sailing220

I keep hearing that 3.73s are better for autos than 4.10s. Why is this? I want to do gears soon and I'm wondering what the problem with 4.10s is. [/align]

Heavyg72

I believe it has to do with where you are starting from. I believe the auto are standard with 3.31's while the manuals are at 3.55's. So for example...going from 3.55 to 3.73 is not that noticeable. However, you can run either in either car as it just matters with what you are looking for. If you plan on going FI then I would stick to the 3.73's as they work well in supercharge applications. There are several folks on here that are running 4.10's in their autos.

sailing220

You have the 3.73s, how do you like them? Did you have them before your paxton? How were they w/o FI? [/align]

drbobvs

+1 to above, auto's are stock 3.31, so going to a 3.73 is about the same jump as going from a 3.55 to 4.10 in a manual. Manuals were 3.55 stock in '05 and possibly '06. Going to a 4.10 in an auto is similar to going to a 4.30 in a 3.55 manual. Of course, if your manual came with the 3.31, as they did standard in '07, '08, the taller trans gearing in them can justify going to 4.10, but i would not recommend 4.10 in an auto. Even without F/I, 4.10's in an auto can wreak havoc on traction and if you do alot of hwy driving, it can become annoying. I know of at least one stock auto driver who changed back to 3.73 from 4.10 for this reason, and I know of at least one manual driver who went to 4.10 then to 3.73, than back to 4.10 b/c hewould just bog down at the track with the 3.73 in the manual.

sailing220

Alright, thanks for the info. If (when...) I do gears I'll go with 3.73s.[/align]

Pwny

Also, if you go 4.10's, you have to reprogram the shift points. Your car will still shift at its usual points, but be about 200 RPM's higher than normal due to the new ratio.