My shifts leave something to be desired (99' f250 V10, auto) seems to flare up before the shift and then slip into the next gear. Not really any different than the other 99' I had, and it always bothered me too. Just looking for something to make the shifts a little firmer, not bark the tires or anything.
Anyone had any experience with whats out there?

 

I was going to buy a transgo PSK, but I ended up getting the Factory Tech valve body. I went with the FT because I wanted all of the mod's it included and would have to add some items to any other shift kit to get it that way.

With my old BFGs I could reliably chirp 1-2 shifts and sometimes 2-3 shifts. With my new Toyos it's much more difficult to chirp even with the 4.56 gears. Shifts are a little stiff until 3-4, I'd like a little more umpf, but not as much as when I dial up the line pressure with the VB. Overall though, I'm glad I did it.

 

Factory tech valve body (accumulator) won't do anything for the torque converter lockup in any way. What you'll notice it does is provide increased holding pressure in 1st and firm up the 1-2,2-3 and 3-4 shifts a lot. I had the FT VB on my V10 for a little, I took it off and am trying to sell it to recoup at least some of my money. Lesson learned. I went with all tuning with a custom performance tune. Controls the TQ lockup, shift firmness, shift points basically everything needed. Might put a Sonnex spring kit and a line mod valve in sometime, not shure if I will or not.

 

I've installed a Transgo Tugger in a couple of 4R100's behind a diesel. It does firm up the shifts, and it modifies both the main valve body and accumulator valve body.

As mentioned, for complete control, you'll also want a tuner that can adjust line pressure and control lock up on the torque converter, or just do the DIY torque converter lock up.

Of course if you want real control of how firm or how soft your shifts are, and you want it to be adjustable, then you need to do what I did.

Order the truck with a stick.

 

I ran with my tuner doing "race" shifts, and I am currently using stock pressures with the factory tech. Shifts feel quicker and more solid with the VB over electronic, but with my tuner, I have lock up in 2,3 and OD, making it feel like a 7 speed. One of the things I've read and sounded highly likely was, the transmission engineers spec'd the pump in the transmission for a certain pressure, and the fluid was designed to lubricate everything at that velocity. When you bump the pressure up electronically, it should put more strain on the pump and if you get it very high, the fluid may not lubricate the parts as it should. I liked the idea of pushing a higher volume of fluid at nominal velocity to create the extra pressure and using the tuner to control the electronics other than the pump/line pressure.

I know it's called pressure and it probably even reads as pressure, but remember you can't really compress ATF. Just like with water, you can put pressure on it or you can give it velocity to make it exert a force you can measure in pressure. Bumping the line pressure up in the electronics should be pushing the fluid faster, rasing the pressure with an opened up valve body, you're doing it by pushing more fluid through the opening.