Re: Can anyone point me to fluid flow schematics for 727?
[Re: BradH]
#2554122
09/24/18 04:22 PM
09/24/18 04:22 PM
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Joined: Dec 2005
Posts: 11,557 Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
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Fulton County, PA
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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.
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Re: Can anyone point me to fluid flow schematics for 727?
[Re: BradH]
#2554130
09/24/18 04:29 PM
09/24/18 04:29 PM
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Joined: Feb 2003
Posts: 10,208 Someplace you aren't
SomeCarGuy
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I Live Here
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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
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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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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
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Romeo MI
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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
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Re: Can anyone point me to fluid flow schematics for 727?
[Re: BradH]
#2554178
09/24/18 06:38 PM
09/24/18 06:38 PM
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Joined: Jan 2003
Posts: 25,791 Rio Linda, CA
John_Kunkel
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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.
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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
09/24/18 06:45 PM
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Joined: Jan 2003
Posts: 25,791 Rio Linda, CA
John_Kunkel
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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.
The INTERNET, the MISinformation superhighway
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Re: Can anyone point me to fluid flow schematics for 727?
[Re: BradH]
#2554203
09/24/18 08:08 PM
09/24/18 08:08 PM
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Joined: Dec 2005
Posts: 11,557 Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
Joined: Dec 2005
Posts: 11,557
Fulton County, PA
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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.
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Re: Can anyone point me to fluid flow schematics for 727?
[Re: BradH]
#2554215
09/24/18 08:27 PM
09/24/18 08:27 PM
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Joined: Jan 2003
Posts: 27,421 Balt. Md
383man
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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.
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Re: Can anyone point me to fluid flow schematics for 727?
[Re: BradH]
#2554336
09/25/18 02:01 AM
09/25/18 02:01 AM
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Joined: Jan 2003
Posts: 15,439 Val-haul-ass... eventually
BradH
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Taking time off to work on my car
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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... 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...
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Re: Can anyone point me to fluid flow schematics for 727?
[Re: BradH]
#2554346
09/25/18 03:05 AM
09/25/18 03:05 AM
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Joined: Jan 2003
Posts: 27,421 Balt. Md
383man
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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.
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Re: Can anyone point me to fluid flow schematics for 727?
[Re: BradH]
#2554581
09/25/18 05:03 PM
09/25/18 05:03 PM
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Joined: Jan 2003
Posts: 10,022 MN
JERICOGTX
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I Live Here
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Your brain shuts down when there aren't three pedals, doesn't it? FACT.
69 GTX
68 Road Runner
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Re: Can anyone point me to fluid flow schematics for 727?
[Re: BradH]
#2554587
09/25/18 05:11 PM
09/25/18 05:11 PM
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Joined: Dec 2005
Posts: 11,557 Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
Joined: Dec 2005
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Fulton County, PA
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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.
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Re: Can anyone point me to fluid flow schematics for 727?
[Re: BradH]
#2554625
09/25/18 06:12 PM
09/25/18 06:12 PM
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Joined: Jan 2003
Posts: 25,791 Rio Linda, CA
John_Kunkel
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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.
The INTERNET, the MISinformation superhighway
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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
09/25/18 06:54 PM
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Joined: Jan 2003
Posts: 15,439 Val-haul-ass... eventually
BradH
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Taking time off to work on my car
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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... 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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Re: Can anyone point me to fluid flow schematics for 727?
[Re: moparx]
#2558891
10/04/18 02:05 PM
10/04/18 02:05 PM
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Joined: Jan 2003
Posts: 15,439 Val-haul-ass... eventually
BradH
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i too, wonder about those billet accumulator pistons. another question on those. do you run them with springs, or get the one that has the rod on the tip, keeping it up ? I mentioned above in my 09/25/18 12:01 AM post that I'd read a lot of discussions (that's putting it nicely) about using springs, no springs, blocker rods, etc. People have different opinions and approaches. FWIW, I'm going to try a heavy outer spring w/o restricting the piston travel and see how that works for me. "Your results may vary!"
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Re: Can anyone point me to fluid flow schematics for 727?
[Re: BradH]
#2558914
10/04/18 02:40 PM
10/04/18 02:40 PM
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Joined: Jan 2003
Posts: 25,791 Rio Linda, CA
John_Kunkel
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No matter what you do with the accumulator springs you won't feel any difference in the seat of your pants. The only change that's noticeable is blocking the accumulator piston.
The billet piston without the built-in blocker rod does seem like the solution for a problem that doesn't exist.
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Re: Can anyone point me to fluid flow schematics for 727?
[Re: John_Kunkel]
#2558993
10/04/18 06:18 PM
10/04/18 06:18 PM
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Joined: Jan 2003
Posts: 1,544 CT
mrrandyj
pro stock
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pro stock
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Posts: 1,544
CT
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The billet piston without the built-in blocker rod does seem like the solution for a problem that doesn't exist.
I don't think that all the people who have broken a stock plastic accumulator piston would agree with that statement.
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Re: Can anyone point me to fluid flow schematics for 727?
[Re: mrrandyj]
#2559005
10/04/18 06:54 PM
10/04/18 06:54 PM
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Joined: Jan 2003
Posts: 25,791 Rio Linda, CA
John_Kunkel
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You don't need a pricey billet piston to replace the plastic one, a factory cast aluminum one will do.
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Re: Can anyone point me to fluid flow schematics for 727?
[Re: John_Kunkel]
#2559081
10/04/18 09:26 PM
10/04/18 09:26 PM
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Joined: Jan 2003
Posts: 1,544 CT
mrrandyj
pro stock
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pro stock
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You don't need a pricey billet piston to replace the plastic one, a factory cast aluminum one will do. Believe it or not, good used factory cast aluminum accumulators are not as easy to find as they use to be, especially if you need to have a regular supply of them. Chrysler hasn't put them in anything since the 80's (over 30 years). No Cummins powered truck came with the cast aluminum accumulator, no overdrive transmission ever came with the cast aluminum accumulator. The switch to plastic happened before either of those even existed. There is a huge market for people that are building transmissions for Cummins trucks and people building performance overdrive gas transmissions. Most shops that specialize in rebuilding those transmissions wouldn't even reuse the plastic accumulator in a completely stock rebuild. If someone building a transmission thinks that 45 bucks is too "pricey" for a part that is readily available and completely solves a problem that does exist, well, I guess I don't really have an answer for that.
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