How to build a spring assisted trailer tailgate made from an old leaf spring and some scrap steel. Read more to see how we did it!
This post was originally created in Dec of 2013. I just went in (Jan 2019) and updated the whole post with more research, a parts list, better descriptions, and two videos! Hope you enjoy.
Story & Research
My FIL has been working on rebuilding this old trailer. He built a nice fold down gate on it, but it ended up being too heavy for anybody other than him or myself to lift.
We looked at some coil springs like they put on the big heavy equipment gooseneck ramps, but it seemed complicated to setup and the springs we found were way too heavy duty. Then I remembered seeing some small utility type U-haul trailers with leafsprings mounted underneath that were attached to the gate with a shackle.
After some research I was able to figure out that they are actually ‘motorcycle hauling’ trailers from U-haul. Here is a good video from U-haul with the spring loaded gate so you can see it in action:
Building our own assisted tailgate
Now it was time for us to build our own. We started by drawing some pictures and dug through my random offroad parts bin. When the project was initially finished, the spring held so well that the (really heavy) gate didn’t even touch the ground when we let go. We added some washers above the spring on the brackets and now it just lightly comes to a rest on the ground when you let go.
PLEASE be careful if attempting this project. Obviously standard precautions need to be made when welding/grinding but in this particular case I am talking about stored energy. Springs by nature have A LOT of energy when they get stretched/compressed/bent depending on what kind of spring they are.
In our example today we are using a leaf spring which when bent contain enormous amounts of energy (the same energy used to lift your trailer tailgate) so please be careful and stay out of harms way from the spring and any other hinge/pinch points.
Here is an approximate parts list assuming you already have a welder, grinder, and the associated safety equipment. Your needs will vary based on the weight and length of your gate, and the setup of the tail of the trailer and gate crossmembers.
One leaf spring with bushing (the one in the pics was a primary leaf spring from the rear of a ~2000’s Chevy S10). The most common automotive width is 2.5″ wide which is what I used. You could also look into using a trailer leaf spring like the one linked below which is narrower at 1 3/4″ but I can’t say what weight spec you need having not tried that type of spring before.
Two u-bolt plates or ~6″x6″ pieces of 3/16″ or thicker pieces of flat plate. Just make sure they are wide enough for the spring you selected. Typical automotive leaf springs are 2.5″ wide (Fords are usually 3″ wide) and trailer type leaf springs are typically 1.75″ wide.
Four heavy duty bolts (1/2″ or larger with washers and locknuts)
Some extra steel for creating a crossmember (if needed) and reinforcing the top gate mounted bushing
Shackle material this can either be an actual spring shackle from a junkyard vehicle (probably the same one you got the leaf spring from), or a ‘shackle lift kit’ from Amazon like the one below. If you want to make it yourself, you can find a ~2ft long section of 2″ wide by 3/16″ or 1/4″ thick steel strap then cut to length and drill the holes you need.
More pics of the self lifting tailgate
The beauty here is that both bushings came from a single leaf spring. We simply cut the leaf spring into several pieces with a grinder and cutoff wheel. One consists of the part we used for the spring (about 2/3 of the leafspring). The other consists of a short section from the other side with the bushing and ~1-3″ of spring to be welded to the gate (any leftover length is just scrap).
The top plate welds to a crossmember under the trailer, then the spring will get sandwiched between the two plates and bolted together. The bushing for the gate will be welded on and reinforced with a small piece of scrap on the top side (you can see in the pic below).
Shackle length – I can’t be prescriptive here, you will need to figure it out for yourself. The U-haul shackle appears to be very short ~5″ or so. The shackle in our example was much longer at about 10″. Therefore there is probably a pretty wide range here depending on the spring you use and how heavy/long your gate is. There will likely need to be some trial and error.
A little ingenuity, some scrap parts, and some hard work made a very useful end product. Between all of our family and friends this trailer gets used almost weekly. Best of all, it is small enough to tow behind my “Honda Hauler”!
Can’t weld? Don’t have the time?
Here are some other options from Amazon that are very solid and install with a couple of bolts:
Update with user video!
We had a user Nick that posted in the comments below take this article and built a spring assisted gate for his golf cart trailer down in Australia! Thanks for creating this video Nick!
Now you go build something!
Questions? Comments? Tried it yourself and have pics or video? Post below like Nick did!!