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727 build up #1657063
08/10/14 03:45 PM
08/10/14 03:45 PM
Joined: Jun 2004
Posts: 378
bc canada
6
67valiant Offline OP
enthusiast
67valiant  Offline OP
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bc canada
looking at going to a trans brake what should I swap out to make it better right now its 100% stock car is lite 3000 with me in it I have a spare one with good steels and clutches but never seen any diff in times over the 15 years of running the car I swap them out every 2 years so I can go through them just to make sure theres no prob with them

Re: 727 build up [Re: 67valiant] #1657064
08/10/14 03:52 PM
08/10/14 03:52 PM
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Posts: 5,744
Ontario, Canada
Dodgem Offline
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Ontario, Canada
Ultimate sprag and billet front drum for sure and a shield or blanket and a steel gear set would be advisable.

Re: 727 build up [Re: Dodgem] #1657065
08/10/14 04:07 PM
08/10/14 04:07 PM
Joined: Jun 2003
Posts: 52,968
Romeo MI
MR_P_BODY Offline
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Romeo MI
Quote:

Ultimate sprag and billet front drum for sure and a shield or blanket and a steel gear set would be advisable.





I'm not gonna tell you how to spend your money but isnt
the Ultimate sprag a blow proof sprag.. if so then why
the billet drum... I dont run either but I do have the
bolt in sprag which isnt blow proof but I dont pedal
it in low gear to break it.. if I spin or start to
loose it I shift.. thats the only time you can break
the sprag(in low gear)... but to the OP.. you have to
change the vent location to the tailshaft for the
trans brake

Re: 727 build up [Re: MR_P_BODY] #1657066
08/10/14 08:44 PM
08/10/14 08:44 PM
Joined: Jan 2003
Posts: 23,250
Rio Linda, CA
John_Kunkel Offline
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No such thing as a "blow proof" sprag.


The INTERNET, the MISinformation superhighway
Re: 727 build up [Re: John_Kunkel] #1657067
08/10/14 09:15 PM
08/10/14 09:15 PM
Joined: Nov 2005
Posts: 655
Kokomo, IN
540dust Offline
mopar
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Posts: 655
Kokomo, IN
Yes any driveline failure in low gear can kill any sprag. I just replaced one of the best premium sprags available after a wheelstanding ring and pinion failure and it was absolutely trashed. But there is no question the premium sprags are stronger than the stock units which some of the cheaper bolt in units are (stock with a bolt in cam). The first rule is run a blanket or good shield, second rule is after any driveline failure take it out and check the sprag. After that it becomes opinion but my opinion is billet drum, premium sprag, and steel front planet set.

Re: 727 build up [Re: 540dust] #1657068
08/10/14 09:29 PM
08/10/14 09:29 PM
Joined: Jun 2003
Posts: 52,968
Romeo MI
MR_P_BODY Offline
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While I understand what you guys are saying..IF you
DONT pedal a car it WONT blow the sprag.. if you loose
traction on a 727 its a useless run(either in TT or
finals).. if you want to get back on it SHIFT before
you get back at it.. it will only blow in low

Re: 727 build up [Re: MR_P_BODY] #1657069
08/10/14 09:45 PM
08/10/14 09:45 PM
Joined: May 2003
Posts: 12,882
aZLiViN
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J_BODY Offline
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aZLiViN
Break a few ring gear teeth, shock the driveline, you can roll a sprag.... and the drum can explode. Friends low 11 sec car did just this. We didn't know what caused it until we tried the pull the axles out of it and they wouldn't come out. Couple years later we saw another car break an 8.75 on the launch. The guys were going to throw a set of gears in it and go. Convinced them to pull the trans...where they found the sprag was a mess. Does it always happen? nope... prior to my friends car exploding I had broken a set of gears, and we put in another set and away we went... knowing what I know now there is no chance I'd do that again without a teardown and inspect.

Re: 727 build up [Re: J_BODY] #1657070
08/10/14 09:55 PM
08/10/14 09:55 PM
Joined: Jun 2003
Posts: 52,968
Romeo MI
MR_P_BODY Offline
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Quote:

Break a few ring gear teeth, shock the driveline, you can roll a sprag.... and the drum can explode. Friends low 11 sec car did just this. We didn't know what caused it until we tried the pull the axles out of it and they wouldn't come out. Couple years later we saw another car break an 8.75 on the launch. The guys were going to throw a set of gears in it and go. Convinced them to pull the trans...where they found the sprag was a mess. Does it always happen? nope... prior to my friends car exploding I had broken a set of gears, and we put in another set and away we went... knowing what I know now there is no chance I'd do that again without a teardown and inspect.




I've broke rear gears before.. if you DONT get back on
it, it wont blow.... I've run a 727 for about 45 years
and NEVER blew a drum... it has to have the momentum
to trash the sprag... I wont bother arguing about
this.. but there have been 100s of thousands of passes
with limited explosions due to hitting the power again

Re: 727 build up [Re: John_Kunkel] #1657071
08/10/14 09:56 PM
08/10/14 09:56 PM
Joined: Oct 2003
Posts: 7,506
Az
Crizila Offline
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Crizila  Offline
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Az
Quote:


No such thing as a "blow proof" sprag.


Is there considerable strength difference between 3 and 4 gear planets?


Fastest 300
Re: 727 build up [Re: 67valiant] #1657072
08/11/14 11:54 AM
08/11/14 11:54 AM
Joined: Jan 2003
Posts: 16,690
Western NC
440Jim Offline
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440Jim  Offline
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Posts: 16,690
Western NC
Quote:

looking at going to a trans brake what should I swap out to make it better



  • Aftermarket front drum (aluminum or steel) - safety item
  • Plug front vent and relocate. Griner valve body instructions have a good location.
  • Either put a relief hole (1/16") in the front drum pressure cavity, or the front piston.
  • Heavy Duty or reinforced front servo strut (front band).
  • 15 springs in the front clutch (many stock are 9)
  • I like the "ported" reaction support between the large rings. See CRT web site, etc.
http://www.tciauto.com/tc/fileupload/download/download/?d=0&file=custom%2Fupload%2F121900.pdf

Re: 727 build up [Re: 440Jim] #1657073
08/11/14 01:38 PM
08/11/14 01:38 PM
Joined: Jan 2003
Posts: 16,690
Western NC
440Jim Offline
I Live Here
440Jim  Offline
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Western NC
Reaction support between large rings modified for flow.

Re: 727 build up [Re: Crizila] #1657074
08/11/14 07:13 PM
08/11/14 07:13 PM
Joined: Mar 2006
Posts: 9,038
MI, usa
dvw Offline
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Quote:

Quote:


No such thing as a "blow proof" sprag.


Is there considerable strength difference between 3 and 4 gear planets?



I've never seen a planet gear itself break. The carrier or the roller bearing yes. The gear itself is not the weak point. The 3 gear style live fine in my 64, 9.20s@147. In fact I've seen old S/S trans with only 2.

Doug

Re: 727 build up [Re: Crizila] #1657075
08/12/14 05:07 PM
08/12/14 05:07 PM
Joined: Jan 2003
Posts: 23,250
Rio Linda, CA
John_Kunkel Offline
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Posts: 23,250
Rio Linda, CA
Quote:

Is there considerable strength difference between 3 and 4 gear planets?




The weak point in the aluminum planetaries is the spline in the front planetary but there is more spline contact in the 3-pinion than the 4-pinion so the strength is a tossup between the two stockers.

It's rare to see the gear itself fail but it does happen.

8238070-brokenpinion.jpg (127 downloads)
Re: 727 build up [Re: John_Kunkel] #1657076
08/12/14 05:19 PM
08/12/14 05:19 PM
Joined: Jun 2003
Posts: 52,968
Romeo MI
MR_P_BODY Offline
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Posts: 52,968
Romeo MI
Quote:

Quote:

Is there considerable strength difference between 3 and 4 gear planets?




The weak point in the aluminum planetaries is the spline in the front planetary but there is more spline contact in the 3-pinion than the 4-pinion so the strength is a tossup between the two stockers.

It's rare to see the gear itself fail but it does happen.




In your pic there is some longer flatish steel strip
type material... where did that come from.. my buddy
had a 700r4 quit(all gears) and he has something
like those strips of L shaped sorta straight steel..
he didnt see anything on a quick tear down but didnt
take the sub assemblies apart yet.. sorta looks like
a torrington bearing housing

Re: 727 build up [Re: MR_P_BODY] #1657077
08/12/14 08:39 PM
08/12/14 08:39 PM
Joined: Jan 2003
Posts: 23,250
Rio Linda, CA
John_Kunkel Offline
Too Many Posts
John_Kunkel  Offline
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Joined: Jan 2003
Posts: 23,250
Rio Linda, CA
There's a thrust washer at each end of the gear, could be one of them after it's been run through the remaining gears.

When you get hit in the butt with a buzzsaw it's kinda hard to know which tooth gotcha first.







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