Jmod how to, a DIY shift kit write up for your 4r70w

Jrgunn5150

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So the Jmod topic has been beaten half to death on Mustang boards and people seem to think it's some kind of mythical creature that can only be captured on full moon nights with a leprechaun guide and a bag of pixie dust. The truth is, if you can walk by a window without licking it, you can do your own Jmod.

I have here a valve body already removed from a car, but I'll briefly cover the whole R&R procedure.

I Copied this from Stangnet, you don't really need to pull the dipstick tube and pump fluid out, it's just cleaner. This little write up covers the basic Jmod procedure using the drill sizes found on TCCOA.com, the procedure found there is fine for car's making up to about 350 rwhp. This particular valvebody is for Justin (justinschmidt1) who is making a good deal more power and is custom calibrated for his car, converter, and transmission.

Remove the ATF dipstick and put the fluid pump inlet hose down the dipstick
tube (of course make sure the hose and pump are clean). You should be able to
pump out at least one or two quarts of ATF. Now you are ready to clean the
outside of the trans pan and surrounding areas. Just remember the cleaner you
keep everything in the vicinity, the cleaner the internals of the trans will be.

Note, on my 2002 GT the torque converter does not have a drain plug!!!

Remove the transmission pan by loosening the 14, 10mm pan bolts. Drop the
pan carefully to avoid spilling any remaining ATF. Remove the filter assembly
and verify the filter seal was removed from the bore. If it stuck in the bore of
the valve body you can remove it later when you have the valve body removed
from the trans. Drop the filter into the pan. Discard the plastic plunger that may
be floating in the pan. It was used to plug the dip stick hole during the factory
assembly. Allow the transmission to drip thoroughly before removing the main
controls (valve body).

Now it is time to remove the molded plastic electrical connector. This is a large
connector that has a main connection on the front passenger side of the trans
case. The connector then runs to the various solenoids located on the valve
body. There should be something like four places that the connector is attached
at every solenoid. They are all standard ford notch clips, it only takes a small
precision screwdriver to wedge in between the two and gently release the
connection. Be careful not to damage any of the clips.

Remove the 25-8mm not the 10mm main control (valve body) bolts. Start with
the 13 bolts around the valve body plate or the shorter length 8mm bolts. Then
remove the 12 longer length 8mm bolts inside the valve body plate. Keep track
of where they came from on the valve body.

Note one of the bolts retains the Rooster Comb Spring (with the roller attached to
it). Make a drawing, take a picture or write down a brief description of the manual
valve and the detent lever set-up.

NOTE: The orange dot on the rooster comb spring designates the part facing
down.
The old style manual valve is the valve shown here in this photo. Note that the
third reinforcing plate shown in the picture is not present on 99+ valve body.

The detent wheel's pin attaches in the FIRST section on the valve (the very thin
part before the c-clip ring). Also note that the rooster comb spring is in the
general area of the manual valve detent (it will all make sense when you pull the
pan and look at it).

Carefully lower the valve body into the original transmission pan and move it to
the work bench. Be careful, as the 2-3 accumulator retainer and spring may fall
out and drop into the pan. There is a small filter (approx 1" tall) that will fall out of
the transmission casing when the valve body is removed. The filter goes on the
front driver side of the trans case not the valve body (you have to really look to
figure out where it goes and it's orientation (but it will only go in one way).

NOTE: To perform the main control modifications, your working environment
should be sterile and clean.

1-2 ACCUMULATOR PISTON (if applicable). To remove the 1-2 accumulator
piston, remove the snap ring using snap ring/retaining ring pliers. The 1-2
accumulator piston should pop out of it's bore fairly easily. If not, push up on it
with your fingers or an extension to re-act the return spring. Use Scotch-Brite on
the accumulator bore if it is slightly scored. Spray brake cleaner to clean out the
bore before you install the new updated accumulator piston. Allow the brake
cleaner to evaporate before installing the new piston. Apply some fresh ATF with
your finger to the rubber seals on the accumulator piston before installing it.


2-3 ACCUMULATOR PISTON (if applicable). To remove the 2-3 accumulator
piston, simply remove the main controls (valve body). The retainer and return
spring will fall out freely maybe. if not just get a small 90? bend allen wrench
and pull it out by the holes in the bottom of the retainer. Do not re-install the
stock return spring, or any return spring for that matter (there is only one spring in
the 2/3 accumulator). You will have to bend the tabs out on the retaining clamp
slightly with a pair of pliers in order to keep the 2-3 accumulator in its bore.


Re-install the main controls (valve body) at this time. Be sure that the 1-2
Accumulator, 2-3 Accumulator, are up in their proper locations (especially the 2-3
accumulator) before proceeding. Also be sure that the filter seal has been
removed from it's bore, if not now is the best time to remove it.

There is also a little black cone-shaped filter that goes into the transmission
case; this is the one that I told you would fall out whenever the valve body is
removed.

ok now that you have the valvebody out and hopefully cleaned up, you can put it up on the bench. You can see by the pics the nicest feature of Ford transmissions vs their Chevy counterparts, the valve body is self contained, there are no little check balls or springs flying around, everything is under the separator plate. The complete valve body looks like this, on the top side

002.jpg


And this on the bottom side,

003.jpg


Ignore the bottom bolts and remove the 11 10mm headed bolts on the top, should look like this now,

004.jpg


Pull the little Pac Man covers off and set them aside, then carefully pull the separator plate up. Two little post's usually locate it, so be careful not to break them off (although it doesnt matter terribly if you do). When you get the plate off your valve body will look like this,

005.jpg


And here's the separator plate by itself,

006.jpg


Following the directions on TCOAA, mark your hole locations, they have a nice diagram and everything. If you don't have all the holes on the diagram (Justin didn't) don't worry, you got a drill! We'll deal with that in a few.

007.jpg


See we're missing hole 5, and 8,

008.jpg


011-1.jpg


I went ahead and marked where they should be for now. If you are missing holes, slots whatever, lay your old gasket on the vb like this,

009-1.jpg


And peen, punch, or somehow mark the holes you are missing so you can add them.

At this time I went ahead and drilled all the holes out to my own specifications for Justin's application, if your car is under 350 rwhp, you can pretty much do the following to make it real easy, remove bottom 1-2 spring, remove 2-3 spring altogether, drill holes 2, 4, 5, 9, and 11 with a 7/64 bit. Hole number 10 is for the reverse clutch, if you want reverse to engage quicker, drill it to 3/32.

After all your drilling is done, go back through and stick the proper bit in each hole to ensure you actually drilled it, then use a file to knock the burrs off. After that I use a copper scratchy pad to clean it up as much as possible. Once you get it nice and clean, lay your new gasket (pn XW7Z-7D100-AA, it was 1.38 when I just bought one for Justin) on the separator plate and make sure none of the holes in the gasket need to be opened to match (sometimes they do, it depends on how they felt in Dearborn that day).

There's also one more mod to make. Observe this slit in the gasket, if you don't have hole 8 in your VB this is the exhaust for the OD Servo release. If you have a mild car, you can ignore it as long as you have hole 8 on your VB, if you don't either drill hole 8 to 3/16 or englarge the slit with an exacto knife to about 1/8 of an inch (specifically .100 so err small).

Now you can lay the separator plate gasket on the VB and replace the separator plate itself. Then replace the Pac man cover's, look at this photo for reference,

016-1.jpg


Put a new valvebody gasket on, PN 1L3Z-7C155-AA 1.65 at my local Furd dealer, and it's ready to reinstall. If you have any electronic tuning done to your trans, return it to stock because electronic tuner's accomplish their goal by boosting line pressure a crossed the board, thus accomplishing the same thing in a stupid fashion, all the time, for every hole. This method is more selective, but you don't want both doing the same thing at the same time.

That's it, easy cheesy, enjoy barking your tires now.
 

sneaky98gt

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Nicely done. The problem I'm having isn't doing it or knowing how to do it, I've got that. I just can't decide IF I want to do it or not. I REALLY don't want harsh part-throttle shifts, and I just haven't convinced myself to do it. Yet.
 
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FullThrottleStangs

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this is gonna sound stupid, and im jw, but what does this do? i saw something about a valve gasget, then the trans, so im kinda confused.
 
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Jrgunn5150

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sneaky98gt said:
Nicely done. The problem I'm having isn't doing it or knowing how to do it, I've got that. I just can't decide IF I want to do it or not. I REALLY don't want harsh part-throttle shifts, and I just haven't convinced myself to do it. Yet.

If you leave the top 1-2 accumulator spring in your part throttle shifts won't be harsh. I don't build transmissions to bark the tires when all you're doing is driving about from point a to point b, it's unnecessary
and hard on parts.

FTS said:
this is gonna sound stupid, and im jw, but what does this do? i saw something about a valve gasget, then the trans, so im kinda confused.

in summary, it's a shift kit.
 

forcefedhatch

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ok bringing this up from the dead lol.. but can you do the jmod on the aode as well.. i have heard of people doing it but not too sure..and if the aode and 4r70w are soo close in the family tree are the valvebodies interchangable..my cousin has a 95 auto gt he wants to jmod, but he also has a cracked 4r70w but the valvebody has a shift kit already installed.. can it be swapped into the aode?..the casting on the valvebody he said is an F6 i believe..
 

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