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Old 05-21-2012, 11:29 AM   #1
ehinch19
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Default Regearing?

I understand the purpose behind getting a higher gear ratio to get more torque and I have only changed gearing in off-road jeeps when you get into the 33-39 inch tires. My question is on my slightly modified 75 which I donít do much highway driving and more playing around in town would this make any improvement over stock?
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Old 05-21-2012, 12:25 PM   #2
69 Chevy
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Quote:
would this make any improvement over stock?
Stock what? performance? fuel mileage? something else?
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Old 05-21-2012, 01:05 PM   #3
damoroso
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What's slightly modified?
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Old 05-21-2012, 01:37 PM   #4
my 76 ray
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There are a lot of variables but you should get quicker acceleration and worse fuel economy.
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Old 05-21-2012, 03:14 PM   #5
ehinch19
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Originally Posted by 69 Chevy View Post
Stock what? performance? fuel mileage? something else?
It is the stock 350 automatic bored .030 over with a mild cam and soon to upgrade the intake and carb. Also planning on a shift kit. I realize it will hurt my fuel mileage but its an in town fun car so it doesnt matter as much. What ratio will give me a better more " agressive " you could say acceleration.
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Old 05-21-2012, 04:42 PM   #6
iokepakai
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Shoot for a 10:1 first gear ratio.Your 75 with a TH350 will most likely have a 3.08 rear gear.Your TH350 has a 2.52 1st gear ratio X your rear gear 3.08 = 7.76 first gear ratio not an ideal 1st gear.You can change the rear gears or change the transmission to a have a better first gear and OD.I kept my 3.08 rear gears and installed a Richmond 6spd manual with a 3.27 1st gear and a .76 od 6th gear. Good luck....
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Old 05-21-2012, 04:45 PM   #7
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Need to consider what transmission you have and current rear end ratio.
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Old 05-21-2012, 05:21 PM   #8
ehinch19
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Quote:
Originally Posted by iokepakai View Post
Shoot for a 10:1 first gear ratio.Your 75 with a TH350 will most likely have a 3.08 rear gear.Your TH350 has a 2.52 1st gear ratio X your rear gear 3.08 = 7.76 first gear ratio not an ideal 1st gear.You can change the rear gears or change the transmission to a have a better first gear and OD.I kept my 3.08 rear gears and installed a Richmond 6spd manual with a 3.27 1st gear and a .76 od 6th gear. Good luck....
So what would you recomend for my rear gear ratio?
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Old 05-21-2012, 08:42 PM   #9
Mr NAVYRET
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I like the 3:70 gears in my 74
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Old 05-21-2012, 09:24 PM   #10
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If your gonna keep the TH350 with that 2.52 1st gear you need something around 3.96 rear gears to get that 10:1 launch ratio.However your highway mileage is going to be in the toilet.Hence the suggested OD trans.You can compromise and use a 3.55 rear gear.Another option would be a 700R4 trans from Bowtie Overdrives.You will get a good launch from the 3.06 first gear and you'll have OD.First off you need to know what you have in the rear end before you make any decision's.When I was researching all my options.I felt it was better to spend the money on a OD trans that would match my existing rear gear of 3.08,instead of changing rear gears and still only have a 3spd auto trans....Aloha's
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Old 05-21-2012, 09:24 PM
 
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