How do I Correctly Measure Drum Brakes?

Question

Question:

I want to know what I need to measure to get the correct brake system for my trailer. Do I measure the inside width of the brake drum and the diameter of the drum? Thank you.

asked by: Aaron L

0

Expert Reply:

When measuring the brake drum, you measure the interior diameter on the drum.

I have attached a photo to help during the measuring process.

If your brakes are 7 inches part # AKEBRK-2 works for your application. You also need hardware part # BRKH7

If your brakes are 10 inches part # AKEBRK-35-SA works for your application. You also need hardware part # BRKH10B

If your brakes are 12 inches part # AKEBRK-7-SA works for your application. You also need hardware part # BRKH12

expert reply by: Clayton O

0

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Kenny

9/3/2025

Hello, I have a shorelandr pontoon bunk trailer, the drum measures 8.5 inches inside, I can not find anything like it, any ideas. I need to replace the complete backing plate, master cylinder and shoes.

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Jerred H.

9/4/2025

@Kenny I am not seeing anything that size either. Do you have a part number off of one of your brake assemblies or hubs?

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Kenny

9/4/2025

@JerredH looks like 15652

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Jerred H.

9/4/2025

@Kenny Thanks for the information. We ran into this exact situation back in May and found out there is no modern replacement/equivalent for a 15652 hub and we do not have a brake assembly that small for it. Our only option, that doesn't require going up to a larger rim, is to upgrade your brakes to disc using the Kodiak Disc Brakes - 8" Hub/Rotor - 5 on 4-1/2 item # KOD87FR. If you go this route, I recommend verifying the part numbers stamped into the sides of the bearings or the spindle size. They should be inner bearing item # L68149 with 1.378" ID and outer bearing item # L44649 with 1.063" ID.

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See All (7) Replies to Kenny ∨

Answer 1

To determine the size of the brake assemblies you need you have to measure the depth and width of the hub drum on the axle like what you see in the picture I attached. The most common size is 2-1/4 inch wide like the #T4071600-500 that you…

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Answer 2

No worries. We can help you pick out the correct type and size of replacement brakes you need for your trailer. We carry electric and hydraulic drum brakes as well as disc brakes, all shown on the linked page. Just click on your brake type, such as…

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Answer 3

I attached a picture of a 7-way wiring diagram for you to check out to help show you where all of the pins of the connector are. If your 7-way is upside then yes the diagram would need to rotate 180 degrees. You can use the notch of the 7-way to…

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Answer 4

From what we've found in the past people with the number 90817 are for 6K brake systems so you need the following parts: - Right Hand Assembly #23-106-09 - Left Hand Assembly #23-105-09 I've a photo showing the mounting bolt pattern for these…

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Answer 5

If your 1968 Airstream has 12 by 2 inch brake assemblies and the mounting flange has 5 bolts, 4 that are 2-1/16 inches on center from each other and the bottom two being 3 inches on center, then the #23-106, and #23-105 brake assemblies will work on…

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Answer 6

It sounds like you have the brake mounting flange for Hayes/AL-KO brakes. The standard 5-bolt brake mounting pattern on #AKEBRK-6 will not work. We do have brakes that have that mounting pattern though. You will need #23-105-09 for the left and…

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Answer 7

The magnet looks to be fine, a little dirty perhaps, but it doesn't look like the copper windings are coming through. The melted wire though indicates that there was likely a short that caused the wire to melt. A short could have been at the…

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Answer 8

Brake magnet wires like what are on the brake assembly #23-106 that you referenced can be wired up with either wire getting the positive and the other getting the ground. As long as current runs through them it doesn't matter which wire gets the…

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Answer 9

You didn't mention adjusting the brakes so I believe that is where your problem lies as this is a very common problem. You want to tighten the brake assemblies so that there is a light drag on the hub/wheel as you turn it otherwise the brakes…

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Answer 10

To replace your 12" brakes I recommend checking out the 7K TruRyde Electric Trailer Brake Kit #TRU96FR or the 5.2K - 7K Hydraulic Trailer Brake Kit #AKUBRK-7 depending on what kind of braking system you have. You'll also need the Mounting…

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Answer 11

The left side is the driver side, right side is passenger side. On a trailer brake assembly like #23-105 the arm that the magnet is on points to the front of the trailer and the magnet always will be on the bottom. I have included a picture that…

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Answer 12

You'll need to do some quick measuring of your backing plate/brake flange to see if you can use the 6,000 lb Dexter Electric Brake Assembly for 4 Bolt or 5 Bolt Flange - 12" - Left Hand #23-105-09. I have added photos below that I hope will…

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How do I Correctly Measure Drum Brakes?

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