I am thinking about going from my stock gear ratio to 4.10 gears. I want to know just about how much my gas milease will decrease after swapping in the 4.10's. Oh my car is a 1998 mustang GT with a 5 speed.

 

Depends on what type of driving you do, highway or city? combo?

If you do all city driving like my, I was told that 4.30s only decrease a couple miles TOTAL in the tank if you drive like a normal sane person. But if you have a lead foot, expect a significant drop I think.

 

oh and do I need a modified cross pin to install these gears?

 

No that's for the 7.5" rear end. Your GT has an 8.8".

 

you'll lose like 3 mpg. Highway driving that is.

 

you shouldnt hardly lose any city driving because those gears makes it easier for you engine to get up in rpms and speed so that means less strain on your engine but like they said..if youve gota lead foot..you better belive you will be able to watch the needle drop down..and you will lose some on the highway driving because of course your going to be buring more rpms but its well worth the few extra bucks.. gears really wakes up the stangs

 

i lost about 2 miles a gallon with 4.10 but i try to drive reasonable untill some *** in a chevy / pontiac starts acting a fool....