.060" bleed hole in direct drum (CK 4B-22)

[9SECVSIX]

CK Manual 4B-22 Undecided on drilling this hole, the motor is a Stg11 Hyd roller motor capable of 6000+ shifts but for the most part I doubt it will see many, will this bleed hole soften the direct apply under normal conditions

thanks
9sec.

 

[blackplague]

I don't think it's going to be a problem.

Especially if you dual feel the directs. The most important thing is that the spring retainer have ALL THE SPRINGS!! If your not going over the high side of 6500 too often you can get away with not drilling the hole. {in my opinion}

 

[chris718]

the purpose is to reduce centrifucical apply AND burp air out of the circuit.this is more important.

 

[Alky V6]

If a bleed hole must be used, I prefer .030 to .040". Whether it makes a big difference or not, I don't know. I just don't like the idea of bleeding off too much of that precious apply pressure.

 

[9SECVSIX]

Thanks Guys, am still listening. It's going togeather tomorrow, I hope.

9sec.

 

[chris718]

don with all due respect take this into consideration:the bleed is not nearly as large as it seems when you are using the inner and outer areas of the piston to apply the direct clutch .this approximates to roughly 3 times the amount of the area a constant oil volume is fed,verses the stock direct set up using only the small inner piston.the main reasons for the bleed is to remove air in the circuit that accumulates after the third clutch exhausts .this air enters the circuit from the 3rd accumulator checkball which vents off or exhausts pressure into the higher area of the case(where internal components rotate.why the higher area?why when we examine most gm transmissions do they exhaust oil at a higher level than the valve body?because it reduces foaming and its a faster escape route.this works but has small negative side effects.as the oil drains back thru the 3'2 control valve and or seperator plate it pulls the checkball down and draws air in.this air is now present in the circuit.on the next 2/3 upshift this air must be purged before full and multiplied(dual feed)pressure can push on the piston causing the ratio change.if too much air is present a reduced pressure is present.a simple test of blowing air thru a straw will illustrate this.this foamy aerated oil is not as efficient at applying pressure to the piston in comparison to the same volume of oil un aerated.also it takes oil exiting the checkball capsule to pull the ball shut on a ratio change(third clutch apply).by burping the air out at the piston it seats the accumulator ball capsule much faster resulting in better third gear apply.another reason is because we are dual feeding there is so much more oil to exhaust on the 3/2 backshift that the original orificing is not enough.this results in a remaing apply pressure on the third clutch even after the 2/3 shift valve has closed.the hole speeds up the exhaust of residual clutch apply pressure as well.this cause the transmission to remain in third while the band is trying to hold the direct drum from spinning.if the direct clutch drives the drum with the input shaft and the band is supposed to hold it we can see why the partial apply is not good when we need the band wrapped around a staitionary drum.no im not trying to play the professor just thought this would be of some help.

 

[Alky V6]

Thanks Chris. I understand where your coming from. I can only add that I have had zero problems by using a slightly smaller bleed hole. I know 1/16 seems to be the standard size in various trans models, but I have never felt completely comfortable with that large a size and have experimented with smaller sizes all the way down to .030" with no adverse affect. I'm not claiming that one size is better than the other, just adding my experience. Do with it what you will.