727 build up

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

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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

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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.

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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

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No such thing as a "blow proof" sprag.

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

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• 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

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No such thing as a "blow proof" sprag.

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

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

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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.

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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