Suspension Coil Spring

Coil springs don't have a predictable lifetime because it depends a lot on the loads they carry. Generally, over time they compress more under the same load as they lose their strength. This causes rear end sag and also poor handling.

Also the tongue load of a trailer is far back of the rear axle centreline. So 100 pounds on the trailer hitch adds more load to the rear springs than 100 pounds behind the middle seats. So trailering shortens the life of the rear coil springs.

Both rear shocks and springs are easy to replace.

Another option is to replace the coil springs with air bags. Then you can adjust the pressure in the air bags to match the load in the van. So the van always rides level and secure.

SuperDad said:

I might be wrong, but I thought the air bags actually get installed inside the coil springs, and do not act as a replacement for them.

There are several descriptions of their install around here somewhere.

Click to expand...

SuperDad, you are correct - the air bags go inside the coil spring.

Here is a good writeup of air bag installation challenges and options.

jhnharvy773, Your dad is mostly correct. The force of the spring is contained within the strut assembly when the strut assembly is fully extended. There is spring force, but not on any of the suspension components. So with the strut fully extended, you would be free to disconnect the ball joint and the A-arm.