Weird thump thump thump...
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From: OHIO
Weird thump thump thump... My wife and I went to see a movie last Saturday night in my 99 SS and the car was just fine up to the movie theater but on the way home is the problem. We got in the car, I pulled out onto the main road and heard and FELT a thump thump thump...almost like a flat tire but we could feel the thump in the floor board right by our feet. We both thought it was a flat tire by the feel but it sounded like someone was under the car hitting the floor everytime the thump was felt. I don't know how else to explain it other than say something was on the thread on one of the front tires and every time the tire rotated, the object in the tread came into contact with the pavement making a thump noise and the faster you go and faster the noise is. I haven't gotten under the car to look yet...I was curious if anyone had run across this yet. My Moser 12 bolt is leaking from the pinion seal but I don't think that is the issue. As this was happening it stopped for like a minute or so then started again, thats when I pulled off the road to check for a flat. I looked briefly under the car and didn't see anything out of the ordinary. 
Thread Starter
TECH Enthusiast
Joined: Jan 2007
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From: OHIO
I looked under the car and didn't notice anything, no loose bolts or anything. Driveshaft isn't hitting anything and the torque arm bolts to the Moser are still tight (I thought that may have been it but its not). The noise isn't rpm related, meaning when I rev the motor theres no increase in noise speed and the noise is non-existent when the car isn't moving, only happens when its moving. Would a bad hub cause this? Are hubs commons on our cars, I have never had to replace any hubs on any of my F-bodies. Like I said the noise seems to be a rotating noise...like if a big rock was in your tires tread and every time the tire rotated and the rock hit the pavement, you get a thump
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Thread Starter
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From: OHIO
I pulled all the wheels off and you guys were right...screw in the tire on the inside edge. Hopefully it can be plugged; I know I will lose the speed rating but as I'm getting older(33, lol) I don't drive like an idiot anymore, so that doesn't matter. I can' see replacing the tire. I bought them about 3-4 yrs ago and they have 95% tread left since I only drive maybe 1000 miles a year, if that.
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12 Second Club
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Joined: Dec 2007
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From: Between Bowling Green/Owensboro
I have the same thing. Headers smacking k-member, ORY smacking floor, poly mounts didnt help.... trying to find a cheap muffler shop around here that will touch it...
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TECH Enthusiast
Joined: Jan 2007
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From: OHIO
Maybe you could put a torque strap on your motor. I can't believe motor is moving that much with poly motor mounts! I would do a torque strap and go to Mufflexs website, they have a bracket thats suppose to help the y-pipe from hitting the floor. What kind of headers do you have?
12 Second Club
iTrader: (4)
Joined: Dec 2007
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From: Between Bowling Green/Owensboro
Maybe you could put a torque strap on your motor. I can't believe motor is moving that much with poly motor mounts! I would do a torque strap and go to Mufflexs website, they have a bracket thats suppose to help the y-pipe from hitting the floor. What kind of headers do you have?
