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Discussion Starter #1
so im sorry if some of you dont approve but here is what im planning on doing....maybe.

i have a 2.5L tj manual. i want to regear the rear axle to 4.56 or 4.88. with 33's on it. and keep the front stock gears and put on some 31's.

Ok so i probably wont do this, i just want to hear your thoughts
 

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1st? Why two different tires sizes... It will drive incredibly terrible....
2nd. You won't be able to use 4 wheel drive because of the different gear ratios.
 

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If you want a race car, why not buy one instead of ruining a decent Jeep? lol
 

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It can be done, as long as you keep the effective gear ratio the same front/rear.

Your 2.5 should have come with 4.10 gears and 29 (approx) inch tires.
I messed around with a gear ratio calculator to see what combinations would work with 4:56 or 4:88 gears in the rear and 4:10 in the front. The closest I could come up with has you running stock 29 inch tires on the front and rear tires with a 34.5 inch diameter and 4:88 gears in the back.

Here's the calculator I used: 4Lo.com :: Tire Size Change, New Gear Ratio Calculator
 

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Discussion Starter #5
i wouldnt be using 4 wheel drive i just saw a vw baja bug with 31x10.50x15 in the front and 33x12.50x15 in the back and it looked pretty awesome. im never really going to do this i just wanted to know if it could be done.

and unfortunatly the stock tires on a 2001 tj SE is 27.5 ish tires
 

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Discussion Starter #6
1st? Why two different tires sizes... It will drive incredibly terrible....
2nd. You won't be able to use 4 wheel drive because of the different gear ratios.
why would it drive terribly ?
 

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It will drive bad because a Jeep's suspension is setup to have the same size tires front and rear. Other vehicles can be built to handle properly with front and rear mismatched. None of them are four wheel drive. They are always rear wheel drive.
 

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It's weird, but I don't see why it would handle poorly. Sparky and Slater 451 need to be more specific with their comments.

You have a part time 4wd system anyway, so a slight difference in effective ratios is no big deal in the snow. But you would be better off if the front wheels were affectively trying to travel faster then the rears, I think.

Remember, in our Jeeps the front wheels always travel farther than the rears as you drive, or for that matter, in any four wheeled vehicle. But the Jeep front and rear ratio is the same. This difference is always there unless the car is running absolutely straight. There is no compensation for this in a 4WD system with no center differential.

My buddy had two different ratios in an old Ford pickup where someone had changed the front or rear axle at some point. It worked OK.
 

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Remember, in our Jeeps the front wheels always travel farther than the rears as you drive, or for that matter, in any four wheeled vehicle. But the Jeep front and rear ratio is the same. This difference is always there unless the car is running absolutely straight. There is no compensation for this in a 4WD system with no center differential.


How did you come to this conclusion?
 

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whetstone,

Whenever a vehicle makes a turn, the front wheels make a wider arc than the back wheels. The wider arc is a longer path. This is why we Wranglers should not run in 4WD on hard surfaces. The front and rear wheels travel a different distance in curves so there must be slipping somewhere if we are in 4WD.

Now, there really is no such thing as driving straight. We always are making small corrections to a more or less straight path. So, the front wheels are always traveling farther than the rears are unless we are actually driving absolutely straight.

No ratio difference, between the front and rear diffs, will correct this problem because it's variable. But a center differential will compensate for it.

On slippery surfaces we don't notice this happening, but it is, and so if there was a different ratio in the front and rear, and different size tires that made the difference small, we wouldn't notice it.

Don't you agree?
 

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Discussion Starter #12
whetstone,

Whenever a vehicle makes a turn, the front wheels make a wider arc than the back wheels. The wider arc is a longer path. This is why we Wranglers should not run in 4WD on hard surfaces. The front and rear wheels travel a different distance in curves so there must be slipping somewhere if we are in 4WD.

Now, there really is no such thing as driving straight. We always are making small corrections to a more or less straight path. So, the front wheels are always traveling farther than the rears are unless we are actually driving absolutely straight.

No ratio difference, between the front and rear diffs, will correct this problem because it's variable. But a center differential will compensate for it.

On slippery surfaces we don't notice this happening, but it is, and so if there was a different ratio in the front and rear, and different size tires that made the difference small, we wouldn't notice it.

Don't you agree?
mind = blown

thanks for the input. much appreciated
 
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