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#1505644 - 09/22/13 05:20 AM 727 - Air Check - Not Going Well?
80fbody Offline
mopar

Registered: 10/25/06
Posts: 462
Loc: Mass.
Been trying to get this BB 727 together, 1st build as I mentioned in a previous post. I'm just not happy with the "air check" on the front pack. I've tried it just on the pump & now twice bolted together. I just pulled it apart & changed the inner seal on the pack again. Lips are down.

At about 35 psi the rear pack has a good "thump" & then bleeds down. Now the front does have an okay "thump" but holds absolutely no pressure. It comes out as fast as it's going in. Tried to take a video of the "air check". Never tried to video with the phone before.

I did replace the complete pump (rebuilt unit) with the hopes it was just something there but no luck.

Would you tear it back down or close it up & hope it's ok?
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1980 RoadRunner 360,4 speed,4:10 ---------------- 1968 Dart 451/727/4:30

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#1505645 - 09/22/13 08:22 AM Re: 727 - Air Check - Not Going Well? [Re: 80fbody]
MR_P_BODY Online   content
Master

Registered: 06/13/03
Posts: 44373
Loc: Romeo MI
Tear it back down... you have some issues
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#1505646 - 09/22/13 08:31 AM Re: 727 - Air Check - Not Going Well? [Re: 80fbody]
Cheatham Offline
enthusiast

Registered: 08/10/09
Posts: 386
Loc: corpus christi tex
have you tried to prime the port with a little tranny fluid then air check it ?

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#1505647 - 09/22/13 08:50 AM Re: 727 - Air Check - Not Going Well? [Re: Cheatham]
Joesixpack Offline
master

Registered: 01/21/03
Posts: 9920
Loc: Joliet IL
if it was me i would have a pro trans builder check it out first,its not worth it to install it and have problems, and face this sight on your back on a creeper....dont ask me how i know...


Attachments
7861380-904004.JPG (51 downloads)


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#1505648 - 09/22/13 10:41 AM Re: 727 - Air Check - Not Going Well? [Re: Cheatham]
80fbody Offline
mopar

Registered: 10/25/06
Posts: 462
Loc: Mass.
I just tried to prime the ports with ATF but no luck. Also put another set of front clutch seals in & put it back together. No change. So what else could cause a severe air leak? Couple things. I bought this as a supposed running core a few years ago. Was not in very good shape when I opened it up. Had water damage in it but did seem to clean up ok. It's stamped 3674, i believe, which I translated to a 1971 core. That's what I've been ordering parts for.

I know some changes were made around 70-71. Is there anything there that could be screwing me up? Did any sealing rings change slightly, etc? I can mic it up if you guys have any direction.

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#1505649 - 09/22/13 12:23 PM Re: 727 - Air Check - Not Going Well? [Re: 80fbody]
J_BODY Offline
master

Registered: 04/30/03
Posts: 9194
Loc: aZLiViN
Not following you on "air checking with the pump". I've always air checked using the ports toward the top of that pict with the valve body removed.

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#1505650 - 09/22/13 12:36 PM Re: 727 - Air Check - Not Going Well? [Re: J_BODY]
rickraw Offline
pro stock

Registered: 10/29/10
Posts: 1578
Loc: Ambridge, Pa.
Since we can't see any of ur parts, might be time have a builder check things out. U could have nicked a seal or have installed the incorrect one. u never know.

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#1505651 - 09/22/13 12:43 PM Re: 727 - Air Check - Not Going Well? [Re: rickraw]
Joesixpack Offline
master

Registered: 01/21/03
Posts: 9920
Loc: Joliet IL
air check


Attachments
7861579-904008.JPG (50 downloads)


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#1505652 - 09/22/13 12:43 PM Re: 727 - Air Check - Not Going Well? [Re: Joesixpack]
Joesixpack Offline
master

Registered: 01/21/03
Posts: 9920
Loc: Joliet IL
4 areas to air check


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7861582-904013.JPG (43 downloads)


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#1505653 - 09/22/13 06:44 PM Re: 727 - Air Check - Not Going Well? [Re: Joesixpack]
dartman366 Offline


Registered: 01/18/04
Posts: 12191
Loc: Mt. Vernon, Ohio
Could of rolled a lip seal in the high gear drun during assembly, some times they can be a real bear trying to get the seal past the clutch plate/disc retaining ring groove.
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#1505654 - 09/22/13 06:47 PM Re: 727 - Air Check - Not Going Well? [Re: dartman366]
Doc Fiberglass Offline


Registered: 07/04/08
Posts: 17475
I always used to use lots of ATF ....

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#1505655 - 09/22/13 08:10 PM Re: 727 - Air Check - Not Going Well? [Re: Doc Fiberglass]
80fbody Offline
mopar

Registered: 10/25/06
Posts: 462
Loc: Mass.
I just cleaned all the vasaline type assembly lube off the lip seals & re-assembled. Now that I've also learned I can install only the front clutch on the pump & air-check it's so much easier to see what's going on. Definitely better this time.

Going to get all new lips seals tomorrow & only use ATF on them this time. I think it may just give a better feel on the air-check.

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#1505656 - 09/22/13 08:58 PM Re: 727 - Air Check - Not Going Well? [Re: 80fbody]
dvw Offline
master

Registered: 03/16/06
Posts: 4679
Loc: MI, usa
There are only 2 points of leakage when air checking with the pump. The seals on the piston and the large diameter rings on the reaction shaft (back side of the pump) that seal the pump to the drum. Are there grooves inside of the drum where they ride? If the drum is worn, they're cheap. I just bought a new Dorman drum at my supplier Thursday for $32. That being said the front clutch is always lazier during air testing than the rear drum. And yes it's easier to air check with the pump rather than assembling the unit.
Doug

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#1505657 - 09/22/13 09:28 PM Re: 727 - Air Check - Not Going Well? [Re: dvw]
80fbody Offline
mopar

Registered: 10/25/06
Posts: 462
Loc: Mass.
You know, that's it. It's lazyier than the rear clutch. That sums it up. Guess I really don't have an issue. Not knowing how it "should" act is my biggest problem. The drum isn't grooved & the rings fit nice. With new lip seals, I'm going to run it.

Thanks, that really eases my mind.

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#1505658 - 09/22/13 10:23 PM Re: 727 - Air Check - Not Going Well? [Re: dvw]
jamesc Offline
master

Registered: 01/20/03
Posts: 5869
Loc: communist bloc of new jersey
Quote:

I just bought a new Dorman drum at my supplier Thursday for $32.




can you elaborate on that?
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