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Re: 727 - pulls motor down on 2-3 shift
[Re: dOoC]
#960920
03/28/11 02:35 PM
03/28/11 02:35 PM
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Joined: Jan 2004
Posts: 13,247
Mt. Vernon, Ohio
dartman366
I Live Here
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I Live Here
Joined: Jan 2004
Posts: 13,247
Mt. Vernon, Ohio
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Quote:
Shift timing is waaay off.
What are the critical specs?
 some time's you have to fudge the band adjustment a little to get it where it want's to be, is the band lever ratio the same as before? try backing off the band adjustment 1/4 to 1/2 turn and see if that help's,,if you tightened up the clutch running clearance then it engages before the band has released fully. 
Light travels faster than the speed of sound,,,this is why some people seem bright untill you hear them speak.
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Re: 727 - pulls motor down on 2-3 shift
[Re: boscosis]
#960922
03/28/11 03:21 PM
03/28/11 03:21 PM
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Joined: Jan 2003
Posts: 75,058
U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,058
U.S.S.A.
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Quote:
Do you guys think it's a valvebody issue?
It's an issue CAUSED by the valvebody.
The 727 walks a very fine line on overlap , which is what you are seeing. The factory went to pains to make it as small as possible, when you increase line pressure, change clutch front pack clearance, change the lever ratio, change band adjustment and change spring count in the front drum you change that oh so delicate shift timing from the factory setting.
Now you have to deal with it. Playing with the band adjustemnt is the easiest way to try to fix it.
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Re: 727 - pulls motor down on 2-3 shift
[Re: boscosis]
#960928
03/28/11 06:15 PM
03/28/11 06:15 PM
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Joined: Jan 2003
Posts: 6,840
The Swamp
Sixpak
master
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master
Joined: Jan 2003
Posts: 6,840
The Swamp
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Quote:
Thanks for the help guys; I'm considering finally building my own 727 along with my brother this time around. I've pulled them apart before but only to salvage parts like drums or planetaries.
What manual/book do you guys recommend that I buy as a first-time "builder"?
One of the best 'books' I ever got came with a complete rebuild kit from Fairbanks transmissions - the instruction manual. Similar kits from B&M, etc. had virtually identical steps in them. I still refer to them when doing my 727's. Go to Mancini's - I think they sell one or more of the popular TF mod books...
http://chucker54.stores.yahoo.net/toatrha.html
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Re: 727 - pulls motor down on 2-3 shift
[Re: Sixpak]
#960931
03/28/11 08:40 PM
03/28/11 08:40 PM
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Joined: Jan 2004
Posts: 13,247
Mt. Vernon, Ohio
dartman366
I Live Here
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I Live Here
Joined: Jan 2004
Posts: 13,247
Mt. Vernon, Ohio
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Quote:
Quote:
Thanks for the help guys; I'm considering finally building my own 727 along with my brother this time around. I've pulled them apart before but only to salvage parts like drums or planetaries.
What manual/book do you guys recommend that I buy as a first-time "builder"?
One of the best 'books' I ever got came with a complete rebuild kit from Fairbanks transmissions - the instruction manual. Similar kits from B&M, etc. had virtually identical steps in them. I still refer to them when doing my 727's. Go to Mancini's - I think they sell one or more of the popular TF mod books...
http://chucker54.stores.yahoo.net/toatrha.html
the two best book's to have and will tell you a boat load of info and they are Torqueflite A-727 Transmission Handbook by Carl H, Munroe and the ATSG manual(automatic transmission service guide), I have both and they are indespensable.  I do 904's but the 727 book still has a lot of pertinate info.
Light travels faster than the speed of sound,,,this is why some people seem bright untill you hear them speak.
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Re: 727 - pulls motor down on 2-3 shift
[Re: dartman366]
#960932
03/28/11 09:55 PM
03/28/11 09:55 PM
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Joined: Mar 2011
Posts: 3,087
Michigan
A727Tflite
master
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master
Joined: Mar 2011
Posts: 3,087
Michigan
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You're not real clear with the problem at hand. You state that the trans almost locks up on the stands on the 2-3 shift, then you state it is lazy on the track. It's not uncommon to get overlap on the stands. What does it do on the track, run away on the 2-3 or overlap on the 2-3. What's lazy mean, it feels like it is slipping or not very quick to respond to the shifter movement? Watch the tach, if it jumps up on the 2-3 that's runaway, if the tach immediately drops and the car noses down on the shift that's overlap. Over lap means the front band hasn't come fully off before the front clutch has come on. Runaway means the band came off before the front clutch came on with sufficient capacity to pull the motor down. Any good valve body (A & A, Turbo Action, etc) out of the box installed in a properly built trans will not be off the mark, the rest is all timing. The number of front clutch springs vs. front band operating ratio and the front band release spring/s makes up the timing. Just the correct combination of parts. Believe it or not, go to the old Direct Connection manual, pick out the front clutch spring combination for your engine size, and match to the front servo release spring stack. You won't be disappointed. Remember, those packages were done by the engineers with only one motivation - make the Mopars as fast as possible.
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Re: 727 - pulls motor down on 2-3 shift
[Re: John_Kunkel]
#960934
03/28/11 10:20 PM
03/28/11 10:20 PM
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Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
BradH
Taking time off to work on my car
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Taking time off to work on my car
Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
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Quote:
Easiest way to cure severe overlap is to place an orifice restrictor in the front clutch feed passage in the case. (circled in red below)
Remove the VB, tap the passage in the case to 1/8"-27 NPT and place a pipe plug with a drilled orifice in the case. I'd start with a .140" orifice.
I think this is what "LAR 414" mentioned doing to help fine tune the 2-3 shift, too. I think I need to try something like this... 
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Put the car up on jackstands and disconnect the shifter cable, start the car and shift the tranny manually from underneath the car at 1500 to 2500 RPM and see if it does the same as before, if not it is the linkage 
