Low speed vibration
Racer
Joined: May 2001
Posts: 401
Likes: 0
From: Carlsbad CA
Re: Low speed vibration (brooksman9)
I had a problem like the one you describe on a 1979 Blazer. Everyone I knew and every shop I went to had a different opinion. Turned out to be the rear tires. I had them rotated and the problem went away for a time, then reappeared as a front end vibration. I put new tires on it and hte vibration went away. The tires were substantially different from anything you're running on your Vette, but may be worth a look. Plus, a rotation is a cheap way to eliminate one possibility.
Good luck!
Good luck!
Thread Starter
Burning Brakes
Joined: Oct 2003
Posts: 1,097
Likes: 0
From: Olive Branch MS
St. Jude Contributor
Re: Low speed vibration (thebruce)
Finally replaced half shafts with brand new from bairs. still having vibration. While test driving I did finally notice that while it is vibrating at about 35 mph, if I drop it in neutral it stops vibrating. Back in gear, back to vibrating. Anyone else? :banghead:
Drifting
Joined: Mar 2003
Posts: 1,608
Likes: 3
From: Canberra AUSTRALIA
St. Jude Donor '05-'06
Re: Low speed vibration (brooksman9)
So is this where you are at?
New T-Arms.
Diff has no play in yokes? (did you check when hakf shafts were out?)
Four wheels all balanced.
Half Shafts and driveshaft replaced.
Car vibrates at 35MPH UNDER load.
How old is your clutch?
Might be your pressure plate. If this is cracked or has an uneven surface (or runout) then it may cause clutch and pressure plate to "jitter". Only way to check is to pull it out. You cannot get a visual on it while it is in the car.
How old (since a good rebuild) is your gearbox?
With the main driveshaft removed check for end play. Remove the yoke and try to push the gearbox driveshaft up and down, left to right. How much slop? This shaft runs on a bearing and there should not be much. It is also easier to check it out of the car as the front of that shaft is attached to the clutch and may give a false reading of how much slop it really has as it is pivoting on the pilot bearing when you move the rear end of the shaft.
Don't give up. The truth is out there.........
[Modified by stingry, 1:10 PM 3/15/2004]
New T-Arms.
Diff has no play in yokes? (did you check when hakf shafts were out?)
Four wheels all balanced.
Half Shafts and driveshaft replaced.
Car vibrates at 35MPH UNDER load.
How old is your clutch?
Might be your pressure plate. If this is cracked or has an uneven surface (or runout) then it may cause clutch and pressure plate to "jitter". Only way to check is to pull it out. You cannot get a visual on it while it is in the car.
How old (since a good rebuild) is your gearbox?
With the main driveshaft removed check for end play. Remove the yoke and try to push the gearbox driveshaft up and down, left to right. How much slop? This shaft runs on a bearing and there should not be much. It is also easier to check it out of the car as the front of that shaft is attached to the clutch and may give a false reading of how much slop it really has as it is pivoting on the pilot bearing when you move the rear end of the shaft.
Don't give up. The truth is out there.........
[Modified by stingry, 1:10 PM 3/15/2004]
Thread Starter
Burning Brakes
Joined: Oct 2003
Posts: 1,097
Likes: 0
From: Olive Branch MS
St. Jude Contributor
Re: Low speed vibration (stingry)
New T-Arms...yes
Diff has no play in yokes? (did you check when hakf shafts were out?)...yes
Four wheels all balanced...yes
Half Shafts and driveshaft replaced...drive shaft u-joints replaced...half shafts replaced w/u-joints
How old is your clutch?.....it is an automatic.
moving to motor mounts and trans mount.
:chevy :crazy:
Diff has no play in yokes? (did you check when hakf shafts were out?)...yes
Four wheels all balanced...yes
Half Shafts and driveshaft replaced...drive shaft u-joints replaced...half shafts replaced w/u-joints
How old is your clutch?.....it is an automatic.
moving to motor mounts and trans mount.
:chevy :crazy:
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Safety Car
Joined: Jun 2001
Posts: 4,004
Likes: 2
From: Severna Park Md
Re: Low speed vibration (brooksman9)
Are you sure its drivetrain related and not engine related? I ask this because you mentioned that when you put it in neutral the vibration goes away. I assume that when you you put it in nuetral you take your foot off the gas and the rpms drop. If it is engine related it would likely be less noticable at idle than it would at say 2500rpm. Start the car and let it warm up. While in park slowley bring the rpms up to what they would be at cruising speed, maybe 2500 or so. Hold it there long enough to determine if its engine related.
I had gotten a tourque convertor once that caused a vibration. I also replaced my ujoints only to have them go bad in less than a year. The problem was the driveshaft itself was out of balance. That vibe was wearing the joints. I took the shaft out and took it to a driveshaft specialist and had them install 2 new joints and balance the shaft. It took a sizable weight on one side to get it right. Since then the vibes are gone. It cost about $90 to have the joints put in and the shaft balanced.
[Modified by Jvette73, 1:43 AM 3/22/2004]
I had gotten a tourque convertor once that caused a vibration. I also replaced my ujoints only to have them go bad in less than a year. The problem was the driveshaft itself was out of balance. That vibe was wearing the joints. I took the shaft out and took it to a driveshaft specialist and had them install 2 new joints and balance the shaft. It took a sizable weight on one side to get it right. Since then the vibes are gone. It cost about $90 to have the joints put in and the shaft balanced.
[Modified by Jvette73, 1:43 AM 3/22/2004]
Le Mans Master
Joined: Sep 2000
Posts: 5,635
Likes: 4
From: Orlando Floriduh
Re: Low speed vibration (verskel)
Half shaft im-balance can cause this. Did you replace all of the U-joints? Sometimes rotating the half shaft half a turn will fix it. Sometimes a balance wieght came off. Make sure all of the half shaft ends are seated in their cradle properly Another problem not to overlook is tire balance. Computer balances are not very good despite what the shops say. I have had terrible luck with the balancing jobs I have had done. I had one place that only lety the tire spin about two turns at 10 mph and the guy was going to put weights on. When I aske him to spin ift faster his answer was that's as fast as it goes. Naturally when I drove the car I had a terrible vibration at 62 mph. When I returned the manager said.. "So? the speed limit is 55..." If it 'sok there then that's all I can do. :rant:
[Modified by bluevetteman, 2:48 AM 3/22/2004]
[Modified by bluevetteman, 2:48 AM 3/22/2004]
Thread Starter
Burning Brakes
Joined: Oct 2003
Posts: 1,097
Likes: 0
From: Olive Branch MS
St. Jude Contributor
Re: Low speed vibration (bluevetteman)
Half shafts replaced with new units including u-joints from bairs. I was under the car the other day looking at the motor and tranny mounts and the right motor mount looks like it has some cracks running the length of the rubber. I am expecting all new mounts from volvette anyday. Hope this fixes this problem. :banghead:
Instructor
Joined: Apr 2002
Posts: 163
Likes: 0
From: rices landing Pa.
Re: Low speed vibration (brooksman9)
You didn't by chance change your damper size did you?I changed one once and did not have it match the engine , though I thought I did, and had vibration low speeds. Put the correct one on and it smoothed out
Thread Starter
Burning Brakes
Joined: Oct 2003
Posts: 1,097
Likes: 0
From: Olive Branch MS
St. Jude Contributor
Re: Low speed vibration (john V. zemba)
You didn't by chance change your damper size did you?I changed one once and did not have it match the engine , though I thought I did, and had vibration low speeds. Put the correct one on and it smoothed out
Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
Re: Low speed vibration (brooksman9)
No real wrong size it is whether it is int or ext balanced, usually the 6" sizes are for int and the 8" are for ext but that is not always the case. I have a OEM type 8" damp that has a removable weight so it can be used for either and I have used on both types of engines.
Thread Starter
Burning Brakes
Joined: Oct 2003
Posts: 1,097
Likes: 0
From: Olive Branch MS
St. Jude Contributor
Re: Low speed vibration (Fevre)
No real wrong size it is whether it is int or ext balanced, usually the 6" sizes are for int and the 8" are for ext but that is not always the case. I have a OEM type 8" damp that has a removable weight so it can be used for either and I have used on both types of engines.
Thread Starter
Burning Brakes
Joined: Oct 2003
Posts: 1,097
Likes: 0
From: Olive Branch MS
St. Jude Contributor
Re: Low speed vibration (Fevre)
OK. I thought you might be talking about the harmonic balancer but I wasn't sure. I haven't touched that end for anything yet. Although, the power steering pump pulley does wobble considerably. The belt will sqeek when you rev the engine. getting around to that soon. :smash: :smash: :smash:
Instructor
Joined: Apr 2002
Posts: 163
Likes: 0
From: rices landing Pa.
Re: Low speed vibration (Fevre)
crankshaft balancer , harmonic balancer, I rebuilt a dodge once and had a 318 balancer on a 360 . It fit but was the wrong weight. , it idled nicely, but at low rpm's it vibrated at high speed it seemed ok. Maybe the rubber is coming apart between the two halves. ... just my thought
Instructor
Joined: Apr 2002
Posts: 163
Likes: 0
From: rices landing Pa.
Re: Low speed vibration (brooksman9)
Sorry I answered you once but I either sent it wrong or did not send it. the harmonic balancer. On a dodge I rebuilt once I put a balancer off of a 318 on a 340/360 and they fit the same but the balance was different, you may also want to check the rubber between the two halves it may be going bad
Advanced
Joined: Jan 2001
Posts: 83
Likes: 0
From: Snellville, GA, USA
Re: Low speed vibration (john V. zemba)
List everything that you have done trying to find your vibration. Sometimes we look for all the hard things and then find something simple. Did I read that you had the vibration until you kicked it into neutral? And you have an automatic, correct?
steve
steve