When do drooping axles need a lift?

[Isaac M]

I was wondering how much clearance you have between the top of the tires and the wheel well for a 16' or 19' Scamp? I'm trying to figure out at what point the axle needs to be replaced.

As always, thank you for your help.

-Isaac

[Herb P]

I was wondering how much clearance you have between the top of the tires and the wheel well for a 16' or 19' Scamp? I'm trying to figure out at what point the axle needs to be replaced.

I don't know the answer but I do know that it's not the axle that gets replaced, just the springs and that should be relatively inexpensive... Chances are, your springs are probably fine unless you leave the trailer fully wet and stored with all the weight on its tires instead of on some stabilizer jacks...

[Roger H]

Actually Herb, very few fiberglass trailers have springs. Most use rubber torsion axles for their suspension. Scamp used Dexter and more recently AL-KO rubber torsion axles under their trailers. They have never, to my knowledge, used leaf springs.

As a rule of thumb on a good rubber torsion axle, there should be about 3" of "bump room" or clearance between the top of the tire at rest and the wheel well. As a practical matter, some trailers may have more or less than that even with a bad axle.

The easiest "axle test" is to have a good sized person "bounce" in the doorway while you stand outside and watch to see how much deflection your axle has. If all you see is tire sidewall flex, then you probably need to replace the axle.

Roger

[Herb P]

Actually Herb, very few fiberglass trailers have springs. Most use rubber torsion axles for their suspension. Scamp used Dexter and more recently AL-KO rubber torsion axles under their trailers. They have never, to my knowledge, used leaf springs.

Sorry. You're probably right. I assumed anything bigger than 14 would have leaf springs. My Boler 17 has leaf springs.

[Brian B-P]

On the other hand, having heard about smaller "eggs" and their rubber torsion suspensions, I was surprised to find that the Boler 17' trailers had leaf springs!

Rubber torsion suspensions are the common practice in moulded fiberglass trailers from just about everyone except Bigfoot; even the biggest Casitas (17'), Scamps (19'), Escapes (17' and fifth-wheel) and Trilliums (5.5 metre) have them. There's even at least one Boler B1700 out there with rubber.

There is one rubber torsion design which allows replacement of just the rubber spring unit, but that's Flexiride, and I have never heard a travel trailer with that brand as factory equipment.

I agree with Roger: if the suspension doesn't moves properly with changing load, then the springs are likely dead, regardless of how much room is left in the wheel well.

[Pete Dumbleton]

Sorry. You're probably right. I assumed anything bigger than 14 would have leaf springs. My Boler 17 has leaf springs.

The entire Casita and Scamp lines use rubber torsion suspension, as does the entire Airstream line. Many of the stick-built BulgeMobile trailers are also using torsion axles.

One way to tell if the axle is hanging in there is to call Scamp with the VIN and find out what the original axle angle was (likely 22.5* down) and then observing the current angle. If it is level or pointing up, it's likely time for a replacement.

But definitely, if you can't stuff a clenched fist between the top of the tire and the wheel well, or if there are tire marks on the inside of the wheel well, it's time!

[Isaac M]

Thanks everyone. I checked the clearance and it definitely needs a new axle. I put a 22.5 degree down 3500 lb axle on our 1988 19' Scamp, but that was to create enough clearance for 14" wheels and tires (it is raised perfect for full size trucks). I'm trying to figure out the best way to make it so that the "lift" is not so much when I replace the axle on our new 19' project, for which I am planning on keeping 13" wheels and tires.

Pete, I'll take your advice and call the factory to find out what it originally had. I suspect it was a 22.5 degree down axle, but a much lighter duty axle.

-Isaac

[Brian B-P]

While calling for original specs is a good idea (I did this with my Boler), I don't think it is necessary in order to determine the start angle. The inner bar of the Torflex and similar axles is 45 degrees rotated from the outer square tube at zero load, so if you look at the end of the bar where is goes through the arm, you can see that its corners point straight up, down, left, and right. The square hole is the arm is made at the desired start angle.

The following image is "borrowed" from a Dexter document, and I have added (in blue) where I would read the start angle, regardless of current axle position, as the angle between the arm and the diagonal (line between opposite corners) of the inner bar.




This won't be really precise, because the outline of the inner bar is somewhat obscured by the welded joint, but with only a handful of start angles available, it should be reasonably easy to determine which one it is. The example has a 22.5 degree down start angle, just guessing by eye (it looks like half of 45 degrees).

If the rubber has really sagged, the diagonal line of the inner bar will be as much as 30 degrees off of horizontal with the trailer weight, but the angle between that diagonal and the arm is always the start angle.

So, people with rubber torsion axles and mechanical inclination, does this make sense to you?