Charger Forums banner
1 - 8 of 8 Posts

·
Registered
Joined
·
8 Posts
Discussion Starter · #9 ·
The dual black marks don't always mean it's an LSD, but it is usually a good sign. In this case though, my money is on it having an LSD rear end that was swapped in at some point prior.

Most likely it would have come from an A5 equipped SRT car, as they had 3.06 LSD rear-ends, and that would be a completely reasonable rear diff ratio for an upgrade to another A5 equipped car.

The possibility exists that a 3.92 LSD from any M6 car, SRT or R/T, could have been swapped in, but that would be less streetable since it would leave the highway cruising RPMs much too high for most folks to live with.

The cruising RPM in 5th gear at 70 mph would be a good indication of which rear-end the car currently has. Get the car's original rear-end ratio off its build sheet, and that will give you an expected 70mph RPM (in 5th gear) to compare against the car's current 70mph RPM (in 5th gear). If they are not the same, the rear end has been replaced with something else, most likely an LSD.

Assuming the tires are 225/60/18, here are the 70mph RPM numbers to use in comparison when trying to figure out which rear-end ratio is currently in the car:

2.82 Open (OE for that car?) - I believe this would have been the OE rear-end's ratio, but the build sheet will indicate for sure (other possibility is a 2.65, but I don't think those were available before 2011):
View attachment 301872

3.06 LSD (SRT w/ A5):
View attachment 301873

3.73 LSD (M6 R/T w/ 18" wheels) - while technically a possibility, I doubt the car would have one of these. They are exceedingly rare to find from what I have seen, so it's unlikely to have one of these:
View attachment 301874

3.92 LSD (SRT or M6 R/T w/ 20" wheels):
View attachment 301875
I am running 245 45 20 tires (20x9wheels) and @70 mph I'm at 2100-2200 rpm.

What does that equate to? I'm guessing a 3.06.
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #17 ·
I just bought new rims/tires and will have them on the car come Dec 6th. I will video the car on the lift and get a good visual on the rear end and have the techs spin one wheel to show the other wheel spinning as well...or not.

All I know is when I take traction control off, it lights up both wheels effortlessly when I floor it, hence why I got bigger rims and tires all the way around.
 
1 - 8 of 8 Posts
Top