After doing the valve body mods, cranking the line pressure 7 turns and playing with the governor my 1-2 wot shift is great at about 5600 rpms but it's still not holding out the 2-3 long enough to suit me. It shifts as soon as it hits about 3700 rpms. Well I was thumbing through my fsm and was looking at the 2-3 shift valve spring. What would happen if I changed the spring tention on the 2-3 valve? Would i need to make it stiffer or lighter?
Hmmmm no one has an opinion?
The 2-3 shift is also controlled by the governor. I don't know if stretching it will help.
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I was meaning more of trying to put in a different spring on the 2-3 shift valve than stretching or cutting it down. I was trying to avoid grinding on the governor weights but it might come to that if I change out the blue spring for the orange and it doesn't work.
I would say its a governor issue too. The governor and the throttle pressure valve work in conjunction with each other (or opposition to each other depending on how you look at it). This is mainly what controls shift timing. Have you tried messing with the throttle pressure?
Now if its shift "quality" you want, than changing the spring might help. The main issue with the 2-3 shift quality is that you cant disable the accumulator because it serves a double function as an apply for the 1-2 shift as well.
For an unknown condition trans with over 100k miles, the shift quality is suprisingly good. I think John's interested more in getting it to hold the 2-3 shift longer @ WOT without affecting the 1-2 WOT shift point. It seems to me like anything done to the governor to raise the shift points is going to affect both 1-2 and 2-3 and since it's already shifting 1-2 at 5600, it could cause him to hit the rev limiter in 1st at WOT without ever shifting.
What happens if he manually shifts it?Originally Posted by Tony Hanna
He can tell you better than me since I've only been in it a couple times since the trans install, but from what I can remember, it's fine when shifted manually, just early on the 2-3 shift @ full throttle when left in drive.
I can hold it out as long as I want if I manually shift it but to just pop it in drive and head into town the 2-3 shift is soon enough to bog the engine at part and WOT. I am happy with the quality of the shift. Tony hit the nail on the head when he said what I want to do is raise the 2-3 shift points without changing the 1-2 shift points more than 500 rpms.
The first thing I would do is back off the regulator pressure. There is a good chance that with regulator pressure so high it is boosting governor pressure to the point that the shift is coming in too early on the 2-3. You could check this if you had a gauge you can tap into the gov pressure port. You should see roughly 1 PSI (maybe a little more) per mph. If your reg pressure is too high (without compensating throughout the unit) it boosts the governor pressure so that you get an early shift.
There is a delicate balance between throttle pressure, regulator pressure and governor pressure. If one is out of whack, without compensating with the others, it can cause strange shift characteristics.
If that is not the case, you might want to take another look at the governor and make sure its not hung up. There are two valves (primary and secondary) on the governor. The larger one (secondary) controls the 2-3 shift. If its hung or the spring is not right, this could cause the problem you have.
Finally, if you dont find the issue there.....you can go into the VB and take a look at the 2-3 shift valve and the 2-3 shift control valve. They could have issue as well. This would be my last bet though.
Youve got to be real careful to be as CLEAN as possible. One spec of dirt in the VB can cause problems like this.
Well I did all the valve body mods, blocked the accumulater, turned the line pressure 7 turns and in the governor I am using the large hollow weight from a turbo car, the blue spring from a tbi car, and the smaller solid weight from a tbi car to compensate for the extra pressure. Beyond that I'm happy with the wot 1-2 shift but the 2-3 is too soon after the 1-2. So I'm wanting to do something to make the 2-3 shift later in the rpm range as 3200-3700 is too soon and it's even sooner at part throttle.
Up around 5600 @ wot so it matches the 1-2 shift would be perfect. Then you could go from there with line pressure adjustments and governor mods. At least it shifts ok manually though.
If you cant check the governor pressure.....back down the regulator pressure and see what happens.
Since it's only affecting the 2-3 shift at WOT *and* at part throttle, you
either have a problem with the 2-3 shift valve, or the secondary weight on
the governor. You may have the wrong combination of spring and weight on
the secondary valve, or the valve may be sticking. The secondary weight is
not directly responsible for the 2-3 shift, but it starts doing it's job
(which is keeping the governor pressure linear) at the vehicle speed where
the 2-3 shift usually takes place.
If you have a lighter spring on the 2-3 shift valve, it will shift earlier.
Did you have the vb apart and get the red shuttle valve spring mixed up with
the white 2-3 shift valve spring? (the red shuttle valve spring is lighter).
Throttle pressure does not affect the shifts at WOT because throttle
pressure becomes the same as line pressure at WOT. This is why cranking up
the line pressure adjusting screw only affects shifts at WOT. Even though
there's added line pressure, the throttle valve will still make throttle
pressure when you step on the gas the same way as it did when you had line
pressure turned down. So since it's affecting both part throttle and WOT,
and it's only affecting the 2-3 shift, it can't be the throttle valve.
So I'd be pointing my finger at a faulty governor.
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Chad Kilback "Kil-time Tranny Tuning" ckilback3@nucleus.com
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Calgary, Alberta SDAC
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That's what i was thinking. I'm going to try to toss out the blue spring and go with the heavier orange one and the hollow weight and see what happens.
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