How do you do that?

 

No I dont have ladder bars spinning wasnt really the issue I could control that but it just didnt go like I had hoped.

 

https://www.dieseltruckresource.com/...djust+pressure

See post #1 for pics -
Heck READ the entire post - good info...

 

um, maybe the truck didn't like trying to squeeze power out of 90 degree hot air ?

 

Yea But the weather was the same the last time I took it there and it went two tenths faster. It might not have been as humid though. The other thing I just thought about was the fuel tank was full that is 250 pounds or so maybe that made a difference also. They say one tenth for every 100 pounds I think

 

Nothing in the valve-body is going to effect shift points . .. . directly. The drilling of the separator plate etc in the VB effects shift quality (shift speed, engagement firmness, gear overlap, etc). Raising line pressures won't by itself alter shift points.

- At the end of the day, the mechanical governor on the output shaft determines when the trans shifts gears. The throttle-valve (operated by the throttle valve cable) influences the part-throttle shift points based on the load on the engine.
- Regarding the throttle-valve, there is a spring that can be swapped to further alter part-throttle shift points.

If anyone considers installing a VB kit, I strongly urge you to call your VB kit maker and ask them what's the best kit for your intended application.


I have learned that transmission fluid temperature greatly effects the ability of the converter to hook. Cooler (thicker) fluid will transmit more power. With that understood, Don't sit at the line with boost built-up waiting for the green light. If your Christmas tree has the little blue light at the top/center, as long as it's flashing, nobody's going anywhere.
Personally, I pre-stage and wait for my opponent to fully stage. I then wait till that blue light goes solid and then I quickly build boost and creep forward fully staging knowing the lights are fixing to come down. (NOTE: Ya gotta be quick here as you can be red-lighted for taking too long).
- In my heap, a 100*F increase in trans fluid temperature is good for loosing a solid .10 of a second in the eighth.

 

I was wondering how the info that unixcowboy gave was going to change the shift points it didnt make sence to me. I have to call fairbanks the maker of the shift kit I installed and see what they have to say about my problem. When I installed the shift kit there was 3 stages of performance I did everything that they said for the middle level towing /rv. I need to figure out how to move the 2-3 shift point with out moving the 1-2 shift.

 

Do you have a tachometer? Are you judging where the gears are shifting by the sound of the engine?

I ask this because;
- As JustRamIt91 has hinted, many drag-races are won in the first 60 feet.
- As mentioned above, the tuning of the valve-body controls the shift qualities. With our interest being in racing here, we want fast and firm clutch engagement. That's where the valve-body "Shift" kits can help.

* A slow shift from one gear to another is cutting into the ET.
* To keep shifts smooth, there is a lot of clutch/gear overlap. At one point in the shift, 1st & 2nd, 2nd & 3rd, etc, those two gears are BOTH engaged. Obviously there's some drag. Reduce that to a minimum for the race.
* The Throttle-Valve (TV) tells the trans what kind of a load is on the engine. For example:

Shift Quality
- Granny's got a pot of fresh butter-beans (seasoned with real bacon fat ), and is on her way to the church luncheon. She's barely on the throttle. The throttle is not moved much, the TV cable tells the trans VB that a gentle ride is in order and as a result, the line pressures a low (compared), shift quality is very smooth, almost to the point one can't feel it occur.

On the other hand . ..

- Granpa jumps into the truck just as soon as granny gets home, mumbling under his breath something about the fish are gonna be long gone by the time he gets there. He hooks up the boat and hauls hinny. He's tugging 4000lbs and in a hurry. He's into the throttle and accelerating hard from the stop lights. The TV cable sees this and the VB responds by increasing the line pressures so the added power and load doesn't have the clutches slip and burn. The shift quality is changed such that we now have much faster shifts, less overlap, and a much firmer clutch engagement.


Shift Points
- The mechanical (centrifugal) governor mounted on the output shaft is responsible for determining the shift-points.
- The VB modifies said shift-point (at part-throttle) based on the feedback the TV cable provides.




Clear as mud?


I would think something's wrong with the VB stuff if you were seeing the trans shift at different engine RPMs with each gear, with a constant throttle position. I know from my own experience that the 1st to 2nd shift is fast as fire coming off the line in auto. There's no way I could shift 1st to 2nd manually and be sure I was still in the power-band.
I have experimented with leaving the line in 2nd (auto) and manually shifted to 3rd and 4th. I was doing this for the sole purpose of determining if there was any ET advantage over shifting fully automatic. The end result was that considering the mechanical governor determines the shift-points at WOT, if I wanted to move the WOT shift-points up, I'd need to mod the mechanical governor weight(s).
Seeing where the power was in terms of engine RPM, the dyno graph was a big help. With that, I left the governor alone.

With my mess, I've found the best 1/8 mile times are had with disabling OD altogether. My mess wants to shift into OD in the last 100 or so feet of the eighth, and if I let it go into OD, that short time the trans is shifting into OD, is ultimately added to my ET ~ slower time. The engine is wound-up at the finish line though.

 

I do have a tach and I was shifting at about 2700 rpm IIRC. I was just getting into od in the 1/4 mile I cant imagine being in od before the 1/8 mile. I am sure fairbanks will be able to tell me something to do to change my 2-3 without messing with the 1-2. It worked fine before the shift kit. But of course my old converter was so sloppy you could barely feel the shifts. Even when I was manually shifting it the when I moved the shifter from 1st to 2nd gear the shift was immediate. Then when I moved the shifter from 2nd to 3rd it would stay in 2nd gear till like almost 4,000 rpm and that was killing my et. So I backed the tv cable off some so that at least I had control over the shift manually until I find a better fix. But that was the best I could do while I was at the track.

 

I think you're shifting way too late (you've got the same drive-train as I according to your Sig). What size tires you got?

IIRC, I'm at around 3800RPM at the 8th finish line in 3rd. I can't remember for sure right now.

 

My tires are 215 85 16 my 1/8 mile trap speed was 66 mph. Maybe you are right now I gotta go take the truck for a ride and beat up a little and see.

 

should run faster, temp dropped about 20 degrees since the t storms. watch out for puddles, don't need to swap er end for end while out playin. the usual suspects been checked ? air filter, fuel filter........... know ya mentioned 13 psi at wot, is that before the filter or after ?

 

I was just doing a little testing nothing crazy it is mostly dry down here lol. Them storms were quick but they sure were nasty. I have 13 psi @WOT after the filter. The air filter is @ months old with a new outerwears The fuel filter is also about 2 months old.

 

I think you are right sir. I did a little testing and I think I am reving it to high and didnt realize it. I kept it in third gear and took it up to 66 mph my trap speed and I was turning 2500. So I should be in going into od right around 1/8 mile and that deffiantely wasnt the case. Then I ran it through the gears like I did when I was at the track I shifted 1-2 at 35mph and 2-3 at 55 mph. Man by the time I am shifting third I should almost be in od already. I let the trans do the shifting once from a dead stop WOT and it didnt do bad it was a little early tomorrow I will give it a little more throttle pressure and see what happens. Thanks so much for the advise I feel like a moron but at least we figured something out.

 

My truck shifts better when i let it go by its self. Especially if i burry my foot to the floor after i gain traction in 2nd. but i don't have an od....