Moparts Tech Archive

Automatic Trans.

Adjusting Line Pressure

Exactly how do you increase line pressure in an auto 904? Where is the adjustment at? Driver's side of passenger side? I see in the manual there is an adjustment on the passenger's side, but what is the lock nut/adjuster on the driver's side right about the linkage that goes into the gear selector? Thanks! Need info quick because i am doing this tommorrow,,, Also, which way increases/decreases and how sensitive is it? 1/8 turn increases a lot? little? thanks!!!!
============================================

mark gates
Moparts Member
Posts: 1462
From: cambridge vt.
Registered: Jul 2001
posted 06-30-2002 04:56 AM

Lengthen the adjustment on the linkage that goes from your throttle to the top transmission lever on the driver's side.(kickdown) This will increase line pressure, generally cause your shift points to be higher, and your kickdown (3-2 downshift) will be affected as well. You will know that you've gone too far when you can't get any upshift into high gear. The only other way is to pull the pan and adjust the pressure on the valvebody by turning the allenbolt counterclockwise to increase pressure. The adjusters you speak of on the other side of the tranny are band adjusters, I believe.
============================================

thunderhead
Moparts Member
Posts: 1453
From: Tucson, AZ
Registered: Aug 2000
posted 06-30-2002 06:02 AM

I adjusted mine by opening the throttle to wide open then adjusting the rod till it had 1/8 inch left till it was full rearward. I have over 10k on the new tranny and it shifts nice and hard!
Thunderhead
===========================================

moparmac
Moparts Member
Posts: 215
From:
Registered: Dec 2001
posted 06-30-2002 11:49 AM

In the tech archives it shows that on the passenger side there is an adjusment for line pressure

Is this how you control line pressure? Thanks@!
============================================

John Kunkel
Moparts Member
Posts: 2246
From: Rio Linda, CA, USA
Registered: Nov 1999
posted 06-30-2002 01:29 PM

The line pressure adjuster is a hex socket on the drivers side of the valve body (must remove pan) near the shift shaft. Using a 3/16" Allen wrench turn the adjuster counterclockwise to raise the line pressure.

The previous post shows the ports for testing the various pressures. They are pipe plugs that are removed to hook up a test gauge.
============================================

max
Moparts Member
Posts: 698
From: Ohio
Registered: Jul 2000
posted 06-30-2002 03:08 PM

John, how many turns do you usally turn yours out for a nice crisp shift?
years ago a friend of mine who was a tranny man used to drop the accumalator(?) spring and then raise the line pressure but the shifts were so violet that even idling into second gear would cause a chrip of the rear tires. i always thought that was to much pressure and have always been looking for a happy medium.
===========================================

John Kunkel
Moparts Member
Posts: 2246
From: Rio Linda, CA, USA
Registered: Nov 1999
posted 07-01-2002 04:40 PM

Removing the accumulator spring does nothing to improve upshifts, blocking the accumulator piston will improve the 1-2 upshift.
Two full turns on the line pressure adjuster is good, 3 turns is about max.
============================================

CrAlt
Moparts Member
Posts: 2085
From: CT Posts: 45,909
Registered: May 2000
posted 07-01-2002 05:03 PM

I adjust the kickdown so it is all the way when the car is at WOT...
Thats how i was told to do it and thats how my truck came setup from dodge.
============================================

info provided by members listed above

Tech Index