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Discussion Starter #1
I am about to regear. I am going with 4.56 gears up front. In the 9" I can't decide between 4.56 or 4.55. Either will work and 4.55 is stil whithin 1% so it works.

I was thinking of going with 4.55 because it will have more teeth contact at any given time therefore making it slightly stronger. The 4.56 has 7 pinion teeth and 32 ring gear teeth. The 4.55 has 9 pinion teeth and 41 ring gear teeth.

The only reason I thought of this was because some of my friends run the 4.55 on drag cars because of the added strength along with after market 9" and with 35 spline axles. I know the Bronco wont be putting out 700-800 ftlbs of torque like there drag cars.:histerica

So what is everyones thoughts on this? Or is the 4.56 strong enough that it wont make a diffrence? Or has anyone blown 4.56 gears and wish they had a little added strength? :popc1:
 

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Whats the price diff? That would be the decider for me. If the 4.55's are more expensive I'd say fawk that.
 

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I don't know if the 4.55 is stronger or not, but aside from that I'd match it perfectly and go with the 4.56. The 4.55's wouldn't give you any trouble, but I'd rather have the front axle turning faster then the rear and not the other way around. I'd go with 4.55 in the front and 4.56 in the rear, or 3.54 in the front and 3.55 in the rear, and if I couldn't do that I'd do an exact match.
 

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I'm willing to bet it will make no difference what-so-ever. In driveability, strength, cool-factor, anything. No difference. Listen to your wallet on this one
 

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where are you getting your numbers from?

Precision gear list a 4.57 gearset for the 9" that is 32 and 7

and your standard 4.55/4.56 set will be 41/9...divide this number and you end up with 4.55555

The 4.57 gearset is kinda an oddball with 32 ring gear teeth, but then again there is that whole bit of info. from performance unlimited talking about the 9" being stronger as you numerically go up in gearsets, typically because you get fewer pinion teeth (the 4.57 set only has 7) and so the teeth are spiraled more and on a 9" this gives more contact area and more strength.

It's not really the gearset that's the problem anyway. If you don't have a nodular third that will be your likely break point.
 

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Discussion Starter #7
Shadofox, I'm doing the math.:thumbupand got the original info from a website, dont remeber which one now but it was deff wrong as you pointed out.Thanks
41 divided by 9 = 4.555
32 divided by 7 = 4.571

I understand that both are considered a 4.56 gear ration depending which company you go with. But was more or less looking for input from you gearheads. Maybe no one has ever considered this diffrence before? And yes I have a N case with the extra webbing that I could use. Price, about the same but I will probley go with a used set from a Drag car because I can usaly get them prety cheap with very few passes on them. But it looks like 41/9 for me...

Thanks for the input so far.:beer
 

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I know the Bronco wont be putting out 700-800 ftlbs of torque like there drag cars.:histerica
Forgot to mention in my earlier post...
It will probably have more torque on that pinion gear in low range. It probably won't have the shock load the race car will on a launch, but it will still have that much torque easilly.
 

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keep in mind though too, if you are buying a true racing gear set, I'm not sure how well that would hold up if you run your truck daily???
 

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Discussion Starter #10
keep in mind though too, if you are buying a true racing gear set, I'm not sure how well that would hold up if you run your truck daily???

No, they wont be the high dollar strange gears(500-700 bux) or anything like that. Most of the guys around here use Ford motor sport, Motive gear, Yukon,or Percision gears for the most part. What they do is use the less expensive gears to set the car up with to see which they will be useing and then buy the all out race gears. (atleast with the unlimted outlaws) Alot of the time the gears will only have 4-10 passes on them but I just have to wait until another car is going through this trail and error. But that was something I didnt consider, Thanks.
 

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Discussion Starter #11
Forgot to mention in my earlier post...
It will probably have more torque on that pinion gear in low range. It probably won't have the shock load the race car will on a launch, but it will still have that much torque easilly.
Very good point. My crawl ratio in low and tow/granny gear will be around 60/1 with 4.56 gears IIRC.
 
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