Rear end knocking sound - help needed
1/29/07, 09:54 PM
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Rear end knocking sound - help needed
I've got a problem. A week ago starting getting a knocking sound every time I engage the throttle from an idle state 
. The knocking is coming from the area of the upper control arm. Anytime I take my foot off the pedal, then engage the pedal I hear the knock. The harder I engage the louder the knock. I can hear it after every gear shift. I also get the sound when the rear tires ride up a speed bump. It sounds like something is hitting the underside of the car.
And of course, I have been modding the rear myself
. I have installed an upper control arm and lowers. The lowers have been on a year, the upper about 2 months. All BMR parts. The stock upper control arm bracket is being used.
It seemed to me that upper control arm or bracket is the problem. I got under it yesterday, everything looked ok. I put my torque wrench on the three bolts for the upper control arm bracket and tightened them up to 90 ft-lb from 80 ft-lb. I expect something to be loose, but everything seemed tight.
Nevertheless, tightening the UCA bolts didn't help any, the knocking is still present.
I had a buddy ride with me; he described it like a U-joint on the drive shaft was loose. So every time the throttle is engaged it knocks, but that doesn't seem consistent with the sound over speed bumps. I've never intentionally messed with the drive shaft. Maybe it moved around with the rear was loose installing the UCA?
Could the UCA bracket be flexing under load? But barely tapping the throttle produces the knocks. Could the UCA itself be hitting up against the car?
Any ideas?
Taking the car to the dealership will be my last resort (warranty scares).
. The knocking is coming from the area of the upper control arm. Anytime I take my foot off the pedal, then engage the pedal I hear the knock. The harder I engage the louder the knock. I can hear it after every gear shift. I also get the sound when the rear tires ride up a speed bump. It sounds like something is hitting the underside of the car. And of course, I have been modding the rear myself
. I have installed an upper control arm and lowers. The lowers have been on a year, the upper about 2 months. All BMR parts. The stock upper control arm bracket is being used.It seemed to me that upper control arm or bracket is the problem. I got under it yesterday, everything looked ok. I put my torque wrench on the three bolts for the upper control arm bracket and tightened them up to 90 ft-lb from 80 ft-lb. I expect something to be loose, but everything seemed tight.
Nevertheless, tightening the UCA bolts didn't help any, the knocking is still present.
I had a buddy ride with me; he described it like a U-joint on the drive shaft was loose. So every time the throttle is engaged it knocks, but that doesn't seem consistent with the sound over speed bumps. I've never intentionally messed with the drive shaft. Maybe it moved around with the rear was loose installing the UCA?
Could the UCA bracket be flexing under load? But barely tapping the throttle produces the knocks. Could the UCA itself be hitting up against the car?
Any ideas?
Taking the car to the dealership will be my last resort (warranty scares).
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