Custom Sled Vents

Have you ever run your sled up a hill climb a dozen times because your buddy keeps trying to beat you and has a new excuse for loosing every time? Do you feel your sled progressively lagging in power the more times you make a hill run? As your engine compartment gets hotter, your clutch and drive belt begin to under perform. After letting your snowmobile cool down for a few minutes, your performance returns. 

So now you want a way to keep your snowmobile compartment cooler to extend the amount of time that you can keep the throttle pinned. Heat dissipation is one of the main reasons people install aftermarket vent kits on their snowmobile. After shopping for vent kits, you will discover they are very expensive. The average cost of a five vent kit is about $190. If it's a popular kit, on the mountain you will notice many other people with the same vent kit as you. Many of the kits sold are not great looking, susceptible to damage from trees and branches, and can be flimsy. Some of the vent kits require you to cut out much of the factory plastic. And then the kit is not shaped to match your sled correctly causing the vent to reshape your plastic. 

Because of the expense and the poor quality of some of the vents, sledders have resorted to building their own vents. That is probably why you are on this blog post right now. Some people who build their own vents bring shame upon the sledder population with their trampoline material, staplers, and liquid nails. You know who you are. 

If you are interested in building your own vents the right way, you will not save money and you will not save time. What you will gain is personality and individuality for your sled. You will have the power to fix your vent kit for a really low cost after a close encounter of the tree kind. And finally, you will have a product that is sturdy, withstands water and snow while allowing air to pass though, and a style that is unique and personal.

This is what the finished product looks like. The shape is custom and was designed by me. I could have squared the back and gained a couple more square inches of vent, but I wanted the forward slash lines, similar to the panel where the "X" sticker is.

A survey of the existing plastic is needed to create a palette for new vent. The easiest way to do this is to take a large sheet of paper or a couple pieces that are taped together and place it on the area you are going to vent. Locate a crayon, remove the paper wrapping and rub the long side of the crayon across the large sheet of paper. The edges of your snowmobile panel will transcribe onto the large sheet of paper.

The next steps is to import the survey into a computer drafting program. I use AutoCAD because I have the program and I know how to use it. It's an expensive program and is not self taught easily. However, there are classes in college that teach AutoCAD and you could build your vent as a school project. The free way to draft your vent is to use Google Sketchup. It's not very difficult to learn and the machine shop should be able to transfer a Sketchup file into a format that their computer understands. They may charge a little more if they can't directly import your drawing and they have to create the model on their software.

This is the drawing of my vent. I would prefer that you don't steal my design, but it's not like I could stop you. If I do see another sled with this design on the mountain, I may hit you with a snowball. 

The next step is to find a local machine shop that either cuts with laser, water, or drill. A plasma cutter wont do the trick with the precision that is needed. You should also ask the shop what the tightest corners can be. In my case it was 3/8". That's why the inside corners of the picture above have 3/8" radii. Also, don't sacrifice too much structure for vent. The outside band on my vent is 3/4" wide and the inside webs are 5/16". 

The material I used, which has proven to be very strong and lightweight is 6061 T6 Aluminum (or .080). The machine shop had a few scrap pieces laying around so they gave me a good price. Programming and setup cost about $25 and each panel was about $15. Obviously, the more you order, the lower cost you are going to get. I ordered 12 pieces to get that pricing. 

This is what the vent looked like when I got it back from the machine shop. I had to file off a few edges where some product was still attached, but it wasn't too difficult. Don't be too worried if there are scratches or blemishes in the product because this material is covered by the mesh.

The next step is to install the mesh over the aluminum. A lot of vent makers will tell you their vents are made of some special fabric with superhuman characteristics. I picked up this mesh from a local awning retailer. It was such a small amount that they gave it to me for free. You can put the mesh up to your mouth and you will breath through it easily, but you can pour water on it and it won't percolate. Snow won't go through it either. Nobody likes a wet clutch. The mesh appears to be plastic coated fibers that are woven. After a full season of use, it has not melted from the heat of the exhaust or clutch, and tree branches have not made their way through. And yes, I do plenty of boondocking and tree hugging.

Next, place some double sided tape on one side of the aluminum frame. The product is listed in the picture and it can be found at an automotive paint supply store. I'm not sure if Autozone or Pep Boys carries this product.

Wrap the straight side over first, pulling as tight as possible. The corners are a little trickier. First, fold them over like you are wrapping a gift. Then, using a soldering iron or a similar product that gets really hot without creating a flame, melt and weld the plastic together until it's a mushy pile of plastic. Using a flat metal object, press firmly on the mushy plastic corner for a few seconds to flatten and cool the plastic. Use the soldering iron sparingly to touch up any rough corners. Do this plastic melting in a well ventilated area.

Buy some large aluminum rivets. You may have to get these on the internet. Home Depot isn't the greatest resource for aluminum rivets. Drill (4) or (5) holes in your vent corners that are the same size as the rivet requires.

Here is the stock plastic on the snowmobile. You can print out your original template you sent to the machine shop on paper to scribe the hole opening. Using a knife or router to cut out the hole is difficult. I know it sounds rudimentary, but I use sheet metal snips (the red handled ones you can buy from Home Depot) to cut the plastic. It's fast and accurate. Just don't make real sharp corner cuts with them. I clean it up with a utility knife if needed. 

Use your vent to locate the holes in the plastic where the rivets go. I usually install the first rivet before drilling any other holes. Make sure to use stainless steel or aluminum washers on the plastic side of the rivet so that the rivet will expand in the proper location.

And just like that, your finished. It will take a lot of time to do this project and you may ask yourself several times throughout the process if you should have just coughed up the $200. However, when you get to the end and see how sick your install is, you will have no doubt that you did the right thing. Happy sledding.