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2002 Mustang GT J-Mod for Automatic Transmission

10K views 7 replies 5 participants last post by  Bullitt5339 
#1 ·
The reason why I am posting this is because I was wanting to hear from some people that have had personal experience with the J-mod for the valve body on a 2002 Mustang GT automatic. What I want to know is has anyone done it? Do they like it? does it make the tranny operate better?
 
#2 ·
Also can someone give me a more up to date website on how to do the j-mod and a detailed list of what I need to do it..... is there any extra things i need to replace on the valve body when i have it out?
 
#3 ·
I have done it for a few friends, but I have a stick. It works great, the trans lasts longer, shifts better and faster, all around its a good mod, and cheap. You buy the separator plate already modified or do it yourself. I'd recommend using a drill press. Other than that you have to change the filter, fluid, and pan gasket.
 
#4 ·
what about the 1-2 or 3-4 accumulators? I have heard of people replacing them because they have the tendency to go bad in the 4R70W rather often so they just replaced them when they do the j-mod... you know anything bout that?
 
#8 ·
Depends on the mileage and year of the car. '98 and up cars came with the bonded rubber accumulators, it's the older cars that have the ones with the tendency to leak.

If you aren't good with transmissions, DO NOT PULL OUT THE 3-4 Accumulator. The overdrive band has a dimple in it that matches up with the accumulator, and if you don't get the OD band wedged into place properly so it doesn't move before you pull the accumulator, it'll pop out of place, and is impossible to line back up without taking the transmission apart. Ask me how I know this...........:nono:

You can replace the 1-2 and 2-3 accumulators with no problems though.
 
#6 ·
I never tried the J-mod myself but have a buddy that did his. His hits a little harder then stock as it shifts but not nearly as hard as mine with a tuner. I been running my auto with a tuner for about 2 years and love the way it shifts. You can not only adjust the shift pressure but also the shift points. I run on a 1/8 mile track atleast 2 days a month and run it hard and never had a problem with it.
 
#7 ·
Depends on what level JMod he did also. If you do the highest level, it can get pretty rough.

Bumping line pressure on the 4R70W through a tuner is OK to a certain point, but if you get too much, the solenoids in the transmission go crazy and can fail prematurely. By doing the JMod, and then go to say 10% on the tuner, you'll have neck snapping shifts without any bad effects on the transmission.
 
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