Rear end........?'s
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Junior User
Joined: Nov 2007
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From: Fort Lewis, Wa
Rear end........?'s
What kind of gear ratio am I looking for for drag racing, or just general speed? I am naive in this area..... Like what is a 9" rear, and positraction? I need a quick PHD in this **** so I can make a decision.
Posting Guru
Joined: Aug 2005
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See if you have a metal tag attached to one of the bolts on rearend. Post the id#s here and someone can decipher them. You probably have a 9" rearend already. rearend ratios can't be for speed and drag racing for best performance. One or the other. With that said there is a set for all around performance that may suit your needs. Your differential is most likely "open",meaning only one wheel spins.
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Joined: Apr 2004
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Is this for your 1980 F 100 302 4bbl twice pipes as listed in your profile?
A drag race gear ratio, at it's best, allows the engine to reach redline in the top gear at the finish line. (give or take due to the length of the traps)
Let's see, your engine, your truck, your aerodynamics, you're trans is probably a non od automatic....let me take a wag:
85 mph top speed in quarter
29 inch tires
1:1 high
5500 redline
you need 5.6 : 1 ratio.
That puts you at an easy 4217 rpm at 65, just right for instant power on the freeway....
Plug numbers in here. Use 1:1 for transfer case ratio. 2nd and 3rd ones down.
http://www.novak-adapt.com/knowledge/gearing.htm
Post your info regarding trans, tires, what the tag says, what you REALLY want to end up with and you'll get some better answers.
A drag race gear ratio, at it's best, allows the engine to reach redline in the top gear at the finish line. (give or take due to the length of the traps)
Let's see, your engine, your truck, your aerodynamics, you're trans is probably a non od automatic....let me take a wag:
85 mph top speed in quarter
29 inch tires
1:1 high
5500 redline
you need 5.6 : 1 ratio.
That puts you at an easy 4217 rpm at 65, just right for instant power on the freeway....
Plug numbers in here. Use 1:1 for transfer case ratio. 2nd and 3rd ones down.
http://www.novak-adapt.com/knowledge/gearing.htm
Post your info regarding trans, tires, what the tag says, what you REALLY want to end up with and you'll get some better answers.
Thread Starter
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Junior User
Joined: Nov 2007
Posts: 80
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From: Fort Lewis, Wa
yeah, it is for the F100, but the rear end came from a Lincoln mark something or other, as well as the tranny, which..... no, is not an OD, it's a C-4 with a B&M shift kit in it. I just want some explosion from the start, I am not a drag racer, but I am sick and tired of not being able to beat these little tuner cars between lights. Put me on the strip with them, and I will beat them soundly. Good info though keep the flow coming please, I am considering a Posi rear, which if I am not mistaken, is both rear wheels turning.....? right
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From: Anchorage Alaska
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Yeah with a 302/C4 combo, I'm thinking if you want the best of all worlds (mileage, drag racing, and all out speed) I'd think you would be happiest with 3.73 or 4.10 gears. While neither will be good for mileage, the 3.73 will help you out in that aspect while the 4.10 will benefit the other 2. Yes posi spins both of them and would definitely help out your take offs. The 9" which i assume came with your truck, is easy to spot because the case is welded in on the rear side, doesn't have a removable cover. Depending upon what year linclon the rear came from, it could either be a 9" or a 8.8". The 8.8" has the removable cover. But I cant recall when they ever put a C4 together with an 8.8"... Tough to say without having the tag ID
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From: Anchorage Alaska
Originally Posted by kaboom10
Use 2 rearends since the pumpkin can be changed so easily. I had 4.88 for the strip and would drive iy on street tires. The 3.73 was the street gear.
Ray
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Originally Posted by kaboom10
Thanx. The things you learn while at the track. The circle track car had a quick change rear in it. Pop the cover and switch the gear set and race.
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Joined: Dec 2007
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From: royal oak, mich
Originally Posted by 85e150six4mtod
Ford 9 inch = Poor Mans Quick Change