suspension questions for a new build...

[hidefxj]

Greetings all,
1. I am modifying an axle for my trailer and it currently has an anti sway bar. Seems to me that this would limit articulation in most cases. Though some say the anti sway bar helps with fish tailing.
What's the prevailing thought?
The sway bar is a single diagonal bar connected at two points, one point on the axle tube and the other on the frame.

2. When I fabricate the shock mount points, do I need to position them so that the shock is partially compressed or totally uncompressed? Assume the trailer is on its back with no weight on the shocks.

Thanks guys!

 

[hidefxj]

Anyone?

 

[Mark Harley]

Coil springs or leaf springs?

Sounds like a panhard bar?

http://en.wikipedia.org/wiki/Panhard_rod

 

[hidefxj]

They are leaf springs. Very similar to what you show but shorter, a little over half the length.
About a foot in from the wheels.

 

[hidefxj]

Thanks for the link!
I guess the bigger question is, do I need the panhard bar on an expo trailer with leaf springs?
If it's advised then how do I go about getting the proper angle/placement when mounting it to the trailer?

 

[FredB]

A panhard rod, or trackbar, is just used to locate the axle under the rig. I can't see the need on an undriven axle. Nor have I ever seen one under a trailer, at least a light weight trailer.

For your shocks, measure the minimum compression and longest extension while it's on it's wheels. The top of the shock should be on the trailer frame, and I"d mount the bottom mount even with the axle.

 

[hidefxj]

I didn't think I needed it either but it is on the caravan rear axle that I am using complete with leafs and shocks (no coils). So it only stands to reason that I should be using it in this application too. Right?
BTW, the caravan was fwd.

 

[Heinz Modricky]

Most SA trailers are built only with leaf springs and shocks. It's a good idea to fit a progressive rubber bumper or bump stop between the centre of the leaf spring and the chassis to prevent the leafspring from bottoming out under extreme condition. This maximun point is your compressed limit of the shock's upward travel.

On elongation, it's actually quite difficult to determine because when your trailer's wheel becomes airborne after hitting a huge hole, the leafspring initially compresses, but then with no resistance on the wheel, the spring will push the wheel and leafspring beyond it's normal rest point. Obviously the leafspring's strength relative to the shock size is a factor. So it is important to have sufficient extension on the shock, or this will bottom out and be damaged on a single hit.