Can anyone help me out with the "J-Mod"?

Maza4ever14 · Jan 30, 2006

Here is the link:

http://www.tccoa.com/articles/tranny/index.html#

it's the one that's named " Modifing Valve Body to Jerry's specifictions"

It helps with the firmness of the shift on the 4R70W. It really wakes up the auto tranny from what I heard, but I never talked to someone with it pretty much just word of mouth.

I'm thinking about gettin it done, but someone recommened me gettin a handheld tuner as it can do the same thing. but this seems cheaper as im 19 w/ bills. would a tuner AND the J-Mod be the best?

I read the whole thing and i dont trust myself doing this.

thanks in advance!

thomas91169 · Jan 30, 2006

the tuner AND the jmod would be an excellent combo, but i rarely heard of mustang guys doing the j-mod to their 4r70's, as the mustangs use a upgraded valve body over the older 4r70's used in the 4.6 birdies. then again, its been years since ive brushed up on the 4r70, so i could be wrong.

basically the j-mod is a mechanical way to firm up the shifts, but with the jmod and a tuner, you can firm them up even more.

also, i dont know if the stangs have them, but a B&M tranny cooler will also be very beneficial with that setup(or even stock). the cooler the tranny runs, the longer itll last.

Stangdriver1119 · Jan 30, 2006

yeah I personally dont think you need the j-mod...a tuner can firm up the shifts in the auto as well as change the wot points...most people with autos agree on having a tranny cooler as its just one of those things you'd rather have than not and its around 50-70 bucks so not that expensive

Kilgore Trout · Jan 30, 2006

I think only early 4r70ws need the J-mod, 96-98 4r70w trannys only I believe...

TGJ · Jan 30, 2006

The J-Mod can be done to any 03 and older 4R70W. The 99+ do not need all of the components of that article.

I would recommend the J-Mod especially after a tuner has modified the shift points and firmed them up.

sgarlic · Jan 30, 2006

The J-Mod firms the shifts the way old school shift kits do. Tuners just modify the fluid pressure and crap in certain places to firm the shifts up.

I remember reading an article back when the E4OD electronic shift kits were breaking out, and read a lot of comparisons about how an electronic shift kit doesn't provide the same benefit as the valve body modification shift kits do. The mechanical shift kits actually are supposed to increase the life of the tranny, whereas the way I remember it reading was that simply modifying the fluid pressure doesn't actually reduce any wear on the components.

Kilgore Trout · Jan 30, 2006

I have carefully studied the tccoa website... It does not seem that 99+ Mustangs need the j-mod according to what I have read there. Am I missing something?

03ghoststang · Jan 30, 2006

Kilgore Trout said:
I have carefully studied the tccoa website... It does not seem that 99+ Mustangs need the j-mod according to what I have read there. Am I missing something?

i also read it and think that its for the early trans but not entirely sure either ......but a trans cooler and modifying the shifts and firmness with a handheld tuner should do it, thats what i did with out the J-mod and it work great

propellerhead · Jan 30, 2006

03ghoststang said:
i also read it and think that its for the early trans but not entirely sure either ......but a trans cooler and modifying the shifts and firmness with a handheld tuner should do it, thats what i did with out the J-mod and it work great

Same here. And I can undo the mod in two minutes.

98blackmagic · Jan 30, 2006

My 98 has a Trans-go shiftkit and has also been helped with increased pressure and a revised shift pattern from my custom burnt diablo chip, Im happy with what I have.

TGJ · Jan 30, 2006

Kilgore Trout said:
I have carefully studied the tccoa website... It does not seem that 99+ Mustangs need the j-mod according to what I have read there. Am I missing something?

Have you now?

Then if you have done so, you would know that the 99+ 4R70W does not have the extension house lube modification which the J-Mod calls for. Also the 99+ 4R70W valve bodies are not drilled to the specs of the J-Mod in all locations. A 99+ 4R70W can still benefit from the J-Mod article.

Edit: Added threads from TCCOA

Thread 1!

Thread 2!

Kilgore Trout · Jan 30, 2006

TGJ said:
Have you now?

Then if you have done so, you would know that the 99+ 4R70W VB does not have the extension house lube modification which the J-Mod calls for. Also the 99+ 4R70W valve bodies are not drilled to the specs of the J-Mod in all locations. A 99+ 4R70W can still benefit from the J-Mod article.

Edit: Added threads from TCCOA

Thread 1!

Thread 2!

Thanks for the links I will read them tonight. Thanks for clarifying issue of what model years can benefit from the j-mod also.

san~man · Jan 30, 2006

I can tell you this much from experience:

A 99+ GT will benefit from the Jmod, as I did it to my 01GT.

You will notice that the car shifts faster, both at WOT and regular driving. During regular driving, you will sometimes not even notice that it shifts and during WOT, it shifts hard and firm. Can chirp 2/3 if I want to. Everyone who has ridden in my car can tell the difference between a normal auto trannied GT and mine. A 4R with 4.10's, Jmod valve body, and a TC is hella fun.

I didn't want to take chances drilling the valve body, so I bought a new one already drilled and sold my old one on ebay.

FWIW, I set mine to the hardest shift setting (because of my TC) and it is in no way too harsh or jarring when it shifts.

Nick03gt · Jan 30, 2006

what stall tc do you have?
and how much was a new pre drilled VB?

san~man · Jan 30, 2006

Nick03gt said:
what stall tc do you have?
and how much was a new pre drilled VB?

PI 2800 stall, and I don't recall how much I paid Dom for it. "Think" it was somewhere around $300.00 (part plus labor), but it was like 4 or so years ago.

'13_ImpactBlue_GT · Jan 30, 2006

Does it feel sluggish off the line until you hit the stall speed?

Can anyone help me out with the "J-Mod"?

Maza4ever14

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