West Coast

I had a good friend of mine rebuild my tranny in my 96 4 x 4. Trans shifts great. Truck runs great. But I have a hard time getting the truck to shift much past 2200 rpms when I hammer the pedal. I did the washer 3k spring mod. I can hit the 3k plus mark sitting in park in a second. ruck has no issues reving up. So it seems like the transmission is keeping the truck from reving. So my question is what in a auto trans would limit the RPMS on shift points? Is it in the valve body? Cable adjustment?

My trans was built with a custom shift kit. Billet converter. And custom valve body.

I occasionally tow my 14K dump trailer will ease. Once the truck gets into 3/lockup, 4/lockup it rips. But 1st and second seem a little sluggish.

This is my first auto dodge diesel. My last two trucks where 5 speeds so having a auto trans and getting it to have good performance is all new to me on these trucks.

Thanks.....

Don T

I bet if you had stock tires on it you would not have that problem. big rubber takes a lot of hp to get her moving . My .02

9812vram

If it rips when the TQ is locked, then it's more than likely the TQ that's making it feel sluggish....as usual! Where does your TQ stall at? Don T's right too, big tires like that suck a lot of power out of a rig. Around that 2200rpm mark you're probably running out of power which is why it won't rev higher.

West Coast

Thanks for the input guys. I am going back to 235 or 245 in a few weeks. When I purchased the truck it came with six 35's. So I am just wearing them down to nothing...... LOL.

98 my truck seems to stall around 2100-2200.

So the big tires will make me run out of RMP's quicker? That would be great if I get some more performance from the stock size tires.....

9812vram

Big tires are like tall gears - they'll push your truck to faster speeds and they lower your engine rpm at highway speed but they need more power to do it...and more power to turn them. Smaller tires will help make it feel "snappier" if you will. I'm thinking by the time you hit that 2200 mark, the engine just hasn't got enough jam to push the truck faster until it shifts and the RPM goes back down more into the range where it makes more power.
That said, I've never run a Cummins with the higher rpm mods and fuel plate that you have. Of course, you could just be running out of fuel too. Do you have a fuel pressure gauge? Maybe see what the fuel pressure is in those high rpm's...
One thing I know - a stock-stall converter (2000-2200) makes these trucks feel like they have lickerish for a drive shaft!! If you throw a lower stall converter in there, it would help a lot power wise (before lockup), but it wouldn't make the eingine RPM's go any higher before it shifts....

9812vram

Just had another thought: Is it possible the new billet TQ has a higher stall than the old one? That would definitely feel like a loss in performance! Where did your old one stall at?

West Coast

98 my old converter was the original stock one that was in bad shape. And I made a typo on my previous post. My current billet converter stall around 1800-1900.

I do not have a fuel pressure gauge. But that is next on my list. As well as a larger turbo.....

I will report back once I get the new tires......

Don T

I just installed a billet single torque converter with a stall of 1600 ,It has way more get up and go than stock. I don`t think your washer mod is working either. I have the 3000 rpm g spring installed and I can feel the drop off of fuel at around 2850.The truck will go now with the new TC. I will be taking my fiver out today to try out the new TC and will report back, but the way the truck works with no load now I think I will have a big smile when I get it towing 10000 lbs down the road.Lock up now is way faster and no wait to lock in OD. I`am going to be happy with this new TC.I had no idea that a stall TC at 1600 rpm would make sooooo much of a difference in my truck. with the mods I have done I now have a great truck. I do plan on water meth and exhaust brake next spring. Later Don

West Coast

Don what size tires are you running?

j-fox

This is controlled by the throttle valve cable and the combination of parts in the TV in the VB. Nothing to do with tires, it is a calibration issue.
First check the cable adjustment. Does it move as soon as the throttle moves?

West Coast

j-fox TV cable seems good. Is the Valve Body adjustable for shift points?

West Coast

Update:

When I did my Dowel Pin fix I set my Crank Speed Sensor at .050. Not sure if a lower number would help with anything so I set it at .037. Truck would not idle. So I bumped the idle back up. Truck seemed to run much better but still shifted a little to soon. Then I open up the holes on the TPS unit and now my truck will shift from 1-2 at 2900 and 2-3 at 2600. Pulls extremely hard. And the shift points have extended out. My truck use to shift into 3rd lockup by 24 mph. Now hits 3rd at 35 and 3rd lockup around 49.

I will hook it up to my buddies scanner to see what my TPS voltage is. But I think my trans issues are solved. And I did not have to buy a new TPS..... for now... LOL