Pressure question

[Russ Merritt]

Lets get one thing clear first. I've beat this CK stage 2 tranny to death this summer and it still works good!

All tests were done with a mix of Amsoil supershift and Amsoil hydraulic oil.


I am wondering why with a 13 vane pump, 570/400 or 500/296 boost valves, shallow PTS pan and bottom feeder filter the line pressure at WOT will not go over 200psi? Full tv at idle is 245ish cold, 180 hot. Reverse and about 1300 rpm will goto 230ish and no slip. There is no change in pressure with the differant boost valves. I had to block the 1/2 accumulator to get the WOT shift fast enough, I have tried 2 differant CZ valvebodies also. PTS guage too btw. Every now and then it will go to 220 psi part throttle then it will pop back down to 190/200 again.


I have had in the past, trannys that had 280 psi WOT and didn't shift as good as this one does. I was thinking that if I had more pressure, I wouldn't have to block off the 1/2 acc to get the shift right. I know there should be more, I just can't get anymore.


It's getting it's first track time Oct 1st. Like I said, it works pretty good, I just know there should be more pressure.


Don't fix what ain't broke. I can hear it already. I just can't stop playin

 

[chris718]

HEY RUSS.could be that after a certain point the larger boost valve becomes a boat anchor?i personally feel that by opening up the modulatated tv holes in the seperator plate the pressure regulator assembly and its responses to boost valve diameter become less sensitive to boost valve OF THESE SIZE.many oil circuits in a 2004r raise pressure in a fed circuit by allowing a higher volume of oil to act on a valve.i know theory speaks of valve land diameter etc .but anyone who studys the line bias ,accumulator,tv up and down valves,tv limit valve and boost system will start to understand that other factors are at work besides the so called written in stone theories.the tv boost valve exerts a force on the pressure regulator valve which results in an increase in the amount of pressure thatt must be generated to open the valve.and as long as this pressure does exceed the blow off limit of the pressure relief ball a steady increase in pressure should result in the circuit.i bet if you installed a stock seperator plate you would see something different.HOWEVER I WANT EVERYONE TO SEE WHY I FEEL MORE THAN 200 PSI IS IN MY OPINION A WASTE OF TIME.NO NOT A CHEAP SHOT ,JUST A VALID ARGUMENT.the more the boost valve tries to backshift the pr valve the more pressure that is generated in the pump rotor and slide area,mixing decrease oil for the slide and pr valve feed oil .THIS IS WHAT CAUSES THE PUMP ROTOR AND SLIDE TO BREAK IN MOST CASES RESULTING IN TRANSMISSION FAILURE.the 245 you see cold and the 200 hot is a reduction in pressure because of oil viscosity changes and oil bleed off found in all automatic transmissions.it is inherent in the design.more than 240 psi overstresses snap ring and there grooves in clutch drums ,distorts parts and erodes sealing rings and their mating surfaces.

 

[Russ Merritt]

Well I'll say this......... If 200 psi wasn't enough, I'd think it would have died already. Even with all my "parts swapin" tryin other stuff, it still hits em hard WOT. Can't wait for Oct 1st as it will be my first track visit in 2 yrs. Should be a world of differance. I've added a bunch of power, have a good trans in it now, 28" rubber, and ME-R. Can't wait.