rear end gears - Chevy Nova Forum
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Old 4th-March-2007, 06:26 PM   #1
youngin69nova
 
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rear end gears

how big of a difference do gears make? is there a general rule? would there be a noticable difference in the 1/4 between 3:73's and 3:55
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Old 4th-March-2007, 06:34 PM   #2
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I doubt you'd notice a thing.
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Old 4th-March-2007, 06:40 PM   #3
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so why would someone choose the 3:73's over the 3:55's
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Old 4th-March-2007, 07:14 PM   #4
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You may not notice a 3.55 change to a 3.73, I sure you would notice a 3.08 to a 3.73 or 411. On a street car I would not want to go larger then a 3.73 because unless you had a 700R4 trans the Hi/Way speeds of 60 MPH and higher would keep the RPM of the motor to high. I run a 3.36 gear on mine and can go anywhere I want without fear of this happening. Now if my car spent more time at the strip then it did on the road I would want a 4.11 ring gear so when running the 1/4 mile track I would enter the end of my run in 4th gear at max RPM.
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Old 4th-March-2007, 09:19 PM   #5
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Quote:
Originally Posted by youngin69nova View Post
how big of a difference do gears make? is there a general rule? would there be a noticable difference in the 1/4 between 3:73's and 3:55
not much diff, but i wouldnt go deeper than 3.73 if you like to drive it on the street, run the 3.55 for BBC and 3.73 for a sbc, on the strip i would go 3.73 for BBC and 4.11 for a sbc.
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Old 4th-March-2007, 09:33 PM   #6
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I run 4.11's on the street with a 26" tire. I run about 3000 rpm at 55mph.
My trips are short though cruise through town a few times and thats about it.
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Old 5th-March-2007, 10:48 AM   #7
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On my Nova I went from 308 to 373, very noticable difference. Could tell big difference from a dead stop, from 20 mph up and at cruising speed on highway. I have 355 on my Mopar and it is what I consider a perfect gear if you are going to be driving it mostly on the street. Not bad at all on the highway and good everywhere else.
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Old 5th-March-2007, 12:36 PM   #8
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Try this calculator. http://www.chevellestuff.com/generic/rpm_calculator.htm

It'll let you know what RPM you'll be running at in any gear at a specific speed. I played with it and changed the rear gear ration from 3.55 to 3.73 and got these results (using a 235/60-15 tire):

3:55 gear final RPM at the trans' 1:1 3rd gear ratio:
75MPH = 3428RPM


3:73 gear final RPM at the trans' 1:1 3rd gear ratio:
75MPH = 3602RPM


As you see, it's not a ton of difference between 3.73 and 3.55. At the track that 174RPM difference could alter ET/MPH at the traps slightly though and help keep you in your power band more easily.

I used 3.55 gears in my car and it's great for cruising around town. On the highway it's a bit much, but that's the price we pay for quick acceleration.
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