Rear brake sizes.

I am upgrading from 8 inch rear end. The old rear brakes are 10 inch by 1.75. The new brakes on the 9 inch rear end are 10 inch by 2 inches. Does the 1.75 to 2 inch increase make much difference?

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IMHO, yes it will make a slight difference. You may need to adjust the portioning valve to compensate for the additional drag of larger shoes. Test drive first prior to making any adjustments.

Pastorpat,

If you are going in that direction, take a look at the Kit from Master Power Brakes. I installed this kit on 1973 Coupe. Much bigger than stock. It is a direct bolt on kit!

https://www.mpbrakes.com/rear-brake-conversion-kit/1973-ford-mustang-legend-series-rear-drum.asp?catid=9017D315D38A4E4CAE68621E7D3759A2

Rear Drum Brake Conversion Kit - Legend Series Deciding to keep drum brakes on the rear of your vehicle is not a bad thing. What is a bad thing is not upgrading them to a system that makes sense. Our rear drum upgrade kit utilizes a large 11 inch drum, all new components and 1 inch wheel cylinders giving disc brake feel without the expense.

The kit includes the following items:

11 inch Finned Brake Drum

Stamped Backing Plate with Black Powdercoat Finish

OEM Quality Brake Hardware

New Brake Shoes

1 inch Bore Wheel Cylinder

Fully Assembled and Ready to Install

IMHO, yes it will make a slight difference. You may need to adjust the portioning valve to compensate for the additional drag of larger shoes.  Test drive first prior to making any adjustments.

Click to expand...

No adjustment possible on the stock prop valve. Factory engineers calibrated the drum brake action by varying the internal diameter of the wheel cylinders.