Frames and Suspension Systems
I recently was contacted by a person regarding a problem with her vehicle. The contact is below in italic print. The only thing I changed is the removal of a swear word and replaced it with the phrase ‘pulling my leg’.
Your profile says you’re familiar with automobiles. I have a 1995 Chevrolet Silverado pick up truck similar to the ones I see you owned. Mine is a little like your black one in your image gallery. We used my truck to get a new television before February, as my friend followed behind me in her little car she informs me my truck is going down the road crooked. Driving it I can’t tell the difference but she swears the back of the truck is almost a foot farther to the right than the front. Is she pulling my leg. Is this possible.
Sandra A.
Yes this is possible on numerous types of vehicles. Usually vehicles equipped with leaf springs will show this odd behavior if the suspension is broken. When this happens it is called ‘Dog Tracking’. Some usual causes for dog tracking are collision damage or broken suspension components that broke from age or abuse (abuse such as jumping curbs or four wheeling in fields), a bad pot hole can also help a already weak suspension to do this.
First of all, after being told your vehicle is doing this, … Do Not Take The Vehicle On Any Expressways or Highways At All. Your Suspension is the only thing holding your rear axle in place. Find a way to get it to a nearby repair shop for a full frame and suspension inspection telling the shop why you want the inspection.
Usually the fault lies in the leaf spring assemblies (usually), however anything is possible. When leaf springs break, … a crack can be found in the leaf cluster itself. Sometimes the broken leafs discharge themselves from the vehicle leaving a gap where it used to be. These cracks can happen in places near the U-bolts or near the spring bands.
The center pin is another point of concern. If the leaf springs are very old and see a lot of aggressive duty, these center pins may shear inside the leaf cluster where the human eye can’t observe the break. A mechanic can tell if the center pin is sheared by looking at the leaf cluster for signs of the leafs ‘shifting amongst themselves’. When they shift, they will shift forward and backward from the main leaf which is attached to the spring perches, usually causing a spring band to come loose from parts movement. The forward and backward shifting is one of the ways that the axle can move around giving the ‘dog tracking’ appearance on the road.
This is common among pick up trucks that are always empty because the back of a empty pick up truck is very light causing the rear end to bounce around undetectably. Unloaded springs and heavily loaded springs are more susceptible to breakage over springs that usually have some sort of mild load on them.
There are some things that can be done to help the health of your suspension. Go around pot holes. If you have to drive over things like curbs, approach the object slowly, … when you feel the first wheels touch the curb give it a little gas to go over the curb slowly, then do it for the next set of wheels. Never drive over curbs going any faster than a crawl. That will only cost you money down the road.
Don’t do offloading with the family 4x4 unless it has off road suspension installed for that purpose. I’ve seen what off roading can do to family 4x4’s. Trust me, you wouldn’t want the repair bill’s for some of the things that can happen, we’re not talking about just the suspension either.
Reporter Joseph Toth
Washington Micro Bank BBS
