3.09 gears vs traction

Discussion in 'SRT Hellcat General Discussions' started by Viper, Mar 22, 2016.

  1. Viper

    Viper SRT Hellcat Supporter Gold Supporting Member

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    I would like to know if anyone is using the 3.09 gears in an A8 automatic with 20 inch tires and did it make the ET better or did the loss of traction actually slow the car down and cause a slower ET. I plan on using drag radials on the street and track and do not want to go the wrong way
     
  2. Toolman_42

    Toolman_42 Gold Member

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    Going from 2.62 to 3.09 should improve launch (reduced spin rates with improved ratios) and 60ft times. Not sure how you are tying loss of traction to gear change...doesn't compute.
    Impact from gear change will be to loose a little top end speed so you might not be able to reach 204 mph but you will will reach terminal velocity quicker!
     
  3. DGatzby

    DGatzby Gold Member Hellcat Car Club HCC Charter Member Midwest Regional Pres.

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    Help me. How does installing a numerically higher gear reduce wheelspin? Damn if my first gear was lower, it would seem to me it would spin even easier, and so on with second and third...

    I agree with the OP, great and legit question. Inquiring minds want to know.

    When I can get that 2.62 rear end to stop spinning only then would a guy need more IMO anyway. Yesterday went out in manual mode with my little stocker that I am just adding suspension pieces and larger and more sticky rubber to get it in a condition I can control. First gear, forget it, second gear with any amount of throttle over about 30% forget it, if that much, finally eased into third and we hooked. I don't plan on slicks at my very few if any drag strip runs nor do I expect to set a world record.

    I will be more than prepared when my little blue car makes its first formal quarter mile run (CF DS and drag radial tires), but I will be absolutely delighted to document 25 mpg on the way to the track and log a time in the tens. But my last $1,500 went towards that DS for lots of reasons, $2,000 plus for different gears just don't seem right, unless you are knocking on the door of breaking ten seconds in these things. My opinion, but to each his own, I am glad these cars have multiple personalities to keep us all happy.
     
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  4. Viper

    Viper SRT Hellcat Supporter Gold Supporting Member

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    I don't care about top end. But some people have to switch to an 18 inch tire after changing gears to get more side wall to help launch. I do not want to change to an 18 inch wheel but if the 20 inch side wall does not flex enough to launch the car because it is too stiff then wheel spin will increase and ET will be slower.
     
  5. TNCHARGER

    TNCHARGER SRT Hellcat Supporter Gold Supporting Member

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    I haven't been to the track with my HC with 3.09 gears but my experience racing shows that changing rear end gears will result in lower ETs to a point. I run a 4.30 rear in my 2013 Challenger 426 stroker. I notice very little traction difference between the 4.30 and the 3.06 at a well prepared track with DRs but the car will run 2-3 tenths quicker (4.30) with a slightly lower trap speed.

    Choosing the right gear is a calculated effort not a random one. You don't want to shift right before the stripe or cross the stripe at the bottom of a gear. The 3.09 calculates very well for the HC. Some members here like Linda and John Tout have proven this.
     
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  6. Viper

    Viper SRT Hellcat Supporter Gold Supporting Member

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    So the general consensus is that with DR and automatic and stock gears you can't hook up at the track???
    I think it would be more fun on the street but if it is slower at the track due to increased wheel spin and 20 inch wheels with DR then why spend the extra money to go backwards.
     
  7. TNCHARGER

    TNCHARGER SRT Hellcat Supporter Gold Supporting Member

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    It's not the gear that is the issue...it's the driver...many here are cutting 1.5 second 60' with the 3.09....I believe a few have hit 1.4...
     
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  8. Viper

    Viper SRT Hellcat Supporter Gold Supporting Member

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    20" Drag Radial tire or 18" Drag Radial?
     
  9. TNCHARGER

    TNCHARGER SRT Hellcat Supporter Gold Supporting Member

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    Both the 20" and 18" are capable of cutting a 1.5. I have used both at the track on my 426 stroker and found the 18" to be more consistent than the 20". I would use 20" if I wanted a good street/track tire. The 18" would be better if the track was more important as it is with my 2013 Challenger. I run it in the Modern Street Hemi Shoot races every year and I need every advantage I can get. I run summer tires on the car when driven on the street.
     
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  10. themarshall

    themarshall Silver Member Hellcat Car Club Gold Supporting Member HCC Charter Member

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    Just made the 3:09 change with alu. drive shaft also but, with this weather we have been having cant get there from here. S.E. Pa. DAM!
     
  11. Hubbs

    Hubbs Silver Member

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    If you're doing this for track use only, why not just go with the 18" tire?

    Yes, numerically higher gearing will reduce traction due to the increased torque hitting the ground. Anyone that's ever done a gear change can attest to the difference.

    I completely agree with TNCHARGER on the math that's involved to get it right for track use. If you're doing this for the street, go for it, but expect a little more difficulty hooking up.
     

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