U-Joint help?!

[Smith]

Anyone know anything about U-Joints or CV joint on a 2004 Pontiac Montana minivan. Thing drives fine but hums like my old bike with a baseball card in the spokes! Is it easy to fix or something that is gonna cost me dearly?

Edited November 21, 2009 by Smith

[jay1313g]

Smith,

Lie down in front of the van and look near the inside of the front wheels. You should see a shaft coming from the transmission to the wheels. (about 2-3 feet long) This is your Constant Velocity axle. There are two rubber "boots" on each axle. One is near the transmission and the other is near the wheel. These boots cover the moving joints that allow the axle to move up and down while still spinning the wheels. More than likely, you'll find one that has rotted or been cut by road debris and slung its grease all under the van. When that joint is no longer greased, it will start "clicking" and eventually break. Better to get it handled sooner rather than later.

Let me know what you find.

Jay

[Smith]

Well looked under there and all four boots look to be in good shape and "dry". No grease to speak of. While driving there isn't any "drag", acceleration, or steering issues. The only thing is this stupid buzzing sound that comes on at about 25-30 MPH and increase with speed. Weird.

[oldogy]

Ok, lets talk. Sounds like the hum of a baseball card in the spokes would be a high frequency noise / vibration. You would probably get the high freq with a u joint but not a cv joint as a U joint turns at or slightly less than engine speed where a wheel or cv joint noise is usually much less in frequency. Front drive= no u joints anyway.

We are trying to determine if the noise vibration is driveline / engine or axle / wheel.

1. On a flat level road with the noise occurring drop the car into neutral and see if the noise continues, stops, or becomes lower in frequency. Try to determine if the noise follows engine speed or vehicle speed. With the noise occurring and speed below 50 mph drop the transmission into a lower gear and note if the frequency changes, stops, or what.

Wish you luck.

BTW, lightly loaded mini vans have been know to cup the rear tires badly and a cupped tire can give you quite a hum/vibration.

oldogy

Edited November 21, 2009 by oldogy
btw added