Suspension Knock: Sorted
Posted: 20 Dec 2010 17:24
I have been battling to find the source of a suspension knock on Imvubu, my Patrol, for some time now. It seemed as though it originated from the front of the vehicle and sounded like a dull knock or sometimes almost like a creak.
It was not easy to determine when it would occur. Sometimes it happened on pull-away, sometimes when changing gear and at other times when the wheels mounted an obstacle or ridge.
At one time it vanished for a long time, but then returned with a vengeance after a Moz trip and seemed to get worse and worse; on a dirt road the suspension would chatter away rather irritatingly.
After some research on the Aussie Patrol4x4 forum, the initial prime suspects were the anti-roll bar links. I removed the front anti-roll bar completely and checked all the suspension and body mounting fasteners for tightness. I was so certain that the noise originated from the front of the car (although a colleague said that it sounded to him as though it was from the rear), but it was not the case: the knock was still there.
Today the rear anti-roll bar came off as well after I had noticed that a feint knock was audible from outside the vehicle when rolling the body heftily by gripping the roof rack. Now Imvubu is quiet and dignified on dirt again.
It seems that the sealing boots that cover the anti-roll bar link spherical joints had perished, thus allowing water/dust/sand in. Then it was but a question of time until the ball joints wore to the point of having play and making knocking noises.
I am actually tempted to leave the anti-roll bars off permanently. It is my conviction that they are not that essential to safe handling on a beam axled vehicle anyway, but that a major reason why they are fitted is to minimize body roll for the sake of the occupants: humans seem to get disproportionately uncomfortable when the body rolls...
Perhaps I must get a price on those links from Nissan for interest's sake
.
I was once again amazed by the ability of a vehicle's structure to transmit and amplify sounds in totally confusing ways.
It was not easy to determine when it would occur. Sometimes it happened on pull-away, sometimes when changing gear and at other times when the wheels mounted an obstacle or ridge.
At one time it vanished for a long time, but then returned with a vengeance after a Moz trip and seemed to get worse and worse; on a dirt road the suspension would chatter away rather irritatingly.
After some research on the Aussie Patrol4x4 forum, the initial prime suspects were the anti-roll bar links. I removed the front anti-roll bar completely and checked all the suspension and body mounting fasteners for tightness. I was so certain that the noise originated from the front of the car (although a colleague said that it sounded to him as though it was from the rear), but it was not the case: the knock was still there.
Today the rear anti-roll bar came off as well after I had noticed that a feint knock was audible from outside the vehicle when rolling the body heftily by gripping the roof rack. Now Imvubu is quiet and dignified on dirt again.
It seems that the sealing boots that cover the anti-roll bar link spherical joints had perished, thus allowing water/dust/sand in. Then it was but a question of time until the ball joints wore to the point of having play and making knocking noises.
I am actually tempted to leave the anti-roll bars off permanently. It is my conviction that they are not that essential to safe handling on a beam axled vehicle anyway, but that a major reason why they are fitted is to minimize body roll for the sake of the occupants: humans seem to get disproportionately uncomfortable when the body rolls...
Perhaps I must get a price on those links from Nissan for interest's sake
.I was once again amazed by the ability of a vehicle's structure to transmit and amplify sounds in totally confusing ways.
.... I also couldn't figure out where the hell this "clunk" was coming from. I looked at the stabliser link and noticed that the bolts were not as tight as I thought they should be. I tightened them up a bit and it seemed that the problem was cured..... then I went on one of the Nissan4x4 outings... and after some good axle twisters..... my delicate "clunk" was back.
