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Can anyone point me to fluid flow schematics for 727? #2554103
09/24/18 03:07 PM
09/24/18 03:07 PM
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BradH Offline OP
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I've tried to find something using The Google, but am not seeing any fluid flow charts like I recall seeing in the old factory service manuals. In particular, I'm looking to see how the various trans settings change what's happening with the accumulator. Thanks - Brad

Re: Can anyone point me to fluid flow schematics for 727? [Re: BradH] #2554122
09/24/18 04:22 PM
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CMcAllister Offline
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I have a '73 manual here with those charts. Of course it's all based on a stock trans. The accumulator basically acts as a cushion for the front servo to soften the 1-2 shift. On a stock unit the pressure controls in the valve body and the governor also influence that shift firmness.


If the results don't match the theory, change the theory.
Re: Can anyone point me to fluid flow schematics for 727? [Re: BradH] #2554130
09/24/18 04:29 PM
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SomeCarGuy Offline
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Try 69roadrunner.net

They had a full pdf of the 69 service manual. Full color iirc. Those manuals have the circuits in them.


You might have to register to see the forum that was in. Been a few years since I was a regular there. Seems that was how that went.


I want my fair share
Re: Can anyone point me to fluid flow schematics for 727? [Re: SomeCarGuy] #2554145
09/24/18 05:00 PM
09/24/18 05:00 PM
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You want to buy the 727 bible(its out in my
shop) but I forgot the author.. but I think
his name is Monroe
wave

Re: Can anyone point me to fluid flow schematics for 727? [Re: MR_P_BODY] #2554158
09/24/18 05:39 PM
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Nukechargerboy Offline
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Carl Munroe. that book is a great teaching aid and will guide you through a complete rebuild. Has all the flow diagrams.

Re: Can anyone point me to fluid flow schematics for 727? [Re: BradH] #2554160
09/24/18 05:42 PM
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AndyF Offline
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The FSM has the best pictures I've ever seen. Do you not have a FSM for your car?

Re: Can anyone point me to fluid flow schematics for 727? [Re: BradH] #2554178
09/24/18 06:38 PM
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There were two incarnations of the accumulator, '60-'70 and '71-later. On the pre-'71, line pressure acts on only two surfaces of the accumulator piston but, starting in '71, a new fluid circuit was added that is controlled by the new 1-2 Shift Control Valve.

In all configurations, the outer accumulator spring serves only to cushion the application of the front clutch and has no function on any upshift. On the 1-2 upshift the fluid pressure acting on the piston offers resistance to the piston's movement and provides a cushioning effect.

These pics are of the early piston location in both 1st (top pic) and 2nd (bottom pic); the blue fluid is line pressure.

Early Acc 1st.PNGEarly Acc 2nd.PNG

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Re: Can anyone point me to fluid flow schematics for 727? [Re: John_Kunkel] #2554181
09/24/18 06:45 PM
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These are of the late piston locations in 1st (top pic) and 2nd (bottom pic); again, blue is line pressure the green striped fluid is from the 1-2 Shift Control Valve. The fluid pressure from the 1-2 Shift Control Valve offers a variable resistance to the piston's movement and, therefore, cushions the shift in proportion to the throttle opening.

Late Acc 1st.PNGLate Acc 2nd.PNG

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Re: Can anyone point me to fluid flow schematics for 727? [Re: AndyF] #2554198
09/24/18 07:53 PM
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Originally Posted By AndyF
The FSM has the best pictures I've ever seen. Do you not have a FSM for your car?


Exactly, I though everyone who rebuilt there own transmissions had one. LOL



The pictures have been edited to show right, takes a bit of time for the edit to kick in.

Re: Can anyone point me to fluid flow schematics for 727? [Re: BradH] #2554203
09/24/18 08:08 PM
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CMcAllister Offline
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Yes, multi years of factory manuals, Monroe's book, the ATSG book, etc., but with a manual valvebody and a race setup, much of that goes out the window.


If the results don't match the theory, change the theory.
Re: Can anyone point me to fluid flow schematics for 727? [Re: BradH] #2554215
09/24/18 08:27 PM
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Also on the old and newer style line pressure is not applied to the larger spring side of the accumulator until it shifts into second gear. Ron

Last edited by 383man; 09/24/18 08:28 PM.
Re: Can anyone point me to fluid flow schematics for 727? [Re: BradH] #2554336
09/25/18 02:01 AM
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BradH Offline OP
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My case is a '70, so it's the early accumulator.

I read a WHOLE BUNCH of threads from here and other forums with the debate over using a spring (outer and/or inner), running no spring, running no spring plus modifying the piston to remain fixed in the "extended" config... catfight

It got me wondering if running a stiff outer spring would allow for keeping the "shock absorption" feature when applying the rear clutch, while also providing some mechanical assistance with the line pressure to reduce the time for the piston to top out into the case when the front servo is applied. Or, maybe some combination of outer spring and reduced -- not completely blocked -- piston travel.

Kind of thinking out loud on this... work

Re: Can anyone point me to fluid flow schematics for 727? [Re: BradH] #2554346
09/25/18 03:05 AM
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Many run them different ways to their liking. Myself I run no springs and block the piston so it wont move. But I like a harsh shift all the time. Not all are like me though. Course I always run manual valve bodies in my hotrods also as I like to shift them when I want to. Ron

Last edited by 383man; 09/25/18 03:06 AM.
Re: Can anyone point me to fluid flow schematics for 727? [Re: 383man] #2554450
09/25/18 12:45 PM
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BradH Offline OP
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Re manuals, I have both a 1973 FSM and the late Carl Munroe's book (he passed away in 2012). However, I had to dig them up since, like so many things of mine, they got stuffed in some obscure place and were not readily at hand.

The FSM flow diagrams are IMO a bit better than Munroe's book. The '73 FSM TF-727 diagram shows the '71-up version (obviously), but I believe the TF-904 flow diagram shows the same as the pre-'71 since it doesn't incorporate the flow control valve / part-throttle circuit.

Re: Can anyone point me to fluid flow schematics for 727? [Re: BradH] #2554474
09/25/18 01:50 PM
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I think this is it.

btop-dreams-how-an-automatic-transmission-works-power-loss-crushing-5488059.png

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Re: Can anyone point me to fluid flow schematics for 727? [Re: JERICOGTX] #2554573
09/25/18 04:51 PM
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BradH Offline OP
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Your brain shuts down when there aren't three pedals, doesn't it? grin

Re: Can anyone point me to fluid flow schematics for 727? [Re: BradH] #2554581
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Originally Posted By BradH
Your brain shuts down when there aren't three pedals, doesn't it? grin


FACT.


69 GTX 68 Road Runner
Re: Can anyone point me to fluid flow schematics for 727? [Re: BradH] #2554587
09/25/18 05:11 PM
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Blocking the accumulator up has always been a basic thing to do in a performance trans for me. That alone makes the shift "firm", I don't know if I would call it harsh. Clutch and band materials, valve body mods, clearances, lever ratio, fluid choice, etc., also contribute to shift feel.


If the results don't match the theory, change the theory.
Re: Can anyone point me to fluid flow schematics for 727? [Re: BradH] #2554625
09/25/18 06:12 PM
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Originally Posted By BradH


It got me wondering if running a stiff outer spring would allow for keeping the "shock absorption" feature when applying the rear clutch, while also providing some mechanical assistance with the line pressure to reduce the time for the piston to top out into the case when the front servo is applied. Or, maybe some combination of outer spring and reduced -- not completely blocked -- piston travel.


You're thinking correctly; the stiffer the outer spring, the more cushioning for the rear clutch apply and the presence of the spring does help make a quicker (firmer) shift. The factory used a variety of outer springs, some so weak that even a geriatric like me can compress one to coil bind with two fingers.

Reduced piston travel would mitigate the cushioning effect so it would be counterproductive.

Accumsprings.jpg

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Re: Can anyone point me to fluid flow schematics for 727? [Re: John_Kunkel] #2554661
09/25/18 06:54 PM
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Originally Posted By John_Kunkel
Originally Posted By BradH


It got me wondering if running a stiff outer spring would allow for keeping the "shock absorption" feature when applying the rear clutch, while also providing some mechanical assistance with the line pressure to reduce the time for the piston to top out into the case when the front servo is applied...


You're thinking correctly...

shock

Source(s) for springs from which to select? I don't have anything in my trans parts boxes that appears to be an accumulator spring, and suspect there won't be one hiding under the valve body when I pull it, either.

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