jamesivey24 Posted March 31, 2011 Report Share Posted March 31, 2011 So I know the car has been around awhile and she has a few miles on her but she runs nice, now that I have fixed all the vacuum leaks, replaced the maf, tune-up etc. No, I do not have a valid history of the car. The trans fluid does look nice and does not smell burnt, although I have owned the car for several months I have not driven it much and haven't dropped the tranny pan to see whats in there, i did pull the plug to get some volume of fluid and check for shavings that possibly weren't on the magnet and all looked good, still a deeper red color, but by no means burnt. Yes, the modulator does have fluid, yes i know this means its bad. can i just plug both the valve and the line? this just makes the shifts as firm as possible correct? under easy to moderate acceleration the trasnsmission shifts extremely smooth and the ride is wonderful. please forgive my ignorance - i dont think ive ever considered the diffrence of what the torque convertor locking up and unlocking feels like in these cars. thanks in advance. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted March 31, 2011 Report Share Posted March 31, 2011 (edited) That bad modulator can create some interesting issues. Keep in mind, if you're seeing fluid in the modulator, you've got a vacuum leak in the modulator itself. Replace it, you might find some or likely all of your issues are resolved. Get an adjustable modulator, and you can still get firm shifts, without living with a vacuum leak. Should cost less than 10 bucks. Edited March 31, 2011 by Galaxie500XL Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted March 31, 2011 Report Share Posted March 31, 2011 ^^ correct, adjustable vacuum modulator, look for one intended for a TH350. Quote Link to comment Share on other sites More sharing options...
Crazy K Posted March 31, 2011 Report Share Posted March 31, 2011 (edited) you need to replace the vacuum modulator, the firm shifting from it being bad will likely shorten the transmissions life... as for rob's advice, a modulator from a thm350? autozone and advance both carry modulator in the $10-12 range, i think advance carries an adjustable one while autoones may not be adjustable... Once you have the vac modulator replaced You should do a pan drop and change the fluid. Go take a look in the FAQ thread for a simple modification you can do with shims and springs to the 1-2 and 2-3 accumulator pistons. Edited March 31, 2011 by Crazy K Quote Link to comment Share on other sites More sharing options...
jamesivey24 Posted March 31, 2011 Author Report Share Posted March 31, 2011 Well...i dont have a firm shifting issue..infact if anything its a zlow or sluggish and i have to get out of the pedal before it will shift into the gear...i was asking if unplugginthe modulator and plugging both sides would make the shifts firm..not a permanent fix but would atleast give me some direction to turn to. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted March 31, 2011 Report Share Posted March 31, 2011 i have yet to see one marketed for a 3T40/4T60 and it's derivatives, they use a modulator identical to one found in all other GM Hydramatics. Quote Link to comment Share on other sites More sharing options...
Crazy K Posted March 31, 2011 Report Share Posted March 31, 2011 the modulator should only service the 1-2 shift.... say again rob? are you saying the the aftermarket modulators are intended for thm350s? there is a modualtor that is much smaller than the stock one carried by local parts stores.... which is what they pull up when I have looked for one fore a 4t60e before... Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted March 31, 2011 Report Share Posted March 31, 2011 the adjustable modulators meant for a TH350 (and even the TH400s IIRC) work in a 4T60/4T60E/TH125, they all use the same design. i've just never seen an adjustable modulator that was marketed as "meant for a 4T60/etc" Quote Link to comment Share on other sites More sharing options...
jamesivey24 Posted April 1, 2011 Author Report Share Posted April 1, 2011 Go take a look in the FAQ thread for a simple modification you can do with shims and springs to the 1-2 and 2-3 accumulator pistons. i looked in the FAQ and could not find this. i also picked up an adjustable modulator and have played with it a llittle bit.. seems likt it has helped my partial throttle shift points a bit. ..im assuming via increased pump pressure. Quote Link to comment Share on other sites More sharing options...
slick Posted April 1, 2011 Report Share Posted April 1, 2011 http://www.w-body.com/showthread.php/35870-4T60-e-Shift-Kit-Write-Up Quote Link to comment Share on other sites More sharing options...
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