From a performance stand point and reliabilty stand point which is better the J-Mod or the Shift kit? I want that old school feel when pushing it hard and i want that chirp action between gears. Are both of these doing the same thing?

Sorry Im out of breath...Took me a while to get past your SIG pic.

The J-mod was designed by Jerry. Hence the name J-mod. The J-mod is better for the transmission overall.

The J-mod is basically the DIY shift kit. You can buy the separator plate kit, or you can modify yours for free.

I just did the J-mod on my new 03 today.

yea i should have tested that sig first i'll chop it down. lol

I don't know about shift kit but, I hear it's a big no-no. Here's a link to all the tranny info you would ever want to know about the 4r70w http://tccoa.com/articles/tranny/index.html. Heres a link to the body of knowledge on J-Mod https://www.crownvic.net/tech/4R70Wnotes.pdf. I did the J-Mod on my tranny a couple of weeks ago it's like a whole new transmission fast nice crisp shifts absolutely no lag at all. And yes @ WOT it will give you whiplash and bark the hell out of the tires and best of all it's free other than your time and filter & gasket kit, 2 valve body gasket about $4 and tranny fluid about 14 quarts if you drain your convertor.

The J-mod is NOT a DIY shift-kit.

My 04P71 came to me with a shift kit installed - and a toasted TC that had pretty-much killed the tranny as a result.

My advice is to get a modified valve body from Darrin at bc-automotive - better than just doing the J-mod and he will customize it to suit what you are looking for. Better still - take a drive down to Indy and have Darrin put it in for you.

To be perfectly clear, Jerry was on the DESIGN TEAM for the 4R70W, even today Ford admits that no one knows the 4R70W as well as Jerry. It's his name that was given to the "J-Mod".

A "shift kit" can be a couple things. To many it is simply a method, and some parts to improve the shifting of an automatic transmission. In THIS definition, the J-Mod qualifies as a "shift kit", although there is no "kit" for doing it.

Another definition of "shift kit" is a modification to a transmission to make it as durable as it can be and to improve it's function and feel WITHOUT DOING ANY DAMAGE. To meet this definition, the ONLY method is the J-Mod!

The last definition is a "kit" that you buy to install in or on a transmission that (may or may not) improve shift quality. To THIS definition, every KIT applies and the J-Mod DOES NOT APPLY.

In short, the J-Mod is THE BEST thing you can do for your AODE/4R70W/4R75W/4R75E transmission.

no problems yet in over 2 years with my j mod love it then and still do. easy to do about and hour and a half if i remember right. I also change my fluid alot more often then req as well.

As John said the JMod is the way to fix the transmission, most shift kits increase line pressure i.e. they force more fluid through the same size holes in the separator plate where as the JMod opens up these holes allowing faster flow with the same line pressure into the VB

Check out tccoa for complete details on the JMod

I just got my tranny Jmod'd last week and even though I haven't had much of a chance to get into it, I can really tell a difference.

i don't know why, but i thought this applied here. like the word of god speaking or something lol

What???


The jmod is the only shift mod to do! Darrin is also the only one I would go to for performance parts for the 4R70W.

Johnny,
Your links to both the J-Mod and the TCCOA don't work...
You have put an extra period at the end of the link which results in a 404... or a blank screen...

I wish the J-mod was simple on my 97..on the 98+ all you do is just drill a hole in the seperator plate???

should be pretty much the same thing on the 97. Your dill like 4 holes a little larger in the seperator plate, then you remove some acumilator springs and then put the trans back together. Easy and works very well.

I have had the J-Mod for over a year now and I love it. I can't wait to get my MZT to compliment the mod.

i thought i would have to replace springs also

I believe that is an option to customize how you want it to shift.

I might do this mod once i finish my control arms

sorry about the links..just take the period off in the address bar in your browser and they'll work fine...some very good reading on our transmissions

I just had a local tranny shop do the JMod on my 97 and they didnt have any problems, you can replace your 1-2 springs and 2-3 springs or just leave them out (as I did) for firm shifts but its not to the point where its annoying. (although much quicker then anyone in a manual could shift )

oh ok so all i have to do is drill holes and remove 1-2 2-3 springs and thats it?

is the j mod can also be applied to the newer 4r75w for the 04 ?

That's it!

I left my 1-2 spring in because my snap ring pliers broke (crappy pair) and it was Sunday at 6:30 so I wasn't going to run to sears to get a new pair.

Yes.

GREAT! i,ll go for it

I'll be doing mine this weekend. Sounds like a piece of cake.

let me know how it went

I have rebuilt A ton of automatics and the key to sucess with any automatic is work clean, follow the directions exactly and keep track of your parts. NO EXTRAS! Anybody can do it following that advice.

it is very easy and messy. It will take like an hour or 2 to complete.