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So I was talking to my buddy earlier today and I was telling him how I'm looking to upgrade my rear gears and he mentioned something about the 9 inch rear but it was all negative. He said their pretty common but not such a good swap for my appication. here's what he mentioned about the 9'
same car/gears with an 8.8" \will be faster then with a 9"
there is a difference in efficiency
: same is true between an 8 and 8.8, but not as bad
: the 9 eats a lot of power
What do you guys think? does that sound right?
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Eh. The 9" is heavier and slightly less efficient, but unless you're doing some serious drag or track racing, the difference is probably going to be negligible.
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Tad H.
'67 Fastback
331 stroker
It's only like a 2% difference iirc. But the reason is because Ford put the pinion gear lower and deeper in the 9", and though it slightly reduces efficiency, it allows for greater contact area on the gear teeth for increased strength. 8.8 or 9 each have advantages and disadvantages, but it's about the same either way. 9" tends to be easier to find parts for and has a wider selection of gear ratios because everyone and their brother runs a 9". Either one is plenty strong though.
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Who cares how much horsepower it has, all that matters is how fast it goes!
13.20's with 2.25-2.30 60's, 40+ year old suspension sucks!
Best trap 107.11mph, we'll see what the new intake/carb setup does.
12.80 at 110.5mph NHRA DA corrected
The 8 inch is a mini 9 inch and i have seen a 8 inch last longer then a 8.8 in a drag car.From i seen my self out of many rear ends even owned a 9 inch and dana 70 are the best two i have used and i couldn't break.I had a 8.8 in a ranger i shattered the spider gears in with a 400hp small block and slicks.Tell him if a 9 inch is so bad why do they make bolt in ones for almost any rwd ford and gm and a top fuel car uses a beefed to hell 9 inch.
I see you what you guys mean. I'm only running a 5.0 from a 89 stang with, edlebrock intake and carb. everything else is pretty much stock. I got a 5spd tranny with a weak 2.75 gears in the back axle
Yeah, it's true. A 9in in one of our cars killed .3 in the 1/8 mi!!!! No other changes. Got tired of blowing up 8in's, swapped in the 9in and changed nothing else, nothing. 8.0's to 8.3's consistently. Sum bitch is a good bit heavier. In your 67, the 8.8 is a perfect swap if you are looking for stronger, without the strength of a 9in. they can be found to right length for your car pretty easily. Just cut old junk off, weld on new perches, and shazam !
An 8.8 with a Detroit True Trac would be nice, plenty of strength, more efficient than the 9" and no spider or side gears to break or clutches to wear out.
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Who cares how much horsepower it has, all that matters is how fast it goes!
13.20's with 2.25-2.30 60's, 40+ year old suspension sucks!
Best trap 107.11mph, we'll see what the new intake/carb setup does.
12.80 at 110.5mph NHRA DA corrected
An 8.8 with a Detroit True Trac would be nice, plenty of strength, more efficient than the 9" and no spider or side gears to break or clutches to wear out.
you really think the 8.8 swap would be easier? what about the yoke of the driveshaft and the brake and brake lines?
Any driveline shop can get you a yoke, or a conversion joint. Brakes and axles are easily had from certain Rangers and Aerostars. Brake lines are easy to custom fab.
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Tad H.
'67 Fastback
331 stroker
you really think the 8.8 swap would be easier? what about the yoke of the driveshaft and the brake and brake lines?
Yeah, probably. It's easier to ifnd 8.8's in the right width for that year than 9's now a days. Cut some stuff off, weld a little bit to it. Not shortening makes life easier/cheaper.
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8' 8.8 and the 9'
