JMod: Done. The Smile on My Face: Much Bigger

[sneaky98gt]

2.5 gallons of transmission fluid: $40
Transmission fluid filter: $10
Valvebody gaskets: $4
Drill bits: $4

Barking the tires from first to second and second to third: priceless.

It took me around 6 hours start to finish. I really took my time and double checked everything as I went along. I doubt the second time around would take me more than 3 hours. It took me a while to get off that black plastic piece with the electrical connectors on it. And after reinstalling the valvebody, I realized that I forgot to install the little cone shaped filter above the VB, so I had to take it all back apart. That added over half an hour. But other than that, it was pretty straightforward.

I followed this write up to the tee, more or less. http://www.crownvic.net/tech/4R70Wnotes.pdf

I drilled the #2, 4, and 5 holes to 7/64, and the #9 and 11 holes to 3/32. I left all the stock springs in. I am really happy with the way it shifts. Not bad at all at part throttle, and barks the tires WOT. Basically, if you are thinking of doing the Jmod, stop thinking and do it.

Before the Jmod, the car actually shifted from 1st to 2nd right at 6000 rpm, although it started shifting earlier. After the Jmod, it shifted at 5600 rpm. That shows just how much slipping it was doing before the Jmod. I have since adjusted the shift points back up to 6k rpm.

I'll get a video of it later this afternoon. Hopefully going to the track next weekend in which case I'll post some times up.

 

[hotstang_46]

a very worthwhile mod indeed. It makes such a nice difference. When I had an auto I did it as well. The only thing that it didn't cure that bugged the you know what out of me is the 3-4 wandering that sooo many cars have.

congrats on the jmod....

 

[sneaky98gt]

I was playing around with the settings in my programmer on Saturday and something crazy happened. I backed the shift pressures back down to 0%, and it actually shifts better at wide open throttle, AND softer at part throttle. I couldn't really ask for more. I should have done this years ago. And to reiterate: if you are considering doing the J-mod, stop thinking about it, and just do it. I promise you will be satisfied.

And as promised, I finally got a video. For reference, the first video linked is a before video; second link is after.

YouTube - 1998 Mustang GT FRPP/SVO Supercharger 0-60

YouTube - 1998 Mustang GT J-mod

a very worthwhile mod indeed. It makes such a nice difference. When I had an auto I did it as well. The only thing that it didn't cure that bugged the you know what out of me is the 3-4 wandering that sooo many cars have.

congrats on the jmod....

Thanks! Yea, I know what wandering you are talking about (my granddad's 01 GT does it), but for whatever reason, my car has never done it. Adding a trans cooler supposedly will solve it. I'm going to get one and get it installed sometime in the next couple of weeks.

 

[scupking]

Yup awesome mod for the auto. Now you need a trans cooler and 3200rpm Stall.

 

[ran260gt]

Welcome to the Jmod club and its about damn time, the mod has only been around for like forever !

 

[bhuff30]

The first video makes me cringe. It takes forever for that poor transmission to complete the shift. I bet if you look at the video frame by frame, you'll see it take nearly a full second to make the shift.

Looks like a lot of fun with the blower on, but I agree that it is time for a looser converter. Soon as you get the rpms up, it hauls ass, but takes a bit to get there. Don't ya love watching the speedo needle swing quickly?

 

[Night Shifter]

damn your car sounds good

 

[sneaky98gt]

Yup awesome mod for the auto. Now you need a trans cooler and 3200rpm Stall.

Awesome indeed. Trans cooler is next on my to-buy list. Stall....don't start tempting me...lol. I'll just say that it won't happen anytime too soon.

Welcome to the Jmod club and its about damn time, the mod has only been around for like forever !

lol, don't be a hatin'. Up until I got the blower on, upping the line pressures was enough, so I didn't really bother with it. And I just haven't really had the time to do it since the blower until now.

Either way, I wish I would have done it a long time ago.

The first video makes me cringe. It takes forever for that poor transmission to complete the shift. I bet if you look at the video frame by frame, you'll see it take nearly a full second to make the shift.

Looks like a lot of fun with the blower on, but I agree that it is time for a looser converter. Soon as you get the rpms up, it hauls ass, but takes a bit to get there. Don't ya love watching the speedo needle swing quickly?

Ha. I actually datalogged with my X3 last time I went to the track a couple of months ago. I looked at the RPM data graphed over time; it was taking it .9 seconds from starting to shift out of 1st to completely into 2nd. So your guess is right on. It was terrible, and I hated it, but I sure do love it now. I'm heading to the track Friday night, hoping for some good results on the track with it.

There y'all go again tempting me about a stall..... I'd love to have one, and I might one day, but it won't be in the near future. And yes, the needle gets to 60 very quickly, especially from any kind of roll.

damn your car sounds good

Thanks man! I'm actually currently in the process of making/compiling some videos of my car's exhaust. Hoping to have it done in a week or so.

 

[kuwait]

yep , looks good on the video not as much slip as stock. awesome work and props for doing it yourself , most impressive

 

[Mike97gt]

I think the j-mod, stall and gears should be the first mods for a auto gt.

personally I would go minimum 3600 stall. 3200 is what I used to like in the LT-1 F-bodies with a stock cam and those have WAY WAY more bottom end then we 4.6 guys do.

 

[sneaky98gt]

yep , looks good on the video not as much slip as stock. awesome work and props for doing it yourself , most impressive

Thanks. Doing ALL of the work on my own car is one of the very few things I really pride myself on.

I think the j-mod, stall and gears should be the first mods for a auto gt.

personally I would go minimum 3600 stall. 3200 is what I used to like in the LT-1 F-bodies with a stock cam and those have WAY WAY more bottom end then we 4.6 guys do.

More low end torque than my little 4.6???

I may do a stall one day, but gears are probably not in my future. I like my 25+ highway fuel mileage.

I'll post up my track results after Friday night. Hoping to make my first 12 second pass.

 

[Winters98GT]

I'll post up my track results after Friday night. Hoping to make my first 12 second pass.

I think you should be there! Good luck. Car sounds great!

 

[SVT32VDOHC]

Watched both videos...definately a worthy mod. The shift is firm and much quicker. Older auto's were kinda slushboxes, so this mod is the $hit!

 

[sneaky98gt]

I think you should be there! Good luck. Car sounds great!

Thanks! I hope so. The predicted DA for tonight is about 1500 feet less than the time I ran 13.12, so I'm sure hoping the better weather plus the jmod will get me that extra tenth I need.

Watched both videos...definately a worthy mod. The shift is firm and much quicker. Older auto's were kinda slushboxes, so this mod is the $hit!

Describing the 98 auto as a slushbox is an understatement. Very worthy mod that I should have done years ago. They should have come from the factory like this.

 

[N8Dogg98]

That's awesome sneaky... Must be a fun car, I wish I was supercharged...

 

[SRT Handz]

I am glad that blower you bought off me is getting used good

 

[sneaky98gt]

That's awesome sneaky... Must be a fun car, I wish I was supercharged...

It is a lot of fun. It's definitely not a record setter by any means, and really doesn't even lay down that terribly impressive numbers, but having 300+ ft-lbs of torque on the wheels from 2000 rpm to 5500 rpm makes for a very fun car to drive.

I am glad that blower you bought off me is getting used good

haha, yes it is.