Vibration at high speeds
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From: Garden City, KS
Vibration at high speeds!! Ok my car vibrated really bad at around 85-90 when i first got it. Well I replaced my driveshaft with one out of an LS1, now it still does it but it doesn't really start until above 100. Well, could my driveshaft need to be rebalanced??? Should I maybe replace my wheel bearings??? Any info please.
Could be unbalanced tires, or loose lug nuts. I just found my front lug nuts were loose the other day when i felt a vibration and thumping abover 20mph. I also had a bad constant vibraiton before i replaced the wheels. Once i replaced the front wheels everything was when i tightened the lug nuts. steers straight and no vibrations.
Launching!
Joined: Nov 2004
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From: Blaine, MN
I would say it's your driveshaft again. I would check into rebalancing it. Otherwise, check the wear on the innnermost part of your tires and see how it is. That could give you a good indication on if they're unbalanced.
Staging Lane
Joined: Feb 2005
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From: Detroit area (Waterford)
Most likely the driveshaft since worped rotors or tires out of balance would pulsate at lower speeds. Tires will also cancel themselves out periodically leaving a smooth spot inbetween the shaking. I think all the LS1 cars got the aluminum shaft with the better yoke which dealt with this prob (you guys will tell me). If it is an aluminum shaft, yeah, get it ballanced and enjoy. I had the same exact prob (right at 90) and bought a new one for my 94. After that it was smooth sailing up 150+ (so far not enough road for more).
-Jon
-Jon
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From: Garden City, KS
Well I Work At A Tire And Wheel Shop And Ive Been There For 5 Years, I Put On The Wheels And Tires And Balanced Them So That Is Not The Problem. As Far As Getting The Driveshaft Rebalanced Ill Do That. Thanks Everyone
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Teching In
Joined: Nov 2004
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From: Houston, Texas
In the case of your original begin replaced. You may need to look at replacing the front bearing on the pinion. I believe that the vibration from the previous driveshaft may have cause some premature wear and damage to that bearing. I have seen this before on a friends car. Once we replaced it the vibration was gone. His situation was almost identical to yours.
1LE cars arent lowered from the factory they just have different spring rates amoung other things. dont be so sure that your pinion angle wont cause a vibration problem.
http://frrax.com/rrforum/index.php?a...&hl=vibration&
i promise that car in question sees sustained high speeds more often than anyone else on here.
http://frrax.com/rrforum/index.php?a...&hl=vibration&
i promise that car in question sees sustained high speeds more often than anyone else on here.
TECH Enthusiast
Joined: Oct 2004
Posts: 607
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From: Anna, OH
If the driveshaft is brand new, you'd see the following...
D/S Type** Dia (in) Mat'l Critical Speed (rpm)
Lingenfelter 3.50 Aluminum 13,252
LS1 3.00 Aluminum 11,292
1LE (Gen III) 2.75 Aluminum 10,312
LT1/L98 2.50 Steel 9,724
When the driveshaft is at it's critical speed, it will resonate (vibrate) and there is nothing you can do about it. In reality it's very difficult to hit the critical speed. For example...
A 4L60E in 4th @ 4800rpm turns the shaft at only 6857, which is 163mph,
A T56 in 5th @ 7200rpm turns the shaft at 9600, going 180mph.
Obviously, these are way above the speeds you're talking about. Keep in mind that if the shaft or joints are unbalanced for any reason, you'll get vibration way below these numbers.
**Disclaimer: I've made some assumptions to compute this that may or may not be 100% accurate. These figures should provide some sense of the relative performance of these common driveshafts.
D/S Type** Dia (in) Mat'l Critical Speed (rpm)
Lingenfelter 3.50 Aluminum 13,252
LS1 3.00 Aluminum 11,292
1LE (Gen III) 2.75 Aluminum 10,312
LT1/L98 2.50 Steel 9,724
When the driveshaft is at it's critical speed, it will resonate (vibrate) and there is nothing you can do about it. In reality it's very difficult to hit the critical speed. For example...
A 4L60E in 4th @ 4800rpm turns the shaft at only 6857, which is 163mph,
A T56 in 5th @ 7200rpm turns the shaft at 9600, going 180mph.
Obviously, these are way above the speeds you're talking about. Keep in mind that if the shaft or joints are unbalanced for any reason, you'll get vibration way below these numbers.
**Disclaimer: I've made some assumptions to compute this that may or may not be 100% accurate. These figures should provide some sense of the relative performance of these common driveshafts.
another thing to look at is see if your axles are still straight and true. hard launches may sometimes "tweak" 'em a bit.
best way to find out is put it on a dyno and have a guy on each side to watch the rear tires rotate and high speeds.
best way to find out is put it on a dyno and have a guy on each side to watch the rear tires rotate and high speeds.
