What's normal 1-2 shift point in 4R70W? - TCCoA Forums
 
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post #1 of 9 (permalink) Old 12-04-2004, 04:33 PM Thread Starter
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What's normal 1-2 shift point in 4R70W?

I've got a 95 4.6 bird with a 4R70W. At or near WOT, it seems like the 1-2 shift takes Waaayyyy too long. It winds up so far that it feels like the car is falling off the cam. I don't mean crazy high revs but approaching 5 grand. I basically have to lift to get it to shift; either that or wait what feels like forever. It's not conducive to going fast... I've had the 1-2 accumulator thing done, otherwise the car is stock. My trans guy, who seems to be pretty good although not a 4r70 specialist, says that all the cops here complain about the same problem in their Crown Vics. (and he doesn't have a fix)

First of all, is this "normal" behavior for this trans? Any easy fixes?

Second, I'm thinking about putting a chip in the car- probably one of the SCTs from Blue Oval. Would that allow someone to reprogram the 1-2 shift point down to say 4000?

Thanks for any clues you can offer.

George
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post #2 of 9 (permalink) Old 12-04-2004, 05:08 PM
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Shift points around 5000 are normal at WOT. The problem is the tiny ports in the intake. That's why the car wheezes out around 4000. A PI intake conversion would help, but it's a bit more complicated for a 94-5 than a 96-7. There are a bunch of threads on this already so I wont repeat it all over again.
A j-mod to the tranny will make the shifts much quicker, and an SCT chip can also do a lot for you in this area.

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post #3 of 9 (permalink) Old 12-04-2004, 07:55 PM
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hehe, go take a ride in scott's car, his car pegs the tach before it shifts.

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post #4 of 9 (permalink) Old 12-04-2004, 09:42 PM Thread Starter
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Lonnie just posted a pointer in the engines forum to this article on Modular Depot. In it, they say:

To be precise, the optimum shift RPM is the point at which the engine’s power output is the same before and after the shift. So your ride the power curve to the peak and over just far enough so that when you shift, you’re at the same power output but you’re climbing the curve again. Thus, how far past the peak power RPM you go, depends on how close together your gear ratios are. Since most cars have the lower gears spaced farther apart than the higher gears, the optimum shift point is usually redline in 1st gear, dropping by a hundred RPM or so in each successive gear.

So I guess I was wanting to shift by feel, but really I was shifting too soon for overall speed. Wish I had PI stuff, but I think I'm gonna pray that an 02 explorer motor falls off a truck and lands in my yard. Meanwhile I'm leaning towards the chip first cuz it's so easy to do.

If I was to do the JMod, how would the car behave in normal grocery-getting type driving? I don't want to scare the wife or get the cops all excited.

George

ps: I wish I'd found TCCoA a long time ago- You guys really know yer poop!

Last edited by George; 12-04-2004 at 11:02 PM.
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post #5 of 9 (permalink) Old 12-04-2004, 11:50 PM
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[QUOTE]If I was to do the JMod, how would the car behave in normal grocery-getting type driving? I don't want to scare the wife or get the cops all excited.



i use mine jmodded and chipped 4r70w as daily grocery getter. i love it.

My daily job is to fry rice for my customers....

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post #6 of 9 (permalink) Old 12-05-2004, 12:44 PM
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George,

The nice part about the J-mod is that you can make it as mild or as aggressive as you want. Do you have a place to work on the car there? And are you good mechanically? And BTW, welcome! It's nice to have another PA member around. Home home for me is near wilkes-barre, that's not too far. You're in a good spot, there is a Philly group, a NJ group, and the Mid-Atlantic group all within a relatively short distance.

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post #7 of 9 (permalink) Old 12-05-2004, 11:12 PM
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Furthermore, the JMOD gives you a shift that is only as firm as your right foot wants it to be.

Around town driving yields shifts that are barely noticeable. faster, but not so firm you spill your coffee(with lower spring in). With lower spring out, you'll feel a little jolt at low rpms, but still, totally liveable.

But if you up the ante, and mash the go-pedal into the higher RPM's, the shifts get firmer as the rpms increase. its like a totally driver-adjustable shift. Want to break the back-end loose? mash the gas until shift point. getting up there in the rpms, but dont want to bark the back tires? back out of the throttle slightly, and enduce a slightly softer shift.

I know the JMOD is designed to speed up the amount of time between shifts. the pay-off, is firmer shifts at the same time.

The part about the article that most people miss is, the lower the torque your engine produces, the firmer the shifts will be. its as if more torque slips the tranny more, so the JMOD shifts arent bone jarring, like they can be in a stock motor-equipped car. Up the torque, soften the blow, so to speak.

as far as late shifts, the W in 4R70W stands for "wide" ratio. This means, a day and a half in each gear. I drive a Mark VIII, which has factory shift points at 6000 rpms at WOT. coupled with 3.08 gears, talk about a long lag between gears. My car doesnt even see third gear on the 1/4 mile!!! And thats a trap speed of 95.5 mph!!!

On my Mark, the ECU retards timing before the shift. The ECU gives the shift command at about 5400 at WOT. The shift solenoids react, and the tranny takes its time following orders. In the mean time, the engine seems to stop pulling "as hard" due to the timing drop. This timing drop feels like you just backed out of the throttle ever so slightly, as if to 'enduce' a shift.

A chip can change all that. Our 97 with SCT 4-bank chip has the timing retard effect removed, and line pressure increased. it pulls hard into 6000 rpms, and shifts clean/firm. So, my 94 with JMOD, Mach 1 TC, and a 98 tranny shifts harder than our 97 with chip. But my 94's timing still retards at shiftpoint.
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post #8 of 9 (permalink) Old 12-05-2004, 11:16 PM Thread Starter
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Hey, thanks Silver95Bird. I just read everything I could find on the J-mod. BlackIceLSC, your LincolnsOnline article is a great addition to the other stuff on TCCoA. It looks like something I could do. At least the machining would be easy for me. The part about going into my tranny is scarrier, given that it's my daily driver. Still, dang, man, everyone who's done it just raves about it, and from what you say here it sounds perfect for me. Right now I just barely have the tranny shudder under control. I guess I need a cooler, too!

George

Last edited by George; 12-05-2004 at 11:26 PM.
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post #9 of 9 (permalink) Old 12-06-2004, 09:57 AM
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yea, definately get a cooler. its something that is easy to install, and is a low-cost investment. Peace of mind is hard to put a price tag on. Knowing that heat is the number one enemy of a A/T, you pretty much have to get one.

I just wish you could drive my car, and feel exactly what a JMOD feels like. Most people figure it makes the tranny shift like a racecar. it can, if you remove the lower 1-2 spring, and drill for the 450 specs. but as far as simple driving goes...JMOD simply provides a "sport" shift, as opposed to a lazy shift.

I am glad my article helps define the simplicity of the job. When I did my JMOD, I had never felt the shifts before. All I knew was, my 1-2 shift accumulator MUST have a broken spring. Everything I read told me I did. The shifts from 1-2 were firm enough to easily chirp the tires. I loved it!!! I didnt want to fix the problem, and end up with a lazy shift. So, I decided to JMOD.

best thing I ever did to my car. Well, that, and upgrading to a 98+ tranny!

If you lived near me, I'd take you for a ride. Once you felt the shifts, you'd be hooked for life.

The reason we didnt JMOD our 97 is, my GF drives it, and prefered the shifts obtained from a chip, over the JMOD. (she had a 95 mark VIII with a chip, and loved the shifts). So, we ended up with a 4-bank chip, and the 97 is *almost* as fun to drive as my 94!
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