A Hum (Sound) When Driving..

Nishan.dj · January 18, 2012

Hello friends,

Recently I reshaped the leaf-spring of my jeep (Mitsubishi - 4DR5 J44) and now I hear a hum noise when I drive. The sound comes when the speed is over 40KmPH and It is a sound that comes as a wave like "increasing in a second and decreasing in next second and then again increasing...decreasing... ". This was there even before reshaping leaf-spring but after reshaping its more now. Also there is a play in the deferential (may be 3/4 inch) as well. When I engage the 4WD that hum sound comes little more even on any level of speed. The engine is 4DR51.

Bass said, Have to check the gear box razors and its not much to think about and not going to brake anything. But the noise is not nice when driving. So Any of you have anything about this issue please post a reply. Highly appreciate it. Thanks in advance.

Edited January 18, 2012 by Nishan.dj

jdnet · January 18, 2012

Check the wheel bearings

Nishan.dj · January 19, 2012

On 1/18/2012 at 7:56 AM, jdnet said:

Check the wheel bearings

Thanks for your reply. But when there is a load, (such as many people on board) the sound is less. If it is the wheel bearings, it doesn't get changed based on the weight it gets; isn't it? Anyway after re-shaping of the leaf-spring, the height of the jeep went up a little bit like few inches. So wouldn't that be the issue? (the angle of the drive shaft also got changed). Thanks again.

Edited January 19, 2012 by Nishan.dj

harshansenadhir · January 19, 2012

It's the universal joints of the drive shaft (local context they call it differential) what cause the sound.

Since you have reshaped the leaf springs, the distance between the chassis and the wheel / rear axle got increased. To compensate that change, the angle of universal joints of the propeller shaft changes and that explains why it gets reduced when there's a load.

Nishan.dj · January 19, 2012

On 1/19/2012 at 5:26 AM, harshansenadhir said:

It's the universal joints of the drive shaft (local context they call it differential) what cause the sound.

Since you have reshaped the leaf springs, the distance between the chassis and the wheel / rear axle got increased. To compensate that change, the angle of universal joints of the propeller shaft changes and that explains why it gets reduced when there's a load.

Thanks harshan,

Would you suggest what would I do to fix it? Any idea? No need to look in the gear box then. (as baas said). Thanks.

Edited January 19, 2012 by Nishan.dj