Choosing Replacement Trailer Brakes, Hubs and Actuator for 1978 Calkins Tandem Axle Boat Trailer

Question

Question:

Hi, I need to rebuild the brake system on a 1978 calkins tandem boat trailer. It originally came with a 1979 21foot glasply boat which weighs about 5500lbs. I believe it was rated at 6900 lbs. i need to replace the actuator, all lines, drums brakes and hubs. The 14inch tires and wheels seem ok. Can you help me assemble a parts list? Soaps I dont leave anything out. Thanks.

asked by: John S

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Expert Reply:

You'll want to check a few details on the trailer so you can select compatible replacement parts.

First, you want to confirm the axles' rated capacity; this should be noted on a sticker or plate on the axles themselves. Based on the info you provided it may be that you have two 3500-lb axles. Your brakes and hubs must match the axle rating.

Next you'll want to take note of the size of the current brakes. You need to confirm the diameter and depth. You also want to note their mounting bolt pattern so you can match this as well. The linked page will show you all 3.5K hydraulic drum brakes; all of these happen to be the 10 x 2-1/4-inch size with a 4-bolt mounting pattern like left and right free-backing brakes # AKFBBRK-35-D. (Free-backing brakes allow for reversing your trailer without need for a lockout on the coupler.)

With free-backing brakes you can use a standard coupler (with no reverse lockout) such as 7.5K-rated # 099-175-00 from Dexter which is a fit for 2 inch hitch balls. It bolts to a 3-inch-wide trailer tongue. You'll need a brake line kit like # HS496-252.

For hub/drums you can use the linked page to select your wheel bolt pattern, axle rating and your bearings. New hub/drums must use the same inner and outer bearing as your current hubs. For example, if you need 5-on-4-1/2 hubs with inner bearing 68149 and outer bearing 44649 then you can use Dexter hub/drum # 84546UC3.

Please feel free to let me know the details noted above and I'll be glad to help you select the items you need.

expert reply by: Adam R

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Answer 1

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 2

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 3

Hey Richard, thanks for reaching out! The Dexter DX7.5 Drop-N-Go Brake Actuator #099-175-00 is a great option for a replacement actuator because it's a direct replacement for the common Model 60 actuators that were popular in the '90s.…

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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

Traditionally, trailer manufacturers did not use electric brakes on boat trailers because the brake magnet wiring and trailer wiring did not always have the best insulation or water protection. These days, more and more manufacturers are using…

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Answer 6

To find the load capacity for your axle you should look on the trailer VIN plate or sticker that lists the VIN number. The weight rating of the axle should be listed on that same plate or sticker. Also, the axle could have a tag or plate on it that…

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Answer 7

The manual lockout on your Atwood 85778 surge brake coupler is there so that you can back up the trailer without the brakes locking up on you. Yes you can safely tow your trailer with the broken manual lockout, you just have to make sure you…

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Answer 8

There really isn't a particular maximum trailer weight that is used to determine when brakes need to be added to both axles of a tandem axle setup. While I do still recommend checking your local laws, I am also not aware of any general laws that…

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Answer 9

Depending on how the trailer was made, there will be a few spots you can check to identify the axle. First, if the trailer was pre-made by a specific company, you may be able to find this information in either the paperwork or on a placard somewhere…

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Answer 10

Torque specs for wheel lug nuts will vary depending on the diameter of the lugs, type of lug nut and the wheel's material. The linked chart details the recommended torque for many combinations. Dexter Hub/Drum #84546UC3 has 1/2-inch studs and…

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Answer 11

The torque for the Dexter Trailer Hub and Drum Assembly - 6,000-lb and 7,000-lb Axles - 12" - 5 Spoke Utility #8-174-5UC3 is not specified by the manufacturer. For 9/16 inch studs, the typical lug nut torque will be 120-140 ft lbs based on most…

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Answer 12

To determine the size of the hub assembly you need to purchase you have to determine which bearings are in the old assembly. If the old assembly has L44649 inner bearings, you would use the hub you chose #8-258-5UC1. If the inner bearings are marked…

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