What will 3.73s do for my '01?

Discussion in 'SVT Tech Forum' started by Ganton, May 4, 2004.


  1. 99SVTAddict

    99SVTAddict New Member

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    I have 4.30's in my s/c'd 99. A few things to consider though:

    1. What tires will you be running? Street tires went up in smoke through 4th gear for me. Nitto's did good, but couldn't hold 1st gear with my old 4.10 gears. I now have BFG DR's and they keep the power planted in every gear...and that's with 4.30 gears.

    2. Is it a centrifical or roots blower? You said KB, so you will have much more torque at a lower RPM than I have. In this case, 3.73's might be a better choice as I mentioned in my original post.

    3. What transmission? I now have the Viper T56, so my first gear ratio in the trans is only a 2.66. That's a steeper gear by far compared to a T45 or T3650. So, my first gear matched with the 4.30's I have is like still having a 4.10 gear with my T45 ratio. But every gear after that is killer. When I'm WOT and shift to 2nd, the gear is over in about 2.5 seconds....

    Side note: if you put that KB on, you are going to HATE that IRS...hop, hop, hop.....that's why I finally put in the solid axle.
    #21
  2. Shalenboy

    Shalenboy New Member

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    As if you haven't heard it enough yet.... go 4:10's!!! I was worried about gas mileage too as most of my driving is highway, but I have not seen ANY change in MPG whatsoever. It is a completely different car with the 4:10's dude, don't hesitate.
    #22
  3. SVTRacer01

    SVTRacer01 New Member

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    I've got an '01 Cobra and always wanted to do the gear swap to 3.73, but after hearing all of you talk, I think I am set with the 4.10's. Any brands you recommend over another? Is it true that you need to install an aluminum driveshaft or else you will feel a ton of vibration? How much did the install cost, or how much should I expect to pay for install at a regular performance shop? Did the gears throw off your speedo at all?
    #23
  4. Craig Mack

    Craig Mack Busted Buffing the Bishop Founding Member

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    The ONLY brand to go with is Ford Racing. Richmond makes them, but Ford Racing is the only trusted brand to go with, steer clear of all else. I am running my stock driveshaft and have ZERO vibration and ZERO gear whine...it's as quiet as a mouse. I payed $200 for the complete install and oil change at my shop. Do not pay more than $300 for install. The gears haven't thrown my speedo off, it is actually extremely accurate, but I hear over time you will EVENTUALLY need a SpeedCal, but I dont and so far everything is perfect.
    #24
  5. tfritz

    tfritz Founding Member

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    I thought a speedcal is a must with the install. It does throw your speed off when you're going to a different gear.
    #25
  6. jpbaker22

    jpbaker22 Founding Member

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    4:10's is a must for a street car.
    I wish ford would offer this from the factory.
    my gas milage dropped when i first put them on, but i bet that has alot to do with that fact i was driving it like i stole it! I can't help it. It really wakes the car up.

    my .02.
    #26
  7. Craig Mack

    Craig Mack Busted Buffing the Bishop Founding Member

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    :confused: Maybe once the one that comes with the gears breaks, but it hasnt been the case for me. I know my speedometer is dead on becuase cops set up those big radars that display the MPH you are going, and what it displays is dead on with my speedometer.
    #27
  8. travis0712

    travis0712 New Member

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    I had 327s in my 99GT, I went to 373s and wish I has went 410s or even higher. It through my speedo off... either a chip or drive gear swap is needed. The only thing I hated about my 373s was the loud wine from the gears.... but... that is because I went with crappy gears instead of Ford...

    I have 355s now stock in my car... I think I should stay right where I am at... but I sure would love to see how she feels with 410s :)

    It is hard enough as it is to get the power to the tires... smoking them is easy... so 410s would burn them up for sure...
    #28
  9. cold96snake

    cold96snake Active Member

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    You need a speed cal or speedometer gear. I have 4.10's and when doing 60 my speedo would read 85. Drive a mile down the road and it put 1.2 miles on the odometer.
    So let me get this straight:
    1)3.73's for a lot of highway cuising above 75, but only if you care about a minimal decrease gas mileage and aren't expecting a huge sotp effect
    2)4.30's for the track, and less highway driving and n/a
    3)4.10's best all around choice for the street
    #29
  10. travis0712

    travis0712 New Member

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    anyone have 410s in their 03/04 cobras??? how do they feel? wheel hop?
    #30
  11. MystiChrome Coupe

    MystiChrome Coupe Founding Member

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    Correct, you must calibrate your speedo, it will be off.
    #31
  12. 103

    103 Founding Member

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    4.30s are a great all-round gear and I get great gas mileage city and highway.
    #32
  13. RDvenom99

    RDvenom99 Founding Member

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    Does someone have a chart that tells what the different top speeds are in different gears with the different gear ratios? For example:

    3.27 gears 1st 44mph 2nd 77mph 3rd 115mph ect..
    3.73 ?
    4.10 ?
    4.30 ?
    4.56 ?

    Thanks!
    #33
  14. BlackVNM

    BlackVNM New Member

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    I just bought 4.10's for my 98, and I'm debating between buying a speedcal or just buying a 23 tooth speedo gear to correct my odometer and speedo. The 23 tooth fix is a FRPP part, so I figured I'd try it, but I've also heard that they can wear out quick. Anybody with experience in these?
    #34
  15. Blk99SvtCobra

    Blk99SvtCobra New Member

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    i went 4 10s and still could get 4 30s
    #35
  16. SVTRacer01

    SVTRacer01 New Member

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    Check out this page, pretty nice.

    http://www.corral.net/tech/gearcalc.html
    #36
  17. RDvenom99

    RDvenom99 Founding Member

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    That's pretty cool but I don't understand how the tire width effects the speed. When I put 335 width the top speed in a given gear goes up around 5-10 over 245 width tires. :shrug:
    #37
  18. SVTRacer01

    SVTRacer01 New Member

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    They need the size of the tire (diameter) in order to determine the number of revolutions the tire will make in a certain time period. I remember seeing some of this stuff in between naps during my college physics classes, so if you're interested you can check out this link.

    http://webpages.charter.net/griche/pt/u3s1bprb.htm
    #38
  19. DirtySanchez

    DirtySanchez Founding Member

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    Here you go:

    http://www.svtoa-atlanta.org/cgi-bin/trans.cgi

    That one allows you to compare different gearing.
    #39
  20. RDvenom99

    RDvenom99 Founding Member

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    That ones nice too but it also takes into account the tire WIDTH that has nothing to do with the diameter. Someone please explain to me how having a wider tire with the same diameter is going to increase my speed at any given RPM? A 245/40/17 tire should run the same speed as a 315/40/17 tire shouldn't it?
    #40

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