AKA_Rizzo and I are doing the J-mod to my whip this Thursday and I'm having a tough time deciding on whether or not to remove the (I believe) the 1-2 spring or replace it with the "Mustang" spring.

I am the sole driver of the car and want firm shifts, hands down.
If I'm going to spend the time to do this I only want to do it once.

Is there anyone else on here that has done this and can share your experiences? I'm only looking for people who have done this and their opinions ONLY. Thank you.

I would vote to remove both the 1-2 springs and 2-3 springs..

That is what I did with mine. I am very happy with the results.

Also depends on what you are looking for.

Myself I like the crisp feeling of gear changes like in a manual trans..

With a JMOD and full performance trans settings in the tune I could not be happier.

To give you an idea...

http://www.youtube.com/watch?v=BE7gf4NETro

I know we have already talked, This is just for anyone else who may search this later.


I have developed a system that works great for me. Everyone knows when their car is going to shift. If I don't want to feel any effects of having gone "Springless" I will let up on the throttle a split second before the shift from 1-2 starts, This seems to lower trans pump pressure by lowering the engine's RPM's just enough that as the car shifts you can't even feel it.

You are allowing firmer and quicker shifts by doing the Jmod and bending the guidelines a little by removing the springs, But you can control how much and how often you feel it via throttle control.

I thought about using cranberry juice in a clear bottle to show the results of the shifts on the juice in a video. But I can't find a good place to put the camera while I am driving.

Thanks. That's what I'm after.



Are you sure? Because I don't remember. J/K bro!

x2, feel the exact same way. Too harsh of a shift is relative to each person, but I love mine without either bottom spring and the performance shifting tune from BOC. I've heard people say they felt their's was shifting too harshly after removing the 1-2 spring, but I can't see where they're coming from to be honest. If you like a good firm snappy shift, remove the bottom 1-2 spring.

I just did the jmod on my 2006 P71. I replaced both the upper and lower springs with a custom set from BC automotive. 1-2 is fast, but not too firm. Even at WOT, its more mellow than I thought it would be. 2-3 is fast, and firm. At WOT it lets you know its there, but nothing violent. All in all I'm happy with it. I didn't want the rear tires breaking loose on a WOT 1-2 if I had to get on it in the rain, etc. It also seems like at some point that much of a jerk has to be hurting other drivetrain components. From what I've read the harshness can vary a bit depending on the year. My 2000 P71 without the JMOD would snap 1-2 hard when it was warm, the 06 with the JMOD isn't near as harsh. Don't know until you try it... Nice thing is you don't have to drop the valve body if you want to take the 1-2 springs out, or put lighter ones back in. Definitely remove the lower 2-3 spring.

It would be great if there were a chart simply listing the J-Mod options and their effects. J-Mod has become a huge topic when searching.

Should I use conventional or synthetic oil and then do a Sea Foam treatment after doing a J-Mod, or should I save my money for a new pushbar?

I would just get good quality Mercon-V and you will be fine.

Get something like Motorcraft, Royal Purple, Amsoil..

Remove both lower springs, it's not harsh at all.

Cranberry and Vodka is a good drink....

That's what I did. I can drive the car so you would never know
or I can step on it and chirp those gears. There's
nothin better than steppin on it at the light to get past an ass
and havin them hear me chirpin tires as I blast ahead.
REMOVE THE SPRINGS!!!!!!

Springs removed and J-Mod done. Very happy with results.

I will start another thread tomorrow when I post pics.