Looking for some input on pretty good vibrations above 60 mph. There really isnt much vibration in neutral or lower gears at the same rpm but if i'm in 4th gear on the interstate above 60 mph there is a good amount of vibration. What do you all recommend i start with first? make sure tires are balanced first, then what would you move to?
Vibration at higher speeds
jsm172
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Looking for some input on pretty good vibrations above 60 mph. There really isnt much vibration in neutral or lower gears at the same rpm but if i'm in 4th gear on the interstate above 60 mph there is a good amount of vibration. What do you all recommend i start with first? make sure tires are balanced first, then what would you move to?
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An easy place to start would be to check the u joint for wear or play.
Guy
Guy
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314 Posts
I had a similar issue. Higher speeds is when I felt the vibe. Checked the u-joints first, like Guy said. Make sure in neutral with chocks to check. Strike one.
Had tires balanced. Strike two.
Now for the twist. Lucky for me, A center screw backed out of the carb.... through the intake and right in the corner pocket. Cylinder # 7.
Long story short....engine rebuild revealed my crank wasn't balanced properly ( from previous owner rebuild ) and that was the difference. My engine builder asked me if I had a vibration at higher speeds. There it was.
Hopefully, you just need a u joint or possibly a driveshaft re- balance. I did all that as well. Nice and smooth now. $$$$$$
Not a poor man's hobby.
Had tires balanced. Strike two.
Now for the twist. Lucky for me, A center screw backed out of the carb.... through the intake and right in the corner pocket. Cylinder # 7.
Long story short....engine rebuild revealed my crank wasn't balanced properly ( from previous owner rebuild ) and that was the difference. My engine builder asked me if I had a vibration at higher speeds. There it was.
Hopefully, you just need a u joint or possibly a driveshaft re- balance. I did all that as well. Nice and smooth now. $$$$$$
Not a poor man's hobby.
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7,858 Posts
as someone that has been fighting vibrations for a long time, I would recommend a few things:
Operating angles of your driveshaft. Ideally you want equal and opposite angles. At the same time, check for worn out U-joints as suggested
Get a dial indicator and check how the concentric and parallel run out of your tires, wheels, brakes, and axles. Check out some of my videos to see how bent axles can get for no good reason.
You can also check your front wheels, though this should be felt more in the steering wheel than seat of the pants.
Operating angles of your driveshaft. Ideally you want equal and opposite angles. At the same time, check for worn out U-joints as suggested
Get a dial indicator and check how the concentric and parallel run out of your tires, wheels, brakes, and axles. Check out some of my videos to see how bent axles can get for no good reason.
You can also check your front wheels, though this should be felt more in the steering wheel than seat of the pants.
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Could be a bent rim or out of round tire.
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314 Posts
I'm sure it would.
I'm saying, put it in neutral to check your u-joints.
Not sure if you can check for an unbalanced crank. I only found out that was my issue when the engine was torn down.
I almost would point towards drivetrain if you're feeling it in the shifter.
May not be the same for you, but I'd lowered my car, had short 25" diameter tires, and 3.73s gears. That equals stupid high driveshaft RPM when you open it up.. I found the critical speed of my driveshaft and just about pretzeled it. Our cars have long driveshafts, that reduces the critical speed RPM of the shaft. Think of dangling a rope and spinning it with your wrist until it bows out and doubles up on itself. The longer the rope, the easier it is to do at lower revolutions, same exact principle applies to our cars unfortunately.
While you're under the car checking u-joints, make sure the car is 10000000% sturdy, all wheels off the ground or at least front wheels chocked and rear axle on solid axle stands, start the car, put it in 1st or 2nd then watch the driveshaft to see if it has any runout. Mine looked like a dying snake. This also gives you the ability to visually inspect for bent wheel, bent wheel lip, or possibly tire out of round.
Good luck!
May not be the same for you, but I'd lowered my car, had short 25" diameter tires, and 3.73s gears. That equals stupid high driveshaft RPM when you open it up.. I found the critical speed of my driveshaft and just about pretzeled it. Our cars have long driveshafts, that reduces the critical speed RPM of the shaft. Think of dangling a rope and spinning it with your wrist until it bows out and doubles up on itself. The longer the rope, the easier it is to do at lower revolutions, same exact principle applies to our cars unfortunately.
While you're under the car checking u-joints, make sure the car is 10000000% sturdy, all wheels off the ground or at least front wheels chocked and rear axle on solid axle stands, start the car, put it in 1st or 2nd then watch the driveshaft to see if it has any runout. Mine looked like a dying snake. This also gives you the ability to visually inspect for bent wheel, bent wheel lip, or possibly tire out of round.
Good luck!
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Good tips here but it is hard to guess when so little info is given. We know virtually nothing about the car.
Like what have you recently changed, how old are some of the parts, what kind of trans, etc.
Guessing here, vibration in 4th at speed. Drive train goes through rpm faster in lower gears. The vibration might be there in lower gears but you are only in them for a short time so it might not be as noticeable.
Does it clunk going from reverse to drive?
Could be the bearings in the trans.
Rick
Like what have you recently changed, how old are some of the parts, what kind of trans, etc.
Guessing here, vibration in 4th at speed. Drive train goes through rpm faster in lower gears. The vibration might be there in lower gears but you are only in them for a short time so it might not be as noticeable.
Does it clunk going from reverse to drive?
Could be the bearings in the trans.
Rick
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1,408 Posts
Since he feels it the worst in the shifter....put checking the driveshaft run-out with his new dial indicator as item #1 on that list.
Been there, done that, got the T-shirt. A vibe that makes the shifter buzz in your hand and the inside rear view mirror fuzzy is driveshaft or yoke/yoke bushing.
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Always have any wheel checked before mounting.
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brake drum/rotor unbalance can cause high speed vibration that can be fixed with an on car tire balance-if you can find anyone with that equipment anymore, and knows how to run it.
Some drums are cheap enough now just to replace to see if it helps
Some drums are cheap enough now just to replace to see if it helps
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Check to see if vibration is in the engine or in the drivetrain (put the car in gear, hold the clutch pedal down and check for vibration). If it isn't in the engine, then check ujoints, transmission output yoke bearing or bushing, differential yoke, pinion bearing, and driveshaft (tube straight, yokes indexed, and balance). Then check front wheel bearings, rear axel bearings, wheels, tires, and brake rotors. My best guess would be transmission output yoke bearing or bushing or driveshaft problem.. Having the driveshaft checked and balanced and put a new bushing or bearing in the rear of the transmission would be the first thing I would do. Solid motor mounts and solid transmission mount will let you feel every engine vibration in the seat of your pants. Might be a good idea to check the bellhousing and transmission mounting bolts.
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I had a car did that and it was a rear axle bearing mine was not a posi so I jacked one side up at a time and found it.. check u-joints by choking front tire put in neutral jack up rear end and push up and sideways on driveshaft at u joint if one is bad you should have some slack also pinion nut could have backed off. If you feel vibration in shifter it is in drivetrain, if not most likely a tire
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