Spring motion can make horrendous noise

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This article was published 11/06/2010 (5640 days ago), so information in it may no longer be current.

QUESTION: My problem is with my 2010 MazdaSpeed3. Everything was great until winter came. At that point a crunchy noise showed up — both front and rear end, symmetrical and identical. The noise intensifies as temperatures get colder. Since then, control rods and bushings and sway bars and bushings were replaced but no fix.

Mazda Corporation’s Engineering was involved from the beginning but it seems that they don’t care too much because this whole situation has lasted for almost three months now. The demo vehicle in the dealership and at least one customer’s vehicles have the same problem. I would appreciate any advice you could give me.

ANSWER: The Mazdaspeed3 is virtually a "tuner car" right off the showroom floor. With a high-performance engine, transmission and suspension, it will fit right in on the racetrack, as I am sure you well know.

It also has a high-performance suspension, with stiffer spring rates, larger sway bars and low-profile tires with narrow sidewalls and wider tire tread. While the handling is superb, there are some drawbacks too. The ride is firmer and the narrow tire sidewalls provide very little cushioning. Cold weather makes this even more noticeable, as the oil in the suspension struts is thicker and doesn’t move as easily. Also, rubber parts have less flex. None of this fixes your car however.

I have worked weeks trying to fix noises similar to yours, so I wouldn’t give up on the Mazda engineers after only three months. The sales volume of Mazdaspeed3 cars is low, and few are subjected to the cold climates found in Canada. This makes finding a solution even more difficult.

I suspect the noise could be coming from the springs and struts. A coil spring moving even a couple millimetres in its spring seat on the strut can make a horrendous noise. Because the suspension on the Mazdaspeed3 is tuned differently than the Mazda3, I am wondering if the rubber spring seats used on most cars isn’t there on the Mazdaspeed3. I have a Mazdaspeed3 in my driveway right now but can’t tell by looking. The springs may have to be removed to see.

Spraying a little white lithium grease on the spring ends may allow the springs to slide easier rather than "crunching." Applying a little lubricant selectively can be a great diagnostic tool. If the noise disappears, then a thicker lubricant or a change of components can fix the problem more permanently.

QUESTION: We have a 2007 Focus. The tire size is 205-50R16. These tires seem to be harder to find and have a much narrower selection. What would you say to putting 205-55 R16’s or 205-60R 16’s on this car? The car has plenty of power for us and it looks like there would be enough clearance for a little taller tire. Much of our driving is on gravel roads and we would appreciate a little bit more tire sidewall.

ANSWER: While I generally recommend that replacement tires on passenger cars be the same size or diameter as the original equipment, it is possible to change sizes slightly without any serious problems. You should try to stay within about three per cent of your original tire size. Installing a tire larger or smaller in diameter than this will not only alter your speedometer accuracy, it can affect how the antilock brakes activate and at what speeds the automatic transmission shifts.

Let’s compare the three tire sizes you are looking at. All have the same 205 mm width and all fit the same 16-inch diameter wheel. Only the aspect ratio is different between the three tire sizes. The aspect ratio is the height of the tire sidewall as compared to the tread width.

For example, the 50 series tire would have a sidewall 50 per cent of 205 mm or approximately 102.5 mm high. The 55 series tire would have a slightly higher sidewall and be just over three per cent larger in diameter. The 60 series tire would have a taller sidewall again and be about 6.25 per cent larger in diameter than the original 50 series tire. I would not recommend installing the 60 series tire because of this larger difference.

Installing the 55 series tire would be acceptable and would affect your speedometer display slightly. It would now show 97 km/h when you are actually going 100 km/h. The ABS brakes and transmission shifting should still work effectively.

Jim Kerr is an experienced mechanic, instructor and member of the Automobile Journalists’ Association of Canada.

kerr.jim@sasktel.net