how much loss through a 9"?
how much loss through a 9"? Hey guys, I'm going with a 9" ford for brute strength, however I do know they aren't the most efficient rear ends available. What kind of power loss (parasitic) can I expect going from a 10 bolt with 4.10's to a 9" with 4.10's? Thanks guys!
3% loss of horsepower because the pinion gear is meshing at the bottom of the ring gear instead of the middle. This causes more strength because of more surface area of the gears are touching but it also causes more friction, the 3% loss. But look at it this way, you can now launch at 6 grand with slicks if you wanted to, a 10-15 horsepower loss is worth it. 
Originally Posted by mooreperformance
But look at it this way, you can now launch at 6 grand with slicks if you wanted to, a 10-15 horsepower loss is worth it.
I know I'm so pumped, I fear for my transmission though.
My buddy and I must have had the most inneficent rear ever!! Same rear (originally his, then I bought it) -- he lost 27 rwhp, I lost 29rwhp!! However it was fun going to the track and launching at 6500 rpm and dumping the clutch on slicks and not even worrying about it
Another 9'' is going under my car this winter.
Another 9'' is going under my car this winter. 
TECH Senior Member
Joined: Apr 2004
Posts: 6,157
Likes: 1
From: Texas
Heres a link to the search function ---> https://ls1tech.com/forums/search.php
Here is one that was started that I found ---> https://ls1tech.com/forums/gears-axles/214946-how-much-e-t-mph-loss-9-inch.html
Searching is fun, you should try it
Here is one that was started that I found ---> https://ls1tech.com/forums/gears-axles/214946-how-much-e-t-mph-loss-9-inch.html
Searching is fun, you should try it
Originally Posted by mooreperformance
3% loss of horsepower because the pinion gear is meshing at the bottom of the ring gear instead of the middle. This causes more strength because of more surface area of the gears are touching but it also causes more friction, the 3% loss. But look at it this way, you can now launch at 6 grand with slicks if you wanted to, a 10-15 horsepower loss is worth it.
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TECH Senior Member
Joined: Apr 2004
Posts: 6,157
Likes: 1
From: Texas
Originally Posted by LOnSLO
Yep, it's probably 3% more than a 12 bolt, but like a 30rwhp loss over the stock rear.
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wait then hows a 12 bolt compare to the 10 bolt? or to the 9"
What a lil off topc i guess but how would
a 12 bolt 3.73 33 spline, 1350 yoke, ABS/TCS, 8.875 axles compare to stock 10-bolt with 3.73's?
how about to a 9" with the 3.73's?
What a lil off topc i guess but how would
a 12 bolt 3.73 33 spline, 1350 yoke, ABS/TCS, 8.875 axles compare to stock 10-bolt with 3.73's?
how about to a 9" with the 3.73's?
Originally Posted by 2MuchRiceMakesMeSick
I have never seen any dynos that has proven 30 rwhp. I have seen between 15-20 but never 30. Maybe its 30 for people who make 900rwhp...