Can I run dex6 in my th400.

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Originally Posted By: joegreen
Im still confused about front end play. I have been finding conflicting reports about loading the output shaft towards the front of the case before checking front end play. When i dont have any forward load on the output shaft my front end play is .020". when i do have the weight of the transmission on the output shaft pushing the output shaft towards the front of the trans my front end play is .013". So which is the proper way to check front end play? With the output shaft loaded forward or unloaded?



Both methods work, The method I use is faster & just as accurate.

As your readings indicate....
.020" - .013 = .007" that was already indicated on the rear unit end-play reading.
 
Oh yeah check that out. I see how both ways get the same info now. I'm going to try a thicker washer under the front pump and see what the front end play comes out to be with the output shaft loaded. I'll make sure the pump has enough engagement in the forward drum with these washers too.
 
All of these measurements are with the output shaft loaded forward. I tried to use the larger washer but the front end play came out to be .001". It looks like .013" is the best i can get unless i sand down the thicker washer to get the front end play greater than .001" What do you say. I have no problem sanding down the washer.
 
I started putting all the valves back into the valve body but i am not sure where these two springs go. When i took the valve body apart i individual baggied the components for each bore. Im following the diagram in the atsg manual but im not sure which spring is #331 and which is #329. One of the springs looks like it had blue paint on it and the other looks like it had red paint on it. Maybe it does not matter which one goes in first because they are inline with each other?



Also could you tell me where this valve goes. I dont see it in the atsg manual and there are no spaces left in the valve body for it.
 
Originally Posted By: joegreen
All of these measurements are with the output shaft loaded forward. I tried to use the larger washer but the front end play came out to be .001". It looks like .013" is the best i can get unless i sand down the thicker washer to get the front end play greater than .001" What do you say. I have no problem sanding down the washer.


Sand a washer down to get the minimum .003".
 
Its been so long since i took everything apart but yes i think i remember that valve behind the modulator. Any thought on which spring goes in first and which goes in second? Sorry for so many questions lately i just finished a project that took precedence over this transmission and now im back to working on this again.
 
There are hundreds of calibrations for TH400's, Some don't even use 2 springs in the 2-3 shift valve line-up.

My advice is to install the lighter of the 2 springs at the Inboard position (2-3 Shift Valve Spring), And the heavier of the 2 in the Outboard position (2-3 Modulator Valve Spring)
 
I used some pennies, nickels, and quarters as spacers between the upper most intermediate clutch and pressure plate to determine my clutch pack clearance. The pennies have around .060" thickness. The quarters have around .070" and the nickels have around .075". Ron sessions book said to aim for .075" clearance. I have between .060" and .070" intermediate clutch clearance. Is that a good clearance?
 
Originally Posted By: joegreen
I used some pennies, nickels, and quarters as spacers between the upper most intermediate clutch and pressure plate to determine my clutch pack clearance. The pennies have around .060" thickness. The quarters have around .070" and the nickels have around .075". Ron sessions book said to aim for .075" clearance. I have between .060" and .070" intermediate clutch clearance. Is that a good clearance?


I run a 3 Friction Intermediate set-up at .040"-.050" with Face Grooved Frictions....You are in no danger at .060"-.070" as it's plenty of breathing room for Flat Faced Frictions!

IIRC your running Cellulose Borg Warners?
 
Yes just the plain tan paper Borg Warner flat frictions with one wave Steele and 2 .100" flat steels.
 
I also sanded the pump washer and got front end play to .007" with the output shaft loaded. Had to cut some new lubrication grooves in the washer because the original ones got sanded off. It came out great. Got the washer from .1190" down to .1130". It sanded down quicker than I expected.

 
I found an article from ck performance about rear band adjustment. He showed how to make a tool to check if the rear apply pin length is proper. I just made the tool and it came out great. I bought a spare servo cover just for this.


 
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Im having trouble figuring out how to properly measure what the reverse apply pin length should be. I am trying to follow this article from ck performance http://www.ckperformance.com/Files/112573/Rear%20Band%20Adjustment.pdf. I torque the bolt down to 55inlb like stated. Here are my issues.

1. Ck says that the resting height of the servo piston is approximately .025" below the surface of the servo cover mounting surface on the transmission. My resting piston distance is .032" to .042".

2. Ck says the specification for travel is .125" to .150". I think thats from when the piston is at its resting position to when it is fully applying the band. Right now i have the servo cover on without the metal gasket in place. In the article ck did not have the metal gasket in place. Should i measure the pin travel from rest to applied with the gasket in place?

3. What about the spacer i bought from ck performance http://www.ckperformance.com/View/TH400-LOW-DRAG-REAR-SERVO-SHIM. How does that factor into the apply pin travel specifications.

The way that i measured the apply pin travel was i put the homemade tool cover on and torqued the bolt to 55inlb making the reverse band at maximum apply. I then set up the dial indicator on top of the bolt head and slowly backed the bolt out until i had no more pressure on the bolt and the apply piston was at max relaxed height. I got a measurement of .176" from full apply to relaxed state. Also i made sure that the reverse band was not touching itself when fully applied. I want to be able to set up the reverse pin length to allow me to have the most room for wear of the band surface (use reverse a lot when plowing). I dont want reverse to slip one day because the pin can apply the band any further even though the band still has friction material left on it. If i do need to lengthen the apply pin i can weld it longer and grind it down but would this be a good option. https://www.ebay.com/itm/REVERSE-FIX-EXTENDO-PIN-Servo-Piston-Pin-Extender-Fits-GM-TH400-3L80-4L80E/142419119694?hash=item2128d74e4e:g:aRYAAOSwAO9ZRzBb&vxp=mtr.

I also ended up having to weld a nut to the top off the tool i made because the tapped threads i made stripped out. It is the most horrendous of welding jobs.



 
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.125" is a good target spec for total apply pin travel with NO Gasket or Spacer during the check procedure. You are doing it correctly!

To be completely honest, .176" would run for a while in most cases....... Forever in a light car like my Camaro, Way shorter
amount of time in a hard working plow truck.

What causes the loss of Rear Band apply on TH400/4L80E is the apply piston bottoming out against the case. The machined depth of the piston bore varies from Case to Case.

*Remove the apply pin & cushion spring from the piston.
*Install the piston in the case all the way to bottom.
*Measure & record the depth with a dial caliper. (Mark the point on the Case where your taking the measurement as the the bore is machined at a angle)

*Install the Apply Pin back into the Piston with the Washer & E-Clip. Leave the Cushion Spring & Spring Seat off for this test!
*Install the Piston back in the case along with your test tool, Tighten the check bolt to 55 inch pounds.
*Force the Piston down against the Washer.
*Take another Piston depth measurement at the same spot as before.

Subtract the two readings from each other......This will give you exactly how much piston travel you have before the Piston bottoms out against the case.

The CK spacer just prevents the Band from dragging on the Reaction Carrier which TH400's are notorious for, But can be used with a longer Pin than what would normally be allowed in a stock set-up giving you more "Travel to Bottom" distance.
 
My Piston travel before it bottoms out is .182". Does that sound right. That's the distance from the Piston pin and Piston being tightened to 55inlb and the band at full grab to no pin installed and the Piston all the way bottomed out in the case bore.
 
My Piston travel before it bottoms out is .182". Does that sound right. That's the distance from the Piston pin and Piston being tightened to 55inlb and the band at full grab to no pin installed and the Piston all the way bottomed out in the case bore.
 
Woops double posted. So what does that number actually mean and how is it correlated to my apply pin taking .176" from rest until the band is applied?

I bought a extendo pin for the reverse pin to make it longer. I didn't really feel like welding and grinding on the current pin out in the cold. I can grind this extendo pin if it's too long.
 
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