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3.55 to 3.73s

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  #1  
Old 09-18-2011, 08:05 PM
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3.55 to 3.73s

Right now i am running 35s with my stock 3.55 gears and have no intentions of changing them out. now the opportunity has came up where someone is upgrading there gears and is going to let me have his 3.73s. Now i know what everyone is going to say and that is to go with 4.10s. For everyone's information i am not going to re-gear to 4.10s and am only re-gearing because i have the chance to get some 3.73s for next to nothing. Now my question to everyone on the forum is will 3.73s be a nice difference from my 3.55s?
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Old 09-18-2011, 08:36 PM
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The real cost of regearing is the labor involved. 3.55 to 3.73 would be a complete waste of money, especially with 35's. 4.10's or 4.56's with 35's. Gears aren't that expensive. The difference between 3.55's and 3.73's is not worth the cost
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Old 09-18-2011, 08:55 PM
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My friend is a ford mechanic and can do it. Im not worried about labor. I plan on installing a locker at the same time. I just want to know if it will be noticeably better
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Old 09-18-2011, 10:09 PM
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Quote:
Originally Posted by NastyNate12 View Post
Now i know what everyone is going to say and that is to go with 4.10s.[/B]
4.56s, not 4.10s If you can get the 3.73s pretty much for free, then I would do it. There won't be a lot of difference though. If you plan on putting in a locker, then you might as well put in the 3.73s while you're working on it
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Old 09-18-2011, 10:42 PM
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If you can get em installed for cheap go for it. It will be an improvement, just not enough to pay much for IMHO
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Old 09-18-2011, 10:46 PM
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your not going to notice hardly anything, i think its only a 50-100 RPM difference. i wouldnt do the work if i got them for free! not worth setting up the backlash and gear pattern.

if youre not worried about labor, why not spend the 500 and get the right gears? it would definitely be worth it!
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Old 09-19-2011, 01:08 AM
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i miss my 4.56's with 35's every day... having to go back to 3.55's is a nightmare... i got better mpg with 4.56's then i do 3.55's
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Old 09-19-2011, 12:16 PM
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USED GEARS WILL WHINE! gears develop wear patterns and unless they are set up to the exact same specs (it's never gonna happen no matter who installs them) the wear patterns WILL NOT MATCH, causing them to whine. get new gears ford racing gears will only cost you $150 per set at most.
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Old 09-25-2011, 04:44 PM
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I"m with the OP - for the cost, it couldn't hurt... and any improvement is better than no improvement.
having said that, i'd like to know more. besides being nearly free, what are you looking for? mileage, top end, acceleration, offroad, what? what engine and trans?
i have a 2000 4.2LV6 with the POS mazda 5 SPD that gets 12 mpg in traffic with the 3.55 axle and 245/15 kevlar MT/R tires. I am seriously considering getting a lower gear set, but i have the same question - what should i switch to? I suspect my poor mileage is due to having to keep my foot in it during my daily commute because that engine has poor acceleration due to the 3.55's. But, as someone else here noted, if a 3.73 swap doesn't make any significant difference, then what's the point? what gearset would make a difference?
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Old 09-25-2011, 05:40 PM
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^^^ 4.10's would make a difference.
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Old 09-25-2011, 06:33 PM
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enquiring minds want to know!

Quote:
Originally Posted by str8t six View Post
^^^ 4.10's would make a difference.
would you care to expand? better accel, mileage, torque, lower engine RPM, what? in town, highway,offroad?
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Old 09-25-2011, 06:34 PM
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Correction - those are 245/16 tires, not 15. measured radius from hub center to pavement is 14.5", ergo it's a 29" wheel and tire diameter
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Old 09-25-2011, 06:56 PM
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they would provide better acceleration when taking off. they take strain off the trans and engine making it easier to get up to speed. gears would increase your final drive ratio making you turn more rpms for a given speed.


what kind of driving do you do?
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Old 09-25-2011, 08:26 PM
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Joe, I don't have any issues like that with my 4.2 5 speed with 3.55's. I get about 15 in the city with 87 octane E10. Highway is right around 20. It has plenty of power to keep up with traffic. 255-70-16.
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  #15  
Old 09-25-2011, 10:58 PM
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3.73's will raise your RPM's by about a 100. Any bit helps but 4.10's would raise you about 300 RPM's and 4.56's would raise you about 450 RPMs. I used a calculator with 70 MPH as the baseline speed and 35" tires and .80 OD ratio..hope it helps
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