Et to be had

Doug McCue · 01-05-2015, 01:25 AM

Can there be an et decrease by using different wheel bearing assemblies in older combinations 1967 through 1974?

Greenlight · 01-05-2015, 02:32 AM

From an engineering standpoint, the rolling resistance changes with the ratio of the radius of the tire vs. the radius of the bearing.

So, for a 28" tall tire, and a 2.5" diameter vs. 2.0" diameter bearing you would have a 20% reduction in rolling resistance.

14/1.25 as compared to 14/1.0
(14.0-11.2)/14 = 0.2 or 20%

Now if you consider the actual rolling resistance is about 1% to 1.5% of the vehicle weight, a 3000 lb. car would require 30 lbs. to 45 lbs. to "push" at a steady low speed (no air resistance effects).

Reducing the 30 lbs. by 20% is a 6 lb. improvement (45 lbs. = 9 lb. improvement).

Is it worth any ET, I don't know. But I'm sure it won't slow you down.

Try pushing your car with a bathroom scale between your hands and the bumper and see how much rolling resistance your car has (no the force to get it to start moving, the force to keep it moving at a steady speed). Push in a straight line.

If reducing the car weight by 10 lbs. equals 0.01 seconds, then it could help you about 0.01 second with the smaller wheel bearings.

Try pushing the car with the scale and change tire pressure. You will see a bigger difference.

01-05-2015, 01:25 AM	#1
Doug McCue Member Join Date: Jun 2007 Posts: 232 Likes: 7 Liked 13 Times in 2 Posts	Et to be had Can there be an et decrease by using different wheel bearing assemblies in older combinations 1967 through 1974?

01-05-2015, 02:32 AM	#2
Greenlight Member Join Date: Dec 2004 Posts: 208 Likes: 9 Liked 70 Times in 18 Posts	Re: Et to be had From an engineering standpoint, the rolling resistance changes with the ratio of the radius of the tire vs. the radius of the bearing. So, for a 28" tall tire, and a 2.5" diameter vs. 2.0" diameter bearing you would have a 20% reduction in rolling resistance. 14/1.25 as compared to 14/1.0 (14.0-11.2)/14 = 0.2 or 20% Now if you consider the actual rolling resistance is about 1% to 1.5% of the vehicle weight, a 3000 lb. car would require 30 lbs. to 45 lbs. to "push" at a steady low speed (no air resistance effects). Reducing the 30 lbs. by 20% is a 6 lb. improvement (45 lbs. = 9 lb. improvement). Is it worth any ET, I don't know. But I'm sure it won't slow you down. Try pushing your car with a bathroom scale between your hands and the bumper and see how much rolling resistance your car has (no the force to get it to start moving, the force to keep it moving at a steady speed). Push in a straight line. If reducing the car weight by 10 lbs. equals 0.01 seconds, then it could help you about 0.01 second with the smaller wheel bearings. Try pushing the car with the scale and change tire pressure. You will see a bigger difference.