Axel over springs

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Axel over springs

Postby Tukanu » Tue Oct 29, 2019 9:22 am

I realize this question has been asked a thousand times, but I am looking for opinions about my specific suspension.

My frame seems to be fairly light…no more so than a HF 4x8. I would guess it is about 200# because I can lift a corner. The welder estimated the capacity at 1,200 lbs. There are two leafs. There is 4 ½” of travel up to the frame. 3/8” U-bolts hold the axel in place. There is a post on the axel that mates with the hole in the spring. With the weight of the sidewalls and floor in place, there is no movement in the springs…even when I stand over the axel and jump up and down.

The build, so far, also seems to be light. I am sure it will be between 600# 700# (with chassis) when complete. Add a hundred lbs when fully loaded, and I would still be under 800#.

I have attached a couple of pictures of my axel and spring.

The bottom of the sidewalls is 19” off the ground. Flipping the axel would drop the body a few inches, but would reduce the travel to the fame down to about 2”.
Here are my options:
1. Do nothing and live with the high clearance.
2. Flip it and hope the u-bolts don’t snap.
3. Beef up the u-bolts and plate.
4. Finish the built and duck-tape a raw egg above the axel to see if there is enough travel to smash the egg .
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Springs.JPG
Springs.JPG (26.25 KiB) Viewed 1391 times
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Re: Axel over springs

Postby Atomic77 » Tue Oct 29, 2019 9:42 am

Our builds are completely different, yet I remember being in a similar quandary during my build. I felt like the springs were very stiff and sat too high. As it turned out, by the time it was finished and loaded for a trip, I actually needed the 'extra' hight that was actually perfect in the end.

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Re: Axel over springs

Postby twisted lines » Tue Oct 29, 2019 12:11 pm

I flipped mine but I also have shackles and different springs with eyes on both ends that may give you a in between height but another hassle and added expense :thinking:
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Re: Axel over springs

Postby MickinOz » Sat Nov 16, 2019 6:41 pm

I guess I'm a bit late for this, but I'd like to make a couple observations.
1) Those u-bolts stand out when I look at them, because they are square u-bolts on a round axle. Here in Oz that wouldn't be acceptable, a round axle would require round u-bolts. Dunno if I'm using the right technical terms, but the u-bolt should wrap around the axle, taking the load in tension.
2) It seems much more common here in Oz to see the axle sitting on top the spring, with the u-bolts taking full weight.
3) When I googled the part number of my springs, I learned on the ALKO website that the spring rating is two times the weight that causes 2 inches of deflection in a single spring.
e.g I have a pair of 600kg springs. This means that each spring will deflect 2 inches with 300kg on it.

If the manufacturer of those springs rates them the same way ALKO does, then room for 2 inches of movement would satisfy me.

P.S. have a careful look at your fishplates. Do my eyes deceive me, or are they bending?

I tighten my u-bolts in accordance with this:
https://www.alko.com.au/wp-content/uplo ... ations.pdf
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Re: Axel over springs

Postby Tukanu » Mon Nov 18, 2019 6:45 pm

Mick,
Thanks for the response.
I think you are right. round bolts make more sense on a round axel. I'll take a closer look at those plates to see if they are bent. This is a very narrow trailer, and I am concerned about it siting so high off the ground. An unexpected cross wind while traveling concerns me.

It is curious that you almost never see an axel under the spring.

This is going to be a light trailer, and I'm leaning toward switching the axel over the spring.
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Re: Axel over springs

Postby Sparksalot » Mon Nov 18, 2019 7:54 pm

I’d be tempted to build it out and see what travel is left before you make the final decision. Be sure to consider your fender mounting method as part of that.

I did the axle flip after about 8 years. I had to notch the spring perches to get any travel. The perches, not the frame. The flip dropped Rose 4 inches overall, so the fenders definitely had to be remounted.

Btw, Rose comes in about 1,500# when loaded.
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Re: Axel over springs

Postby Tukanu » Mon Nov 18, 2019 8:12 pm

Sparky,
You have mentioned that before. It makes a lot of sense. I need to practice restraint.
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Re: Axel over springs

Postby Tukanu » Mon Nov 18, 2019 8:18 pm

P.S. have a careful look at your fishplates. Do my eyes deceive me, or are they bending?


Just an illusion…the plates are perfectly flat.
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Re: Axel over springs

Postby Sparksalot » Thu Nov 21, 2019 9:25 pm

I was out in the garage measuring stuff, and remembered your initial question. How much Clearance...

Overview of the setup
160333

Clearance to the perch. Note frame is not notched.
160334

This has been my setup since mid 2016. Over 10,000 miles since and zero evidence of the ubolts touching the spring perch.
Done? Surely you jest. A teardrop is never "done".

The Compass Rose build thread: viewtopic.php?t=23213

Inspiration: http://tnttt.com/Design_Library/Trailer%20for%20Two.htm

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Re: Axel over springs

Postby Tukanu » Thu Nov 21, 2019 10:18 pm

Right now, I have 4 1/2" of travel. The builds about half done and the travel hasn't changed...still 4 1/2".
My concern is that my wheel base span is only 45" and I sit with 19" of clearance off the ground. This is very high for my tow vehicle (Subaru). I am afraid of sway while towing, and cross winds. I would be more comfortable if I could drop a few inches.
Like I said, I see very few trailers with the spring over axel, and I am just wondering what other people have experienced when flipping.
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Re: Axel over springs

Postby MickinOz » Thu Nov 21, 2019 10:38 pm

Assuming you can still locate your axle properly, i.e. there is a rivet/bolt head sticking out of the top side of the spring that will locate the spring pad on the axle, I say flip em over.
This is the more usual way to do it in Australia and no one bats an eye.
The only caveat - get the right u-bolts and fish plates for the job.

Check out the Spinny Things Technical Guide

https://spinnythings.com.au/image/catal ... _guide.pdf

All the illustrations show the axle on top of the spring.

Same with the AL-KO guide for fitting springs
https://www.alko.com.au/wp-content/uplo ... ippers.pdf
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Re: Axel over springs

Postby swoody126 » Fri Nov 22, 2019 8:43 am

PLEASE NOTE: THE BLOCK CAPS IMBEDDED IN THE BODY OF THIS POST ARE STRICTLY FOR ANSWERS... NOT YELLING

Tukanu wrote:I realize this question has been asked a thousand times, but I am looking for opinions about my specific suspension.

MAYBE A MILLION...

My frame seems to be fairly light…no more so than a HF 4x8. I would guess it is about 200# because I can lift a corner. The welder estimated the capacity at 1,200 lbs. There are two leafs. There is 4 ½” of travel up to the frame. 3/8” U-bolts hold the axel in place. There is a post on the SPRING that mates with the hole in the AXLE. With the weight of the sidewalls and floor in place, there is no movement in the springs…even when I stand over the axel and jump up and down.

THE AXLE MANUFACTURER BUILT IT STRICTLY FOR MOUNTING AS SHOWN IN PIC #1

AXLES ARE TYPICALLY NOT STRAIGHT PIECES OF TUBING

AXLES ARE SLIGHTLY ARCHED UP IN THE MIDDLE(HARD TO SEE IF YOU DON'T KNOW WHAT YOU'RE LOOKING FOR) TO ACCOMMODATE THE WEIGHT OF THE TRAILER PRESSING DOWN INSIDE THE POINTS WHERE THE TIRES REST/RUN ON THE GROUND

THE UPWARD PRESSURE FROM THE TIRES IS CALCULATED TO STRAIGHTEN THE AXLE TUBE ITSELF PROVIDING A PERPENDICULAR POSITIONING OF THE TIRE ON THE GROUND UNDER LOAD

THIS POSITIONING PROVIDES EVEN WEAR OF THE TIRES

IF THERE IS NO ARCH AND THE AXLE TUBE BOWS UNDER LOAD YOUR TIRES WILL WEAR ON THE INSIDE FIRST AND PULL A BIT WONKY

HERE IS A QUOTE FROM E-TRAILER.COM

https://www.etrailer.com/question-154877.html

AND A PIC OF WHAT THEY ARE/I AM TALKING ABOUT

img_73246_18_55af4579c9916bb7308868788f58af58.jpg
img_73246_18_55af4579c9916bb7308868788f58af58.jpg (36.2 KiB) Viewed 764 times


The build, so far, also seems to be light. I am sure it will be between 600# 700# (with chassis) when complete. Add a hundred lbs when fully loaded, and I would still be under 800#.

WE CAN ALL DREAM ABOUT HOW MUCH WEIGHT WE WILL CARRY IN A TRAILER

BUTT LIFE DICTATES MOST FOLKS WILL HAUL EVERYTHING THAT CAN POSSIBLY FIT INTO THE CAVITY CREATED

I have attached a couple of pictures of my axel and spring.

The bottom of the sidewalls is 19” off the ground. Flipping the axel would drop the body a few inches, but would reduce the travel to the fame down to about 2”.
Here are my options:
1. Do nothing and live with the high clearance.

RECOMMENDED

2. Flip it and hope the u-bolts don’t snap.

THURNIG THE AXLE TUBE UPSIDE DOWN WILL POTENTIALLY CAUSE PREMATURE TIRE WEAR/FAILURE

3. Beef up the u-bolts and plate.

THE WEIGHT OF THE BUILD RESTS ON THE AXLE(IN STOCK/INTENDED POSITION) AND THE U-BOLTS ARE SIMPLY POSITION HOLDING DEVICES NOT LOAD BEARING DEVICES

4. Finish the built and duck-tape a raw egg above the axel to see if there is enough travel to smash the egg .

YOUR TRAILER BUILDER/MANUFACTURER PROVIDED YOU W/ SLIPPER SPRINGS WHICH PROVIDES LOWER FRAME POSITIONING THAN SHACKLE MOUNTED SPRINGS

THE ONLY OPTION FOR LOWERING THE DECK AS I CAN SEE IS TO CHANGE THE WHEEL/TIRE CONFIGURATION TO PROVIDE YOU W/ A SMALLER DIAMETER

REMEMBER REDUCING THE TIRE DIAMETER BY 2" ONLY LOWERS THE DECK BY 1"(1/2 THE DIAMETER)

OR LIVE WITH IT AS DESIGNED/BUILT

"we are the people our parents warned us about" jb
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Re: Axel over springs

Postby Tukanu » Fri Nov 22, 2019 9:08 pm

I appreciate the input...thank you.
It seem the best course of action right now is to do nothing (except replace the square bolt with round ones), and revisit it after the build is complete.
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Re: Axel over springs

Postby pchast » Fri Nov 22, 2019 9:44 pm

I flipped mine on a Harbor freight trailer with new u bolts.
Its traveled over 10000 miles on main roads, with more than a few potholes.
I've had no issues. Casual inspection of the axle shows no stresses.
So far.......... :thumbsup:

I needed to turn over the bolt in the spring pack to maintain the same
orientation of the axle.
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Re: Axel over springs

Postby Tukanu » Fri Nov 22, 2019 10:33 pm

Sparksalot wrote: The flip dropped Rose 4 inches overall, so the fenders definitely had to be remounted.

This is something that I hadn't thought thru: My wheel wells are scaled for 4 1/2" of travel when the axel is under the spring. That is to say, the actual clearance from the top of the wheel to the underside of the wheel well is 4 1/2". By flipping the axel over the spring, I lose 3" of clearance to the underside of the wheel well. This means that the top of my wheel will hit the wheel well after only a inch of spring deflection. Long-story-short, I don't have enough room in the wheel well to do the flip....so, no flipping on this build.

Thanks to all with your input. I think you saved me.
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