QUESTION: I have a manual 2006 Infiniti G35 Coupe. With all my previous cars, I would always downshift while coming to a stop - at least as low as second gear.
However, I'm beginning to wonder if the major purpose of downshifting (to save brakes) makes sense in a world where gas is expensive and maintenance for brakes is far less costly than potential wear-and-tear on the clutch. Does downshifting still make sense or should I just clutch/brake? - Sharif
ANSWER: There are two schools of thought on this one.
One argument is that you bought a car with a manual gearbox because you enjoy the interaction between man and machine, the involvement and control. For those, executing a smooth downshift is a part of the enjoyment.
In this same school of downshift, believers are those who remember when we had unassisted drum brakes. Downshifting was useful in slowing more effectively and saving the brakes.
The other side of the coin is the one I subscribe to - don't bother downshifting unless you are going down a very long and steep grade and want to give the brakes a break.
Today's brake systems are more than capable of doing their job under all but the most adverse conditions.
Downshifting a manual gearbox places extra stress and thus wear on a number of drivetrain components, not the least of which are the throw-out bearing, clutch and the gears themselves. A brake job is a lot less expensive than a transmission or clutch job.
I enjoy a rev-matching downshift and heal-and-toe action when driving energetically, and want to be on the right gear for the exit of the corner or when passing. But when slowing for a stop I don't bother.
A MYSTERIOUS DRONE
QUESTION: I own a 2007 Mercury Grand Marquis with approximately 26,000 km and I'm getting a droning sound when I accelerate or decelerate - it sounds like a subdued hot rod! The dealer can't find the problem and I would appreciate any help you can give. - Ty
ANSWER: I'm afraid I can't provide much help.
It is very difficult for a technician to try to diagnose a noise in the shop with the vehicle at hand. It is nearly impossible to do so in print. There are so many types and sources of noise, you really have to experience them to even start tracking the source.
A drone can be a sympathetic rattle at a certain frequency to a vibration by a single component or a number of them acting in concert. Is it louder with the windows up or down? Is it from the engine compartment, exhaust system or an area of the body?
Have someone drive alongside you in a secure area such as an abandoned parking lot and see if they can hear it from outside. If so, can they narrow down where it is coming from?
The fact it can be heard during both acceleration and deceleration indicates it is happening at a certain road or engine speed.
If you change gears when you hear the noise, does that have an effect? If so, you have changed engine speed and the source may be there. If not, you might have eliminated the engine as the source.
It might be a good idea to tape the noise so you can play it back for the technician charged with fixing it.
globeauto@globeandmail.com