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Author Topic:   have a Gearing ?
popeye14709
Dirt Forum Racer

Total posts: 86
posted May 09, 2004 05:48 AM  
I know you have had questions about this issue before but i have got to ask it again. ok we race on a 1/3 mile Dirt/Clay oval. As of NOW we have 3.45 rear gear and our running gear is 4.9 so our Final is somewhere around 7.04 ok with that said my question is what should our final gear be? The tranny is a 5 spd we have a 4 spd with a 2nd gear of 3.3 and a third gear at 7.11 we check the tranny by turning the front shaft 10 times with the tranny in the preferd gear and count the rear shaft to see how many times the rear shaft rotates and use the clock as your splits exp. 3 complete turns with the last turn ending at 3 o'clock = 3.3 is this a correct way of checking the tranny?

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Dirt is for Racing Asphalt is for Getting there!

juliaferrell
Dirt Freak

Total posts: 370
posted May 09, 2004 08:52 AM  
You need a final around 660. Put the transmission in second gear, mark front and rear shafts, turn the front shaft and count revolutions until the output shaft makes one complete turn. Should be somewhere in the 2.0 to 2.5 range on most ford manuals. The chilton manual at your local parts store for ford manual transmissions will give you the correct gear ratio for your transmission if you have questions.

popeye14709
Dirt Forum Racer

Total posts: 86
posted May 09, 2004 12:57 PM  
TY juliaferrell Now with that how would i find my final gear? and is a 5 spd better or is the 4 spd prefered? also our motor is a 2300 that can and has sustained 7500 to 7800 rpms regularly and how much does your tire's effect your final gear we run track tires 195 70 14's?

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Dirt is for Racing Asphalt is for Getting there!

juliaferrell
Dirt Freak

Total posts: 370
posted May 09, 2004 09:26 PM  
ON the 14's I would run 3.55 gear with 2.14 tranny. The four and five speed (mustang) course splined tranny's are the best however I personally haven't had any trouble with the fine spline tranny's either. I would run 2.0 and 3.45 with 72 and 70 rollout. with 77 and 78 rollouts like your 14's I would go with the 2.14 tranny and 3.55 rear.

juliaferrell
Dirt Freak

Total posts: 370
posted May 09, 2004 09:33 PM  
Also you can use the ratio calculator on here but personally I use the roll out and 5280 times 12 inches to understand how many revolutions my tire is making in a mile. You know that 60 mph is a mile a minute so you can then run your tranny number 2.0 (for instance) and rear gear *3.45* to equal ratio of 6.9. so at 7500 rpms divided by the 6.9 then that total divided by your rev/mile number will give the constant. You then calculate the straight away speed you are trying to achieve (substitute the appropriate numbers) and bingo.

b4racing
Dirt Forum Champ
Total posts: 626
posted May 09, 2004 09:58 PM  
if you are running a 7.5 rearend then 355 is out of the ? but I would try a 197 and a 373 rear. Later Bobby

popeye14709
Dirt Forum Racer

Total posts: 86
posted May 10, 2004 06:36 AM  
thanks for the imput and yeah it is a 7.5 rear. also thanks again to juliaferrell for the formula and ty to bobby. Also juliaferrell you said 72 and 70 rollouts now are you talking about tire diameter or something else?

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Dirt is for Racing Asphalt is for Getting there!

b4racing
Dirt Forum Champ
Total posts: 626
posted May 10, 2004 08:40 AM  
he is talking about the circumference

juliaferrell
Dirt Freak

Total posts: 370
posted May 10, 2004 09:47 AM  
yeah forgot about you having 7.5. the 2.0 and the 3.73's would be about the same thing. Looking for a final around 7.5.

popeye14709
Dirt Forum Racer

Total posts: 86
posted May 10, 2004 09:52 PM  
ty again and I'll post what we found and how it worked....also to Bobby my mistake, circumference is what i ment. but thanks for clearing that up for me...

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Dirt is for Racing Asphalt is for Getting there!

popeye14709
Dirt Forum Racer

Total posts: 86
posted May 10, 2004 10:02 PM  
Now another thing I have to ask have you or have you ever heard of anyone using a automatic tranny and if so how did it work? also would droping our left front from a 195 to a 185 improve our handling right now we to be comletely honest are have no trouble in, through or out of the corners but just say the car is pushing would this change help our handling? also what would the out come be if we left the 195's on the front and placed 185's on the rear just a little insight you know we have never raced 4cyl and have been out of racing for 10 yrs got to do some home work...

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Dirt is for Racing Asphalt is for Getting there!

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