904 Accumulator Spring

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mopar madness

mopar madness

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I pulled the valve body off of the 904 and seen that there was not a spring behind the accumulator. It looks like someone has been in there before. I was wondering if the spring had to be installed for proper shifting. I have read where some 904s do not require the spring. It is shifting good and hard except for the passing gear. I thought this could possibly be the problem. Thanks for any input or suggestion.
 
There's a blocker rod that's supposed to be installed when the spring is left out.
 
The blocker rod holds the accumulator UP in the bore and keeps it from slamming down into the bore.....which it is not supposed to do when the spring is left out. Essentially, the spring is a cusion to soften the 1-2 shift. That's how torqueflites are made They had to have things to soften the shifts because they were so badass.

What I would do if I were you: Buy TWO books. One, the ATSG Service Group book for the torqueflite. Two, The Torqueflite 727 by Karl Munroe. Even though it highlights the 727, the two are so similar, it's a great resource for the 904 as well. They are a cheap education. Get them.
 
mopar madness said:
I'm not sure what that is. Could you please explain it better to me. Looking at it now. Thanks for the quick response.
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The accumulator and spring are a cushioning device for 1-2 and 3-2 shifts and if the spring is removed for firmer shifts the accumulator should be blocked from moving.
The blocker can be anything from a section of tubing to a peice of 1/2 pipe.
The accumulator piston should be blocked in the down position.
There is a specific length it should be but I can't find it right at the moment.
Some block it up and some block it down.
B&M shows to block it down, but I have never seen it make a difference either way.
 

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no...passing gear is your kickdown linkage...and for part throttle kickdown the valve body must have a part throttle kickdown module on it.
 
mopar madness said:
Thanks guys. so thats got nothing to do with no passing gear, I do need a book for sure.
Click to expand...

"Passing Gear" still uses the second gear band so blocking the accumulator can firm it up a little.
Sometimes you will notice the difference, sometimes not.
Opening the oil passage for second gear apply oil will get it there but you don't want to cause a bindup between 1st and second by opening it too much.
The stage 2 Trango kit would handle all of it at once.

There is an aftermarket kit for part throttle kickdown so you dont have to floor it to have it kickdown.
It engages the kickdown at 3/4 throttle, so racers don't have to floor the pedal to get passing gear. (about $50) for the kit.
It replaces the cover plate, valves and spring that activate the kickdown.
 
mopar madness said:
I've played with the linkage making it shift sooner or later with no luck, i'm missing something
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Raising or lowering the line pressure (Which is what the kick down or throttle pressure) adjustment can only do so much.
The idea is to get more apply oil there quicker (opening passages for more volume)

There are a ton of mod video's on youtube that show this stuff.
 
Are you saying the trans does not downshift into passing gear at all?

see where the pointer is pointed that is the PTK module for th 3-2 downshift....
 

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mopar madness said:
No passing gear at all, get a flare up 2 to 3rd.
Click to expand...

Line pressure,Trans wear or band adjustments

You might be able to work with it by adjusting the mainline pressure higher.
That might give you kickdown back also.

Is it better when it's cold and worse as it warms up?
Or the other way around?
 
There are some links to factory service manuals around here...might not be the same exact year...but close enough and see what the manual says about adjustments for the KD linkage...
 
It really makes no difference rather its cold or hot, still no kick down. I've adjusted the bands with no luck. I'm going to change the line pressure next and see if that helps. Thanks guys.
 
mopar madness said:
It really makes no difference rather its cold or hot, still no kick down. I've adjusted the bands with no luck. I'm going to change the line pressure next and see if that helps. Thanks guys.
Click to expand...

I was thinking more about the shifting itself when I asked about cold and hot.

Find the measurement for the pressure regulator valve and see if it's somewhat close to stock first.
If it is, then do three full turns counterclockwise on the regulator valve adjuster bolt.

You will have to readjust your TP rod again after, but this should close up that flair and possibly give kickdown back.
 
Put the accumulator spring back in. The damage it can cause from removing it far outweighs any benefit.

This is what John Kunkel wrote about this subject:
"The purpose of that spring is to cushion the shock of the forward clutch application. Many people remove it thinking it improves upshifts but all it does is put extra strain on the forward clutch parts

Oldest myth in the Mopar world....the spring has no affect on any upshifts"
 
Total BS. Only if you do NOT put the blocker rod in does that happen. John Kunkel needs to keep his opinion to himself.
 
depends...

all the trans have the rod in the accumulator....one time I forgot to put the accumulator back in...and I called Joe at Tranzact...he told me with his brake I could hang the accumulator on the rear view mirror if I wanted too...

so I dropped the valve body and put it back in...LOL...Old habits are hard to break...

with Turbo ACtion valve body..I follow their instruction..and use the blocker rod and put the accumulator back in...
 
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