Setting Auto Oil pressure with Modulator Valve adjustment.

[WGB]

My modulator valve has a very slight oil seep and I have a new one to install when I do my winter makeover.

Obviously it should be set using a pressure gauge which I will make up if I have to but failing that does anyone have any other simple system for getting the modulatyor pressure "near enough" without a gauge.

I have the manual with the procedure but would be interested in hearing anyone elses info.

Bill

[TJ 450]

I'll be needing to do the same after I reinstall my trans. I have a new modulator vacuum box sitting on the shelf. To do it by the book, you do need the gauge(s).
I have considered the idea of measuring how far the adjuster is wound in or out, adjusting the new one to the same position, allowing the key to be seated in the same two slots as the original. I would then test drive the car and fine tune it if needs be.
The last time I "replaced" a modulator vacuum box was on the 450. For this, I ended up removing one from the trans nathan had and just installed the whole unit. It then required a small amount of adjustment, but the trans on that car shifts flawlessly now.

Tim

[koan]

Never read of any method other than  gauges.

It can be done by feel, if part throttle shifts are too hard go one way (unscrew I think), if slipping and flaring go the other. I've given mine about 1/4 turn to make the shifts a bit harder but never been  confident. The doubt is that the adjustment made could be compensating for some problem in the box.

Making up a gauge is probably the way to go.

koan 

[WGB]

I don't think the full set of 3 gauges is really required other than for diagnostic reasons.

Only the modulated pressure is adjustable so really the only required gauge for setting a new modulator is the fitting, tube and gauge for this one line.

The pad warning light is starting to flicker on my 6.9 so I think that is the signal to get the car on the hoist and start replacing suspension bushes, pads and finding/making a suitable pressure measuring set up.

Bill

[koan]

Only the modulated pressure is adjustable so really the only required gauge for setting a new modulator is the fitting, tube and gauge for this one line.

Would be nice to know the other two pressures are correct, still only need one gauge though.

koan

[wolf_walker]

My experience in w123/w126 models has been that unless the trans is in quite good order, the factory specs will not give an acceptable shift.  That being said it's a baseline and the gauge is cheap to make. 

[WGB]

My experience in w123/w126 models has been that unless the trans is in quite good order, the factory specs will not give an acceptable shift.  That being said it's a baseline and the gauge is cheap to make. 

In your experience - does the presure need to be raised or lowered to get a good change.

Bill

[wolf_walker]

It depends on if it flairs or has a prolonged shift, or shifts hard which is less likely, when set to the stock pressure.  I've also known them to have varying shift quality for different gear changes, which is pretty annoying and hard to tune around.  But you can tune and fiddle at least, which is nice.

[WGB]

Just found out that one of my neighbours has a commercial hydraulic setup he uses for testing his agricultural equipment so will be having a beer with him tonight.

Bill