How much HP to break stock input shaft vs billet input.

Big Blue24

Big Blue24

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Jan 5, 2008
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Since I have my stock 47rh 2wd transmission apart, I figured now is a good time to measure the shafts and figure out how strong they are.

Stock input measured 0.978"

Stock output measured 1.17"


How much power does it take to break a stock input shaft?
How much power does it take to break a billet input shaft?

Judging by the output shaft's size, I doubt it will ever break.
 
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You're going to have a hard time getting traction to hurt the output.

And remember, horsepower doesn't break stuff... torque does
 
i busted my stock input making somewhere between 440-470ish rwhp. Took out alot of pieces with it too. Like converter, pump and direct drum.
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It's a little hard to even put a hp number on what a shaft will hold. I've seen stock inputs break in stock trucks and I've seen them last in 600hp trucks. My stock input held up to locked to 4wd 1st-4th gear shifts while drag racing.
 
A big variable is the vehicle weight too. My truck weighs sub 5000lbs v. the opposite end of the spectrum like a mega cab at 8000lbs+.
 
If you can afford, I would do a billet flexplate, and billet input shaft, maybe a billet intermediate also. It is usually the last to break, but when it does if it does, it could take out the whole tranny, which will be costly compared to 700 or 800 for the intermediate shaft. I only did the input and output on my 4x4 but if my intermediate shaft ever breaks my truck might be sitting for a month.
 
If you have it apart make the investment now with a better flexplate and billet input.
 
Good friend of mine snapped his billet input in his 48re at 700+. Stock output survived.
 
haloman said:
If you have it apart make the investment now with a better flexplate and billet input.
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What he said.

Rip at Source Automotive has a nice laminated flexplate for a good price, and Opies input.
 
Forrest Nearing said:
And remember, horsepower doesn't break stuff... torque does
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Remember this...

BFD99 said:
i busted my stock input making somewhere between 440-470ish rwhp. Took out alot of pieces with it too. Like converter, pump and direct drum.
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Seems as though I've seen/heard of more stock 48re inputs shattering like what yours did than I've heard about the older ones doing that. Not saying the older ones won't shatter, but they seem to break more cleanly and don't cause as much colleratal damage.

Or maybe I've just been living under a rock?
 
ya opies input ftw definately. i busted my stock input at about 525hp but in a mega cab dually doin full throttle runs playin w a 12v powered suburban. garmon gave me a great price prob because i sent a good 5 grand his way last year lol.
 
My stock output broke at 438hp rest of the tranny was billet. of course i was trying to launch at 25psi in 4wd...
 
I just broke my billet input @ 600ish HP towing 22K cruising up a hill @ 75-80mph... Its been in the truck for 5yrs. and 140K miles, 230 1/4mi. passes. plus a lot of street play.

Didn't expect it to break but it did take a beating...

Im getting Opie's new shaft and well see what happens.

Lavon
 
So the Sonnax billet shafts are garbage. What about the TCS? If Opie has the best shafts and they're only a hundred or so more, sounds like the right place to buy my billet input.
 
I'm putting my 4th input in right now. I've broke 2 ATS billet inputs, and 1 Suncoast. This time I'm going to try an opie shaft. It's not so much about how much power will break a shaft, it's about how much abuse. Shafts don't like shock.
 
Big Blue24 said:
So the Sonnax billet shafts are garbage. What about the TCS? If Opie has the best shafts and they're only a hundred or so more, sounds like the right place to buy my billet input.
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i would say call around for sure, but garmons price was really low. that fella moves some hardware! he also laughed when i called and told him i broke it, he remembered me ordering his triple disk converter 5 months previous.
 
Local trans builder know throught surrending states for race trans told me sonnex is 100% better than factory but they use the term billet very lose scary part is most places seem to use and sell sonex im thinking of going the opus route but despite several pm and emails I never herd from them.
 
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