in making decisions.

 

[SlyBones]

Can we get a Bill K. Comment?

I think it is much better to drive around with the OD off. In my truck while lockup in OD does not happen until around 50 ( depending on throttle position ), it will go into 4th much sooner. I can be driving at 35-40 in town and press the OD lockout button. I can feel the immediate gear change. Then a second or two later see it go into lockup in 3rd. I assume that immediate change was going from 4th (unlocked) to 3rd.



I believe its harder on the transmission to be running in 4th at that low of RPM, even if its unlocked, opposed to being in 3rd and locked. This is where I would like some Bill education.



I usually I press the button when getting on the freeway, or when driving over 2000 rpms for a sustained period of time.

 

[Bill Kondolay]

opinion



Most 12 valve guys i've dealt with seem to have the opinion that the electronics dont affect their trucks as with the 24 valve boys.



Wrong,



As you crank the power up on your 12 valves and put in tighter converters it directly affects when the od and lock up come into to play under light throttle.



The luxury you 12 valve guys have is that you can adjust your tps to compensate for the added hp and tc.



The pcm monitors the tps signal and vehicle speed sensor to control lock up and od,



Before all the changes to your truck you were probably using 1/2 throttle to get to 30 mph , after the changes you are probably using only 1/4 throttle.



Simply by turning the tps voltage up you can delay lockup and od engagement under light throttle.



REMEMBER, action = opposite reaction.



If you are a light foot driver it makes sense to change the tps. If you are a heavy foot driver i wouldnt do it, as it will also delay lock up past the peak torque of your 12 valve under full throttle.



Personally i dont like to see od come in below 50 mph, with 354 gear ration,

with 410 gears 42 mph this is with an empty truck ,



if you guys are towing

354 gears 55-60 mph

410 gears 50-55mph



One of the benefits with locking it out manually is that everything shifts later.

 

[Joe G.]

Thanks Bill

Bill,



Thanks for the info. One quick question. Is there a difference for those of us who have a 47RH vs a 47RE?



So far, mine is working just right. I had not considered the affect that more horses would have on the TPS position, but since I'm kind of a lead foot (it's fun to drive!) I guess I'm alright.

 

[Bill Kondolay]

Joe



a 47 RH is a mechanical governor vs the electronic governor for the 47 RE's



OD and lock up still come in a little bit earlier on the 47rh's the effect is there but not to extent that there is on the 47re's.



The starting point on the tps determines a great deal on the actual effect of od and lockup.



I usually try to set the voltage at 1. 2 on the 12 valves.



I see a lot of trucks where the tps voltage going to the pcm with as little as . 57 to . 68