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Discussion Starter #1
Not sure where to look for the answer to this question. I have had the J-Mod done to my Thunderbird ("mild" version) and it shifts better and harder than before. I was always under the impression that shift kits and valve body mods determined when a transmission would shift but I've read here that a chip tune controls that for these transmissions and that getting a tune for even a bone stock car will improve shifts and gas mileage.

So my question is, I guess, does the J-Mod change the shift points at all or is it strictly the computer that controls that? Also are there different tune settings for the shift points? I want to end up with a fun modern(ish) muscle car, not a drag car, so I'm wondering with a J-Mod and hoped-for ~300HP engine (head work, PI or equivalent cams) what would be the optimum shift points compared to stock. I suppose the torque converter would also play into it and if I do that head work then I should get a different/better one, too.
 

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J-mod can change clutch fill times which will reduce the delay between shift command and completion. The computer is what controls when the shift is commanded, based on MPH (most of the time) or RPM (at WOT).
 

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Yup.

If you want to change the shift points, they can be set by MPH and throttle position.

You'll either have to buy a tune with those additions, or buy the PRP so you can do it yourself.

I spent more time doing the shift points than any other thing in doing my tune; I probably wrote 30 tunes getting it just right.

You need to do the jmod first; as TT93 said, the jmod sets how fast and firm the shifts happen, and you want that right before you start dinking with the shift points.

"Don't cross the lines" comes to mind, lol.
 

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It really isn’t a one answer question, it depends on exactly how your car is set up as well as personal preferences. I myself had three separate tunes stored in my Xcal with different shift schedules, one for(what I hoped) better mpg with relatively low RPM shifts, one for aggressive higher RPM shifts(which ironically had little effect on MPG) and another I constantly would tweak trying to get the best of both. WOT shifts are relatively easy to set by datalogging accel rate.

Jmods and shift kits effect shift speed, in datalogs you can actually select PIDs for commanded and completed shifts, since it takes time for the clutch packs to fill and drain. The higher spec J-mod the less time this takes, which can drastically alter the completed shift points even though the commanded shift points are the same, which is generally why mild is the way to go without a tuner and loose converter.
 

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Discussion Starter #5
Thanks for the info. I thought also that the torque converter stall speed dictated when the transmission would shift, at least that's what I'd been told in the past. This was for older, computerless cars, of course. But the converter and the valve body (opening up the separator plate holes, using stiffer springs) were what I'd been told control automatic transmission shift firmness and shift points.

As an additional question, what are the stock shift points for the 4R70W computer? And are there "standard" changes to those, meaning that most tuners tend to move the shift points to X, Y and Z for performance vs gas mileage?
 

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On non-electronic automatics shift points are controlled by a cable or vacuum modulator, valve body alteration effects are the same as previously mentioned, simply altering the fill times. Torque converters don’t alter shift points either, the higher the stall speed the higher the rpm the engine turns before the input shaft is (close to) 1:1. The looseness of a converter has an effect on shift firmness though, when not in lockup the shifts are effectively cushioned where a max spec J-Mod feels downright mild compared to a stock converter with its low stall.

It’s been a long time since I could recall them but I think WOT shifts were commanded ~4800, while other shifts between vary depending on throttle. Yes, good tuners do tend to put in their settings throughout, but as I said with your own cars variables(everybody with a modified car will get different results) it isn’t really a copy paste from a spreadsheet deal necessarily, everything needs to be factored in. I’ve played around with other people’s value files for my own when I was trying to shortcut the effort but what worked great for their cammed PI/high stall mild J-mod/4.10 car, didn’t work very well on my PI/stock marauder stall 450+ J-mod/3.55 setup at the time.
 

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My 95 shifted at 5200 WOT with the J-mod. My 97 shifts at 5000 WOT, and it used to be only 4500 on the 2-3 shift, but last couple times it was up to 5000. These are bone stock cars.

Our 96 Cougar shifted at only 4000 on the 1-2 right after the J-mod, though I never tried it again to see if it would go higher since it wasn't my car. But I've been leery of adding the J-mod to any other cars because of it. Wished I had ran it hard a few more times to see how much it changed the shift point.

Al
 

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Where it starts the shift vs where it actually goes into gear is dependent on the jmod level.

Accumulator fill times make a big difference.

All my fill times are below 0.5 seconds, which I think is the upper power range.

The stock transmission might start a shift at 4000, but it take to 5000 for it to actually change.

My shifts tend to happen within 500 rpms, but not everyone wants every **** to feel like a manual you slid your foot off the clutch.
I, on the other hand, Do. :)

I have all 2002 transmissions at this point, and I seem to have stopped breaking them; the last one I broke was the 127mph shift error, which takes a value file to fix.
(High gears and or tire sizes, and an 8 tooth tranny gear can make this way less than 127mph.)

Instead of the Jmod, I've just been putting these in, since my plate got stamped by the 2-3 accumulator piston.
Some of the holes are even bigger than the highest jmod spec.
Note this one if for a 2000 and up tranny; other ones exist.

https://transmissioncenter.net/shop/4r70e-w75e-w-late-00-up-super-tuff-plate/
 

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Discussion Starter #9
Thanks again for the info, this clears up a lot about auto transmissions for me (I usually prefer sticks and almost ordered my first Thunderbird with one since it was an option on the order form but I'm sure someone would have prevented that since it was the LX and not the Super Coupe).

If I may ask those on this list who have done real engine mods to their cars (head work/porting, better cams, larger throttle bodies) beyond just J-Mod and exhaust, if your car is now more in the 300+ HP range, but not set up as a strict drag car, do you find that the shift points are bad enough or inadequate enough to require a custom tune to change them? I'm guessing that the stock shift points are too low or the transmission shifts too early but I have no idea what most Thunderbird/Cougar/Mark VIII fans think about how the stock 4R70W shifts.

I know that the J-Mod is a very popular (practically mandatory) mod but for most owners is that good enough? Or is the common thinking to get the J-Mod followed by changing the miserable stock shift points through a custom tune, meaning if you're going to do the one (J-Mod) then you should also do the other (custom tune the shift points) otherwise it's not really worth it?

This is my second Thunderbird but the first that I'm comprehensively modifying so I'm trying to catch up to all the "everybody knows that" info about these cars.
 

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It's pretty much impossible to get past a point with the engine and not do a tune, although technically it's feasible under certain circumstances. I don't know of anyone who has gone so far as to put bigger cams and/or ported/TFS heads on their car and not get a tune. 5400 RPM rev limiter would leave a lot on the table if that was the case, assuming it would run with the highly modified cam and therefore idle airflow requirements. Nevermind the injector delay table which would probably be having raw unburned fuel go out the exhaust. :)

That said it's possible to leave the shift points where they are on the car (after adjusting the other required components in the tune to get the car running properly) and have it run reasonably well. You'd still be leaving a lot out there because the WOT shifts are commanded down in the low-mid 4xxx RPM range. With a better trans and/or J-modded valve body, your shifts are completing at or before 5000 RPM - chances are your optimal shift points will be over 6000, depending on the cam and intake you end up with.

The PT shift points are also pretty conservative and you could leave them be as well, assuming you adjust the N/V of the program to match any gear changes. But again, the benefit of adjusting them to your driving style is all the more reason to go through the effort. Matt is right though - it's a tough balancing act to find the sweet spot between low TP, in-town conservative shifts and then mid-high TP aggressive shifts. I'm essentially there but there are little things I want to change with the next program I write. TBH I haven't modified it at all this year because it's "good enough". Reality is I need to get the headers installed, which will prompt low RPM timing changes due to the scavenging boost with my cam; once I need to compensate for that, I'll finish the minor tweaks I've got on my list. :)
 

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I've been away for a while, so I don't know what the latest trend in tuning is, but I have a bone-stock 02 Grand Marquis Greenleaf/LKQ takeout in my 97 bird, with a Marauder converter, and a SCT programmer package tune by Lonnie Doll. It has been in my bird since 2010, and has around 100k miles on it since the swap. The only mod to the transmission was the required wiring harness mod. My shifts are firm enough to notice, but will only bark the right rear if I really get on it. Nothing like the last transmission I had, which was a supposed full-race version from some shop in Jacksonville, FL, which was way too harsh and only lasted about 70k miles before it started to slip.

If you're wondering what mpg I get, I average 27 mpg running 60 mph on farm country 2-lane roads, 90-mile commute each way to work, on 87 octane E10. The car is bone stock except for the mods listed in my signature, 288k miles on it.
 
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