How far back is your axle?

[BlackCatRacing]

Hello all, I am going to move my axle toward the back of my HF trailer tomorrow. I was wondering if anybody was unhappy that theirs was too far back or too far forward for whatever reason. I am going to build a 5x8 camper on it. I am also going to cantalever 1 foot of it off the back so I can gain that space for storage up front. So it will basically be a 5x9. I read somewhere that I should be 32 inches from the back. My poor math skills put it about about a little over 2/3 rds from the front. Is this good?

Thanks Patrick

[dguff]

About 2/3rds back is a good location.

Jerome

[bobhenry]

60 - 40 has been my magic numbers and aligns closely with Andrews balance sheet.

What this means is 60% of the BODY length is forward of the axle and 40% behind.

I have a 10' body on chubby so 72" is forward of axle center and 48" is behind.

I actually think I would have been somewhat happier with a 65 / 35 balance since I pull with a 1/2 ton pickup and the added tongue weight would not be a factor. The added handeling benefits especially in backing the unit would have made it even more of a pussycat to pull.

[48Rob]

Patrick,

I've never been unhappy about having an axle too far back, as in my opinion it cannot be "too far" back.
The only practical consideration being your tow vehicles ability to handle the tongue weight.
The further back the axle, the more stable the trailer.

I have had many trailers that had the axle too far forward, that had terrible sway and handling problems.
Rearranging weight generally solves it (adding to tongue weight) but some designs are so close to the edge of unstable that they are never really "right".
Andrew over in England suggests that in his country much lower tongue weights are common, and acceptable.
That combined with an axle fairly close to center gives a trailer that is only "stable" up to 45-50mph.
It seems to work there as trailer speed is severely restricted.
I'm of the opinion if a trailer here in the US. cannot be safely towed at the speed limit plus a little for passing/emergencies, it isn't safe/isn't a safe design-setup.
Andrew has designed and posted a spread sheet/calculator that is a huge help in deciding just where exactly to place the axle.
Takes all the guess work out of it!
Look here if you're interested.
http://www.angib.pwp.blueyonder.co.uk/t ... tear81.htm

Rob

[eamarquardt]

Patrick,

I've never been unhappy about having an axle too far back, as in my opinion it cannot be "too far" back.
The only practical consideration being your tow vehicles ability to handle the tongue weight.
The further back the axle, the more stable the trailer.

I have had many trailers that had the axle too far forward, that had terrible sway and handling problems.
Rearranging weight generally solves it (adding to tongue weight) but some designs are so close to the edge of unstable that they are never really "right".
Andrew over in England suggests that in his country much lower tongue weights are common, and acceptable.
That combined with an axle fairly close to center gives a trailer that is only "stable" up to 45-50mph.
It seems to work there as trailer speed is severely restricted.
I'm of the opinion if a trailer here in the US. cannot be safely towed at the speed limit plus a little for passing/emergencies, it isn't safe/isn't a safe design-setup.

Rob

Ditto!

You can mount your spring hangers and springs to a piece of angle iron. Then you can clamp it in place anywhere you like to get the balance you want/like. Then bolt the angle iron to your frame. As a plus it makes the frame a bit stronger and adds minimal weight. Also if the suspension ever needs servicing it's easy to remove.

[angib]

I've never been unhappy about having an axle too far back, as in my opinion it cannot be "too far" back.
The only practical consideration being your tow vehicles ability to handle the tongue weight.

Rob, one more thing I would add is that moving the axle back will increase the load on the tongue - build the frame tough enough and that's no problem, but that isn't much help with a "store-bought" trailer.

It's probably not a realistic concern on most trailers, even on a HF trailer, but for example on the Tractor Supply trailers that don't seem to have a very strong tongue mount, it could be a real problem.

[BlackCatRacing]

Thank you all for the great advise. I like the spread sheet (even fought my ADD to get through most of it). I have towed the HF trailer with a sailboat many thousands of miles and have never thought it as unstable. I have decided to move the axle to 36" from the back of the cantalevered trailer. I like the idea of an adjustable axle but being 5' wide I am going to need wheel wells. Maybe before I start the frame I can throw some weight on it at different points and see how it rides.

Thanks again.