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2015 Challenger RT Shaker
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I have a '15 RT A8 with a 3.09 LSD diff right now. I wanted to know if anyone knew of some other gears the '15 or newer besides 3.09, 3.70, or 3.90? I had 3.55 in my '12 Charger (but it was getrag, tho, '15s have a different maufacturer) and loved it, not too hard on gas but more torque. 3.70 and 3.90 are little too much for a daily driver to me...

Any help is appreciated
 

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I think the 3.09 is a great all purpose rear end myself. I have a '15 SRT392 and would never hook up with more low end torque. It's hard enough already :) A lot of Hellcat owners are switching to the 3.09 from their OEM 2.62's
 

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2015 Dodge Challenger R/T Scat Pack
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IMO a 3.23 gear would be perfect for drag racing with an A8 392 car. The 3.09 is great as well since the A8 first gear is so steep, but there is a little room left at the end of the track for more RPM in 5th gear. I cross the line around 5400-5500RPM. If it would go up to 6200-6300RPM that'd be perfect.

I'm not sure how an A8 car would even hook with drag radials with 3.55 or 3.90 gears. If you do the math the first gear has wicked torque multiplication already.

4.70 x 3.09 = 14.52:1. That's already hard enough to hook up with.

But I have not seen any other options out there yet.
 

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I have a '15 RT A8 with a 3.09 LSD diff right now. I wanted to know if anyone knew of some other gears the '15 or newer besides 3.09, 3.70, or 3.90? I had 3.55 in my '12 Charger (but it was getrag, tho, '15s have a different maufacturer) and loved it, not too hard on gas but more torque. 3.70 and 3.90 are little too much for a daily driver to me...

Any help is appreciated
People that have installed the 3.70 seem to really like it.

The A8 / 3.92 is very popular with the Ram guys and a RC SB 2wd Ram only weights about 700lbs more than our cars.

I agree that a 3.55 would be ideal, especially for racing. However, the 3.70 is worth a look if you really want to swap differentials.
 

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From what I've seen thusfar, there are not other options with the 15's and above. They use the ZF rear diff, which is supposedly welded on the inside. I have no idea, if this is true or not as I have a Getrag 226 rear diff. But like all the above have mentioned your only options are your current rear diff, or another factory unit with a taller gear set.
 

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I'm surprised no one pointed out to the OP that they do not have a 3.09 lsd. 2015 5.7l a8 only came with a 3.07 conventional (open), no other option.
 

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Maybe I jumped the gun on my previous post. Maybe the OP replaced the 3.07? If so I would love to know what kind of difference it made going to the 3.09.
 

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Maybe I jumped the gun on my previous post. Maybe the OP replaced the 3.07? If so I would love to know what kind of difference it made going to the 3.09.
3.09 LSD exist, as mentioned above this diff is favored by the HC folk.


https://www.highhorseperformance.com/Mopar_3_09_Geared_LSD_Rear_Differential_p/hc309rear.htm
https://www.speedlogixstore.com/product-p/sx-df-lsd.htm
Oh I know it exists. You can get it cheaper than the two links above from any online Mopar parts site. Just would like to know if there uh s any better throttle response and shifting than the 3.07.
 

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You can get it cheaper than the two links above from any online Mopar parts site.
I agree. I bought a replacement 3.90 LSD for just under $740 shipped last year. Although now I am running a SC it might have been better to go with a 3.70 or even a 3.09...first gear whines out in a blink of an eye.
 

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I have a 2017 R/T A8 with an open diff. If I wanted to swap to any of the LSD options, what do I need other than the diff? Axles? Do I need a different driveshaft?

Also, for those that have done it, what is the favorite ratio for a daily street driven car? And what’s my factory ratio?
 

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I have a 2017 R/T A8 with an open diff. If I wanted to swap to any of the LSD options, what do I need other than the diff? Axles? Do I need a different driveshaft?

Also, for those that have done it, what is the favorite ratio for a daily street driven car? And what’s my factory ratio?
You need nothing other than the diff gear of your choice . I picked 3.09 for my R/T but depending on other mods you may want 3.70
 

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I have a 2017 R/T A8 with an open diff. If I wanted to swap to any of the LSD options, what do I need other than the diff? Axles? Do I need a different driveshaft?

Also, for those that have done it, what is the favorite ratio for a daily street driven car? And what’s my factory ratio?
You need nothing other than the diff gear of your choice . I picked 3.09 for my R/T but depending on other mods you may want 3.70
What year is your car?
 

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2018..you would choose a different ratio for 5.7 vs 6.4 cars.
Are they selling gears only for '15+ LSD rears? Last I heard, the gears were welded and a complete pumpkin was needed.

Mine has the stock (3.09?) with the A8. Need more rubber to hook, and I only street drive. Way to easy to smoke in first and second.

Hate to see what a numerically higher gear would do other than make 1st gear worthless.
 
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