Just thought I would share a little peice of info for anyone running high-perf race tunes or fuel boxes and having transmission troubles....

Most upshifting problems with the Torqshift under high HP/Torque conditions occur during the 3-5 upshift (mainly slipping). Even with the best of transmission tuning some trannies will still experience slippage during this shift occasionally due to improper solenoid design.

I've come up with a solution for this and am currently testing it out this weekend. The stock direct drive shift solenoid operates on inversely proportional duty cycle, meaning less current from the PCM = faster shift. Under boosted line pressure, this solenoid has trouble opening at the speeds needed to limit shift slippage under extreme torque, and will result in the engine simply redlining and being forced to back out of the throttle (this is also horrid on the direct drive clutches). I have replaced the direct drive solenoid with a positively proportional (more current = faster shift) intermediate shift solenoid which will operate properly under higher line pressures.

To do this, the shift solenoid duty cycle tables in the PCM will need to be altered via some means of custom tuning. The solenoids are also "keyed" to prevent installing the wrong solenoid in the wrong socket on the solenoid body, so the key will need to be ground off before installing. It is a simple replacement of the solenoid after modification, only dropping of the transmission pan is neccessary to access the solenoid body to perform the mod.

The only main downfall of this is that with stock tuning, you will be without a direct drive gear and codes will most likely be thrown. However, I would imagine anyone who actually NEEDS this mod most likely won't be terribly concerned

I will post more info after driving it some more this weekend, along with install instructions and the part number for the solenoid.

 

PSD, you have entirely too much fun. Good luck with your project. Even though I'll probably never need this mod, it's kinda fun reading of your experiments.

 

wow how do you figure this stuff out, u make pre-med look like 1st grade

 

It really only helps if you are spraying nitrous or injecting propane or methanol; some form of power addition that you can't compensate for in the computer's torque calculation. It isn't a problem of a lack of clutch strength or engagement pressure, its a problem of the solenoid lacking the strength to open under high line pressure.

You have to be a little out of your mind to have done something to your truck to need it

 

Well, I think I've met the a little out of my mind criterian. It's the $$$ part of it that keeps me sane, I suppose. Appearance-wise anyway.

 

I figure this stuff out because...when I am not busy, I get dangerously bored dangerously fast

Lets hope my idea works well; I haven't driven it enough to know for sure. If it doesn't, it will most likely take my Suncoast with it

 

Matt
come on man lol, So even with the suncoast converter and EX-rebuild kit, if that solenoid fails on me im screwed anyway or what? When my tranny was beefed they also had to change all the solenoids and my oil pump(few other things) tell me what happens i hope you dont have to even mention that I might need to do this or ill get paranoid and spend more stupid money on it.

 

You are running the exact same setup I am. You SHOULD be fine since you aren't spraying too much. If it doesn't start faltering when shifting from 3rd to 5th, then there isn't any need at all to bother with this mod. It's reserved when you know you have forced the shifting as firm as it will go with programming and it still isn't sufficient.

Nothing to get concerned about

 

Bump... to post more information tomorrow

 

There is a reason the direct solenoid is inversley proportional. It is in case of a loss of electrical power to the trans it will shift to direct drive. If this solenoid is changed to directly proportional it won't do that.

That may be a good trade off for those that want to put large amounts of power through the box, but for the majority of users I think I agree with the way Ford did it.

 

Matt, i'm having a similar issue. we discussed it on messenger, but mine seems to hang in first gear and not want to shift. when i let out of it it bangs hard into second. i guess this is a different issue since you're talking 3 gear upshifts. btw it only does it on the high power, and insane power tunes

 

Being that only the pressure control, direct drive, and coast clutches are inversely proportional, I would assume you are correct. If there is power failure to the trans, the direct drive and coast clutches will lock (meaning locked in 5th) and the pressure control will go to 0% DC, maxing line pressure out to maintain gear lock. I acutally didn't think of that until you pointed it out.

But, as you said in the second statement...this is only for people who actually NEED it. If you don't have problems during direct drive clutch engagement, there isn't much use...although it does have a far more solid shift feel, if you are looking for a firmer feel.

I've got several pictures to put on here, but they are large and posting them will suck up alot of bandwidth. Admin/Mods, is there a way to upload the files in a compressed folder available for download? If not, I'll just shrink them and stick them in my gallery.