Replacement Axle, Springs, Wet Bolts, Equalizers, and Brakes for Tandem Axle Trailer

Question:

Hello. I had a wheel hub seperate from my rear tandem trailer axle last weekend and im looking to rebuild and improve. i have little experience and can not find a reliable source for information. im looking to replace at lease one if not both axles and get new springs and add wet bolts and a road armor kit. how do i know what springs to get? Can you put just one axle with brakes or do you need 2? if i add brakes how difficult is that? do all springs have the same eye holes? what i do know is the trailer is 5x5 and i belive that the axle is 89/74. we belive that the trailer is a 7000.

asked by: Dominic H

Expert Reply:

I'll start by covering the axle since this information is important for other components as well. The first thing you want to do is identify your axle capacity. Since this is a tandem axle trailer and you're thinking 7,000 lb capacity you probably have tandem 3,500 lb axles. Take a look and see if you have the capacity listed on axle tags. If not, you can measure the diameter of the axle. A typical 3,500 lb axle has a 2-3/8" diameter.

If you find that you have a 3,500 lb axle, and your measurements are indeed 89" hub face to hub face with a 74" spring center, you can use the Trailer Axle Beam with Easy Grease Spindles - 89" Long - 3,500 lbs # e38GR. This would be an exact match for your current axle. It also sounds like you don't have brakes now or a brake flange. I would recommend replacing both axles so you have a brake flange on both.

Once you know your axle capacity, you will want to choose springs based on that capacity. The other information you need is the length of the spring. This is the spring eye to spring eye measurement. The eye holes on your double-eye leaf springs will all be the same size. Also, the number of leaves does not matter, only the capacity of the spring. For example, if you found that you had 25-1/8" long leaf springs and you have 3,500 lb axles then you could use the # e68SR.

To add brakes you will need a hub and drum assembly. Again going off of the 3,500 lb axle you could use the Easy Grease Trailer Hub and Drum Assembly for 3.5K Axles - 10" - 5 on 4-1/2 - Pre-Greased # AKHD-545-35-EZ-K. This matches the bearings on the axle listed above. For brakes you can use the Electric Trailer Brake Kit - Self-Adjusting - 10" - Left and Right Hand Assemblies - 3,500 lbs # AKEBRK-35-SA.

We always recommend adding brakes to both axles of a tandem axle trailer. This will provide you with greater stopping power and will also keep the one set from wearing down faster. When viewed in terms of capacity, assuming you have two 3,500 pound axles on your trailer, you can't expect just one pair of brakes (which would be rated at 3,500 pounds to match the axle) to handle your fully loaded trailer. Brake assemblies would need to be added to the second axle just to give you the needed combined capacity. Only adding brakes to one axle will also increase the wear on your vehicle brakes.

The other thing you will need to do to add the brakes is add the additional wiring. You can use the Hopkins 7-Way RV Style Connector with Molded Cable # H20046 which will require you to cut off your old 4-way connector and then use the Trailer Wiring Junction Box # 3375601101 for a clean connection to your new 7-way connector. You will also need to run # 12-1-1 from the junction box to your electric trailer brakes. It is a good idea to use Heat Shrink Butt Connectors # DW05745-10 to keep the wiring sealed from the elements.

For a breakaway you can use the Hopkins Engager Push-To-Test Trailer Breakaway Kit with Built-In Battery Charger - Top Load # 20400. Then the last thing you will need is a brake controller like the # RED44FR. Depending on your vehicle there may be a custom wiring harness available to connect the brake controller.

For wet bolts I recommend adding the MORryde Suspension Upgrade Kit for Tandem Axle Trailers. This kit comes with heavy duty shackles and bronze bushings in addition to the wet bolts. The correct kit depends on the length of your current shackles which is measured from center of holt to center of hole. If you have 2-1/4" shackles you can use the # MR46ZR. For 3-1/8" long shackles you need the # MR76ZR.

Finally, for the Road Armor Shock Absorbing Equalizer Kit - Tandem Axle - Qty 2 # LC696740 you will want to measure your current equalizers. The most important thing is the side to side length which is the distance from center of left-most eye to center of right-most eye. The Road Armor measures 6" in length so as long as your current equalizers are close to this measurement or the same it will work for you. If you have a different measurement a different equalizer upgrade may be a better choice.

I have attached some review and installation videos for your reference. I also attached some helpful articles on adding brakes as well as trailer suspension that you can check out.