Leaf sprimg help

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Leaf sprimg help

Postby Kaz » Tue Feb 02, 2016 7:44 pm

Hopefully someone can help me. While I built my trailer from scratch without plans, just a lot of help and looking at pictures and reading this forum It is not without flaws. When I welded the rear shackle mount for my leaf springs I think I may have installed them too far forward. The shackles are slightly angled back from center and when loaded with the trailer weight the springs hit the frame on sharp bumps. Should I have made it so they face slightly forward to rest at a more vertical state when the trailer weight is put on them?139157139156
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Re: Leaf sprimg help

Postby H.A. » Tue Feb 02, 2016 8:42 pm

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Last edited by H.A. on Mon Apr 25, 2016 11:46 am, edited 1 time in total.
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Re: Leaf sprimg help

Postby KCStudly » Tue Feb 02, 2016 9:19 pm

They can be slightly forward, neutral or slightly rearward at rest with different handling characteristics. I prefer them to be slightly pitched forward at rest with the load on.

As the spring takes on load it tends to flatten and with the shackle slightly forward to start the weight and compression aren't resisted by the shackle, so the ride is effectively softer. Also, the shackle is less likely to invert.

With the shackle tilted back slightly, as the spring compresses and tries to flatten out and the shackle starts to swing thru its arc it has to first lift the trailer opposing the added load and compression, which tends to stiffen the ride.

The picture you show is on jack stands with the axle drooped out. What does it look like when it's sitting on its own weight loaded? And are you sure that it is the spring eye whacking the frame, or could it be the axle or U-bolts instead? My thinking is that if the shackle geometry is okay, then you are probably under sprung (i.e. under rated on your springs). What are they rated for and how much does your camper weigh when loaded up?

Bump stops are a possible solution to solve any big hits, but this will also reduce available travel, and if you are frequently having hard contact the solution lies elsewhere. If everything checks out and you can allow for a slightly higher ride height, longer shackles might be enough of a difference to solve the problem.
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Re: Leaf sprimg help

Postby drhill » Tue Feb 02, 2016 9:40 pm

As KC mentioned, adding bump stops will lessen the impact of hits, but also reduce the travel and make the hits more frequent.

With my trailer I was occasionally bottoming out on sharp edge potholes on logging roads. The obvious solution was to slow down. But I knew I would only do that until the next time and as the impact is comparable to hitting the trailer frame with a sledge hammer, I thought I best address the problem as there are a lot of joints with nothing but glue holding them together. Three options were:
1. change to a stiffer spring.
2. add longer rear shackles
3. lower (increase the height off) the front spring mount.

My springs were 1250 lbs each so were already more than adequate for the load. From ground level, the front (fixed) mount is higher than the rear spring shackle. So I decided to lower the front mount by an inch. ie - add one inch to the front spring mount. That gave me about 1/2" additional spring travel and that made a world of difference. No more bottoming out. Cost - a few welding rods and scraps of steel I had on hand.

The simplest no weld method would be to just buy longer rear shackles. The way we all used to lift our cars.
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Re: Leaf sprimg help

Postby Redneck Teepee » Tue Feb 02, 2016 11:52 pm

KC is pretty correct in thinking you are under sprung if it is indeed hitting your frame. As he stated your pic is showing the axle unloaded which does not appear all that bad....not sure how much it settles with the trailer weight and how much weight is actually on it.

Here's a chart I've posted before which is what KC was referring to as soft vs stiff ride. Hope this helps: :)
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Re: Leaf sprimg help

Postby KCStudly » Wed Feb 03, 2016 10:42 am

I had a browse thru some of etrailer.com's FAQ's and they recommended a starting shackle angle where the fixed shackle pivot is slightly behind the rear spring eye with the axle assembled and the trailer weight applied (http://www.etrailer.com/question-99723.html), however, they go on to include a chart showing the opposite (?).

There is a lot of good information for Dexter axles on their website, including this catalog/spec sheet.

On pg. 15 of the .pdf (pg. 14 of the printed page) there is a table in the upper left hand corner for 1000-2200 lb D20 leaf sprung axles that lists the hanger eye to eye longitudinal distance, Dimension 'A', for various length double eye type springs. Depending on spring length, they show the shackle hanger pivot point from 1/4 (for a 26 inch long spring) to 1-3/8 inch (for a 21 inch long spring) ahead of the spring eye.

For comparison, I used longer Jeep YJ rear springs and Rough Stuff hanger parts. With the trailer alone, no cabin weight yet, the shackles are pretty much straight up and down. As soon as I put a little weight on it the shackles tip forward at the top. (Incidentally, I installed shock absorbers and bump stops from the get go, but will also likely have to lengthen my shackles to add suspension travel once the final weight is established.)
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Re: Leaf sprimg help

Postby Tomterrific » Wed Feb 03, 2016 10:55 am

Since you welded up your own trailer it should not be too much trouble to weld a set of shock mounts. Shock absorbers make for a much more sophisticated suspension. Shocks allow for softer springs without excessive movement and follow the road better. The next big step would be a sway bar. :-)

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Re: Leaf sprimg help

Postby Kaz » Wed Feb 03, 2016 7:41 pm

KCStudly wrote:They can be slightly forward, neutral or slightly rearward at rest with different handling characteristics. I prefer them to be slightly pitched forward at rest with the load on.

As the spring takes on load it tends to flatten and with the shackle slightly forward to start the weight and compression aren't resisted by the shackle, so the ride is effectively softer. Also, the shackle is less likely to invert.

With the shackle tilted back slightly, as the spring compresses and tries to flatten out and the shackle starts to swing thru its arc it has to first lift the trailer opposing the added load and compression, which tends to stiffen the ride.

The picture you show is on jack stands with the axle drooped out. What does it look like when it's sitting on its own weight loaded? And are you sure that it is the spring eye whacking the frame, or could it be the axle or U-bolts instead? My thinking is that if the shackle geometry is okay, then you are probably under sprung (i.e. under rated on your springs). What are they rated for and how much does your camper weigh when loaded up?

Bump stops are a possible solution to solve any big hits, but this will also reduce available travel, and if you are frequently having hard contact the solution lies elsewhere. If everything checks out and you can allow for a slightly higher ride height, longer shackles might be enough of a difference to solve the problem.


It's definitely the axle u=bolts hitting the frame. I am using a 2200# axle with 1000# springs. Currently looking into spring with the same length but slightly higher arch.
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