AT Modulator pressure tap, Where on 85 300D?

[russb]

Where is the modulator pressure plug located on a 722.416 trans.?
It has the Black modulator valve in it now, and is flaring on the 2-3 upshift. Been doing this since I've had the car, but is getting worse.
Checked vacuum on the main line, gage was fluctuating, took off check valve at the vacuum pump, cleaned it, ok now, gage needle not jumping (looked clean under check valve).
At idle 17 hg., about 2500 rpm 19.5.
Checked vacuum at amplifier (to trans.) idle ok at 17hg, at 2500 rpm about 6hg.
Setting on pump regulating valve .020 (5mm).
Trans. pan looks clean inside.
Part # on new green modulator: 126 270 92 79
Part # on new BROWN pin: 126 277 93 75
The help file says the pin is BLACK, and has some kind of a disk?
Do I have the right parts before attempt operation?
Modulator pressure is supposed to be 3.9 bar, for this trans.
Not much room to work under there, maybe 2 inches, no room to see much.
May have to pull wiring of shift lever?

Hope this is not to long winded, I know you like details:-)

[jbaj007]

The difference in the 722.303 trans and the 722.416 should just be the valve body and the governor, so the port for the pressure gauge hose would be the same? The first hex head rearward of the vacuum modulator. I can't find the pressure values for the 722.303 in my ATSG manual. Where did you find the 3.9 bar value for your 722.416, please?

ATSG says each turn of the modulator scew is worth 0.4 bar. Test with vacuum disconnected at modulator at ~30mph in D.

[russb]

I went down to the local MB dealer and asked the shop forman.
He looked up the pressure setting in the TDM for me.

Guess I'll go crawl under the car and see if get to the tap and find enough fittings to check pressure.
thanx

[russb]

Finaly found enough fittings to build a pressure gage setup.
I have an engine I pulled out of my car, (It threw #2 rod through the side of the block, before I bought it, that's another

story).
Took the oil pressure fitting to IP off, used 1/4" black plastick tubing, pushed right onto that fitting.
Found a pressure gage from my air pressure regulator, 0-160 psi, a little high but that's all I could find.
Used a 1/4" compression fitting on the other end of the tubing and 1/4" pipe coupling to the gage.
Put car on drive on ramps, pulled modulator pressure plug (just below modulator to the rear, 12mm wrench).
Put on pressure gage, (ran line over rear cross member to pressure tap), what a pain to get the bango fitting to start into

the hole, not much room to work in, plus the washer keeps falling off, DO NOT want to cross thread the fitting!
Oh, I did not drain the tranny, just a few drops came out during this whole process.
I fired it up, cold, had 44 psi pressure (with vacuum off from the amplifier, pluged off amplifier line) with OLD black

modulator, if you leave the vacuum line connected you will only get about 5 psi.
Shut it off, pulled pressure line off, put plug back in to keep dirt out, forgot to mention I cleaned the whole area with

brake clean before I started, worked good.
Used 5mm 3/8 drive allen socket to remove retainer screws, retainer stays on the modulator valve.
Tried to remove modulator with my fingers, no go, got a chanell lock plier, pried against the lower pan for a folkrum point,

popped right out, and straight, just be gentle.
The OLD black moulator and pin looks just like the new green modulator and pin, but the pin is lighter in color.
The so called PIN came out with the valve, this looks more like a big hypo needle without the plunger.
The DISK stayed in the hole, have no idea what that looks like, just pushed it back in place, remember this almost done by

the brail method.
Installed new PIN and modulator valve, don't forget to put the retainer on first, and use trans. oil on the o ring and parts.
I tried to push the new modulator in by hand, no go, got a 19 mm 3/8 drive short socket, put the socket over the center of

the modulator, and a small prybar, went right in and straight.
Put contact cement on the 5 mm allen socket to keep the screws from falling off, a good place for a mirror to see if the

retainer is lined up with the holes.
OK, hooked up pressure line again.
Fired it up, 47 psi with new modual.
Watching gage turned T bar in, at 54 psi (about 1/2 - 5/8 turn).
Took car for drive, no vacuum line on modulator, shifts were harsh, but ok, no 2-3rd flare.
After driving and warm up gage is now at 56-57psi.
Hooked up vacuum line to amplifier, much better shifts, 2-3rd now smooth but firm.

Now I will work on the downshift cable adjutment, that was enough work for today.

Let me know if I missed anything, or someone can add to this.

Thanx for all the help that I have received here!

[jbaj007]

Your technique sure beats the old "turn the T-bar and hope" method, and done with homemade tools, too. I like it! I'm gathering that you ran it against the brakes? or rear in the air, rather than snaking a line into the cabin and driving? Didn't quite get the ramp deal. Could you clarify so I don't kill myself by misunderstanding. Thanks

[russb]

The ramps I used are the kind you see in auto stores, drove up on them, front tires.
I snaked the 1/4" tubing over the rear trans crossmember to the modulator pressure tap, otherwise the tubing will have to sharp of an angle and will probably kink.
Then used a tie wrap to attach it to the fuel lines under the car, pull the slack out so it does not drag the ground or get wound up in the drive line. Put gage in through the drivers window, and took it for a drive to check pressures and shifting.
I set the pressure first, before driving.
And I used air brake quality plastic tubing, don't think you want to use just any ol plastic tubing, might be a heck of a mess.

[jbaj007]

OK. got it now. SOP. I had this picture of you on a jury rigged ramp and jack stand home made "dyno". From your obvious experience, I couldn't quite see you doing that, and if you had, I wanted to also