Automatic modulator valves

yellow3800 · Post by **yellow3800** » Sun Nov 16, 2008 7:28 pm

Hello All! I don't think I've ever posted in this section. CRAZY, I need to read about your turbo cars guys! way to go on all those mods by the way! I'll have to join you sometime.

I have 3 vacuum modulator valves: a buick reatta [the lemon, the 3800], '97 grand am [needs a vacuum modulator], and the normal beretta's automatic vacuum modulator valve.

I know there is a correlation somewhere.

My question is WHY/WHAT FOR/HOW are Advance Auto Parts replacment modulator valves ranging from $15 - $70?

What is so special?

I ask because my reatta valve is small, much smaller than the stock bulbous gray looking ones, for obvious reasons, a small diaphragm will pull with less air and helps creates a firmer shift. THAT I comprehend.

Thoughts? Opinions?

Andy

Money pit Beretta · Post by **Money pit Beretta** » Mon Nov 17, 2008 8:37 pm

Yea man, the Pioneer adjustable vac modulater is a good buy. It helped me alot and works well, the # is 747017. That's the one I used for the 4T60E. Not sure if you have the same trans, so that # may be wrong.
All you need to do is turn the small set screw inside to raise the pressure and firm up the shifts(about two turns or so). Mine was 15 bucks and I don't know why they have one for 70(what is it? adjustable or stock?). More or less this is what I have http://www.transmissionpartsusa.com/440T4_4....888.htm

yellow3800 · Post by **yellow3800** » Tue Nov 18, 2008 9:10 pm

yes, my reatta valve is the same way w/the adj. set screw. I dont think I paid over $10 for it over 5 years ago... maybe its the $15 equivalent now, but I just cant see spending $70 on one that does the same thing, with reliability to the transmission [because if we cap the vacuum line, thats ultimate shift, but I hear it will kill the transmission].

Needless to say, the lemon valve is set full tight.

Andy

Money pit Beretta · Post by **Money pit Beretta** » Tue Nov 18, 2008 9:56 pm

All the way? How hard does it shift?

yellow3800 · Post by **yellow3800** » Tue Dec 23, 2008 10:57 am

not as good as a lexus automatic. It shifts respectably, but not enough that youd ride in the car as a passenger and notice that there is a small modulator valve installed with set screw set full tight.

now If I had and HD version trans [supercharged 3.8 trans] I can put a shift kit and mod some tension springs [why bother here? these transmissions don't last].

Again, I just cant see the difference in the $20 modulator valve at advance auto and the $75 one. both are same small size, both have set screws...

Andy

Money pit Beretta · Post by **Money pit Beretta** » Tue Dec 23, 2008 4:11 pm

Mine is set close to three turns and has firm shifts. Electric drag cars? In the old days they had jets.

IsaacHayes · Post by **IsaacHayes** » Tue Dec 23, 2008 5:57 pm

I have the pioneer which fits many transmissions, even TH350 and TH400 and power glides.

Mine is 4 turns in from out of the box. That's the max it said to do, so I figured that's a good point to start with. Even WOT shifts faster which leads me to believe that the original modulator spring was weak as the adjustable part is only for partial throttle shifts.

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