Bolt Pattern of 5 Bolt Brake Mounting Flange for Trailer Brakes

Updated 03/28/2024 | Published 03/24/2017

Question:

I have an oddball question. On the standard 5 hole brake backing plate mounting flange, what is the center to center spacing between the bolt holes? I understand that the standard 5 bolt flange is an industry standard for trailer axles with 5 bolt patern but I would like to know what that standard is. Thank you,

asked by: Keith H

Expert Reply:

The bolt pattern for a 5 bolt brake mounting flange, like # 4-44-1 is 5 on 3-7/8 inches.

What that means is it measures 3-7/8 inches from one corner to its diagonal counterpart. From hole to hole across the bottom is 3 inches and between the others is about 2-1/8 inches.

I've made a diagram that may help.

expert reply by: Charles S

click to enlarge

Jon

3/28/2024

Hi I have a older 6 lug 6 lb axles the bolts all measure the same across like you're saying but the center hole is like three and a quarter would that work for the center hole it's a three axle trailer and the guy when I bought it said it was around early 70s thanks for info