4L80E & TH400 Tech.

[kell490]

Reading another wiki on modifications it was suggested one use only half heavy duty return springs and half stock springs in the direct drum? Do you have any thoughts on that I see you already discussed a .30 bleed hole with 5500RPM and higher applications. My assumption is more pressure is needed in the direct drum to over come the heavy duty springs.

[clinebarger]

Did they mention a reason for Half High Rate & Half Stock return springs?

Because, I can't think of one..... I have ran full sets of high rate return springs in Stock Pressure TH400's with no issues, The springs will hold-off the Piston from moving 'til a little more pressure builds, Resulting in a later but Quicker shift. Buy later, I talking 100th's of a second.

With used stock spring, They could have millions of cycles on them, I testing several sets on my Valve Spring Checker, Set right before coil bind....The weights were all over the place, Springs from CK, ATI, & Hughes are very uniform in weight, Trans Go spring are OK but have the most variance in weight out of the aftermarket springs I tested.

You could use the Half & Half method & probably be OK as long as they are staggered (1 High Rate, 1 Stock, & so on)

Builders have their own practices & beliefs, Some of this stuff can not be proven in a conventional way, We do one mod, Test the trans, Tear it down 100-300 passes later & assess the situation.

The Bleed hole is a secondary guard from centrifugal apply at high RPM, & a faster release on "Detent" Downshift, & "Forced" Downshift.