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Old 07-15-2016, 11:14 PM   #94
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Join Date: May 2009
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Posts: 6,255
Re: 4L80E & TH400 Tech.

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.
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