I have a factory tech valve body (really slick shift kit) and I can dial my trans line pressure up throught my tuner. Question is this, will the additional pressure increase shift heaviness or will telling the computer to up the pressure work with the additional volume of fluid to level the trans down some.

 

I thought the purpose of upping line pressure was to increase shift heaviness.

 

My thinking is the valve body has more flowing volume than stock, so the valve body has a volume similar to the volume it had when stock with a higher line pressure. Shift perfomance is similar due to the increased volume; to when I had the line pressure dialed up. Only with the valve body mod, the computer is oblivious to the change. I am just curious what would happen.

 

Hi Reax,

That is an *excellent* and a very important question, so I'm glad you asked - a lot of people really aren't sure of what to do on this.

The FTVB is designed to fill the oncoming clutch pack quicker by increasing the amount of fluid *volume* flowing in a given period of time - and thus firm up the shifts, and also help the tranny to stand up to more power for a longer period of time. So it all gets down to filling the clutch pack quicker and thus reduce slippage, which generates heat - heat being the #1 enemy of all automatic transmissions. this is the primary purpose of any shift kit, Line mod valve, FTVB like you have, etc.

Now Greg (the owner of FTVB) has historically said no, do not ever increase raw line pressure, and also never alter TQR, just always use his FTVB - well, I don't necessarily agree with all of that - some of that is really designed to sell his parts IMHO (and there's nothing wrong with that). Though I do agree with some of what Greg says in this regard of course, I do not always agree with that policy of never altering line pressure or TQR. In our experience, it's really a matter of the exact type of automatic transmission you have, as well as the desired results, that should dictate what gets done in each case.

For example, let's say you have the typical 4R70W from a 1999-2003 F-150 - now in those transmissions, I am generally not a fan of increasing line pressure *if* you have Greg's FTVB (Factory Tech Valve Body) installed. However, I DO recommend that in a non-towing type of tune, that your tuner remove all of the torque management (TQR) from the 1-2 & 2-3 upshifts - leave the 3-4 upshift, and all downshifts alone, meaning at stock TQR. This will generally result in a nice linear shift firmness that gets increasingly firm as you give it more and more throttle, yet is tolerably smooth at very light throttle and protect the tranny just fine. This also normally gives you a nice "chirp" of the tires on the 1-2, depending on power available and the weight of the vehicle, of course, as the weight varies by over 3000 lb in the F-150s just depending on configuration.

Now if you have the E4OD from the 1997 & 1998 5.4 F-150, the 4R75-E in the 2004 & newer F-150, or the 4R100 automatic (like in a Lightning, Harley, or a 1999-2003 5.4 F-150 that has the heavy-duty payload package), then I once again do not generally prefer to increase raw line pressure (well, if it's a drag race tune for a factory supercharged Lightning or Harley, then I will just a little bit more pressure at WOT) if the FTVB is installed - instead, what I do is to remove the TQR as I described above, and then also shorten up the shift duration times - again, these are things that the tuner actually has to do, those things generally cannot be done on any hand-held tuner via it's on-device adjustments, that must be done in the tuning software.

A friend of mine & a person I respect did Ford transmission calibrations for 12 years and knows all of this very well - he feels that TQR should always be removed, but that you (of course) ALSO have to do a mechanical modification that allows the transmissions to be physically capable of flowing enough fluid VOLUME to fill the clutch packs much quicker and thus avoid burning the clutches on full power full-throttle upshifts. Again, this is what the FTVB does - and what a god shift kit does, and what our Troyer Line Mod Valve does in the E4OD's & 4R100's.

Now some people increase line pressure in their effort to firm shifts - what they are actually trying to accomplish is increased fluid VOLUME flowing into the clutch packs, to fill them quicker - that is what it's really all about, getting the tranny to flow more fluid VOLUME, so that the tranny is physically capable of filling the clutch packs quicker to avoid slippage - so that now we can have firm shifts and still keep the tranny alive even under elevated power levels.

Sooo...........where does this leave you?

I advise *not* increasing raw line pressure via your hand-held tuner, but instead, work with whoever is doing your tuning to have them remove the TQR as I described above, and if you have an E4OD or 4R100, also shorten up shift shift duration times, too - and make sure to do it in a linear fashion, so that the tranny shifts relatively smooth at very light throttle, but still gives you a good jolt at WOT.

I hope that explains it a bit better for you, and lease feel free to call us if you'd like to go over any of this in more detail, or perhaps have us do any tuning for you, etc.

Thanks for your post, that was a great question!