Dieseltrans.com

[Bill Kondolay]

LINE PRESSURE & TRANSMISSION LONGIVITY
There seems to be a great deal of confusion about transmission line pressures and how it affects the life of the transmission.

The amount of line pressure you have in the transmission directly relates to how much power the transmission can hold.

Setting up higher line pressure transmissions can be very difficult even for guys like myself who have done hundreds of them

There are many out there that will tell you that you don’t need extra pressure to hold the power. As long as that is a choice you make and understand the consequences.

I am searching for the politically correct term for these so-called transmission technicians and sales people that so ignorantly advocate lower line pressures.

I think I found it, guys giving this type of advice to run lower line pressures are either idiots or don’t understand the first thing about transmissions and the direct relation between line pressure and longevity or cannot set up the trucks to work with the higher pressures.

Let’s look at a stock transmission: line pressures 1999 and earlier Dodge Rams a typical stock dodge ram will have approx 52PSI line pressure at an idle and 105PSI wide open.

2000 + Dodge Rams have approx 58 PSI at an idle, and approx 140 wide open on some trucks. Most range from 115 –120PSI

This is where a lot of guys (customers / technicians) get lost.

Most guys take their mainline pressure readings from the accumulator port and think that is what their pressures are throughout their transmissions.

That is not necessarily true. Take for example if you took a pressure reading of 80PSI in your accumulator port most consumers and technicians assume that they would have 80PSI in the first gear, 3rd gear and the TC lockup clutch as these are the ones that are applied at that time.

If you move the same pressure gauge to your front servo you may be in for a shock.

I have measured some where the pressure was as little as 60PSI. If you have a good solid transmission base the pressure in the front servo and the accumulator should be identical. Keep in mind this is only telling you the integrity of the pressures in first gear and 2nd gear release which is also your third gear apply.

If your pressures are identical chances are your transmission is happy and usually will live a long and healthy life.

If your pressures vary by more than 5 psi you have an internal leak in your transmission.

To check the integrity of the torque converter lockup clutch you should measure your torque converter apply pressure through the cooler line. Most torque converter lockup clutches fail because of internal leaks. Chrysler also gives you a port to measure 4th gear.
Again your 4th gear pressure should measure the same as your accumulator port within 5 psi.

At Diesel Transmission Technology we live and die by the pressure gauge. We pressure test every truck before and after working on it.

Just because you have a higher-pressure valve bodies does not mean you have higher pressures going to your clutch packs and bands in the transmission.

All our hand picked and trained installers I have personally spent time teaching how to use pressures gauges and how to understand the implications of the readings.

BOTTOM LINE IS GUYS, PRESSURES DECIDE HOW LONG YOUR TRANSMISSION IS GOING TO LIVE.

More power you have more pressure you need. The heavier you tow the more pressures you need,

DO NOT BLINDLY FALL PREY TO BELIEVING OTHERWISE. Do some research and your homework.

We spend a lot of time in the development of products to address all the above I have mentioned, i.e.) seals, custom billet pistons, and the new servo product line.
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BILL KONDOLAY
DTT TRANSMISSION BUILDER