Mismatched Front/Rear Axle Gears 4.56/3.73 - Pirate4x4.Com : 4x4 and Off-Road Forum
 
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Old 03-14-2007, 09:20 PM   #1 (permalink)
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Mismatched Front/Rear Axle Gears 4.56/3.73

I am just wondering exactly what happens when you use 4wd with mismatched front and rear axle gears? I know it isn't good and they will be fighting each other but I have never done it and was wondering if anyone has and what actually happens? I'm just curious because I am selling my 1996 Chevy Silverado which has 4.56's in the rear and I never got around to putting 4.56's in the front, so it's still stock 3.73 in the front, and I never use the 4x4 anyway....but I just want to tell the guy who is buying my truck exactly what will happen if he uses 4x4 without re-gearing the front. Thanks for the help
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Old 03-14-2007, 09:28 PM   #2 (permalink)
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depends on the situation,

if your are running appropreatly mismatched tires, nothing
if you have a part time tcase [205,208,241..... not the 203] it will 100% bind up and something WILL break.
a 203 has a differental built into it and will allow some slip but not that much.
it will wear teh living shit out of the tires if it is engauged.
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Old 03-14-2007, 09:30 PM   #3 (permalink)
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ther eis a formula somewhere that can tell you what size tires to run with which gears SPICIFICALY FOR MISMATHED GEARING.

it may be % of gear ratio offset = same % of tire diam offset
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Old 03-14-2007, 11:12 PM   #4 (permalink)
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Just bolt some 37s up in back and tell the buyer it's part sand rail!

No, seriously, nothing good can come from this assuming 4 identical tires. You should get the front gears put in, or at least tell him he's gonna have to before he uses the 4WD.
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Old 03-14-2007, 11:52 PM   #5 (permalink)
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if you do this your going to break something... ive been there... 3.55s up front and 4.88s in the rear. it will plow in the snow, gravel is OK, mud you couldnt tell, but dirt it will feel like the truck is bending in the center like a stick. your truck is goings to try to spin the front end almost a full turn compaired to the rear... id tell the guy to gear it or not use it. those front ends arent cheap-and neither is the transfercase...

or
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Old 03-15-2007, 09:50 AM   #6 (permalink)
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I had an old flatfender I changed the front axle in and didn't even think about the gears. 5.38 rear, 4.88 front put it in 4x4 at loon lake and ran the whole rubicon put 70 lbs. of air in the tires and chirped and hopped all the way. Never broke anything (real light with skinny tires and 4 banger) but I don't recommend it.
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Old 03-15-2007, 01:40 PM   #7 (permalink)
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Something is going to ******* break. That is about the dumbest & dumber!
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Old 03-15-2007, 01:43 PM   #8 (permalink)
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i replaced an np231 on a 2 door blazer that was broke in half because the guy didnt want to put new gears in the front
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Old 03-15-2007, 04:51 PM   #9 (permalink)
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Quote:
Originally Posted by quikchevyz71 View Post
I am just wondering exactly what happens when you use 4wd with mismatched front and rear axle gears? I know it isn't good and they will be fighting each other but I have never done it and was wondering if anyone has and what actually happens? I'm just curious because I am selling my 1996 Chevy Silverado which has 4.56's in the rear and I never got around to putting 4.56's in the front, so it's still stock 3.73 in the front, and I never use the 4x4 anyway....but I just want to tell the guy who is buying my truck exactly what will happen if he uses 4x4 without re-gearing the front. Thanks for the help
to specifically answer the question, the front tires will turn faster than the rear tires. on any high traction surface, it will bind and break something
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Old 03-15-2007, 05:18 PM   #10 (permalink)
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it would either pull apart or the axles would pull towards each other
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