4L60bliss

On your website, you have listed for the 700R-4 rebuild kit:
Is this a spring for the 1-2 accumulator housing? Is it a spring for the accumulator valve? What is it?

Pro Built Automatics

Over the years in the 700R4/2004R, the 2nd gear accumulator (in the valve body) has had different letter codes. From (firm to soft) "B", "A", "N", "M", "L", "K", "J", "K". This letter is found on the 2nd gear accumulator bushing. Most 700R4's in 1988 & later have the "B" accumulator in them. Back in 1995, Gil at Trans-Go recommended using the "M" valve for all HD & Performance applications using the Corvette servo and the large .500 main boost valve to retain nice part throttle shifts. Problem was that the "M" valve was very hard to find, so in 1996 I had Sonnax make the "M", "L", & "K" valves. Sonnax did not release these valves until late 1999, in the mean time Gil solved the 1-2 part throttle bang shifts & released this fix for the 700R4 in his Trans-Go Shift kit & Junior Shift kit by going to a double spring accumulation setup to use the "B" or "A" accumulator valve along with the Corvette servo and large main boost valve. Gil supplied 3 new springs for the "B" or "A" accumulator valve to fine tune the part throttle 1-2 shifts. This setup allows nice part throttle (no-bang) 1-2 shifts, and still retain the WOT firm shifts. I use this setup in all my HD & Performance applications. I have since added the Trans-Go accumulation setup to my HD & Performance rebuild kits. I need to update the website about this. The "M" accumulator valve from Sonnax is still available if desired.

4L60bliss

Isn't that backwards? Why would have have them make the "M, L & K" if those are the softest?

When you say "double spring", you mean like whats in the 1-2 accumulator housing of a '94+ 4L60-E?

Jay 727

Because it is more desirable to have soft part throttle shifts and maintain firm wot shifts.

Pro Built Automatics

Yes, the 4L60EHD2 from Trans-Go has the same 2 spring setup that I use in the 700R4.