Sunday, April 17, 2011

Rattles in late model Land Rovers



Does your Sport or LR3 sound like the spare tire is loose under the vehicle?  Have you looked and looked but found nothing loose?  If so, there's a good chance your problem is a worn sway bar.

What is a sway bar, you ask?  I'll tell you . . .

A sway is a torsion bar connecting the left and right sides of your suspension together.  The bar simply swings up and down when both wheels move together.  When one wheel goes up, as when it hits a curb or pothole, the bar resists that movement, adding to the spring rate.  When one wheel goes up and the other goes down, which is what happens when the vehicle leans into a corner, the sway bar resists doubly as its ends are twisted in opposite directions.

Sway bars are what keep your car flat when it makes a hard corner.  Without them, the body would lean on the springs to the point where you felt you were about to turn over.  Anyone who drove an old 1980s Rover without sway bars will remember this feeling well.

The Sport is a pretty high performance rig, so it has particularly beefy bars.  And of course these are heavy vehicles.  To handle all that the bars on my 2006 truck are almost an inch in diameter.  When they twist against the mounts during cornering, they twist hard.

For many years we have seen sway bar links wear out; not just on Land Rover but on BMW, Mercedes, and most other high performance cars.  The links are the rods with ball-and-socket joints that connect the sway bars to the suspension, out by the wheels.  We're accustomed to finding those worn out and rattly, but when these newer style Rovers began coming in with heavy clunks those links were surprisingly tight.  What gives?

It turns out that the bars themselves get loose in the mounts.  When they get loose, they rattle. At first we thought there was an easy fix - install new bushings.  However, the bars themselves are wearing down from friction with the bushings, so new rubber just fixes the problem for a month or so, and you have a comeback.

We have actually cured some trucks (including my own) by making sheet plastic sleeves that we fit between bar and bushing.  You're probably imagining something pretty high tech, but actually, we cut a strip out of an old windshield washer solvent bottle and wrap that around the bar.  Cheap and effective.  If you don't like that, or it does not work, your next step is to replace the bars themselves but that is a several-hour task involving lifting the truck body from the subframe to get the bars in and out.

Once you've heard a few of these noisy bars you learn to recognize the sound, and repair is pretty quick.. But we struggled many hours to find this one the first time . . .

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