Engine/Transmission (1994 - 1998) automatic transmission

[jimk]

I loaded my diesel backhoe on my trailer an pulled it about 50 miles one way to help a friend out. I had to pull some grades and on some narrow black top roads. To keep up the rmps and not pull in a rpm less the 1850 or 1900 I had to keep the truck in second for several miles. I dont wont to wreck my truck and trailer on a rough, narrow, country road by going to fast.

Question is how long can you pull in first or second and not wipe out bearings or thrust washers in the transmission. As soon as I got on the inner state I got into third and drove 55 or 60. I did not think that overdrive would last or work at the speeds I was going. I wound up using third gear lockup at 55 to 60 and was supprised not sliping the torque convertor going up a fairly steep grade. The transmission is stock and has 92k miles on it. Except for a tps switch that acts up no other problems.

Can any one tell me how or what the flash is to make the 95 go from 45 to 52 or higher in lockup. The dealer did not have a flash for the 95. Thanks for any help Jim

 

[rrausch]

I don't know JimK, but I know when I got my ATS, they installed Torrington Bearings in place of all the thrust washers.

 

[Strick-9]

jimk,



The main problem you run into pulling it manually down into 2nd is HEAT. Stock valvebodies don't allow lockup in manual 2nd.



Pulling heavy with stock fluid coupling causes major heat in the TC. The slow speeds don't allow much air over the coolers. That hurts in both ways. transmission temps can quickly get out of hand when using manual second. Do you at least have a transmission temp gauge to monitor it?



There's really not set time frame I could give you that's safe. It varies with load, RPM, air temp, vehicle speed, grade, etc. It could get VERY hot in less than a minute under extreme conditions. Put a gauge on it ($50) and then you'll know.



This is one of those situations where an aftermarket valvebody with 2nd gear lockup capabilities really help.



For future reference, when it get's hot, let it shift into 3rd with OD off and the PCM will command lockup at about 28 mph. Once lockup comes in, cooler flow increases and transmission temp will go down quickly.



Hope that helps,

Chris

 

[RedRamer]

Strick-9

Using a DTT valve body, what else might be needed for a 2nd gear lockup situation and can it be done locally?

I get really high temps also in 2nd pulling a trailer in about 1 minute or less.

 

[Strick-9]

RedRamer,

This is exactly why the DTT smart controller / valvebody combination was introduced. It allows the torque converter to lockup in manual 2nd gear to keep the transmission cool at low speeds.



The DTT valvebodies ALLOW the transmission to lockup in 2nd gear, but they still need to receive the electrical signal to apply it. That's where the smart controller comes in.



A smart controller will do this automatically, and unlock the converter below about 18 mph to prevent bucking and stalling.



Any "mystery switch" will do though if you can't afford the smart controller and are willing to flip a manual switch each time the need arises.



You asked about having it done locally. Anyone that thoroughly understands the valvebody and is competent at modifying valvebodies should be able to figure out how to allow 2nd gear lockup. That modification plus a mystery switch would help your overheating problem.



I hope that helps.

-Chris

 

[Extreme1]

jimk, here is the TSB info to increase the lock up speed in overdrive.



On adding a temp guage, install the sender in the line out from the trans to the coolers. If you put it in the pan it isn't responsive enough.

 

[RedRamer]

Thanks Stick-9

This modified VB for 2nd gear lockup, does it also increase oil pressure, cause I'm sure I read if that happens, then the transmission should be re-built also.

thanks

 

[Extreme1]

A rebuild isn't necesssary just for the increased pressure. Now, if you try to increase the pressure and you can't... . a rebuild is likely in your future.

 

[Strick-9]

Redramer,



I'm only familiar with the DTT product line, so that's all I can comment on. All DTT valvebodies are modified to allow 2nd gear lockup. They also increase pressure to some degree. Lower HP trucks get a very minimal pressure increase while high horsepower trucks get a larger increase in pressure. It depends on the application. Each valvebody is custom built to fit your profile.



Your best bet would be to call your vendor of choice and discuss your needs with them.



-Chris

 

[Hummin Cummins]

jimk, here is the TSB info to increase the lock up speed in overdrive.

Get that reflash done. It made a tremendous improvement in the way my truck pulls. If I remember right, some trucks you have to swap the pcm which could be $$$. I got lucky with mine. It took the dealer several tries, but the reflash worked without switching pcms.



Chris