A little background first: Mine is a 2019 G/T Plus RWD. Prior to the gear install I had installed Flowmaster 3 chamber mufflers and ended up settling on a Mopar Performance cold air kit, aside from those 2 things the car is all stock but did have a 3.08 open rear end. In cold air one night I was able to get a 6.0 0-60 and 14.6 @ 97 1/4 going by the performance pages but was never able to repeat that. In current air temps (about 60-65 degrees) I was getting 6.3 to 6.4 0-60 times.
I found a 3.90 diff with axles on e-bay from a totaled 2016 Shaker for $789 with free shipping, so I bought it and not wanting to do this on my back in the driveway paid to have the install done - it took the shop about 4 hours on a lift. No computer mods or other work was required beyond the install of those parts. Apparently the computer now gets vehicle speed from the wheel sensors, so there was nothing to do regarding the speedo - speeds are still correct.
My best 0-60 so far in equal temps (it was 61 that evening) is 5.8 seconds - .5 to .6 seconds quicker. I haven't been able to check 1/4 mile times yet. Mileage did drop a little bit, but it's still averaging 30-31 cruising @ 65 and that's not on flat ground. At 55 it will get 36-37. Climbing rolling hills is MUCH easier. Before on rolling hills at a 65-68 mph cruise, the instant mileage would drop to low teens but it's now high teens to 20 mpg instead. I credit the extra toque multiplication of the gears for this. Climbing steeper hills or bridges is also greatly improved and it no longer drops down a gear or two to maintain speed. Punching it at 65 on level road and counting one thousand one, one thousand two gets me to 83-84 mph - passing on the highway is certainly no issue
The only problem I've found is that hammering the throttle at low speed - say under 15 mph - gets a drop down to first gear which pegs the tach (not sure but it might be breaking the tires loose), the rev limiter kicks in and it falls on its face, then it upshifts and goes as expected. I think this is a programming problem that can be fixed with a tune. Later down the road I'll do that and also make sure to include tuning for the other mods.
My goal was to get sub 6 second 0-60 times, run at least 100 in the 1/4 and if possible break 13.99. Just going by what I have so far I think this will do that and a tune should certainly put me at or better than my goals.
Oh, and yes, it will now light BOTH tires - time for stickier, wider rubber than the stock 20" Goodyears.
PS, one thing I forgot to mention: When driving like a "normal" car, it goes into 2nd at 5 mph, 3rd at 10, 4th at 15, 5th at 20 and into 6th just past 25. It's pretty funny how many shifts it does at such low mph.
I found a 3.90 diff with axles on e-bay from a totaled 2016 Shaker for $789 with free shipping, so I bought it and not wanting to do this on my back in the driveway paid to have the install done - it took the shop about 4 hours on a lift. No computer mods or other work was required beyond the install of those parts. Apparently the computer now gets vehicle speed from the wheel sensors, so there was nothing to do regarding the speedo - speeds are still correct.
My best 0-60 so far in equal temps (it was 61 that evening) is 5.8 seconds - .5 to .6 seconds quicker. I haven't been able to check 1/4 mile times yet. Mileage did drop a little bit, but it's still averaging 30-31 cruising @ 65 and that's not on flat ground. At 55 it will get 36-37. Climbing rolling hills is MUCH easier. Before on rolling hills at a 65-68 mph cruise, the instant mileage would drop to low teens but it's now high teens to 20 mpg instead. I credit the extra toque multiplication of the gears for this. Climbing steeper hills or bridges is also greatly improved and it no longer drops down a gear or two to maintain speed. Punching it at 65 on level road and counting one thousand one, one thousand two gets me to 83-84 mph - passing on the highway is certainly no issue
The only problem I've found is that hammering the throttle at low speed - say under 15 mph - gets a drop down to first gear which pegs the tach (not sure but it might be breaking the tires loose), the rev limiter kicks in and it falls on its face, then it upshifts and goes as expected. I think this is a programming problem that can be fixed with a tune. Later down the road I'll do that and also make sure to include tuning for the other mods.
My goal was to get sub 6 second 0-60 times, run at least 100 in the 1/4 and if possible break 13.99. Just going by what I have so far I think this will do that and a tune should certainly put me at or better than my goals.
Oh, and yes, it will now light BOTH tires - time for stickier, wider rubber than the stock 20" Goodyears.
PS, one thing I forgot to mention: When driving like a "normal" car, it goes into 2nd at 5 mph, 3rd at 10, 4th at 15, 5th at 20 and into 6th just past 25. It's pretty funny how many shifts it does at such low mph.