Determining Boat Trailer Drum Brake Size With an Measurement of 14" Across The Backing Plate

Question

Question:

Good afternoon. I need some new boat trailer brakes and the backing plate is measured at 14” diameter as well as the outside diameter of the drum, would this be considered a 14” drum or a 12”?

asked by: Jason

1

Helpful Expert Reply:

The diameter of a drum brake is measured inside the hub so your 14" outer diameter is most likely a 12" drum brake. Depending on the age of your axles on your trailer I may be able to look up what the manufacturer installed on the axle by the serial number. This is generally found on the tag in the center of the axle.

If you are only looking for a replacement brake assembly this is generally determined by the weight capacity of the axle. The Hydraulic Brake Kit # AKFBBRK-7-D fits on 5,200-7,000lb axles that use a 5 bolt flange. The brake size is 12" x 2" and has a Dacromet coating for corrosion resistance on a boat trailer.

If you can provide me with either the axle serial number or more details and pictures of your current hubs and brakes I can ensure you get the correct parts for your boat trailer.

expert reply by: Bud M

1

Brake Assembly Measurement Location
(click to enlarge)

Answer 1

You can refer to the linked photo that shows how to measure both the diameter and depth of a boat trailer hub/drum. When selecting new hubs there are several characteristics you need to match up to ensure compatibility. Those are weight rating (to…

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Answer 2

To run the brake lines on the trailer, you don't need the dual cable. I'd recommend using 10 gauge wire, part #10-1-1 which is sold by the foot. Run the wire from the trailer connector back to the axle, cut the wire and strip the end. Use a…

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Answer 3

In the USA a tandem axle utility trailer with a gross vehicle weight rating (GVWR) of 7500-lbs should have brakes installed. Any trailer over 3000-lbs must have brakes on all wheels in most states, but laws do vary. Some states require braked axles…

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Answer 4

Even though I cannot comment specifically on the grease you used because I am not familiar with it, I can tell you the best grease for trailer bearings is a a grease with a rating of GC-LB, which just means it is made to withstand very high…

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Answer 5

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 6

In order to determine the torque rating for the lug nuts on your trailer you will need to know check out the chart I attached that shows all of the torque specs for all the trailer lugs available based on stud size, wheel material and wheel size.

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Answer 7

Based on the GVWR of your 2019 Jayco North Point 315RLTS it does seem like you have 7k axles. I recommend verifying this information to be sure. These axles typically use the #14125A outer and #25580 inner bearing found in the Timken #TMK92VR.…

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Answer 8

I currently have three diffrent self-adjusting assemblies for your boat trailer with 10" x 2-1/4" electric drum brakes which are attached for you below. eTrailer Electric Trailer Brake Kit part #AKEBRK-35-SA (3,500 Axles) Dexter…

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Answer 9

On Dexter 12" Nev-R-Adjust Electric Brake Assembly #23-458 the shoe pad thickness is 3/16 of an inch. Dexter says that you should replace the shoes if the material gets down to 1/16 of an inch thick or less.

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Answer 10

The recommended lug nut torque for your 7,000lb axle depends on a few factors like wheel size, stud size etc. Check out the attached photo which shows the torque specs for a variety of applications. I see you were looking at the Dexter Nev-R-Adjust…

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Answer 11

I'd be happy to help you out, John! To replace the brakes on your 5th wheel trailer you need the etrailer Electric Trailer Brakes #AKEBRK-7-SA which come with a self-adjusting feature so once you initially set them up you won't have to adjust…

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Answer 12

If your trailer has 7 wires running all the way back to the brakes, then yes, you can tap into the existing wiring. Each of your new brakes will have two wires for the brake magnet. One wire is for 12 volt power to the brake magnets and the other…

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Determining Boat Trailer Drum Brake Size With an Measurement of 14" Across The Backing Plate

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