How to: Using a Transmission Pressure Gauge

[BrooklynBay]

It could, but the most accurate place to mount the sensor is on the pan. Some people mount it on an external filter, but that isn't the best place since the fluid will change temperature after it leaves the transmission.

 

[Naasau]

Thank you all for this (and all the other) tranny analysis threads! I know you all say that auto tranny's aren't rocket science... but to tell the truth most of my Aerospace Engineering classes are easier than this stuff (so far anyway). Which I do believe means that I owe ya'll a beer if/when we meet up on the trails.

P.S. Brooklin, would you by chance still have those PDF's in your possession?

 

[BrooklynBay]

Two PDFs are attached to your email.

 

[Naasau]

Thank you sir!

 

[arco777]

BrooklynBay, could you please send me those PDFs as well? Thanks! rhenbelz@hotmail.com

 

[BrooklynBay]

Send me your email address.

 

[Axis28hunter]

hi im new on here , i have a 1989 4x4 ford ranger 2.9 liter engine , i got a delay fr first to second gear , i have to let off the gas b4 it will shift into 2nd,, , i checked pretty much everything there is too check ,governor ,vacum module ,parts and filings in pan , replaced oil/filter,checked vacum lines , adjusted the bands , and still no luck,, someone suggested that it might me my torque converter goin out on me , and im suppose to presure check it,, how do i preasure check it? help. pls , thanks

 

[Naasau]

Did you read the first post of this thread?

 

[mall]

Will a compression gauge work to check the fluid pressure if it is adapted with a longer hose? It's unclear to me if the gauge is measuring compressed air or fluid.

Also I was wondering how to determine if I have a problem with my torque converter using a fluid pressure gauge.

 

[cross6]

It's kind of a long explanation, and I'll post it more in depth in the Frankentranny thread, but I measured/calculated the spring constants (for both the 5R55E and A4LD) for the main regulator springs (the larger diameter ones) by measuring the free length (zero force) and partially compressed length with a certain weight (in my case it was 5.53lb). With thse spring constants, the only other thing needed was the diameters of the main valves, which turned out to be 0.398" for the A4 and .420" for the 5R.

So for the A4LD, I got a value of 47.7 psi/inch. This means that if I want to raise the pressure by 5 psi, I would insert a spacer with a thickness of 0.105" (47.7X.105=5). A 10 psi increase would be 0.210", etc...

For the 5R55E, I got a value of 71.3 psi/inch.

The other thing that is a limit to how much you can "safely" raise the pressure is how much the main spring can be compressed before it is fully compressed and doesn't allow the valve to open (vent) so that the pressure can still be regulated.

Here's a picture of the regulator valve assemblies (5R55E on top, A4LD on bottom):

So basically, I'm putting in a spacer that will preload the main regulator spring, so it has the same inner and outer diameters as the boost valve sleeve (a little smaller for each diameter to make installation easier). This leaves the boost the same, it just raises the baseline regulated pressure -> so if it normally had 60 psi at idle and an additional 20 psi of boost (to give a 80 psi reading) in a particular gear/engine speed, it would have 70 psi at idle and an additional 20 psi of boost (to give a 90 psi reading).

When shift kits come with EPC springs and stuff, this is what they're doing, right? Adding more pressure?

 

[BrooklynBay]

It's unclear to me if the gauge is measuring compressed air or fluid.

The transmission uses fluid which is under pressure to engage clutch packs, servos, and valve body spools. The transmission is hydraulically controlled (no air pressure).

 

[mall]

The transmission uses fluid which is under pressure to engage clutch packs, servos, and valve body spools. The transmission is hydraulically controlled (no air pressure).

My question is about the gauge. I noticed that glacier attached the gauge to the drivers mirror, which would lead me to believe that the fluid does not flow all the way up into the gauge, and that the gauge may be measuring compressed air. That made me curious if my compression gauge will work. Does the fluid enter the gauge itself? Will a compression gauge work?

My other, more important question is, how do you check the torque converter?

 

[BrooklynBay]

The fluid reaches the gauge. You check the stall speed of the torque converter by first placing the transmission in gear, then step on the accelerator pedal at the same time as the brake, then check the RPMs of the engine.

 

[mall]

The fluid reaches the gauge. You check the stall speed of the torque converter by first placing the transmission in gear, then step on the accelerator pedal at the same time as the brake, then check the RPMs of the engine.

Thanks, My transmission has no movement at all no forward or reverse not even a little. You mentioned in a previous thread that there was a way to check the torque converter with a fluid pressure gauge. How is that pressure test done?

 

[BrooklynBay]

You could monitor the main pressure port while driving, then while stepping on the brake pedal. You could then see a pressure change when the TCC engages & disengages.

 

[mall]

You could monitor the main pressure port while driving, then while stepping on the brake pedal. You could then see a pressure change when the TCC engages & disengages.

I can't drive it it does not work at all it will not move an inch. it acts like it is permanently in neutral unless it is in park .

 

[smegun]

run it up to the ****pit permanently he ha you guys found a worthy candidate to the collection of gages I want to know when im actually blowing apart my tranny

 

[BrooklynBay]

Transmission pressure testing PDF files.

Due to popular demand, I'm posting two PDF files about pressure testing.

 

[Sip]

A few folks have asked about the location of the connection... heer are a couple of pictures taken with the trannie out of the car, and, as compared to installed, upside down... it is very near the shifter linkage bore:

shown on the empty case, with the plug removed. The bore ahead of it is the throttle shaft/shifter bore.

here it is (bad pic, sorry) on the transmission as it is assembled...

The bad thing about painting a trannie black is that it does not photo well. Here is a recently acquired A4LD case... still dirty and much easier to see the plug. I am using an inspection mirror to point it out...

this is on the driver's side, just behind the shift linkage. It is easier to attach the fitting if you pop the linkage free (it does just "pop" off too, and back on)