Transmission Vacuum Modulator adjustment.
 

I'm getting ready to replace the transmission vacuum modulator and will need to adjust it properly. What's the size of the bolt where I have to put the nipple to attach the hose with the gauge? PeachPartsWiki says to use an ALDA banjo bolt. But unfortunately I don't have one and there are no diesels in the YJ's close by to grab one from. Thanks.

PeachPartsWiki: Transmission Vacuum Modulator Adjustment

I say just adjust it to taste...as long as taste isn't soft/mushy shifts that are caused by a Lack of pressure.

My typical with every new modulator is give it @ least 1 full turn clockwise...if the transmission is having Issues/slipping or otherwise worn I give it 3 full turns (3 lbs of pressure for each full, 360 degree turn).

Leave the white cap off, keep the T bar Safe so you can make more adjustments with out Fighting after you test drive.

Nice crisp, positive shifts make for a happy, long lived transmission.

Jono

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Thanks! Installing was a breeze, getting the cap off not so much. For some reason it won’t come off, I wiggled where the slot is, but no success.

Yeah....they can be.... reluctant. I've salvaged some spares as sometimes they don't survive the removal efforts try as I might.

The old style modulators with their rubber caps were So Much nicer to work with...:-/


Jono

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Good idea, I will put it on my jy list.

Didn't found the right nipple or banjo bolt yet to do a proper adjustment. So I followed Jono's advise and turned it one turn when I installed it and after a 10 minute drive gave it three more full turns because it was shifting to soft. A fourth full turn made the shifting worse. It shifts nice and crisp now.

Decided to do a flush as well as the oil was pretty dark and dirty, even that I did a flush about 15K miles ago when I just got the car. It clearly needed a flush, the filter and bottom of the pan had a thin layer of metal residue. No large metal parts or slivers.

Will take it for a ride tomorrow and report back.

If it's slipping you should REALLY try type F. I saved Countless .3/4/5's with F. And all our performance builds run it to.

You can typically run less pressure with F.


Good news on no chunks!

Jono

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3 pounds of pressure per full turn? That is very interesting. I have read many posts about the modulator and have never seen that before. Is it in the FSM someplace?