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

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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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Answer 1

The bushing on the Rear Hanger with Bushing #30-20 has a 9/16" diameter and is 1-3/4" long so you'll need to use one of the bushings in the Dexter Bronze Bushings Kit #K71-291-00 as a replacement.

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Answer 2

Brakes are designed to fit the hubs that fit the axles not the rims. So you want to stick with 3,500 pound, 10 inch brakes like the Dexter Nev-R-Adjust, part #23-468-469. Larger 12 inch brakes won't fit your hubs. It is more common to see 15…

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Answer 3

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 4

The correct hubs for the 4400 Lb Lippert Axle NV178936 are 3,500 lb hubs as confirmed by Lippert. If you need to replace the hubs, I recommend Trailer Hub and Drum Assembly - 3,500-lb Axles - 10" Diameter - 6 on 5-1/2 - Pre-Greased part…

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Answer 5

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 6

The best way to determine the correct hub and drum assembly for your trailer with a 5 on 4-1/2 inch bolt pattern is to remove the hub from the trailer to get the measurements of your spindle. Or take a look at the inner and outer bearing numbers…

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Answer 7

The 5 on 4-1/2 bolt pattern of a hub or wheel such as #AM20365 means that there are 5 lugs and, if you drew a circle that passed through the center of each lug the diameter would be 4-1/2 inches. I have included some links and a picture that will…

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Answer 8

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 9

Yes when you do an over-under kit you have to weld the seats to the axle for it to be installed properly. It is recommended to tack weld the new spring seats into place but a complete weld job is not required when installing the over-under conversion…

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Answer 10

The 2-3/8" measurement you are referring to on the CE Smith U-Bolt Kit part #CE23002 is in regards to the diameter of trailer axle that the kit is designed to be used with. The actual width of the u-bolt from the inside edge of each bolt is…

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Answer 11

I think you are going in the right direction. I would definitely replace the 14 gauge wire going to the trailer brake magnets with 10 gauge wire or larger. Usually larger than 10 gauge is hard to get into the trailer connector though. I would also…

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Answer 12

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

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