Trailer springs (1 Viewer)

[hairy_apple]

For those of you how have built cool camping trailers, what size leafs are you using? I'm designing my trailer and had thought about using some 4runner springs I have but they are going to be almost the whole length of the main box of the trailer.

I realize a trailer doesn't need the axle movement a truck does, but those little trailer springs seem like they would make the trailer more likely to flip... I want it to have some flex.

What are you guys doing for springs?

 

[alia176]

My local spring shop can make leaf springs any length and weight carrying capacity. So, I had them make me a set and am very pleased. I think the cost was $100/side and these are 1,000 lb capacity per leaf pack.

For a long time, I was trying to figure out how to use a set of FJ40 springs but got tired of working around the springs.

 

[ntsqd]

Typical trailer springs are short and stiff for two reasons. They don't change ride height much with varying loads, and they don't, usually, need shocks. Both of these "features" are counter-productive in an off road trailer's leaf spring. Odds of someone riding in/on the trailer for any distance is slim, so wheel travel and ride quality aren't weighed the same as they would be for the passenger carrying vehicle. You want springs supple enough and well damped enough to not break the eggs or shake up the beer. Beyond that is wasted effort.

 

[hairy_apple]

That's kind of how I'm feeling right now as well, I am tried of trying to design my trailer around springs, I'd rather just toss on some trailer springs and be done with it. I don't really see suspension being a huge issue for what I want to do, but like you said... just dampen enough to still have eggs when we get to camp.

 

[Coastline]

" You want springs supple enough and well damped enough to not break the eggs or shake up the beer. Beyond that is wasted effort."

Tap the top of the beer can a few times before opening to settle the foam. Scrambled eggs are good. They are technically omelets without all the stuffing.

I am building a seriously "over the top" off road trailer on 3500 lbs Dexter axles with standard leafs. The customer insisted on having shocks installed mostly for the looks. So, I inquire at Dexter and heard, "why?" What do they know, eh? So I called customer service at Rancho and the tech told me, "why on Earth do you want to put shocks on a trailer that only weighs in at 1500 pounds?" I told him why, and he promptly suggested a Monroe shock designed for heavier trailers. That's what was installed and I must say that those bright yellow shocks sure do look pretty against all the black POR 15 and the black under coat.

 

[hairy_apple]

Huh, I had planned on putting shocks on it actually... didn't really realize trailer springs were not made to be used with shocks. I am still learning about trailer design, I have some awesome ideas, the design is coming along, but I am sure once I'm done there will be a million things I'd have done different.

I actually am planning on building one, using it for a year, and then selling it and building another from what I learned from the first one. I know with my cruiser, there is a million things I wish I knew when I built it, and only could have known I liked or didn't like until I actually used it. I imagine the trailer will be the same way.

 

[alia176]

Our Kamparoo has slipper springs and no shocks. Other than the noisy springs, the ride is fine. Usually, end up airing down to 10 psi for wheeling and it behaves nicely. However, I noticed that the newer Kamparoos have shocks now, which makes me wonder what the reason is..... These trailers are around 1500lbs so not very heavy.

 

[ntsqd]

So go back to the other part of my previous post where I said "Typical trailer springs are short and stiff for two reasons. They don't change ride height much with varying loads, and they don't, usually, need shocks." No doubt Dexter knows a very lot about springs for trailers that, at the worst, see gravel roads. Our intended use is outside of most all of the experts on things trailer area(s) of experience and expertise. I wouldn't bother putting shocks on a typical trailer spring either, but I'd only use those on something like a car hauler trailer and never, ever on anything going off road.

Dexter makes the TorFlex rubber torsion axles and those have been used on true off road trailers at their suggestion. Why those instead of the typical trailer leaf spring? My best guess is for their built-in damping. (Never mind A-T's assertion that they will fail due to grit when if they are properly vulcanized there is no place for the grit to get into.) I do think that in severe or "Overland" service that even those need shocks due to heat build-up in the rubber that will cause the vulcanization to fail.

Ever wonder why car-hauler trailers in particular, but most trailers in general make so much noise going down the road? It is due to those short, stiff springs transmitting the small bumps rather than absorbing them. Ever wonder why trailers just don't seem to last that many actual miles in service? It is due to those short, stiff springs transmitting the small bumps rather than absorbing them.

Typical trailer springs are a very economical solution to most trailer suspension needs, but that does not make them the best choice or even an OK choice for off road service.

 

[hairy_apple]

Got ya, that makes a lot of sense. I am going to be spring shopping here shortly, I think the answer to my issue is to find something in the middle. Shorter then the 4Runner springs I was going to recycle, but longer and softer then typical trailer springs.

 

[climber8483]

HA,
Think about what the military trailers used. The "typical" 1/4 ton jeep trailers used automobile leafs and shocks. I'm sure part of it was to make the parts identical for ease of replacement/supply. They did put shocks on them and that wasn't needed "as a spare part." I would also wager that the military trailers are way more inline with what we use them for than commercial trailers.

 

[alia176]

Got ya, that makes a lot of sense. I am going to be spring shopping here shortly, I think the answer to my issue is to find something in the middle. Shorter then the 4Runner springs I was going to recycle, but longer and softer then typical trailer springs.

My Kamparoo springs fall in that category as well. The trouble is, when I was looking for springs, I didn't find such "in between" length - either trailer springs or vehicle springs are what I found.

 

[TexasD90]

I followed your plan of build one, use it, then sell to start over with all the things you learned! One thing I did on my first trailer that I will do again was use yj jeep springs. They made the trailer ride great. That trailer did not have shocks, and for what it's worth, the new one will. I would not use the standard trailer leads, especially if they are 3500 load springs. Your little 1600 pound trailer will be bouncing all over the place. Just my opinion, take it for what it's worth.

 

[hairy_apple]

I am still kicking around the idea of using the 4Runner springs, I would just have to change the frame design a little to make it work the way I wanted it to, which isn't the end of the world. I really like the idea of using the longer springs for ride as well. I had wanted to center the inside supports with where the springs hit on the frame to help with twisting forces of the springs pulling sideways as the axle dropped away.

I'm not so worried about the bouncing all over, so much as the shock to the trailer that washboard roads and 3500# short stiff springs would cause to the trailer's frame... I would be worried that overtime that the frame would start cracking at the perches.

I am just trying to imagine all the forces the trailer is going to be experiencing going down a rough trail or washboard road and what I need to do to maximize it's toughness and survivability long term. I have no doubt that I could whip out a trailer and it would work fine, I just want my end result to be a trailer that my grandkids could be using (I'm 28).

 

[ntsqd]

One thing to keep in mind with leafs is that they are not a set spring rate. Use a spring with a lot of leaves and you can tune the spring rate by adding and removing leaves.

There is also no foul in using a leaf from something else if you think it will take in the direction that you think that you need to go. So what if the second leaf in the packs is the fourth leaf from an S-10 Blazette if its the right width and its thickness and length do what you need them to do.

Short leaves of the same thickness and width as a longer leaf are stiffer than the longer leaf. Generally the thickness matters more than the width, but width does play a part in spring rate.

 

[Alan "Ace" Brown]

I finished a trailer rebuild this past spring. I used CJ-5 front springs and shocks and my trailer rides and performs better off-road than my highly modified FJ Cruiser. We thought the 5 leaf spring would be too stiff and pulled out two leaves but it was way too soft. Back to the full set of 5 and its perfect. Moderately soft, very compliant. When I'm getting whip-lash in the FJ the trailer is just floating along very peaceful. I believe the shocks make a huge difference and would not build an off-road trailer without. Here is a few shots of old and new springs (top), build progress and finished trailer.

 

[hairy_apple]

Hum, I like that trailer design too. Very slick.

I think I will use the 4 runner springs and see how the work out. I think too much spring is better then too little and I can remove a leaf if needed.

I am now totally torn on my design though... I have found two FJ40 tubs locally that I can get for CHEAP and a FJ40 tub trailer would be sweet. My original idea was a large main box and two side boxes, which might be slightly more functional then a tub trailer... but having a trailer that matched my cruiser would be pretty cool.

 

[croozy]

I have just fitted a set of 2" raised fj40 front springs to a trailer I'm building. I will probably fit some shocks to it aswell. I am building a 40 series style trailer too hairy_apple. I'm building it completely from scratch though.

 

[cruiserpilot]

Hey Ace, I'm wondering why you placed the shocks so far inboard? Why not try to get then closer to the springs? How did you decide on which shock to use? Nice trailer for sure.

 

[ntsqd]

I try to set shocks so that they are as close to the wheel as is possible, and a friend taught me to try to set them up so that as the spring compresses the shocks become more vertical, not less. This induces a slight rising damping rate as you get closer to bottomed-out. More damping when you need it the most and less damping when it matters less.

 

[Alan "Ace" Brown]

Hey Ace, I'm wondering why you placed the shocks so far inboard? Why not try to get then closer to the springs? How did you decide on which shock to use? Nice trailer for sure.

Mainly convenient mounting top of the shock to the big 3x3 backbone. Anywhere else the shock would not have been vertical enough. Shock choice was some take-offs the builder had laying around. On a light trailer shock choice is not important as long as its not stiff. Look for something off a small car.