High Speed slight vibration
Thread Starter
Pro
Joined: Mar 2015
Posts: 681
Likes: 31
From: Nebraska
High Speed slight vibration
The '79 has a vibration that only occurs at speeds arouind and over about 65 mph. It makes me think U-joint. The thing is... I have had the car checked over quite thoroughly about 8 months ago and all was fine. Is it possible for a u-joint to be bad and not show it during an inspection?
The car sat for quite a while before I got it. perhaps about 8 years. I realize that tires can flat-spot, but I would think I would feel that at all speeds.
Thanks for any thoughts.
The car sat for quite a while before I got it. perhaps about 8 years. I realize that tires can flat-spot, but I would think I would feel that at all speeds.
Thanks for any thoughts.
Racer
Joined: Jul 2009
Posts: 338
Likes: 9
From: South Bend IN
NCM Sinkhole Donor
My thought is if those tires haven't been changed after sitting 8 years they should be immediately. 7 -10 years is a rough life of the rubber. Most shops won't touch wheels and tires if they are older than 10 years unless they are replacing them.
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
The '79 has a vibration that only occurs at speeds arouind and over about 65 mph. It makes me think U-joint. The thing is... I have had the car checked over quite thoroughly about 8 months ago and all was fine. Is it possible for a u-joint to be bad and not show it during an inspection?
The car sat for quite a while before I got it. perhaps about 8 years. I realize that tires can flat-spot, but I would think I would feel that at all speeds.
Thanks for any thoughts.
The car sat for quite a while before I got it. perhaps about 8 years. I realize that tires can flat-spot, but I would think I would feel that at all speeds.
Thanks for any thoughts.
A flat spot on a tire or a half shaft u-joint would give you about 775 times-a-minute vibration and a drive shaft u-joint would give you a 2000-2500 times-a-minute vibration. If a front tire was the cause you'd feel it in your steering wheel and if a drive shaft u-joint is causing it you could feel it in the center console.
As the half shaft u-joints are always under a compression load they're harder to check.
Thread Starter
Pro
Joined: Mar 2015
Posts: 681
Likes: 31
From: Nebraska
A flat spot on a tire or a half shaft u-joint would give you about 775 times-a-minute vibration and a drive shaft u-joint would give you a 2000-2500 times-a-minute vibration. If a front tire was the cause you'd feel it in your steering wheel and if a drive shaft u-joint is causing it you could feel it in the center console.
Last edited by COOLTED; Sep 2, 2015 at 08:17 PM.
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
A failing u-joint would be the most likely cause of a high-frequency vibration because of the high rpm that the u-joints operate in. And I would suspect the drive shaft u-joints because they spin at 3+ times the rpm as the half shaft u-joints.
You can easily check the drive shaft u-joints by using two large Channel Lock types of pliers; one to hold the yoke and the other to twist the drive shaft. If you detect ANY movement that u-joint is shot.
Racer
Joined: Sep 2011
Posts: 414
Likes: 55
From: Humboldt county Ca
I had a 55-65 mph vibration. Shop that did my alignment wanted to replace all the u joints. Took it in for a tire balance and that fixed the problem although none of the tires were that far out.
I don't think u joints fail all that often and you usually get a pretty good clunk when putting it in drive if they are going.
I don't think u joints fail all that often and you usually get a pretty good clunk when putting it in drive if they are going.
Burning Brakes
Joined: Apr 2013
Posts: 1,194
Likes: 109
From: Las Vegas NV
The first thing that came to mine was tire balance. If you're considering replacing the tires anyhow, might as well do that and while its up in the air, check on the drivetrain health.
If the tires are still good, it isn't too expensive just to balance them again.
If the tires are still good, it isn't too expensive just to balance them again.
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Racer
Joined: Nov 2014
Posts: 463
Likes: 129
COOLTED
If your tires are old you could also have a problem with the belts coming loose. If this is true you will only feel the vibration at certain speed ranges. When I first bought my 68 it would vibrate only between 50-55 mph on the 15 year old tires it had on it. Above or below that speed everything was fine. Replaced the tires and it went away. My suggestion is replace your tires first, and if that doesn't fix your problem then worry about the rest.
John
If your tires are old you could also have a problem with the belts coming loose. If this is true you will only feel the vibration at certain speed ranges. When I first bought my 68 it would vibrate only between 50-55 mph on the 15 year old tires it had on it. Above or below that speed everything was fine. Replaced the tires and it went away. My suggestion is replace your tires first, and if that doesn't fix your problem then worry about the rest.
John
Drifting
Joined: Apr 2004
Posts: 1,424
Likes: 127
From: Mequon WI
Hey CoolTed,
Does the amount of vibration change when you let off the throttle and coast? Have the same issue with my '78 and the vibration occurs at 60 + MPH and it is constant. Somewhere I think I heard that U joints will vibrate under load bur not while coasting. Curious how yours reacts. I think my issue is tires and im not sure how old they are.
Does the amount of vibration change when you let off the throttle and coast? Have the same issue with my '78 and the vibration occurs at 60 + MPH and it is constant. Somewhere I think I heard that U joints will vibrate under load bur not while coasting. Curious how yours reacts. I think my issue is tires and im not sure how old they are.
Burning Brakes
Joined: Apr 2013
Posts: 1,194
Likes: 109
From: Las Vegas NV
Thread Starter
Pro
Joined: Mar 2015
Posts: 681
Likes: 31
From: Nebraska
Hey CoolTed,
Does the amount of vibration change when you let off the throttle and coast? Have the same issue with my '78 and the vibration occurs at 60 + MPH and it is constant. Somewhere I think I heard that U joints will vibrate under load bur not while coasting. Curious how yours reacts. I think my issue is tires and im not sure how old they are.
Does the amount of vibration change when you let off the throttle and coast? Have the same issue with my '78 and the vibration occurs at 60 + MPH and it is constant. Somewhere I think I heard that U joints will vibrate under load bur not while coasting. Curious how yours reacts. I think my issue is tires and im not sure how old they are.