- Feb 21, 2018
There are a couple of important issues concerning unwanted driveline vibrations and interior noise level. Once you move away from factory rear axle ratios (say 3.08:1) a couple of things happen. The manufacturer made sure to eliminate unwanted driveline and exhaust vibrations when they selected the original gear ratios. Their chosen design took care of unwanted issues but only within a specific operating rpm range. Once you install 3:73, 4:11s, etc. you risk creating unwanted noise and vibration concerns, not around town, but once you get on the highway. Why..... because you are spinning the driveline at an increased rpm where it may hit its "resident frequency. There is an immense amount of engineering when it comes to driveline designs. Once you focus on what you want your car to do (drag race, street, highway) then you can make a more informed choice. Where the problems arise is when you want both drag racer and highway cruiser. I'm running a Malibu 5.3L LS, 4L65e, 3:42 Gears, 26" tire.