trans tuning.

[mustang_gt_350]

Originally Posted by Power Hungry

There are 2 switches which control the trans and converter states.

Switch 1 will turn on or off the ability to lock the trans into a specific gear. There is a values that is used in conjunction with this to select the gear in which to stay locked (1, 2, 3, or 4).

Switch 2 will turn on or off the ability to lock the converter. On 94-97 this is simply an on or off state. On 99 and later, it is used in conjunction with with a value that determines the pulsewidth in which to lock the converter. Normally, this would be set to 100%, but if you're really curious as to how fast you can fry your converter clutch you could set this to 25% or 50%.

We frequently do "sled-pull" applications on a chip that goes something like this...

Pos 1: 2nd Gear, Converter Unlocked, Fuel Curve modified to spool and light turbos
Pos 2: 2nd Gear, Converter Unlocked, Pulling Fuel Curve
Pos 3: 2nd Gear, Converter Locked, Pulling Fuel Curve
Pos 4: 3rd Gear, Converter Locked, Pulling Fuel Curve
Pos 5: 4th Gear, Converter Locked, Pulling Fuel Curve
Pos 6: Normal Operation, Light Fuel Curve

Instead of 1st gear, we can also set up to start in 1st gear.

These types of strategies work really well because they completely bypass most of the delay circuits in the shift strategies and just grab the gear desired. The only drawback is that you have to be very careful when switching or you could accidentally skip a position and jump 2 gears instead of 1. In a bouncy truck it's quite easy.

Anyway, just some thoughts.

Great post. So you would actually be switching tunes as you go down the track? So position 1 would be the spool/off the line tune then once rolling you would hit the next position? Then if you want to lock the converter just go to the 3rd position. Also what would be your thoughts about pulling with the converter not locked vs locked? I know the heat would be very high but do you think there would be a benefit to it?

Edit: SO also if i'm reading this correctly that means you could have the truck in Drive, and if you burn a position on the chip that when selected you would be starting out in 3rd gear?

[cleatus12r]

I would assume you'd like Bill to answer those questions but I can give some insight as a transmission tech.

Yes, you'd be switching tunes as you run down the track. One hand on the wheel, one on the hand throttle, and one on.......wait a minute!

Whether or not the converter is locked depends a lot on the truck itself. With a lower power rig or one with a huge, laggy turbocharger I can assume that having a locked converter (especially early in the pull) would be a detriment. Heat shouldn't be too much of an issue because you're not running for 15 minutes with an unlocked converter....more like 15 seconds. The problem lies in the torque multiplication characteristics of the torque converter. Once the input shaft speed gets closer to the engine speed, the torque multiplication factor goes away. Once you reach redline (not hard to do with an unlocked converter) and the torque multiplication goes away, the input torque to the transmission input shaft is very low.....and so is the power to the wheels at that point.

Your best bet is to try out Bill's suggestion and practice with shift/TC lock points.

[Power Hungry]

Yes, you could have the trans switched to third gear and start out in third. For a pulling truck this may, or may not, be a big deal.

My personal preference is to have the converter locked once the RPMs hit 2400-2500 and then keep it locked form there. Some folks prefer to start out in 1st, and some in 2nd. It seems a little easier to spool in first, but maybe that's just me.

Hope this helps.

[mustang_gt_350]

Originally Posted by Power Hungry

There are 2 switches which control the trans and converter states.

Switch 1 will turn on or off the ability to lock the trans into a specific gear. There is a values that is used in conjunction with this to select the gear in which to stay locked (1, 2, 3, or 4).

Switch 2 will turn on or off the ability to lock the converter. On 94-97 this is simply an on or off state. On 99 and later, it is used in conjunction with with a value that determines the pulsewidth in which to lock the converter. Normally, this would be set to 100%, but if you're really curious as to how fast you can fry your converter clutch you could set this to 25% or 50%.

We frequently do "sled-pull" applications on a chip that goes something like this...

Pos 1: 2nd Gear, Converter Unlocked, Fuel Curve modified to spool and light turbos
Pos 2: 2nd Gear, Converter Unlocked, Pulling Fuel Curve
Pos 3: 2nd Gear, Converter Locked, Pulling Fuel Curve
Pos 4: 3rd Gear, Converter Locked, Pulling Fuel Curve
Pos 5: 4th Gear, Converter Locked, Pulling Fuel Curve
Pos 6: Normal Operation, Light Fuel Curve

Instead of 1st gear, we can also set up to start in 1st gear.

These types of strategies work really well because they completely bypass most of the delay circuits in the shift strategies and just grab the gear desired. The only drawback is that you have to be very careful when switching or you could accidentally skip a position and jump 2 gears instead of 1. In a bouncy truck it's quite easy.

Anyway, just some thoughts.

I know i'm bringing back an old post. But I'm going to play around with gear selections with my chip. I'm guessing that "trans test switch" needs to be turned on for it to actually select the gear your telling it to in the " trans test gear select" correct? I'm not really in need of the TC locking with the software as i prefer to use my manual switch on the dash for locking the TC. But i noticed you said that the "converter duty cycle test value" should be 100% or it will feather the TC when it locks? I notice the default on my sled pull tune you did for me is 0%. So I'm guessing that the "converter duty cycle test value" only applies if you are turning on the "switch to manually lock converter"? So I am safe to let the TC duty cycle at 0 as long as i do not turn on the "switch to manually lock the converter" correct?

Just wanting to verify so i don't burn out my TC.

EDIT: it was late and forgot to mention exactly what i was going for. I'm going for a manual shift, example, pos. 1 is first gear, pos2 is 2nd, pos 3 is 3rd gear, and pos 4 is 4th. Then i'll be able to have an almost 8speed. with having my manual TC lock switch i can drop it in and out of lock, Not really somthing i'll probably use but hey, whatever lol. Ive always wanted to hack into the selinoids in the trans and put push buttons on the steering wheel so i could shift like the flipper shifter cars, but this is close enough and alot less work.




Thanks
andy

[PsdPullerJr]

OK is it possible to leave the chip in one position and have the truck start in 2nd gear and get up to say 15 mph and shift into 3rd and stay there? Also possibly lock the TC at say 10 mph and unlock at the 2-3 shift? (Some power tracks or heavy sleds wont hold 3rd and a locked TC) How are the shifts points controlled on 4x4 low? The actual vehicle mph or is there a conversion factor? Thanks

[cleatus12r]

There are a lot of things going on there.....and quite frankly, depending on the year of the truck in question, may or may not work just the way you want it to. In either case, you are looking at a TON of trial and error with the tuning to make it work just right.

The 4x4 low shifts are handled the same as the high range shifts....only divided by 2.7.

[PsdPullerJr]

Well I got to hook on a real loose track thursday night. I tried playing with shift points to get the truck to start in 2nd which it did. I set it to shift into 3rd at 38 to 43 mph (Which should be appro. 14 to 16 mph in low range) and throttle postion around 3/4 to full pedal. However i was up around 20 to 21 mph on the speedo and 3200 rpm and full throttle and it never shifted to 3rd. Any thoughts? Something I may have missed like a delay or something else? Thanks Edit: Its a NVK4 truck with PMT1 programming

[F-127]

Any changes to the truck such as differential gear ratio or tires size? Might be enough of a change. WOT/WOT 4x4 shift rpms changed? Just some thoughts, I'm not on my computer with Minotaur or I might of had a few other ideas.