Kayak Cart with Independent Suspension

[Steve Horswell]

Erich:
Thanks for the additional, detailed pictures. I am looking forward to the video. I really like what you've done. Maybe I missed it, but what does the cart weigh empty? Also, what is the function of the short pieces of square tubing just above the wheels?

 

[Chuck J]

Erich,

First let me say you made a fine cart, but...I think you might be overthinking how much the suspension is doing. I don't think it is really articulating. Those mountain bike springs are really meant just to take the hard bumps out of the road, and that is pretty much what is going on here. Your hand hold is not keeping the frame from tilitng side to side with the lay of the land, and though the suspension moves with the initial change, it goes back to the same position once the load settles. I don't know what you had before you built this, but my guess as to why you are no longer dumping your load is either the springs are taking out the bumps enough to keep the straps tight, the length of frame is keeping the load in place, or your tye offs from the corner of your frame to the points of your boat is holding it better than what you did in the past.

I've been using a Cabelas folding cart for a couple of years, and have on occaision had the cart slide a little and get crooked. But I have always stopped and resecured the boat before I dumped anything. Your design wouldn't work for me as I generally cartop my double ender, and the cart would either not fit inside my car, or if it did would take up way too much space to let me get in the rest of my gear. I do however like the concept of tying off from all four corners to the bow and stern, and think I will try this (in addition rather than substitution of my usual 1" ratchet strap over the top.)

As far as the flex in the back end of the frame, you can see the aluninum tube bowing under the load in the video taken from under he cart in use. I would look at welding an angle piece down the length, it would add much more rigidity than flat stock. I thought of welding up my own cart, but flat out lacked the time to do it for the price of the store bought unit.

Like I said, nice cart.

Best
Chuck

 

[Erich S.]

Erich, That looks like my next winter project. I have been using a much modified canoe portage cart for my Poleboat but it is really hard to load on the cart and somewhat tippy. Great idea with the independent suspension, did you go that way to keep it from tipping or some other reason? Thanks for sharing and keep us posted as you modify and improve it.

I went with the suspension manly because I thought it would be fun to have a trailer that could handle some bumpy trails towed at a pretty good clip behind my mt. bike.

I'm not quite ready to trust this trailer with that yet and it may prove to be a bad move. I think the current set up is actually less stable than just a ridged trailer of the same configuration. I hope I can address the problems.

Erich

 

[Erich S.]

might I make the suggestion of an improvement?

The question was of the "axle" and you uped it to a 1/2 stainless. I woudl suggest using a grade 8 bolt instead. They are rated in shear loads which appears to be the axis of strain on that bolt and this would be a pretty nice increase in strength for minimal money. At the local Fleet Farm the difference is about 40 cents per pound...

Otherwise, nice cart!!

I appreciate the suggestion and I did consider grade 8 bolts, but I opted to see if I could keep the corrosion protection and try the stainless steel. So far, so good.

The whole idea behind the aluminum trailer, instead of steel, is the corrosion problems associated with launching in salt water for each hunt. I'll have to post a pic of the original galvanized wheels I had before these poly's.

Erich

 

[Erich S.]

Erich:
Thanks for the additional, detailed pictures. I am looking forward to the video. I really like what you've done. Maybe I missed it, but what does the cart weigh empty? Also, what is the function of the short pieces of square tubing just above the wheels?

Here's the video again: http://youtu.be/MHHjkj5a1DA

The tubing above the wheels is my fix for having to use a bolt instead of a welded in rod. It clamps around the aluminum tube to spread the load from the offset tires.

I'll have to see if I can get a weight on it. I couldn't really give an accurate guess off the top of my head.

Erich

 

[Erich S.]

Erich,

First let me say you made a fine cart, but...I think you might be overthinking how much the suspension is doing. I don't think it is really articulating. Those mountain bike springs are really meant just to take the hard bumps out of the road, and that is pretty much what is going on here. Your hand hold is not keeping the frame from tilitng side to side with the lay of the land, and though the suspension moves with the initial change, it goes back to the same position once the load settles. I don't know what you had before you built this, but my guess as to why you are no longer dumping your load is either the springs are taking out the bumps enough to keep the straps tight, the length of frame is keeping the load in place, or your tye offs from the corner of your frame to the points of your boat is holding it better than what you did in the past.

I've been using a Cabelas folding cart for a couple of years, and have on occaision had the cart slide a little and get crooked. But I have always stopped and resecured the boat before I dumped anything. Your design wouldn't work for me as I generally cartop my double ender, and the cart would either not fit inside my car, or if it did would take up way too much space to let me get in the rest of my gear. I do however like the concept of tying off from all four corners to the bow and stern, and think I will try this (in addition rather than substitution of my usual 1" ratchet strap over the top.)

As far as the flex in the back end of the frame, you can see the aluninum tube bowing under the load in the video taken from under he cart in use. I would look at welding an angle piece down the length, it would add much more rigidity than flat stock. I thought of welding up my own cart, but flat out lacked the time to do it for the price of the store bought unit.

Like I said, nice cart.

Best
Chuck

You're right about the suspension, it's intended to take the edge off the sharp bumps. It needs some adjustment and currently the wheel sits too far forward for my liking. Originally the weight was centered on the cross brace where that extra tube is. When I switched to the trailing arms I accidentally moved them forward.

Then by using short shocks the mounting point is significantly farther forward so the unsupported length at the back of the trailer is much longer, allowing you to see the deflection in the tube running to the rear bunk.

When I rebuild it some day, I'll use a longer shock so that it is closer to the wheel, move the wheel back and I will lower the trailer.

I do appreciate your suggestion to weld some aluminum angle along the top, that's a better plan then my idea to use some flat stock on end.

Erich