Thread: Leading/trailing arm suspension

Originally Posted by justinc

Sinplicity suspension. Used on some New Age vans etc.
Can't say I am a fan. ..

Jc

Dad has had two vans with it. He is happy with how it works. Dirt road capable, but not proper off road.

One of the issues are the shocks being on too much of an angle. The closer to vertical they are the better they work.
Also with the angle of the shock there is quite a bit of side load on it and the seals will fail earlier

You may have read this recently---


I reckon the main reason for the laid over shocks is the modern requirement for "no holes" through the floor,
and the only way to control the spring travel is with a laid over shock.
My old Golf has four shock towers through the floor and vertical shocks,, you dont exactly trip over them--
mind you, you cant exactly walk under it either--

Originally Posted by Pedro_The_Swift

You may have read this recently---


I reckon the main reason for the laid over shocks is the modern requirement for "no holes" through the floor,
and the only way to control the spring travel is with a laid over shock.
My old Golf has four shock towers through the floor and vertical shocks,, you dont exactly trip over them--
mind you, you cant exactly walk under it either--

To have laid over shocks is a very poor design. The shock won't work properly which is why some run double shocks.
The Alko off-road set up is better but the G&S Chassis is far superior. I think Kedron Caravans also have a nice system.

With the leading & trailing arm design, if both droop at the same time, the tyres are going to get very close together.

Originally Posted by cjc_td5

With the leading & trailing arm design, if both droop at the same time, the tyres are going to get very close together.

Wouldn't they travel in the same arc and stay the same distance apart?

Originally Posted by Johnno_p

To have laid over shocks is a very poor design. The shock won't work properly which is why some run double shocks.
The Alko off-road set up is better but the G&S Chassis is far superior. I think Kedron Caravans also have a nice system.

VW Beetle front shockers are ideal in this application as they are very short travel, being designed to work at around 50% of the wheel travel (mounted half way down the swing arm). I've built a few trailers with these shocks canted at 45° and they give excellent control.

My opinion on the leading / trailing arm suspension is thst it isnt an appropriate setup.

I think that as a rule of thumb it really should be setup as a trailing setup for both axles.

The crossmember that has the suspension points looks, unusually, like it has been engineered well to take the forces from both axles.

The front suspension will be prone to be rough when offroad as it drives the axle forward rather than rearward when it hits bumps

The front may be prone to driving under (I cant think off the top of my head what the correct term is) when traversing steps, mud etc, especially when unloaded

The front produces antisquat under brakes and the rear will lift which may make it more prone to locking rear wheels under brakes with that braking setup. You'll notice that 4WDs have really long and flat radius arms at the front to help with this problem. Those ones are short and have a lot of angle.

The trailer requires more engineering and weight to provide strength at the right points to prevent failures and fatigue.

The shocks as stated need to be perpendicular to the suspension travel - the more the shock is needed the less they work due to geometry.

To prevent airation from the shocks being so flat you can run monoshell or remote res shocks which will get around that problem.