flipping axel to the top of the leaf spring

[mchin]

I had heard of this and am about to replace my leaf springs, so I'm wondering the pros and cons. Some of the other fisherman in my area have mounted their axles on the top, not the bottom of their leaf springs. I hear the advantage is it lowers the trailer and makes launching in shallow water easier, but it seems like you could also bottom out easier. My boat, motor, gear is about 500-600 lbs, and will be replacing the old single springs with ones rated for either 500 or 750 lbs per spring. Should I mount it normally, or on top? Should I get the 500 or 750 lbs spring?

 

[bitterboater]

Re: flipping axel to the top of the leaf spring

Realistically, spring over only gains you the height of the axle tube and the thickness of the leaf spring. So about 2.5 -3.5 inches, this combined with taller tires will make it harder to launch in skinny water, but not by much. As for the spring weight, first look at what the axle is rated for, and DO NOT GO ANY HIGHER. Remember, the stiffer the spring the stiffer the ride will be as well.

I would go for the 750lb. spring.

 

[jay_merrill]

Re: flipping axel to the top of the leaf spring

The most obvious issue is that you are putting all of the stress on the U-bolts, because every time you hit a bump, the axle will want to push away from the spring, not into it. In fact, it would put all of the stress on the bolt and nut threads. This is not something that I would do!

I don't consider myself to be a trailer expert, but as far as I am concerned, the job of the u-bolts is to hold the axle in place, not to take the stress of every bump on the road.



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[EddiePetty]

Re: flipping axel to the top of the leaf spring

....The most obvious issue is that you are putting all of the stress on the U-bolts

Gotta agree with Jay. By reversing the spring mounting you are compromising the shackles by placing them in tension: bad move.
Additionally, leaf springs, by their construction, are non-linear springs (the more load placed upon them, the stiffer they get).
Considering the lightness of your rig, I would utilize the LIGHTEST spring available.
Springs are rated in their weight carrying capacity per unit of travel. Thus a 500# spring will compress 1" for the first 500#.
Remember, the spring is intended to maintain tire compliance to the road. If you install over-stiff springs, the trailer will bounce and beat the load to death.
FWIW....Ed in 'ol Virginny

 

[Knightgang]

Re: flipping axel to the top of the leaf spring

The most obvious issue is that you are putting all of the stress on the U-bolts,

While this may be true, I gotta disagree that this is an issue...

I have other trailers that have the axle on top of the springs and there are many vehicles on the roads that have the axles on top of the springs. If this was such an issue, no-one would mount the axles this way...

 

[fishingman220]

Re: flipping axel to the top of the leaf spring

i dont know much about the springs, but many vehicles came from the factory with the axle on top the springs such as s-10s, jeep wranglers, explorers, many of the mid size trucks, and they have more weight on one tire than you have on your trailer, you should be more than fine, and yes i would think it would be easier to launch in shallow water. but being closer to the ground you will have more of a chance of bottoming out or hitting something in the road

 

[jay_merrill]

Re: flipping axel to the top of the leaf spring

i dont know much about the springs, but many vehicles came from the factory with the axle on top the springs such as s-10s, jeep wranglers, explorers, many of the mid size trucks .....

They also have shock absorbers attached and were specifically designed to function that way. That means u-bolts that are large/strong enough to handle loads accurately determined by an engineer.

The rig being discussed was not designed as such. If he does it, I suggest that he use a pair of u-bolts, rather than one and I would oversize them considerably.



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[Knightgang]

Re: flipping axel to the top of the leaf spring

They also have shock absorbers attached and were specifically designed to function that way. That means u-bolts that are large/strong enough to handle loads accurately determined by an engineer.

The rig being discussed was not designed as such. If he does it, I suggest that he use a pair of u-bolts, rather than one and I would oversize them considerably.
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The shock absorbers are designed to minimize suspension rebound to provide a smoother ride for the passengers and improve handling for the vehicle. They in no way reduce the load on the Ubolts on the axle.

If it is a concern, be sure the Ubolts are Grade 8, or upgrade them to grade 8. If they are in salt water, be sure they are galvanized. Otherwise, the flip will be fine.

As I said above, I have several other trailers, rated up to 10K that have the axles mounted on top of the springs to lower the deck height. There is no problems with them with the original hardware used by the manufacturer...

 

[CharlieB]

Re: flipping axel to the top of the leaf spring

If it is a concern, be sure the Ubolts are Grade 8, or upgrade them to grade 8. If they are in salt water, be sure they are galvanized. Otherwise, the flip will be fine.

As I said above, I have several other trailers, rated up to 10K that have the axles mounted on top of the springs to lower the deck height. There is no problems with them with the original hardware used by the manufacturer...

Just want to reinforce what Knightgang clearly points out.

NO problem with original equip AS USED by the manufacturer.

HOWEVER, when we take it upon ourselves to make modifications, such as flipping an axle, THEN BE SURE to upgrade the bolt grade and size if possible.

 

[lcdr frank]

Re: flipping axel to the top of the leaf spring

After working for U Haul for over 16 years and building and rebuilding more trailers I care to think about, the placement of the axle should be of little concern....BUT just make sure you enough room for axle movement so as to not bottom out the axle on the frame. You may lose the benefits to frame damage due to a lack of clearance during spring flex. You may have to change your hangers to get back the clearance. Best bet is to go with a drop center axle and somewhat taller tires.


Frank

 

[skargo]

Re: flipping axel to the top of the leaf spring

While this may be true, I gotta disagree that this is an issue...

I have other trailers that have the axle on top of the springs and there are many vehicles on the roads that have the axles on top of the springs. If this was such an issue, no-one would mount the axles this way...

I agree. My land cruiser had spring under suspension when I bought it. I have since made the rear sprung over, and linked the front.

But yes, tons of vehicles and trailers out there sprung under already.

 

[jeeperman]

Re: flipping axel to the top of the leaf spring

You are not going to find any axle spring type u-bolts that are better than grade 5.
Most are only grade 2.
Simply increasing the u-bolt size from 3/8" to 1/2" dia. will nearly double the working load limits.
Your trailer might only have 5/16" or 7/16" u-bolts.

If your fender is not mounted to the axle, you might have to move it up a like amount.
And then it might be hitting or likely to hit the bottom of your boat.

The fenders on my boat trailer are frame mounted and can not be raised 2" or they will be touching the boat.

If your axle is held square on the springs via a spring center bolt, you will have to mount the axle upside down or drill another hole in the bottom of the axle.

If you want it all lower for shallow water launching you could use the fat pontoon trailer style tires on 10" rims also or instead. As well as look at how high your boat sets on the trailer.

 

[trendsetter240]

Re: flipping axel to the top of the leaf spring

My trailer has the axel installed on top of the springs. The day I bought the boat they were installed like that before I could tow it away.

 

[Silvertip]

Re: flipping axel to the top of the leaf spring

Flipping an axle is not even possible if it happens to be a cambered axle. Doing so would put the bend in the wrong direction and you would have severe wheel camber issue (as in the top of the wheel would be severely tilted inward at the top). If it is a straight axle you can do this. As for whether it is safe or not, all you need to do is look at any of the trailer axle sites and you will find listings for "over sprung" and "undersprung" axles to accommodate this very common practice. For those of you who are skeptics about having an axle above the spring, if you ever rode in a leaf sprung car (if you are old enough to know about them) you should know that those axles were above the springs and have been since Hector was a pup. It simply is not a problem. You need to have the right axle if the current axle is cambered.

 

[Robbabob]

Re: flipping axel to the top of the leaf spring

I just had to go out to our trailer and take a look. Of course, we have no idea how the trailer started before we got it, but ours is axle above springs.

 

[skargo]

Re: flipping axel to the top of the leaf spring

Flipping an axle is not even possible if it happens to be a cambered axle. Doing so would put the bend in the wrong direction and you would have severe wheel camber issue (as in the top of the wheel would be severely tilted inward at the top). If it is a straight axle you can do this. As for whether it is safe or not, all you need to do is look at any of the trailer axle sites and you will find listings for "over sprung" and "undersprung" axles to accommodate this very common practice. For those of you who are skeptics about having an axle above the spring, if you ever rode in a leaf sprung car (if you are old enough to know about them) you should know that those axles were above the springs and have been since Hector was a pup. It simply is not a problem. You need to have the right axle if the current axle is cambered.

Actually by "flipping" I think he is referring to doing a spring over, which absolutely can be done on a cambered axle, as long as it's not a drop axle.
Dexter makes a kit for that exact purpose.

Here's the instructions for the kit.
http://i.b5z.net/i/u/1080235/f/Instruction_Sheets/059-551-00A.pdf

 

[jay_merrill]

Re: flipping axel to the top of the leaf spring

If the OP can verify via contact with an appropriate expert, that his trailer and all of the associated hardware, are safe to configure as either an axle under or axle over setup, I would revise my opinion.

As someone offering advice, however, my concern is this - as manufactured, his trailer was set up as an axle under design. That means that all of the bumps in the road will drive his axle into the springs, not away from them. As such, the stress on the u-bolts is minimal. All that they do is to hold the axle in place and they are assisted in this task by the spring bolt.

Conversely, if the axle is flipped to the axle over position, all of the stress related to retaining axle position is transferred to the u-bolts and it will be in tension, not in shear. That means that the threads on the u-bolt and nut, are the weak link. If those u-bolts happen to be the same ones that were on the trailer originally, they may not be of sufficient size and strength to safely do the job.

Certainly there are plenty of trailers with axles in the axle over position. There are also kits to change axle position. What I question, is whether or not the OP's setup has parts of sufficient strength to make such a change safely. Unless I knew this to be the case, not by anecdotal comment, but by expert opinion, this is not something that I would do.



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[cr2k]

Re: flipping axel to the top of the leaf spring

I think this would be more pertinent if everyone was talking in the same language. Putting the axles above the spring has nothing to do with "flipping" them as they will still be in the same orientation to the road. Just above the springs. Also someone mentioned something about shackles. Doing the axle over has absolutely nothing to do with the shackles.

If you have clearance for travel on the frame and the fenders, go for it. Your mentioned weight is minimal and maybe go up one size in u-bolt diameter or not. If your trailer has one diagonal bolt per side, just go with 2 and a plate per side.

Most trailers have straight axles or drop axles without any camber anyway.
Four wheelers do FLIP drop axles to get more ground clearance with no problems.

It's not like you are hauling the QM.

 

[Splat]

Re: flipping axel to the top of the leaf spring

Agreed shackles have no bearing here.

But the point I wanted to add, any mechanic worth his weight will use new suspension hardware ESPECIALLY U-bolts once said item is removed. Never re-use u bolts once you remove them. New ones can be made by a spring and suspension shop, on the spot for around $20 a pair, often while you wait. Its stupid cheap insurance.

We have a local shop here in Medina, you call them with the dimensions, and pickup them up an hour later.

My point here is if you remove the U-bolts to flip the axle, spend the few dollars and get new/larger mounting components.

Bill

 

[jeeperman]

Re: flipping axel to the top of the leaf spring

I think Silvertip's post about flipping a chambered axle is in reference to my post.
Where I said you could use the same axle-to-spring centering hole in the axle by mounting the axle upside down on top of the spring, thus "flipping" the axle.

You certainly can't do that with a drop axle and do not want to do that if it is an axle with chambered spindles via a bend in the axle.

But you can still move the axle to the top of the springs as described in the link posted above for the kit from Dexter.

Different shackles would only become involved if you wanted to get back clearance above the axle. But then you would be defeating the reason you went and moved the axle in the firsst place as you would be raising the trailer slightly.