Line Pressure: How much is too much?

npe3484

npe3484

I hate ATF
Joined
May 10, 2009
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I'm working on getting my 47RH transmission setup right and wanted to make sure the line pressure is alright. The truck gets driven every other day, so it's not a total DD. A DTT valve body, billet accumulator, 4.2 apply lever, billet servos, and billet strut and anchor are the upgraded hard parts that are inside.

What I'd like to know is, what is a good safe line pressure to run on the street? I'll probably log 5-6,000 miles a year on the truck. OEM pressure is 54-96 psi depending on throttle position.

Thanks!
 
I dont have a 47..but my 48 numbers should give you a good ballpark..

Idle in gear...90psi.
Driving with converter unlocked...140-150psi
Converter locked...175psi
Converter locked @WOT 190psi.

Goerend VB....
 
2007 5.9 said:
I dont have a 47..but my 48 numbers should give you a good ballpark..

Idle in gear...90psi.
Driving with converter unlocked...140-150psi
Converter locked...175psi
Converter locked @WOT 190psi.

Goerend VB....
Click to expand...

This isn't a track only truck, is it?
 
I wouldn't go over 200, 180-190 seems to be a good number.
 
If you go to far on pressure then you risk bending over the bellvell spring at the rear clutch. 185 is safe for a daily driver. I run 195 to 200 on my drag truck.
 
pressure is set by your valve body. Put a long line and guage on it run it up to the cab and let your buddy read while you drive. 150 to 190 is fine at full throttle.
 
Do you adjust the screw counter clockwise to increase the pressure on the valve body? or is there another place to adjust? I have a 47RE and a Transgo shift kit!
 
Shambo said:
Do you adjust the screw counter clockwise to increase the pressure on the valve body? or is there another place to adjust? I have a 47RE and a Transgo shift kit!
Click to expand...



Counter-clockwise to increase pressure. The tighter the spring, the higher the pressure. In the attached picture, it's the allen head screw that pushes a small square plate that tightens the orange spring. Turning the screw clockwise moves the plate closer the the allen screw's head and loosens tension on the spring. Turning the screw counter-clockwise moves the plate away from the allen head and compresses the spring which raises pressure.

On my 47rh, with Transgo TFOD-HD2 shift kit, 6 turns counter-clockwise makes 180 psi line pressure. In the picture, the screw is adjusted at 4-1/2 turns counter clockwise about 160-165 psi.
 
Last edited:
Mine is a 48RE of course but Garmon has mine set at:

Idle in gear - 128-132psi
normal driving unlocked - 155-160 psi (a lot depends on TQMT too)
Normal driving locked - 145-150 psi (TQMT here as well)
WOT full out - 215-225 psi

Hope that helps some. For a DD and not a racer I agree with WOT being around 180psi. With the pressures I am running the shifts are quick and hard and all billet (fat shaft input on mine) will be needed for insurance at WOT, especially if you ever think about doing locked shifts. If you do that your head better be against the headrest otherwise you will have a nice bump on your first shift!
 
TXAustin said:
Mine is a 48RE of course but Garmon has mine set at:

Idle in gear - 128-132psi
normal driving unlocked - 155-160 psi (a lot depends on TQMT too)
Normal driving locked - 145-150 psi (TQMT here as well)
WOT full out - 215-225 psi

Hope that helps some. For a DD and not a racer I agree with WOT being around 180psi. With the pressures I am running the shifts are quick and hard and all billet (fat shaft input on mine) will be needed for insurance at WOT, especially if you ever think about doing locked shifts. If you do that your head better be against the headrest otherwise you will have a nice bump on your first shift!
Click to expand...


At the 210psi plus you need something to help the rear clutch spring survive, the phat shaft addresses that. It typically will bend the factory return spring at those pressures.
 
Shambo said:
full 360 turns?
Click to expand...

Yes, full 360* turns. You can only do about 90* till you need to take another bite with the allen wrench. By the way, you have to cut down the allen wrench a little to make it fit between the screw head and the tranny case.
 
Big Blue24 said:
Yes, full 360* turns. You can only do about 90* till you need to take another bite with the allen wrench. By the way, you have to cut down the allen wrench a little to make it fit between the screw head and the tranny case.
Click to expand...


Or by the looks of the picture use a set of pliers?
 
zstroken said:
Or by the looks of the picture use a set of pliers?
Click to expand...

It was a little stiff when I first had the valvebody apart. It was a rebuilt unit the pressure screw bottomed out for maximum pressure. It must have had a drop of locktite or something on it from the rebuilder?

I think I used vice grips and allen wrench together to break it loose. It easily adjust with just an allen wrench now.
 
Im not sure if this helps but my pressure on the Danco (47re) has logged as high as 235. thats right at borderline of blowing the case apart
 
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