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3.09 LSD Swap...the definitive thread on the GOAT Hellcat mod

41K views 151 replies 47 participants last post by  catdodgehell 
#1 · (Edited)
Yeah, so no one ever says its not a good mod...most says it the best mod or one of their favorite mods (if not their favorite) and then there are all kinda comments on how the Hellcat should come with these gears from the factory.

Well...its all true and then some.

I was on the fence but with a DSS aluminum shaft going in, I said "now is the time" since the exhaust had to be dropped...

3.09 Differential =
GOAT
Game-changer
Unicorn
Neckbreaker
Bad ass


etc. etc. etc...

...there just aren't enough adjectives to describe how much this mod helps to really unload and debog the engine...and bring the tranny to life.

You
Must
Do
This
Mod


Sorry if I'm not being direct enough :D

Thanks again to Andrew at Stahley's in Annville PA for a great job (and having a great lift)

Edit: added more pics

Land vehicle Vehicle Car Muscle car Motor vehicle
Auto part Machine Suspension Engine
Auto part Bumper Muffler Automotive exterior Pipe
Auto part Vehicle Engine Car Machine
 
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#2 ·
Ok so i just drank ur Koolaid. So far it tastes good. Whats this mod going to cost me? And assuming im never tracking it, no driveshaft swap needed im guessing. Also, what about the factory warranty? Thought i saw somewhere if a Dode dealer does it then the warranty stays.
 
#9 ·
Cost:

3.09 Diff ~$1,300 delivered
Good 1-piece drive shaft ~$900 delivered (no impact to install cost so you may want to consider)
Labor ~$300 (~$150 more if you need to mod exhaust for clearance which I did due to aftermarket mufflers)

Many on this forum have had a Mopar dealer swap the driveshaft and were promised no warrentee issues.
Regarding 3.09 LSD change...I do not recall seeing forum members comment on that but may have.

In 1-2 weeks, my drive-train warrentee will be completely compromised...due to phase 2:cool:
 
#3 ·
Why was FCA so horny about getting a good top speed number with the 2.62's. Does anyone really need to say there car can go 202mph(Charger) or will ever have the potential to use all of the top speed. Wouldn't the 3.09 be a better suited gear in the car coming from the factory?
 
#6 ·
In short...yes. 195.2 so far and 200 is on the list still. I've actually not done this mod specifically because my interest in high speed events. Car runs low 10.8s and I think I can get 10.7. With this I know I'd be 10.7 and possibly 10.6 but I can achieve that in many ways with out hurting my top end.

I agree though that for the average user who drives on the street and the drag strip it is a great bang for the buck mod without touching the warranty.
 
#4 ·
Does the entire differential need to be replaced, or just the ring and pinion gears?
 
#14 ·
So the one piece ds, basically needed for the track due to increased traction? This gear swap wouldnt necesitate the ds, correct? Never going to the track...
 
#17 ·
Bull car shifts to 7th gear at exactly 195mph. I think with the 3.09's you'd run out of gear. I don't think it will still pull in 8th. I have to find the chart but somebody the speed vs. gear and although it was theoretical math from what I saw it was deadly accurate. Let me see if I can find it.
 
#18 ·
With 2.62

1st -- 4.714 x 2.62 = 12.351 ( x 336 = 4,149 ) = 41.5 MPH @ 6000 -- 42.8 MPH @ 6200
2nd -- 3.143 x 2.62 = 8.235 ( x 336 = 2,766 ) = 62.3 MPH @ 6000 -- 64.3 MPH @ 6200
3rd -- 2.106 x 2.62 = 5.518 ( x 336 = 1,854 ) = 92.9 MPH @ 6000 -- 95.9 MPH @ 6200
4th -- 1.667 x 2.62 = 4.368 ( x 336 = 1,467 ) = 117.3 MPH @ 6000 -- 121.29 MPH @ 6200
5th -- 1.285 x 2.62 = 3.367 ( x 336 = 1,131 ) = 152.2 MPH @ 6000 -- 157.32 MPH @ 6200
6th -- 1.000 x 2.62 = 2.620 ( x 336 = 880 ) = 195.6 MPH @ 6000 -- 202.20 MPH @ 6200
7th -- 0.839 x 2.62 = 2.198 ( x 336 = 738 ) = 233.3 MPH @ 6000 -- 241.11 MPH @ 6200 ( we're past the aero limit here )
Then we enter driving in a vacuum land :)
8th -- 0.667 x 2.62 = 1.748 ( x 336 = 587 ) = 293.3 MPH @ 6000 -- 303.13MPH @ 6200


With 3.09

View attachment 24430
Here it is. looks like 7th gear at 165 and 8th at 197. 3.09's will get it done in the mile. But beyond I think you will gear out.

Edit you have to click on the attachment to see it.
 
#19 ·
Just checked my 2 mile video....car shifted to 5th at 119 on the speedo and 6th at 150. Considering the speedo error (it's about 1-3 mph off depending on speed) the above chart is very accurate.
 
#22 ·
AHHHHHH my eyes!!!! That is an eye chart BULL!!! Lol. Can't get it to scroll down to see the 3.09 gears
 
#24 ·
Yup that matches up good. I'm doubtful it will pull all the way up there in 7th and nearly positive it won't pull in 8th. I don't think the 3.09s get you to 200mph. I'd love to be proven wrong though....because then I can install them and reap the benefits down low!
 
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#27 ·
Yeah, so no one ever says its not a good mod...most says it the best mod or one of their favorite mods (if not their favorite) and then there are all kinda comments on how the Hellcat should come with these gears from the factory.

Well...its all true and then some.

I was on the fence but with a DSS aluminum shaft going in, I said "now is the time" since the exhaust had to be dropped...

3.09 Differential =
GOAT
Game-changer
Unicorn
Neckbreaker
Bad ass


etc. etc. etc...

...there just aren't enough adjectives to describe how much this mod helps to really unload and debog the engine...and bring the tranny to life.

You
Must
Do
This
Mod


Sorry if I'm not being direct enough :D

Thanks again to Andrew at Stahley's in Annville PA for a great job (and having a great lift)

View attachment 151609 View attachment 151617
Your car looks sweet mo-par
Nice!!!!
 
#32 ·
If it weren't for the Demon, I'd be considering a lot of monetary investment, you guys have me motivated if I don't like the Demon...that's for sure!
 
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#34 ·
Oh I am for sure...Only mod I'm doing is exhaust, I want more sound! :)
 
#35 ·
I just did the swap to 3.09s and a DSS dampened DS. Cars feels great daily driving, feels like it gained 50hp. I am headed to the track tonight but Im only on 275s Nitto 555rs. We shall see. My best time so far is 11.02 @ 126.
 
#37 ·
I was worried about that and wasn't gonna do the DS. But the only noise is with the radio off at about 50mph on decal, there is a faint noise.Very Faint. I am very picky with noise and vibration... and I am pleased. If it wasn't a dampened DS, I prob would of put stock back in. But I am happy with it. No vibrations either.
 
#42 ·
No need to correct the speedo. That's why it's a perfect mod!
 
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