HF 1800# Spring Flex Test (kinda long post)

[Nobody]

I have the HF 1800# trailer that I bought a month or so back. Been looking & considering what I wanted to build & have decided on a combination Ultralight/Gruman profile slightly modified. Want it 5' wide outside & that would entail either widening the frame/axle of my HF or building above the wheels. Didn't really want "fender wells" inside the sleeping compartment so when I saw Gratis' pix a few weeks ago showing how he'd solved that with his HF trailer http://www.tnttt.com/viewtopic.php?t=7626, I decided to "borrow" his technique. Only trouble is the HF 1800# fenders set a little higher than they apparently do on the 1175# trailers. Gratis was able to notch his outside 1X4 board leaving approx an inch or so of wood above the fenders. My fenders attached per instructions were 4.5" higher than the trailer frame with at least 3.5" clearance above the tire. I didn't think I'd really need that much clearance so I drilled new mounting holes in the brackets & lowered the fenders about 1.25" leaving me with around 2.25" above the tire. That seemed maybe a little close but I wanted to see how much the springs would flex with a load approximating the max weight I'd expect to have with the completed TD. I clamped a couple of 2X12 boards & a half sheet of plywood to the trailer frame & proceeded to load 1,027 pounds of concrete blocks, a piece of 12" C-channel from a dump truck chassis, yes, even an old cast iron bathroom sink onto the trailer. The spring flex & the frame drop was almost imperceptible, less than a quarter inch with the thousand pound load, still leaving me a couple of inches clearance above the tires . I know there'll be more flex when hitting bumps & such while laden but don't think it'll be enough to cause problems between the tire & fender bracket. In examining the springs, they are 3-leaf & appear identical to the springs on my 3500# utility trailer, & my son's 2500# axle on his ATV hauler. Appears the primary difference in ratings may be in the frames, axles, & the size of U-bolts used to attach the axles to the springs . Anyway, I'm gonna use full 4" lumber ripped from 2X6's to frame my floor, with the outside piece cut from either 1X6, or perhaps full dimension 1" decking ripped to 4". That'll leave me about 1.25" of wood after notching the outside piece for the fender. My TD will have a higher profile than many but I want to keep the ground clearance with the springs mounted on top of the axle. Here's a pic of my flex test -



More comparison pix in my album. Criticism, comments, suggestions are solicited & welcome

[GregB]

Nobody does it better,...

Your experiment is very timely for me. I am extending the Minibago 9" past the edges of my 1800# HF trailer. I've just put mine together and had noticed that the tops of the wheels come to only 1" above the frame and my fenders (which I'm not using) come to 3" above the wheel. I have mounted the axle underneath the springs.

I, too, wondered how much flex the suspension would have with the small load of 1200 lbs or so that I plan on putting on it. My informal tests (two fat guys jumping up and down either side of one wheel) agree with your conlusion; suspension travel is minimal at worst, given the typical loads we will be using. I think that my wheel wells will have this 3" of clearance and will intrude into my sleeping compartment by only 2.25" (vertically) as my floor is 2" thick (and the top of my wheel wells only .25" thick). Since my mattress will be at least 6" thick, I'll have at least 3.75" of soft, foamy goodness under my feet and the wheel wells intrude (horizontally) into the sleeping compartment by the 9".

I hope that this information is of interest to someone else who may be considering building over the wheels.

GB

[gman]

I put 20 sheets or 4x8 5/8in sheetrock on mine, never sank an inch, HD store guy was amazed.

[EZ]

Nobody, that is a good test to hear about. I built my floor 5 1/2 feet wide so it extends over the wheels enough for the tires to fit inside the 2 X with about 1" clearance on the outside. I used 2 X 3s for the framing and I was a little concerned about vertical clearance. I think there is just less than 3" above the tire, and to tell you the truth I think the ends of the U-bolts would bottom out before the tire hit the floor. My trailer is rated 1175# but I'll bet my camper won't weigh more than 500-600 pounds complete.

This is great, more HF trailer good news !!!

Ed

[Nobody]

EZ wrote

and to tell you the truth I think the ends of the U-bolts would bottom out before the tire hit the floor.

Think you're probably right about that EZ. That's one of the main reasons I didn't yet cut off the bottom of the fender mounting brackets after I'd drilled the new holes. Looks like the bottom of the brackets would probably hit the U-bolt plates on top of the axle before the tires engaged the bottom of the fenders. May have to tweak that just a little so there'll be room for a little more flex but still have the "stop" that may prevent the tire & fender from meeting if I should encounter a big "bump" .