- #5094 of 5144
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Re: Intermittent Vibration and Noise Issue [scanman88gt]
by comem47
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May 08, 2009 (6:44 am)
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Replying to: scanman88gt (May 08, 2009 5:34 am)
You said the tires were checked for balance. Have you swapped the fronts to the rear for a while? If not, it will cost you nothing to try this for a while to see if some weird tire belt behavior may be happening. What brand tires do you have? could the ABS be acting up?(should have registered a fault code for the dealer though) You might also try turning off traction control while this is happening and note any change.
Very strange
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- #5095 of 5144
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Re: Intermittent Vibration and Noise Issue [scanman88gt]
by pao
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May 08, 2009 (8:33 am)
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Replying to: scanman88gt (May 08, 2009 5:34 am)
would ask the same question as above....would also ask were they road force balanced.......costs a bit more.....but can solve the problem you are describing...
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- #5096 of 5144
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Re: Intermittent Vibration and Noise Issue [comem47]
by scanman88gt
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May 08, 2009 (1:17 pm)
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Replying to: comem47 (May 08, 2009 6:44 am)
I have Cooper CS4's all the way around on the car. They are all around 6 months old. I can't swap the fronts with the backs because one of the back rims has a noticeable ding, as if someone had hit a curb or something pretty good. It was able to be balanced, however. When I replaced the brake pads, we didn't turn the rotors. My local guy said that we will have to turn them the next time I put pads on. When the car is experiencing one of these "episodes", I did notice that if I apply the brakes to slow it down a little, it seems to intensify the vibrations. I also noticed that right before this happens, the gas pedal seems a bit on the "stiff" side, and doesn't seem to move as frely as it normally does. I know that these cars have a fly by wire accelerator setup, without an actual cable or linkage, so maybe that has something to do with it?
That being said, every one of these episodes starts around 70 mph, when you're going down the highway and not even touching the brakes. By the time it builds to full intensity, it's quite terrifying. I thought it was just my wife overreacting to an out of balance tire until it happened to me...it scared the holy hell out of me. I'll tel the wife to manually switch off the traction control when she is experiencing one of these episodes and see if that has any effect on it.
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- #5097 of 5144
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Re: Intermittent Vibration and Noise Issue [pao]
by scanman88gt
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May 08, 2009 (1:19 pm)
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Replying to: pao (May 08, 2009 8:33 am)
Can you explain "road-force balanced" to me? Not quite sure I know what you mean. Thanks!
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- #5098 of 5144
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Re: Intermittent Vibration and Noise Issue [scanman88gt]
by scanman88gt
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May 08, 2009 (2:08 pm)
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Replying to: scanman88gt (May 08, 2009 1:19 pm)
One other thing that I forgot to mention...although I do have new brake pads on the front and rear, it does seems at times when I first start the car up that there is alot of travel in the brake pedal. I don't hear any hissing or anything that would indicate a leaky brake vacuum booster, the amount of brake pedal travel has me a little concerned at times. At other times, the pedal seems very firm, without this escessive amount of travel. The dealer that checked it out said that they couldn't find anything wrong with the brakes, except for me needing new pads. (I had the pads replaced by my local guy, after finding out how much the dealer wanted for the job).
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- #5099 of 5144
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Re: Intermittent Vibration and Noise Issue [scanman88gt]
by comem47
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May 08, 2009 (2:42 pm)
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Replying to: scanman88gt (May 08, 2009 1:19 pm)
I think he means a version of dynamic (spin) balance vs static. You can get a spin balance of just the wheel/tire assembly on a machine (what most everyone does) or do an "on the car" balance where the whole rotating mass of the wheel as well as disc rotors come into effect.(a motor treadmill spins up the individual wheel and If you have a loose/shot wheel bearing this will find it) I don't really see this type of balance very often these days with FWD cars. Note that you need to note how the tire is indexed to the lug studs when you have an "on the car" to maintain the "as balanced" state if you remove the wheel for some reason. I don't know anyone just getting a static (bubble) balance these days.
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- #5100 of 5144
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Re: Intermittent Vibration and Noise Issue [comem47]
by pao
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May 08, 2009 (6:55 pm)
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Replying to: comem47 (May 08, 2009 2:42 pm)
its actually done off the car...using a hunter balancer......look here for the details:
http://www.gsp9700.com/pub/features/how.cfm
not all tire ships have this type of machine:
the exclusive Road Force Measurement® system applies up to 1,400 pounds (635 kg) against the tire. The loaded roller detects non-balance, radial-force-related vibrations caused by eccentricity and constructional variation of the tire and wheel. Unlike non-contact measurement, the roller samples the entire footprint of the tire including the sidewall’s contribution to ride quality.
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- #5101 of 5144
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Re: Intermittent Vibration and Noise Issue [pao]
by scanman88gt
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May 09, 2009 (7:03 am)
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Replying to: pao (May 08, 2009 6:55 pm)
All 4 tires were definitely spin balanced. The last time I had tires bubble-balanced was when I first started driving, back in 1970. That was back when tires were sized by letter, -i.e. G70-14, instead of the metric system now in use.
I contacted a large Chevrolet dealer about this issue that I'm having with my Maxx yesterday, and they want $80 per hr for diagnostic time. The problem I had the last time I took it in was that it cost me for the diagnostic time, but the dealer couldn't get the car to act up. I paid for the diagnostic time, and was still no closer to figuring it out afterwards...very frustrating when you're on a limited budget, due to being unemployed. I guess I'm gonna have to wait till it takes a major dump on me, and hope to address it under the extended warranty that I have. This is SO damned frustrating...what a P.O.S.!
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- #5102 of 5144
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Re: Intermittent Vibration and Noise Issue [scanman88gt]
by pao
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May 11, 2009 (5:17 am)
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Replying to: scanman88gt (May 09, 2009 7:03 am)
you stated they were definitely spin balanced...but were they specifically done on a hunter machine?......not all spin balancers can do the road force measurement....to more accurately balance your tires....
sorry to hear you are still having problems finding a dealer to work with you....good luck
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- #5103 of 5144
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Re: Intermittent Vibration and Noise Issue [pao]
by comem47
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May 11, 2009 (7:56 am)
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Replying to: pao (May 11, 2009 5:17 am)
I still didn't get whether the tires were rotated (only that they were balanced).
If the severe vibration is definitely felt on the front, simply swapping the tires to the rear can be a cheap way to isolate if something weird is going on with a tire.
(I suppose if all the tires had the exact same problem then it wouldn't resolve it, but it's worth a try and it's free and safe if you have a reliable tire jack to use)
If the problem still exists after swapping then maybe a wheel bearing is breaking out of the race and later resetting itself (had this happen once on a Dakota and I replaced the sealed hub asm myself). The thing would make a terrible noise and then go quiet after either applying brakes or side thrust in the right way.I definitely could detect it when I got home by pulling sideways on the hub for a while and hear the bearing going south. (but you think the Chevy dealer would have ruled this out).
Bottom line is there is a good chance anything tire related can be ruled out for free with a rotation to the rear. If the problem goes away, then more investigating will be necessary to isolate (some $ if you can't diagnose further yourself with trying things like ABS and traction control and overall tightness of all front end parts too.)
Good luck!
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