speed (NOT RPM) related vibrations - culprit?
12-11-2014, 09:23 PM
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speed (NOT RPM) related vibrations - culprit? I've had previous issues with RPM related vibrations, but the LS7 clutch swap seemed to remedy the majority of those. Now I'm noticing other vibrations that are directly related to vehicle speed, NOT RPM. I recently changed over from my summer wheels/tires to my winter set (OEM rims and snow tires) and the vibes are still the same, so that rules out a wheel balancing issue. What do you guys think would be a likely culprit causing the vibrations? They're quite noticeable but to varying degrees from about 50-60 KM/H (31-37 MPH). Would it likely be a driveshaft? Could it be a bearing of any type? I'm all ears to any suggestions 'cause these vibes are KILLING my OCD. 
12-11-2014, 09:54 PM
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DS bearing, or DS itself? Could it have anything to do with the DS being dropped for a clutch install, and then maybe being reinstalled in a different orientation or something? Do they have to be "clocked" in a certain way when being re-installed?
And if it's just a matter of an out-of-balance DS, is this a big deal to have re-balanced?
And if it's just a matter of an out-of-balance DS, is this a big deal to have re-balanced?
12-11-2014, 11:12 PM
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If the orientation is not right there is a good chance it will vibrate but if there was no change after it was dropped and if whoever did it knows what they are doing then it was probably put back in correctly meaning that the carrier bearing has gone bad, there is a thread in this forum by an individual who replaces them so you don't have to buy a whole new driveshaft if that is the issue
12-12-2014, 02:12 AM
#5
Definitely check the driveshaft index. Should be a witness mark on the DS and the tail shaft to show correct clocking, also at the diff. If problem isn't there look into carrier bearing rebuild from other thread. DS index is the quick and easy check, but at that low of a speed I would suspect problem lies elsewhere.
12-12-2014, 02:45 AM
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Interesting you'd mention the carrier bearing. Last year I used to get this random "whistling" from somewhere under my car while I was driving. It would happen at very random times and it was a very faint whistle, but once it started it always stuck around until the car was parked for a while. SOmetimes it'd be around for days. I remember reading a thread about carrier bearings and figuring that maybe this was the whistle I was hearing. I was going to look into it further but I can't even remember the last time I heard it, so it's kind of been put off. Are there any visual cues to a trashed carrier bearing that I can look for next time I'm under there? I'll add it to the list along with the brake lines that I apparently need to have a close look at.
12-12-2014, 06:58 AM
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how can it be the driveshaft?
It rotates at different speeds in different gears but vehicle travel speed is the same.
PO gave a small mph window saying the vibration is not RPM related...so in first gear driveshaft is rotating fast at that ground speed....PO puts car in 3rd gear at same mph and driveshaft is rotating much much slower yet still has vibration.
It rotates at different speeds in different gears but vehicle travel speed is the same.
PO gave a small mph window saying the vibration is not RPM related...so in first gear driveshaft is rotating fast at that ground speed....PO puts car in 3rd gear at same mph and driveshaft is rotating much much slower yet still has vibration.
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12-12-2014, 07:25 AM
#8
The driveshaft is spinning at a multiplication of vehicle speed and is independent of engine speed.
Did you drop the driveshaft when putting the clutch in? Look for dents in it if you did because that can throw it off balance.
The bearing and bearing surround are likely culprits but what kind of trans mount is in the car?
Did you drop the driveshaft when putting the clutch in? Look for dents in it if you did because that can throw it off balance.
The bearing and bearing surround are likely culprits but what kind of trans mount is in the car?
12-12-2014, 07:45 AM
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how can it be the driveshaft?
It rotates at different speeds in different gears but vehicle travel speed is the same.
PO gave a small mph window saying the vibration is not RPM related...so in first gear driveshaft is rotating fast at that ground speed....PO puts car in 3rd gear at same mph and driveshaft is rotating much much slower yet still has vibration.
It rotates at different speeds in different gears but vehicle travel speed is the same.
PO gave a small mph window saying the vibration is not RPM related...so in first gear driveshaft is rotating fast at that ground speed....PO puts car in 3rd gear at same mph and driveshaft is rotating much much slower yet still has vibration.
The driveshaft is spinning at a multiplication of vehicle speed and is independent of engine speed.
Did you drop the driveshaft when putting the clutch in? Look for dents in it if you did because that can throw it off balance.
The bearing and bearing surround are likely culprits but what kind of trans mount is in the car?
Did you drop the driveshaft when putting the clutch in? Look for dents in it if you did because that can throw it off balance.
The bearing and bearing surround are likely culprits but what kind of trans mount is in the car?
Can a shot bearing be readily identified by visual inspection?
12-12-2014, 08:33 AM
#10
how can it be the driveshaft?
It rotates at different speeds in different gears but vehicle travel speed is the same.
Po gave a small mph window saying the vibration is not rpm related...so in first gear driveshaft is rotating fast at that ground speed....po puts car in 3rd gear at same mph and driveshaft is rotating much much slower yet still has vibration.
It rotates at different speeds in different gears but vehicle travel speed is the same.
Po gave a small mph window saying the vibration is not rpm related...so in first gear driveshaft is rotating fast at that ground speed....po puts car in 3rd gear at same mph and driveshaft is rotating much much slower yet still has vibration.
lmao.
12-12-2014, 08:37 AM
#11
You might, might, see some metal flakes around the bearing but by then, it'd be so noisy there would be no doubt it was bad IMHO.
If you grab the driveshaft and push on it with it still mounted in the car, you can see how much flex the factory rubber surround gets in it after a while. I could take mine and literally move it at least an inch in every direction.
What kind of trans mount do you have?
If you grab the driveshaft and push on it with it still mounted in the car, you can see how much flex the factory rubber surround gets in it after a while. I could take mine and literally move it at least an inch in every direction.
What kind of trans mount do you have?
12-12-2014, 11:04 AM
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The whistle you mentioned is right online with a bad carrier. Also the carrier surrounding will be very comprimised. I personally would look at the driveshaft witness marks. Bolts on front and rear. Carrier bearing. And potentially the trans mount. If its OEM it may look good but it could be collapsed.
There use to be a quick window weld filler people were doing to the carrier bearing.
Look into all this.
There use to be a quick window weld filler people were doing to the carrier bearing.
Look into all this.
12-12-2014, 11:52 AM
#14
driveshaft spins differently than vehicle speed. It's not a corvette.Your carrier bearing is likely beginning to go. Mine did the same, spontaneously starting to whine while driving and often continuing to do so until the car came to a complete stop. Filling in the OEM rubber surround with 3M Window Weld on my carrier bearing significantly reduced the number of whining instances and the duration it would occur, but it still happened. I sent my driveshaft off to voodoo and had a new bearing installed along with a new rubber surround (poly not available yet) and it's been quiet since. His turn around is very quick and now offers a core program. I would put that maintenance on your radar sooner than later and then worry about the vibes aftwards, if they even still exist.
12-12-2014, 02:32 PM
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Just to confirm - the comment about the DS spinning at different speeds in different gears is incorrect, right? After working another 12 hour night shift, that kinda made my head spin. I couldn't digest it, and now I'm questioning what I assumed (that he was wrong)... Please don't laugh at me. lol
Thanks for the info, guys. I'll definitely look into the carrier bearing issue sometime over the winter or in the spring. It was on my radar back when I was getting the whistling and when VooDoo had started a thread on carrier issues. Then it kinda fell by the wayside when I got into having this ls7 clutch done, etc.
For the record, I have Creative Steel's "black/soft" transmission mount installed (as well as their "grey" motor mounds with heat shields).
Thanks for the info, guys. I'll definitely look into the carrier bearing issue sometime over the winter or in the spring. It was on my radar back when I was getting the whistling and when VooDoo had started a thread on carrier issues. Then it kinda fell by the wayside when I got into having this ls7 clutch done, etc.
For the record, I have Creative Steel's "black/soft" transmission mount installed (as well as their "grey" motor mounds with heat shields).
12-12-2014, 03:42 PM
#17
12-12-2014, 06:01 PM
#19
how can it be the driveshaft?
It rotates at different speeds in different gears but vehicle travel speed is the same.
PO gave a small mph window saying the vibration is not RPM related...so in first gear driveshaft is rotating fast at that ground speed....PO puts car in 3rd gear at same mph and driveshaft is rotating much much slower yet still has vibration.
It rotates at different speeds in different gears but vehicle travel speed is the same.
PO gave a small mph window saying the vibration is not RPM related...so in first gear driveshaft is rotating fast at that ground speed....PO puts car in 3rd gear at same mph and driveshaft is rotating much much slower yet still has vibration.
