TeeJay3800 Posted February 5, 2005 Report Share Posted February 5, 2005 I just bought an ATP adjustable vacuum modulator for my transmission. I'm not really sure how to remove the old one or install the new one. Its not threaded so what holds it on the transmission? One end has a gold plunger type thing that has some play in it. Any tips or info anyone can give me on how to install and tune the modulator would be appreciated! Thanks! Here's a pic if it helps: Link to comment Share on other sites More sharing options...
Robby1870 Posted February 5, 2005 Report Share Posted February 5, 2005 There's a retainer clip that holds it on. Its got a 13mm (IIRC) bolt that holds it on. Take that off, and the retainer will come loose. Pull the vacuum hose out and then pull the modulator out. Make sure the plunger on the old one comes out. Install is the same procedure. Link to comment Share on other sites More sharing options...
Tim Posted February 6, 2005 Report Share Posted February 6, 2005 I attempted to replace my vac modulator a while back. (fluid in it) The Autozone store showed two numbers, one with California Emissions and one without. The model used for California equipped cars was unavailable from them. So, I go to Napa and they only show one number and I order it. What I received has a much smaller vac diapraghm housing then the original. The original housing is about half the size of a beer can. What difference do you guys think this would make? Tim Link to comment Share on other sites More sharing options...
TeeJay3800 Posted February 6, 2005 Author Report Share Posted February 6, 2005 Mine is less than half the size of the old modulator. I have more install pics if anybody wants to see more..... Link to comment Share on other sites More sharing options...
Jcrow Posted February 6, 2005 Report Share Posted February 6, 2005 Id like to know what difference that makes! How much can you change it (its the shift points right?) Link to comment Share on other sites More sharing options...
Robby1870 Posted February 6, 2005 Report Share Posted February 6, 2005 Id like to know what difference that makes! How much can you change it (its the shift points right?) No, its shift feel (hard or soft). It wont change how fast it shifts. On a non -E tranny, it sometimes will bring WOT shift down a couple of hundred rpm, but thats about it. Link to comment Share on other sites More sharing options...
Tim Posted February 6, 2005 Report Share Posted February 6, 2005 Mine is less than half the size of the old modulator. I have more install pics if anybody wants to see more..... My original modulator looks exactly like the old one in the picture. Will the smaller one work just as well? Tim Link to comment Share on other sites More sharing options...
Robby1870 Posted February 6, 2005 Report Share Posted February 6, 2005 Yeah, Tim, it sure does Link to comment Share on other sites More sharing options...
Jcrow Posted February 6, 2005 Report Share Posted February 6, 2005 Ok, so you can adjust it to make the trans shift harder! I think I'll get one. Is it a generic part for all GM with a vac modulator? Is it hard to get it adjusted right? Link to comment Share on other sites More sharing options...
TeeJay3800 Posted February 6, 2005 Author Report Share Posted February 6, 2005 I know one thing for sure, parts store people don't have a clue when it comes to vacuum modulators (Auto Zone, Pep Boys, etc). I called and called and no one said they had adjustable mods. Finally one small "mom and pop"-type store said they had one. Later on, just to see if the chain stores were correct, I took the adjustable mod I had just bought to Advance, and theirs was the same dang thing. Taylor told me ALL replacement modulators for the 4T60 will be adjustable. Shows that when it comes to some things, retail parts store folks have no idea! Link to comment Share on other sites More sharing options...
GP1138 Posted February 6, 2005 Report Share Posted February 6, 2005 So will adjusting shift feel have any effect on the transmission's durability? Wear and tear? If I adjust it so I can't feel shifts at all, will there be slop? That might be cool. Link to comment Share on other sites More sharing options...
Turbo231 Posted February 6, 2005 Report Share Posted February 6, 2005 In theory, yes. The vacuum modulator controls line pressure of the pump. This is tied to vacuum because you'll want a harder shift at WOT then you will just going down the road or decelerating. My 1993 Service manual has line pressure guideline, thats if you have the right tools, you can test. NOTE this is hard on the transmission. I'm not getting into super details, you'll need a service manual for that, but they want the minimum PSI in D4,D3, or D2 (1250 RPM and 18" of Hg vacuum to the modulator) to be 74-85psi. D1 should be 158-170psi, and P,R,N to be 79-95psi. With no vacuum on the modulator, they want 165-205psi, 158-170psi, and 255-315 psi respectively. There is a port on the top of the transmission to test line pressure and you'd need a hand pump to set your modulator vacuum. Hope this sheds some light on things. Obviously the more pressure, the harder the shifts, but the harder on internal components. Is GM's OEM modulator adjustable? Link to comment Share on other sites More sharing options...
TeeJay3800 Posted February 7, 2005 Author Report Share Posted February 7, 2005 In theory, yes. The vacuum modulator controls line pressure of the pump. This is tied to vacuum because you'll want a harder shift at WOT then you will just going down the road or decelerating. My 1993 Service manual has line pressure guideline, thats if you have the right tools, you can test. NOTE this is hard on the transmission. I have heard from many knowledgable people that changing your adjustable modulator for quicker, firmer shifts actually decreases wear on the transmission. My tranny was slow to shift, sloppy, and clunky with the old modulator. Now all shifts (as well as TCC engagement) are quick, tight, and solid. I hardly feel I am being hard on my transmission by making it take less time to shift. Link to comment Share on other sites More sharing options...
maybe2fast Posted February 7, 2005 Report Share Posted February 7, 2005 2-3 turns in on the modulator makes a nice shift Link to comment Share on other sites More sharing options...
terryk2003 Posted February 7, 2005 Report Share Posted February 7, 2005 will that work with a 4T60-E trans as well!?... Link to comment Share on other sites More sharing options...
94CutlassSLCoupe Posted February 7, 2005 Report Share Posted February 7, 2005 yeah i'm interested for the 4t60-e...i want to be able to bark the 1-2 shift!!! Link to comment Share on other sites More sharing options...
terryk2003 Posted February 7, 2005 Report Share Posted February 7, 2005 yeah i'm interested for the 4t60-e...i want to be able to bark the 1-2 shift!!! mine shifts pretty hard...but, it won't spin em...hell, it won't even spin em from takeoff... :oops: Link to comment Share on other sites More sharing options...
Tim Posted February 7, 2005 Report Share Posted February 7, 2005 Yeah, Tim, it sure does Thanks Robby. I have long considered you the trans expert here and appreciate your help. Tim Link to comment Share on other sites More sharing options...
Robby1870 Posted February 7, 2005 Report Share Posted February 7, 2005 First of all, thanks Tim. Now, to bring up a point on the last page, the adj. modulator does nothing for a WOT shift. At WOT, there is no vacuum, so a non-adj or adj modulator will do the same thing at WOT. Its the part throttle shifts that feel harder, because thats where the adj modulator differs from the stock one. Ive been running an adj mod in Ws for about 3 years now, with no adverse effects and I know of others who have had them in for longer with no problems. Usually 2 turns is sufficeint Link to comment Share on other sites More sharing options...
GP1138 Posted February 7, 2005 Report Share Posted February 7, 2005 yeah i'm interested for the 4t60-e...i want to be able to bark the 1-2 shift!!! mine shifts pretty hard...but, it won't spin em...hell, it won't even spin em from takeoff... :oops: You can't spin your tires at takeoff? I'm able to do that no problem... odd. Link to comment Share on other sites More sharing options...
terryk2003 Posted February 7, 2005 Report Share Posted February 7, 2005 yeah i'm interested for the 4t60-e...i want to be able to bark the 1-2 shift!!! mine shifts pretty hard...but, it won't spin em...hell, it won't even spin em from takeoff... :oops: You can't spin your tires at takeoff? I'm able to do that no problem... odd. i can in the rain...in fact...i can rip the shitttt out of em in the rain...but, not on dry pavement...it might be the fact that i have new yokahama tires on there with a traction rating of AA...or maybe the fact that i'm pretty sure something is not quite right in that engine...i just can't figure it out... Link to comment Share on other sites More sharing options...
GP1138 Posted February 7, 2005 Report Share Posted February 7, 2005 yeah i'm interested for the 4t60-e...i want to be able to bark the 1-2 shift!!! mine shifts pretty hard...but, it won't spin em...hell, it won't even spin em from takeoff... :oops: You can't spin your tires at takeoff? I'm able to do that no problem... odd. i can in the rain...in fact...i can rip the shitttt out of em in the rain...but, not on dry pavement...it might be the fact that i have new yokahama tires on there with a traction rating of AA...or maybe the fact that i'm pretty sure something is not quite right in that engine...i just can't figure it out... Maybe if you've got brand new tires, but I've got a decent amount of tread on mine, and I can still break loose pretty good. Maybe it's because my car's tranny was serviced at 124k (according to Carfax) and it's now... 129k. Link to comment Share on other sites More sharing options...
terryk2003 Posted February 7, 2005 Report Share Posted February 7, 2005 yeah i'm interested for the 4t60-e...i want to be able to bark the 1-2 shift!!! mine shifts pretty hard...but, it won't spin em...hell, it won't even spin em from takeoff... :oops: You can't spin your tires at takeoff? I'm able to do that no problem... odd. i can in the rain...in fact...i can rip the shitttt out of em in the rain...but, not on dry pavement...it might be the fact that i have new yokahama tires on there with a traction rating of AA...or maybe the fact that i'm pretty sure something is not quite right in that engine...i just can't figure it out... Maybe if you've got brand new tires, but I've got a decent amount of tread on mine, and I can still break loose pretty good. Maybe it's because my car's tranny was serviced at 124k (according to Carfax) and it's now... 129k. well, rule that tranny thing out...i serviced mine @ 65k, and i only have 70k on it now... ...i've also changed plugs, wires, fuel filter, etc...i think my car's just messed up...i need a 3400 like...NOW!!! Link to comment Share on other sites More sharing options...
slick Posted February 7, 2005 Report Share Posted February 7, 2005 well, rule that tranny thing out...i serviced mine @ 65k, and i only have 70k on it now... ...i've also changed plugs, wires, fuel filter, etc...i think my car's just messed up...i need a 3400 like...NOW!!! My 94 GP hardly did, and it had 13x,xxx miles on it when I totalled it. I also had hardly any traction on my tires as well. The engine and tranny were in perfect condition too. Terry, I have a feeling that your thinking your 3100 has more power than what it really has (or, if your driving your parents 3400 around, it will make it feel this way as well). With that low of mileage, I would have to assume that there is hardly anything wrong with your engine. If fact, i could almost guarantee that if you found some 15" rims and tires, and swapped them onto your car, that you could get them to bark the tires. Link to comment Share on other sites More sharing options...
GP1138 Posted February 7, 2005 Report Share Posted February 7, 2005 I do have steelies on my car. Idunno, I just have no problem screeching my tires. Maybe I just got a grandpa car or something, or a factory freak! Link to comment Share on other sites More sharing options...
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