How To Determine If Boat Trailer has 10 Inch or 12 Inch Brake Assemblies

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Question:

I have a boat trailer and need to replace the brakes. I know I have a #84 spindle, 15 inch rims 5 lug at 4.5 inch spacing...Is there a way to tell if I need 10 inch or 12 inch brakes? Thanks.

asked by: Paul

0

Expert Reply:

When determining if you need 10 inch or 12 inch brake assemblies there are a couple of easy things to check to confirm the fit for your trailer. The first thing is you can measure the diameter of your hub. The second thing is you can look at the brake flange, if it has 4 bolts then it is 10 inch if it has 5 then it is 12 inch.

Because you know you have a #84 spindle we can be confident that you have a 3,500 lb axle and you will need the 10 inch assemblies. I recommend the Hydraulic Brake Kit - Uni-Servo - Free Backing # AKFBBRK-35-D which will fit your current hubs. If you also want to upgrade your hubs while you are at it, I recommend the Galvanized Hub/Drum # AKHD-545-35-G-K for your boat trailer. If you have EZ Lube Spindles then # AKHD-545-35-G-EZ-K will come with the grease cap that allows for that zerk access.

If you have electric brakes on your boat trailer then you can use # AKEBRK-7-SA for 12 inch or # AKEBRK-35-SA for 10 inch assemblies.

expert reply by: Jason S

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Randell

12/1/2024

I have a two axle trailer custom built for a cobalt 226 with disc brakes on the front axle only. In 2018 I had a shop replace the brakes. We used the boat very little and only made short moves from storage to the ramp. We made a trip to San Antonio from San Francisco when we moved in May 2022. Upon arrival the pads were almost completely worn away. We replaced the pads and have put less than 500 miles on the trailer. While doing maintenance repacking the bearings we found that the right side pads were already heavily worn unevenly. We decided the mounting brackets may have bent so we replaced the mounts. Calipers and pads with new. They are tie down G5 9.6 disc brakes. After a short trip to the storage yard of less than 10 miles the brakes are locking up. Question Should this trailer have larger brakes? Brakes on both axles? Or have we done something drastically wrong? Thanks

Reply

Robin H.

12/1/2024

@Randell assuming you have 3,500 lb axles it is probably safe to assume your brakes match the capacity of the axle so you're putting a lot on a single set of brakes. I would definitely add brakes to that other axle. As an example, say you do have two 3,500 lb axles and your Cobalt 226 is 5,000-6,000 lbs loaded on the trailer. Your single set of brakes designed for 3,500 lbs is going to wear down significantly faster because it has to stop all of that extra weight beyond its capacity. If you share that weight between two sets of brakes, just like you do with the axles, the wear on the brake pads will be normal since the combined rating is 7,000 lbs which is in line with your boat and trailer.

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Randell

12/1/2024

@RobinH Thanks for your quick reply. Sort of disappointed with cobalt’s choice af brakes on the trailer.

Reply

Robin H.

12/1/2024

@Randell if you can identify the axles I can help you find replacement brakes and an extra set of brakes for the axle without them. Tie-down engineering is no longer around so we wouldn't be able to match the other set but we have good replacement options. While you're at, it you will also need to make sure that other axle has a brake flange. If it doesn't, you'll have to add one or replace the axle with one that has a brake flange to install another set of brakes. I'm sure wherever/whenever that trailer was built it only needed brakes on a single axle by law so that is what they did to save money. Just like a lot of utility trailers for heavier loads can come without brakes because the state they're manufactured in doesn't require them by law, even though they really should come with them.

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Answer 1

Alejandro, in order to find out what size brakes your boat trailer needs you can either pop off your hub and measure the width and depth of the drum, or, you can let me know what size axle you have and we'd be able to find out what size brakes…

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Answer 2

I reached out to Dexter and found that the UFP-HD-1877-10 fits a standard 3,500 lb axle. For a hub and drum replacement you can use the #AKHD-545-35-EZ-K or for a galvanized option #AKHD-545-35-G-EZ-K. Then for hydraulic drum brakes you can use the…

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Answer 3

The one piece of info I need from that pic is partially blocked by the bent plate. What is the full capacity number listed? With that I can see what we have that you'd need.

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Answer 4

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 5

It could be a tow package fuse on the vehicle. Use the owners manual to find the locations of fuses/relays related to the tow package wiring to check them and replace as needed. If the issue is not a fuse or relay then you can test the vehicle side…

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Answer 6

Surge brakes use a hydraulic actuator to push fluid to the cylinder piston to activate the brake shoes on drum brakes or brake pads on disc brakes. This pressure should only be applied when weight is pushing against the hitch ball, so no pressure…

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Answer 7

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 8

There is no specific torque rating for the castle nut that holds your hub in place. We recommend tightening the castle nut down until it stops, and then backing it off to the next notch wheel the tang washer will fit into the castle nut. Over…

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Answer 9

We don't have any way of knowing the brakes you need for your Shorelander boat trailer but can tell you how to determine the right ones. To determine the brake assemblies that will fit your trailer, you need to know your axle's weight…

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Answer 10

I do have a couple possible solutions for raising your pontoon trailer, however increasing the shackle strap size will not be your best option. A more efficient way for raising the suspension on the trailer will be to use longer hangers. Unlike…

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Answer 11

Installing brakes on one axle will not make the wheels stick out any further than the idler axle. The brake hubs are designed to be the exact same thickness as the idlers so you would not have to worry about that. I attached a help article that will…

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Answer 12

The number 61101 isn't actually the part number, but I believe you are looking at the Atwood 84132. If this coupler is not opening enough to engage the ball, the first thing to check is the trigger lock. If it is not disengaged, the ball will not…

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How To Determine If Boat Trailer has 10 Inch or 12 Inch Brake Assemblies

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