Hi Rob,
We have 5 kids and a 2004 Honda Odyssey.
The "kids" are now all pretty much adult sized. Needless to say the van is starting to sag in the back end. Are there more heavy duty shocks we could put on to alleviate this?
Thanks! Tom
Tom, you're not alone in your perception that shock absorbers, (or "shocks"), will cure a sagging suspension.
To be accurate, the term sagging describes the vehicle's ride height.
Shock absorbers do their job by using the dampening effect caused when hydraulic fluid is forced through a small opening. This creates resistance of movement to the suspension, limiting the effect of the 'up and down' oscillations. Because of the damping effect, shock absorbers are increasingly referred to as dampers.
Dampers are each a single tube design that connects one end to the body of the vehicle (the piston and rod) and the other end (the tube) to the suspension. The job of the rod and piston is to move up and down the interior of the tube, forcing hydraulic fluid through specifically sized openings. To your point Tom, it does not matter at what point in the stroke of the piston/rod assembly is positioned; the same process takes place, without any effect on the ride height of the vehicle. The real concern however, is that if the stroke is not long enough inside the tube, the piston/rod can bottom out in the tube, damaging the damper.
There is however, one design of damper that does affect ride height; this damper has a coil spring wrapped around the body of the shock absorber. The thing is, using parts like this only compensates, or masks over the real problem: sagging springs. In your case Tom, you either have worn springs, or you are reaching the load carrying capacity of your minivan.
Considering the age of your Honda, I'm going to assume it's the latter and suggest you investigate these "coil-over" shock absorbers. They are available but make sure that you do not compromise the vehicle dynamics – oh, and Tom, if you decide to go with the coil-overs, don't be shocked (sorry), by the change in ride height and the increased stiffness of the ride. Careful what you wish for.
Send your automotive questions to globedrive@globeandmail.com