I have a couple of the inner/upper accumulator springs that IIRC came out of motorhomes with big blocks. I've been wondering if there's a useful application for them, I'm thinking like a "soft" blocker rod? I don't remember now, but is it one spring or the other, or did they install both? I do, and will, always use the lower spring, however. Would using the upper spring have any effect on 1-2 shift timing? I'm thinking it would be negligible, but thought I'd ask anyway.

The outer spring between the piston and the VB has no affect on any upshift, it's sole purpose is to cushion the application of the rear clutch and, therefore, should always be used. The purpose of the inner spring in the piston is a mystery to me, it might have a minor affect on the 1-2 upshift...I always toss it.

Some of the later outer springs (on right below) have so little tension (you can completely coil bind them between your thumb and forefinger) they're almost useless as a spring.

Since reading your explanation (years ago) about the function of the lower spring, I've always installed them. Sometimes I have to find one to put back in a trans when it's missing. I'd never seen the longer lower spring until I rebuilt a '65 904 a few months back.

so what does tossing the spring[s] and using a blocker rod inside the accumulator piston really do, and are there any side effects that will help wear the transmission guts prematurely ?

Blocking the accumulator effectively cancels its function. It's function is to cushion the initial application of the rear clutch by a spring and to cushion the 1-2 upshift hydraulically. Side effects can be a rear clutch Belleville failure and/or a front planet spline failure.

thanks John !

Here' s an older thread that touches on the same subject: https://board.moparts.org/ubbthread...me-to-fluid-flow-schematics-for-727.html

I ended up going w/ the Sonnax spring shown here - https://www.ctpowertrain.com/sonnax-new-hd-enhanced-performance-valve-body-accumulator-spring/

Even though Sonnax doesn't list it specifically for Chryslers, CT Powertrain says it's an option... so I used it. I don't have enough time on the car since we got it running to say how it works one way or another right now.

I put in a Sonnax billet accumulator piston at the same time, FWIW.

That's kinda like the one that came with the Transgo TFOD-HD2 kit i put in a 518. This one doesn't look quite as heavy though. The instructions also said to install the upper spring (if there was one), so I did.