904 Transmission 1-2 shift control valve spring install help.

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LivewireBlanco

LivewireBlanco

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Ok, evidently this is fairly common but my 1-2 shifts are way lower than my 2-3 shifts. I like where my 2-3 shifts are but my 1-2 shifts are about 1000 rpm too low. I've read this is likely from a weak 1-2 shift control valve spring. Does anyone have any pics of where this is located and instructions on how this is accomplished? Can this change be accomplished fairly easily? I've never done any tranny work except filter and fluid so this is all new to me. Thanks!
 
Increasing Shift Speeds On The 727 Torqueflite - Mopar Muscle Magazine

"...To increase the (global) shift speed, the stock governors can be modified by reducing the weight and/or increasing the spring tension. ....A wide range of preassembled high-speed governor assemblies offered by A&A Transmissions in Camby, Indiana. A&A carries governor assemblies rated in 200-rpm increments from 5,000-6,000-plus rpm, offering an easy way to optimize (global) shift timing..."

This wont change the 1-2 by itself, that's where the altered SC valve spring comes in:

"...The solution from A&A was a change in the 1-2 shift-control valvespring. They sent us a selection of 1-2 shift-control valvesprings to bring the 1-2 shift up to match the 2-3 shift point. Three springs were sent, all heavier than the stocker, the tension clearly marked, and what it should do. We dropped the valvebody and popped in the (new) spring..."

1-2.jpg
 
I read that article and that's how I diagnosed what was needed. My big question was how to change the spring.
 
LivewireBlanco said:
I read that article and that's how I diagnosed what was needed. My big question was how to change the spring.
Click to expand...

Once you see the valve body as shown in the picture above it's obvious and super easy.
Slide the valve out and swap springs, slide the valve back in and re install the small section you took off to get to it.
 
TrailBeast said:
Once you see the valve body as shown in the picture above it's obvious and super easy.
Slide the valve out and swap springs, slide the valve back in and re install the small section you took off to get to it.
Click to expand...
Ok so to take that portion of the valve body out I'll need to drain the fluid, drop the pan, then unbolt that section of valve body? I'm really a noob when it comes to internals of transmissions.
 
That's sorta what I did.
But don't go crazy on this cuz you can hold it in gear longer, in manual mode. If the auto upshift rpm gets to be too high, it kindof sucks around town.
I lowered my 2-3 instead,to better balance the shift rpms; then screwed around with the line pressure and governor to fine tune it.
But don't go crazy on these either, if a streeter, cuz too early auto downshifts suck more than not soon enough ones,lol.

To make line-pressure adjustments easier on the 904, I drilled and tapped a hole for a small pipe plug, in just the right place, which you can see where to put, with the pan off. Now you can scoot under there any time and give her a twist.
Don't forget to synchronize your KD linkage, and there are a couple of different levers you can bolt onto the trans to vary the throttle pressure ratios.

Personally,in a streeter, I like a slightly earlier 1-2 shift with performance gears, as long as the KD mech is working right;
but not 1000rpm earlier,lol.If a streeter,don't go crazy on these, you'll just wear out your creeper.
If a streeter, that's why the PT kickdown was invented, and what the manual shifter is for.
Happy HotRodding.
 
It is not that your spring is weak, it is that yours is stock. You need to order the new spring from A&A, they send you two of different strengths. Use the weaker one first, and see what the results are. They come with instructions.
 
d55dave said:
It is not that your spring is weak, it is that yours is stock. You need to order the new spring from A&A, they send you two of different strengths. Use the weaker one first, and see what the results are. They come with instructions.
Click to expand...
That's where I was going to get it from. Glad to hear it comes with instructions!
 
LivewireBlanco said:
Ok so to take that portion of the valve body out I'll need to drain the fluid, drop the pan, then unbolt that section of valve body? I'm really a noob when it comes to internals of transmissions.
Click to expand...

You will have to pull the valve body down to get to it, but yes.
 
LivewireBlanco said:
Anything I need to watch out or be careful for? I'm just being extra careful so I don't screw anything up.
Click to expand...

Just keep things clean, and torque the valve body back down evenly.
The park rod can be a PIA for a beginner, but it's not a big deal.
Generally just a little turn of the driveline will let it come out and go back in.
OR you can just take the clip for the rod off and leave it hanging in there.

Once the electrical connector for the solenoids is loose and the VB is hanging by the park rod hold the VB up in the semi installed position and give it a little yank towards the motor and it should come out.
If it doesn't, twist the driveline a little while you give it that little yank forward.
(Same going back in) as the park gear needs to be in a position to let the park lever move out of the way and let the knob on the end of the rod by to come out.
 
TrailBeast said:
Just keep things clean, and torque the valve body back down evenly.
The park rod can be a PIA for a beginner, but it's not a big deal.
Generally just a little turn of the driveline will let it come out and go back in.
OR you can just take the clip for the rod off and leave it hanging in there.

Once the electrical connector for the solenoids is loose and the VB is hanging by the park rod hold the VB up in the semi installed position and give it a little yank towards the motor and it should come out.
If it doesn't, twist the driveline a little while you give it that little yank forward.
(Same going back in) as the park gear needs to be in a position to let the park lever move out of the way and let the knob on the end of the rod by to come out.
Click to expand...
This is all correct. Also, watch out for the accumulator and spring. The spring may have been previously removed, if it is there just put it all back as it came apart.
 
I modify every tf I rebuild by drilling the vb for firmer 1-2 and 2-3 shifts. It doesn't cost me anything, so I was thinking about adding this mod; all depending.
 
Your on the right track with what you need to do but the 1-2 shift valve and the 1-2 shift control valve pictured above is not the same and not all valve bodies (i.e. older ones) have a shift control valve. But that doesn't matter because what you need to change is the 1-2 shift valve spring to get the 1-2 rpm shift higher. If your VB has a 1-2 shift control valve adding the 1/4" check ball to it (basically blocking it's function because it only moves about 1/4") will not affect shift rpm. At the moment I can't find the picture I'd like to post but here is one showing the location of the 1-2 shift valve. The VB is turned around from the picture in the article but you can see it's next to and much smaller in diameter than the shift control valve spring. You do need to drop the VB to do the swap

Valve body springs.jpg
 
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And make sure to torque the valve body to 100 in lbs when you reinstall it. I've seen valve bodies ruined by guys cranking them down with a std ratchet
 
Found a good picture showing the valves. As soon as I can get this slow as molasses in january scanner to do it's job I'll post it.
 
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