Making a Boat Trailer Tandem Axle By Adding Timbren Axle-Less Trailer Suspension System
Question:
I want to add another axle to my boat trailer because we have added a bunch of weight in the form of batteries, and additional gear and I fear I am getting close to max trailer weight. GVWR is listed as 4200 lbs. The trailer is a heavy-duty aluminum I-beam single axle with torsion suspension. I currently have no working brakes on the trailer as the surge-brake system is broken and possibly un-repairable. I am looking at the Timbren Axle-Less Trailer Suspension System w Electric Brake Hubs - Straight Spindle - 3,500 lbs. Item # A35RS545E These look fairly straight-forward to install and I am planning to do it myself. I am competent working on vehicles but have zero experience with trailer axles, so I have a few questions. -Can this package be installed in addition to my existing non-brake torsion axle? If so, should the Timbrens go in front or back? -Based on the pictures, do I need to re-position my existing axle? If so how do I know where to re-position it? - Will there be any issues with the tires lining up and/or riding at the same height? I will of coarse run the same size tire/wheel combinations on all 4 wheels. The existing wheels are also 5 on 4 1/2 . Tires are 225/75/15. -The existing axle just bolts to the bottom of the I-beam. Will the Timbrens mount the same way or do I also need to bolt it from the side? If so, will I need to put in some kind of spacer between the beam and the mounting plate? For simplicity would a piece of wood work? I already have an electric brake controller installed in my tow vehicle. The existing trailer wiring is new and works fine. It connects to the tow vehicle through a 7 pin connector. Do I need anything else to hook-up the brakes that doesnt come in the package? Finally, can the Timbrens be submerged in water for launching/retrieving without issues? Whew! Thats a lot of questions! Thanks in advance for your guidance!
asked by: Don F
Expert Reply:
First I would recommend contacting the manufacturer of the boat trailer to ensure that you do not exceed the structural strength of the trailers frame with the amount of weight that you wish to be able to tow. It would be heartbreaking to see you put in all the work and the frame not to be strong enough.
I recommend installing 2 sets of the Timbren Axle-Less Trailer Suspension System w Electric Brake Hubs # A35RS545E. This is due to the suspension characteristics would be different between the axles. Having the different suspensions will cause one axle to carry a different load than the other. Secondly most states will require both axles to have brakes over a certain amount of weight. Also if one axle with brakes rated for 3,500lbs is doing 5,000lbs of braking it will cause them to wear improperly and you will risk overheating the brakes.
The axles will need to be placed so that the front of the trailer carries 10-15% of the trailers weight when loaded. This will likely mean that the axle currently on the trailer will be the center point of the tandem axle. I have attached an article we have made specifically on axle placement below for you to reference as well.
The hub face to frame measurement on the Timbren is 6" so if you are trying to line up with your existing wheel and tire this is the measurement to location where the wheel bolts to the axle. It is also generally the center of the tire unless you have offset wheels. The center of the spindle vertically will sit 4" below the frame rails when unloaded, and it will deflect 1-3/4" under full load.
For mounting the Timbren axles you would be best to have steel welded to the outsides of the frame where the unit will bolt. The axles need to bolt through the sides of the frame and piece of wood would not provide enough structural strength to keep the axle from attempting to rotate on the frame under heavy load.
With your trailer not having electric brakes previously you will need the Bright Way Push-to-Test Trailer Breakaway Kit # 3802308. It includes a breakaway cable for if your boat were to become disconnected from the tow vehicle the braking system would be activated with the onboard battery to stop the trailer. There will be some miscellaneous wiring that will also be required. See the article linked below on adding electric drum brakes to a trailer.
Lastly the Timbren's are okay to be used on a boat trailer. As with any boat trailer it is a good idea to check and clean the brake components and hubs more often due to the additional rust and corrosion that will build up due to being in the water.
I hope that this has answered all of your questions. Please let me know if I missed anything or another question has come up with my answer.
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Products Referenced in This Question
Bright Way Push-to-Test Trailer Breakaway Kit with 1-Amp Charger and 5 Ah Battery - Top Load
- Trailer Breakaway Kit
- Kit with Charger
- Top Load
- Single-axle
- Tandem-axle
- LED Tester
- 1 Amp Charger
- Battery Included
- 5 Ah
- Bright Way
more information >
Product Page this Question was Asked From
Timbren Axle-Less Trailer Suspension w Electric Brakes - Standard Duty - No Drop - 5 on 4-1/2 - 3.5K
- Trailer Axles
- Rubber Spring Suspension
- Easy Lube Spindles
- Electric Brakes
- 3500 lbs
- 5 on 4-1/2 Inch
- Universal Fit
- No Drop or Lift
- Timbren
more information >
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