High frequency vibration

J_lope82

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When I get up to ~65 mph + I start feeling a high frequency vibration. Sounds and feels almost like humming. It only does it around those speeds. I turn the engine off at those speeds and it’s still there. I’m thinking it might be the drive shaft but wanted to see if you all had some others ideas of what it might be.
 

J_lope82

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I was thinking of disconnecting the drive shaft and rotating quarter turn in relation to the differential to see if that would maybe help.
 

tinnocker

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Here is a little trick to do if you think your problem may be that your driveshaft is out of balance. Get a radiator hose clamp and wrap it around the driveshaft close to where the factory weight is welded on. Mark on the driveshaft where the screw part of the clamp is located and go for a test drive. Rotating the clamp to see if another area may help the vibration. The weight of the screw on the side of the shaft will effect the balance of the shaft and may change the vibration. It is a trial and error method but it does work if the shaft is not too much out of balance. Be sure to mark each spot with a marking pen. If you find a spot that makes the vibration better but doesn't entirely eliminate the vibration then try adding a small flat washer under the clamp or two clamps side by side with the two screws together. If you eliminate the vibration you can leave the clamps on, weld a small washer to the drive shaft of take it to a driveshaft shop and let them balance it. This sounds crazy but it does work.
 

J_lope82

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Here is a little trick to do if you think your problem may be that your driveshaft is out of balance. Get a radiator hose clamp and wrap it around the driveshaft close to where the factory weight is welded on. Mark on the driveshaft where the screw part of the clamp is located and go for a test drive. Rotating the clamp to see if another area may help the vibration. The weight of the screw on the side of the shaft will effect the balance of the shaft and may change the vibration. It is a trial and error method but it does work if the shaft is not too much out of balance. Be sure to mark each spot with a marking pen. If you find a spot that makes the vibration better but doesn't entirely eliminate the vibration then try adding a small flat washer under the clamp or two clamps side by side with the two screws together. If you eliminate the vibration you can leave the clamps on, weld a small washer to the drive shaft of take it to a driveshaft shop and let them balance it. This sounds crazy but it does work.
Hell yeah this is $$$ thanks man!!
 

GTR

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There is a notch on the flange where it bolts to the rear diff. It must be clocked correctly or it will do exactly what you’re describing. Drop the shaft, if you’re lucky you will see the shadow of where to position the notch. If not your idea of rotating it will also work. It may take 3 tries. Had the same problem after a new clutch was installed. Got it clocked right, smooth sailing after that.
 

J_lope82

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There is a notch on the flange where it bolts to the rear diff. It must be clocked correctly or it will do exactly what you’re describing. Drop the shaft, if you’re lucky you will see the shadow of where to position the notch. If not your idea of rotating it will also work. It may take 3 tries. Had the same problem after a new clutch was installed. Got it clocked right, smooth sailing after that.
Thanks I’ll try it. Is the notch on the drive shaft side? I have to match it up to a mark on the differential side is that correct?
 

J_lope82

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I was finally able to get under the car and inspect the driveshaft. I found a couple of things. First is the flange bolts were loose. I put a wrench on them and was able to spin them effortlessly. The other is my u-joints were bad. Specially the one on the slip yoke. Those were frozen and rusted up. I changed both of them out and reinstalled the driveshaft. now I need to test drive it but until tomorrow. The flange bolts went back in with a dab of blue lock-tite.
 

J_lope82

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The car drives great now. No vibration, super smooth. Thanks everyone for sharing their knowledge and experience .
 

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