Q: I have a problem with my 2004 Jeep Grand Cherokee with 154,000 miles. While driving at speeds greater than 45 miles per hour I noticed a problem in ride smoothness. My tires are fairly new, properly inflated, balanced, and alignment is proper. I replaced all four shocks a couple of months ago. No unusual wear patterns on the tires. Initially, the problem started out when I take my foot off the gas at freeway speeds. During that abrupt deceleration the vehicle seems to "float" and "shimmy." When I resume acceleration the vehicle "shimmies" and "floats" again. Any roughness on the highway surface, crosswinds or following semitrailers cause these symptoms. There seems to be a bit of play in the steering but no pull on the steering wheel. I have been to a Jeep dealership and a reputable private service center — both can replicate the problem but neither can find anything abnormal. Please help.
A: With 11 years and over 150,000 miles on the vehicle, two likely possibilities exist — crash damage or worn parts. Even with new shocks, rubber bushings in control arms, stabilizers and track bars, ball joints, tie-rod ends, steering gear and the like may be worn enough to allow the vibration or shimmy to go undampened.
Residual crash damage, perhaps unknown or not identified previously — like a bent steering sector shaft or pitman arm — can allow excess movement in the steering that creates a shimmy or vibration. Also, don't overlook the tires — a belt shift or separation can cause this type of behavior.
Speaking of steering, the steering linkage on your Jeep features a shock absorber-like steering dampener to help control steering oscillations. At this age and mileage, this may be the primary suspect.
Q: We have had endless tire issues for years with our 2006 Pontiac Grand Prix. The tire was flat yet again tonight and when we brought it to a tire dealer to be repaired, both of the mechanics said "you don't want to do that" when we suggested radial inner tubes. However, we did not get a clear explanation for their disapproval. How do radial inner tubes solve tire-pressure issues?
A: By holding air. As I said in my column, I rate the installation of radial inner tubes as a last resort to tire bead-to-rim air leaks. If cleaning, sanding, polishing, painting and/or sealing the bead area of the rim does not stop the air leaks, a radial tire inner tube might be the only answer short of replacing the wheel. It's very important to differentiate between a standard inner tube and radial tire inner tube. Radial inner tubes are not available for all sizes of wheels/tires. The potential issue with installing radial inner tubes on a tubeless tire is pinching and chafing of the inner tube, eventually causing the tube to fail and the tire to go flat. A correct-sized radial inner tube is less likely to suffer this issue.
Q: Regarding cellphone use while driving, I am told there are several apps available that a phone user can download to disable his phone while driving should the individual choose to do so. Check it out.
A: Every cellphone has a built in "app" to prevent use while driving. It's the "off" button. So does the driver — just don't use the cellphone while driving.
Regardless of the mechanism for disabling or preventing cellphone use while driving, if it is operated or activated by the driver it is doomed to failure. Motorists who are welded to their phones while driving simply will not use any of these systems. Just like seatbelt use — many motorists choose to not buckle up for whatever unfathomable and irrational reasons.
Unless it's an automatic system allowing no human influence, it can't work. And what are the chances of a system like this when carmakers and buyers are focusing on the telecommunication capabilities of the vehicles they are purchasing?