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Old 07-26-2008, 06:57 PM   #1
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Gear Ratio

Can anyone describe what lowering the gear ratio actually means? I may have to have it done but im kinda confused exactly what it is.

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Old 07-27-2008, 08:16 PM   #2
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if your talking about what i guess you are witch would be the gears in your differentials then re-gearing would be something you might be looking into. your basically changing the amount of travel your getting with the speed of your engine..i.e. if you have 4.11 gears then for ever 11 revolutions of your drive shaft translates into 4 combined revolutions of both wheels. an example of high gears would be 3.55 then lower would be 3.07 then lower would be 4.11 then 4.88....etc. .the whole idea is based around how big your tires are and the gears in your diff because those are the typical variables. if you have bigger tires then you are altering the equation of engine speed to axles then to wheels. alot of people try to base the correct gear ratio by high way engine speed, most people want something like 2500 rpms at 55mph. so somewhere around that now that isn't saying other gear options are wrong, its just based on the individuals needs. if this is your dd i would recommend a more streetable gear ratio. but if this is some trail rig then do whatever you want. there is alot of options as far as a trail rig goes, jsut do whatever. hope that helps.

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Old 07-27-2008, 11:09 PM   #3
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yj, I hate to break it to you, but you're gonna have to change your signature.


Gear ratios are written as input:output. If the output is 1, then the 1 isn't written. So, 4.11:1 is the same thing as 4.11. That means that for every 4.11 revolutions of the drive shaft, the wheels will turn once. 3.07 means that for every 3.07 revolutions of the drive shaft, the wheels will turn once.

Lower gears are numerically higher. So, 4.11 is lower than 3.07.

A lower gear ratio will make your RPMs increase faster. This means that you will get into your engines power band quicker. Also, lower gears will transfer more of that power to the wheels. Lower gears will help you crawl over things easier but you lose some top end speed and some overall fuel economy(because the engine has to work harder to maintain the same speed).
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Old 07-28-2008, 06:33 AM   #4
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well i knew the last part and thank you on the first part i wasn't 100 % sure on that. i knew that 4.11 was lower than 3.07 and so on.. and the rpms will also be changed by tire size. i think i made that clear to understand...but thanks for correcting me....

ohh shit now they know the truth....lol
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Old 02-23-2014, 11:33 AM   #5
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Is there an easy way to find out what gears I have. My rig is old and has been modified, so I have no clue on whats in there.Would it be possible to jack up the wheels & count revolutions?
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Old 03-06-2014, 06:40 AM   #6
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Quote:
Originally Posted by akkidd View Post
Is there an easy way to find out what gears I have. My rig is old and has been modified, so I have no clue on whats in there.Would it be possible to jack up the wheels & count revolutions?
Yup, just jack up one side and count driveshaft revolutions per 1 tire rotation.

Hard way is to remove the diff cover and count teeth.
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Old 03-06-2014, 09:44 AM   #7
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You should also look for the tags that were originally on the covers that give the ratio or teeth counts. While there is the possibility they will not correspond to what's actually in there, my experience has been that if someone did put the tag back on, it is correct more often than wrong.

Obviously, if counting wheel revolutions, you need to be accurate. There isn't a lot of difference when doing that exercise between, say, 4.56 and 4.88. Bottom line is if you want to know for certain, pull the cover and either count teeth or check the numbers on the ring gear.

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