Bigger rear drum brakes ??

Since the front brakes do most of the braking ( up to 70%). How much better stopping performance would you get by swaping the GM 9 1/2" X2" rear drum brakes, and replacing them with 11" X 2". ? Don't want to do a rear disc setup. Truck weighs about 3700/ quite a bit of the weight is over the rear axle.

 

Well, it sure as hell wouldn't hurt. I've never heard of having too MUCH braking area on a truck that does any sort of hauling.

 

Will not change your braking power unless you increase the force.

P=F/A

P=Pressure
F=Force
A=Contact area

You would be increasing the contact area by ~ 3sq inches (not accounting for the curvature)

Having more contact area between the drum and the brake pad will create a larger source of frictional forces. However it also reduces the pressure between the brake drum and pad for a given force.

The above equation shows that although you increased the frictional contact area the increases in the frictional generating area are exactly offset by the reduction in pressure.

To get a benefit would require that your braking system be able to apply more force to the surfaces in order to keep the surface pressure the same.

 

Bigger brakes never hurt. HRP

 

OK..my smaller 9 1/2 X2 system has a 15/16" wheel cylinder. And the 11 X 2 system have a 1.00" wheel cylinder (and a possible 1 1/16" wheel cylinder) . Bigger WC=more pressure.

 

In general you can't have too much brakes. BUt you can have too much rear brakes that will lock up prematurely. If you look at some trucks, they have a load sensing proportioning valve that adjusts the rear braking to account for loaded vs unloaded.

The best fix is to upgrade *both* front and rear brakes to be bigger and more capacity.

 

About 28% more with 11x2 and 1.00 cyl, about 37% more with the 1-1/16 cyl..Put an adj proportioning valve in [if you don't already have one] and you will be fine.

 

Yeah I do have an adjustable proportioning valve. Looks like I might be swapping out rear drum systems. Thanks.

 

Larger wheel cylinder will make the 11 inch drums add stopping power.

I had assumed the same wheel cylinder.

 

larger brakes wont heat up as fast and use to be the option on most wagons and trucks for towing.

 

I have found that some chevy trucks had 11 5/32 X 2 3/4 rear brakes, and some had 1" wheel cylinders. Any thoughts ? over the 11 X 2's..or would that be to much ? my truck weighs about 3700lbs with 11" disc / 2 15/16" GM calipers/ and a manual non booster master cylinder.