I'm sure all this has been covered before buy this is my first CTD so here we go:#1 my tranny seems to shift into OD too soon after hitting 3rd. It shifts into 3rd around 2000-2200 rpm's and almost immediately shifts into OD. the Rpm's drop from 2200 to 1400-1600 when it shifts. Is this normal? Is there anyway to prolong the shift into OD to help keep the power and rpm's up?#2 is it ok to pull small(6000-8000 lbs) loads in OD? It just seems that on the highway at 60+ mph that OD off is just too rapped out. Is it safe to pull in OD at those speeds?

If your not certain of the vehicles prior service it would probably be a good idea to change the trans fluid/filter and adjust the bands while your in there. At approximately 50 mph, my truck will shift into OD and rpms drop to around 1500 to 1600 rpm. Typically with a load similar to what youve listed, I will tow in OD as long asr Im running over 55 mph. Anything below 55 or in hilly terrain Ill generally drop out of OD to get the truck back up into the torque curve. Running slightly higher rpms is actually putting less of a load on the engine and egt's and fuel consumption will both drop.P.S. welcome to the site when. You get a minute fill out your sig the best you can so everybody can help you out a little easier

Yea the 47 and 48 trans seem to go in to overdrive and lock up pretty quick. Dont know of any way to adjust it without affecting all of the shifts.

Thanks guys for the responses! Sorry I forgot about the signature hopefully it helps someone else with input. How can you tell if the converter has locked?

Don't think your dropping 600 rpm from ODSounds like lockup to me ? Shrug

Don't think your dropping 600 rpm from OD Sounds like lockup to me ? Shrug

So I would be running higher rpm's in OD if it didn't lock? Is it supposed to lock up at the shift into OD or soon after the shift? When I switch OD off while in OD the Rpm's jump up and then drop 200-400 rpm's. I assume this is the converter unlocking and then locking again.

What does it do of you drive with OD off. Should lock up around 35 mph.

What does it do of you drive with OD off. Should lock up around 35 mph.

I think it does lock around 35-45 but there again that's why I asked how do you know.

When it is locked you can push on the throttle and the rpms will not jump up, they will rise as the speed goes up. When unlocked the rpms will vary with load. Keep in mind that when locked if you push hard enough it will unlock so as not to lug the engine. You will know when it does. And yes, it does unlock when you command it to go into or out of O/D manually but will lock back up quickly. You can leave it in O/D for the most part and let it choose it's own gears unless you are towing real heavy, over 6,000 lbs., and in very hilly terrain.

When it is locked you can push on the throttle and the rpms will not jump up, they will rise as the speed goes up.

^^^^ this:thumbup2:

Ronnie,

Welcome to the forum family.

I experience much of what you're describing. Mine will shift into OD way earlier than yours (but then again, mine has PSM /wiring issues). If you have 4.10s, you should be around 1900-2000rpm @ 60mph; My 4.10s at 60mph, OD, TCC lockup, is just under 2000rpm.

If you have 3.54s, take about 2-300rpm off that (16-1900rpm.)

The TCC lockup occurs really fast when going in/out of OD. Sometimes, I cannot notice it, even when I'm looking/listening for it.

- - - Updated - - -

When it is locked you can push on the throttle and the rpms will not jump up, they will rise as the speed goes up. When unlocked the rpms will vary with load. Keep in mind that when locked if you push hard enough it will unlock so as not to lug the engine. You will know when it does. And yes, it does unlock when you command it to go into or out of O/D manually but will lock back up quickly. You can leave it in O/D for the most part and let it choose it's own gears unless you are towing real heavy, over 6,000 lbs., and in very hilly terrain.

Not so the case with mine. At 60mph, in OD + LU, I can advance the throttle a good bit, and the rpms will rise up (almost like a rpm-flare) faster than the speed increases.

I may put my TCC lockup switch (manually) back into service..

Ronnie, Notso the case with mine. At 60mph, in OD + LU, I can advance the throttle a good bit, and the rpms will rise up (almost like a rpm-flare) faster than the speed increases. I may put my TCC lockup switch (manually) back into service..

Try that - but sounds like your not locked up or your slipping the TC. Could be time for a new TC. For altering OD shift points. http://dodgeram.org/tech/transmission/automatic/TPS_adjust.htm "Always start with the original voltage you had; as you increase your voltage your OD and TCC lock up will start to come in later and later. The down side of doing this is that when you slow down or if you remove your foot from the throttle, the TCC will not unlock unless you step on the brake pedal or your vehicle speed drops below a certain setting."