I just finished my automatic transmissions class at University of Northwestern Ohio in which I started a rebuild on a 200-4r. I understand how the pressure regulator and pump itself works but I was never able to get a good explaination of how the volume of the pump is changed I know the mechanics of how the fluid works against the slide to change the volume but where does it come from? What in the valve body issues the increase/decrease volume command? Is it similiar to how the pressure regulator works with boost valves? Does the tv cable factor into the equation? Why does the tranny need independant control of pressure and volume? Is it all in the name of efficiency? Does the pump ever pump a high volume of fluid with the regulator at low pressures or does it work high voulme/pressure or low volume/pressure? I think it works as the later becuase the p/r works by controlling the volume of fluid that turns into mainline pressure. Am I right? Sorry if your heads are spining now.

------------------
82 z28 350cid, vortec heads, comp 262h cam, Holley 600cfm carb, 2in twice pipes, MSD ignition, turbo 350 trans, 3.73 posi, manly b&m megashifter

 

What no replies! I thought this was common knowledge. LOL

------------------
82 z28 350cid, vortec heads, comp 262h cam, Holley 600cfm carb, 2in twice pipes, MSD ignition, turbo 350 trans, 3.73 posi, manly b&m megashifter

 

Sorry grasshopper, I'm in the middle of doing my exhaust. If I had some time to read the books I would give you some inputs. However everything in a automatic isn't about efficiency - thats a givin. Hince the aftermarkets with shiftkit etc...

Ron C. Terry


------------------
'82 Trans Am
'81 Camaro Z-28
'94 Vette LT1 Coupe

 

OK, off the top of my head, the pump is a variable displacement much like the V5 A/C compressor used in many GM FWD cars. There is a "pump slide" that houses the rotor and the vanes. The pump slide is spring loaded to stay one way. There are two valves that make the pump slide move. the TV boost (relative to throttle position) and the reverse boost (wich is activated in R, 2 and 1) Either one of these valves will cause the pump slide to move, changing the displacement of the pump. Like I said, the pump slide is spring loaded to stay at "MAX" pressure. when the TV boost or REV boost valve allow pressure past them, it is called "decrease fluid" and will compress the pump slide spring allowing the pump slide to reduce displacment and therefore less pressure. Make sense?

------------------
If you live in Southeastern US, check us out!
South East Thirdgen


ASE Master Tech + L1
Savannah, GA

'87 Trans Am
S/D TPI retrofit including functional PassKey, 22# injectors,
JET AFPR, Ported Plenum,
TB Coolant Bypass,
SSM SFC, Boxed LCAs,
8mm Accel wires,
Flowmaster Exhaust,
16" GTA rims,
Corvette Servo,
KYB Shocks
-->14.97 @ 94.9 MPH<--

'97 Bonneville SSE