whats the best increase in mpg you've seen with new wheel/axle bearings
 

has anyone seen a great increase after changing your bearings. wheel/differential bearings.


im running 40psi in my tires. my afr's are always around 14.7-15.5:1 i drove mostly highway and low throttle, and i can't get above 18.5mpg. i know my differential is pretty bad. but whats the worst decrease in mpg anyone has seen from bearings.

...because wheel/axle bearings are part of "bearing friction" loss, which is predominately a function of weight and of speed to a much lesser degree, I'd venture that you'd probably not be able to notice any difference--UNLESS, the original bearings were "totally shot/worn out" before you replaced them.

ya they have 205,000miles, and has been whining for like 20,000miles, the fluid is boiling now and coming out of the top vent. i dont think the pinion bearing rollers are there anymore. i think during accel its probly the worst since thats whens force is greatest on the bearing.

If your bearing are worn out enough that they are burning up the oil that should lube them, then yes, it's way past the time to replace them, I would imagine that you will see an improvement, if you try to push the car by hand right now I'm sure you will feel the drag, just like if you had brake drag.

A Chicago guy (?) here just replaced a bad wheelbearing on his Chevy and saw an increase.... it would have to be really bad for any improvements though, causing other problems like misalignment and dragging against brakes or other stationary parts.