If I switch from a 4:10 Rear end to a 3:73 rear end how will it effect my cars performance? Will it improve my gas mileage significantly. I know it will lower operational RPM's.

Thanks for all answers ahead of time>
John
Charleston, SC

Don't know what you have for a trans but with my T350 and 3:73 turns 3300 or so at 65 MPH. Not a fuel economy ratio for sure but it is probably more driveable than your current ratio. The performance of the 3:73 are good. It's a blast to drive around town.

I don't know if it is worth the effort. If you had a drop out rear end you could try a set of 3.73s but there is a lot of effort and money involved in changing your rear end gears for not that much of a change in mileage.

I agree, probably not worth the effort. If you were changing to a 3.42 it would be a more noticible change. Do you have a 3 or 4 series posi?

Yeah, what is it for a quarter point change.....like 250 RPM. Not a real big deal and might not be worth it.

Although, the 3.42's are an idea. My favorite ratio....

I am doing that same swap, as I have a 4-series carrier and that is the highest (lowest numerically). I also am going to switch to taller rear tires to help lower my RPM. Use a gear calculator to figure out your new RPM's.

The ratio change is 9%, not that great a change.

Keep the 4.10's and switch to a overdrive trans and get the best of both worlds! Lower first gear and better gas economy.