Car starts shaking at 75 mph and continues to shake past that.
#1
Car starts shaking at 75 mph and continues to shake past that.
Basically the car starts having a vibration (feels like its from the back of the car) around 75 mph and keeps going.
The car has:
A different driveshaft
New motor mounts
New clutch
New trans mount
All wheels balanced
I'm thinking a bent rim, even though I have them balanced.
Any ideas?
The car has:
A different driveshaft
New motor mounts
New clutch
New trans mount
All wheels balanced
I'm thinking a bent rim, even though I have them balanced.
Any ideas?
#2
TECH Fanatic
iTrader: (10)
Bent rim can be seen easily when it's on the balancer.
In your case I would flip the driveshaft 180 degrees and see what happens.
It could also be a tire, however that's rare with Z rated tires.
Only other idea is: I believe the clutch/flywheel are balanced as a unit. Might be more info in the Manual Transmission section if you suspect this is the problem.
In your case I would flip the driveshaft 180 degrees and see what happens.
It could also be a tire, however that's rare with Z rated tires.
Only other idea is: I believe the clutch/flywheel are balanced as a unit. Might be more info in the Manual Transmission section if you suspect this is the problem.
#3
I first noticed the problem when I swapped my old rear (the current one) back into the car. That's when it started the shaking nonsense. Maybe something is loose in the rear suspension?
also,
I don't believe I have Z rated tires on the car. But it never did this before.
also,
I don't believe I have Z rated tires on the car. But it never did this before.
Last edited by Ironxcross; 10-23-2009 at 01:18 AM.
#4
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Tires
I first noticed the problem when I swapped my old rear (the current one) back into the car. That's when it started the shaking nonsense. Maybe something is loose in the rear suspension?
also,
I don't believe I have Z rated tires on the car. But it never did this before.
also,
I don't believe I have Z rated tires on the car. But it never did this before.
Hey would like to know exactly what tire you have, size and remaining tread depth, DOT # over all tire condition... spider cracks, etc... maybe some pics.
3 things come to mind right away.
#1 the tire is out of round/seperated, it will balance, the wheel is not bent. this goes overlooked a bunch since most tire balancers have a large "hood" and covers the tires thread, almost no one ever checks the tires tread for lumps, dips, high spots etc... a out of round tire is formed by a tire sitting for too long with low pressure on or off the car, a manufactures defect, excessive speed for sustained time causes the tire to seperate from the nylon or steel belt.... etc...
#2 wheel is slighty bent.
#3 the last guy to balance the wheels made a mistake, or a wheel weight has fallin off, the wheel is counter balanced.
a couple things you can do at home to on a flat surface with chocked wheels, with the rear in the air use the engine to drive the rear tires, check the tires when they are in rotation check for uneven tracking by looking at the tires from the sidewall and watching the tread that would make contact with the road, but is other wise now in the air, it takes a trained eye. you may also have the rear high enough to check the driveshaft for unsual rotational motion
you may also try "hand spining the fronts and checking them as well"
i am sure i missing a bunch of things but this should get you started.
hope this helps.
#5
12 Second Club
Tire vibrations typically start at 45ish MPH. My first thought when I saw the title of the thread was the driveshaft is out of ballance. Then I read that you have a diferent driveshaft installed. I agree with eseibel67, rotate the driveshaft 180 degrees. Check for anything that looks like a wieght has fallen off (a rectangular clean spot, or a spot weld that used to have something on it).
If you installed poly motor and trans mounts with an out of ballance driveshaft you'll feel it for sure.
I need to look it up but i think I have a procedure for ballancing a driveshaft.
If you installed poly motor and trans mounts with an out of ballance driveshaft you'll feel it for sure.
I need to look it up but i think I have a procedure for ballancing a driveshaft.
#6
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I had a very similar problem with my datsun (see in sig) earlier this summer. Turns out the driveshaft bolts had loosened off a tad causing a little play in the shaft at the differential. Tightened them up and vib's all went away. With a new DS install its worth checking out.
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#11
12 Second Club
Did you rotate the drive shaft?
Try this before you swap the rear. It's easier and should only take a small amount of time:
Try this before you swap the rear. It's easier and should only take a small amount of time:
BALANCE
NOTE: Removing and re-indexing the propeller
shaft 180° relative to the yoke may eliminate some
vibrations.
If propeller shaft is suspected of being unbalanced,
it can be verified with the following procedure: Prop shaft= canadian for drive shaft
(1) Raise the vehicle.
(2) Clean all the foreign material from the propeller
shaft and the universal joints.
(3) Inspect the propeller shaft for missing balance
weights, broken welds, and bent areas. If the propeller
shaft is bent, it must be replaced.
(4) Inspect the universal joints to ensure that they
are not worn, are properly installed, and are correctly
aligned with the shaft.
(5) Check the universal joint clamp screws torque.
(6) Remove the wheels and tires. Install the wheel
lug nuts to retain the brake drums or rotors.
(7) Mark and number the shaft six inches from the
yoke end at four positions 90° apart.
(8) Run and accelerate the vehicle until vibration
occurs. Note the intensity and speed the vibration
occurred. Stop the engine.
(9) Install a screw clamp at position 1 (Fig. 1). Screw clamp = canadian for hose clamp
(10) Start the engine and re-check for vibration. If
there is little or no change in vibration, move the
clamp to one of the other three positions. Repeat the
vibration test.
(11) If there is no difference in vibration at the
other positions, the source of the vibration may not
be propeller shaft.
(12) If the vibration decreased, install a second
clamp (Fig. 2)and repeat the test.
(13) If the additional clamp causes an additional
vibration, separate the clamps (1/4 inch above and
below the mark). Repeat the vibration test (Fig. 3).
(14) Increase distance between the clamp screws
and repeat the test until the amount of vibration is
at the lowest level. Bend the slack end of the clamps
so the screws will not loosen.
(15) If the vibration remains unacceptable, apply
the same steps to the front end of the propeller shaft.
(16) Install the wheel and tires. Lower the vehicle.
NOTE: Removing and re-indexing the propeller
shaft 180° relative to the yoke may eliminate some
vibrations.
If propeller shaft is suspected of being unbalanced,
it can be verified with the following procedure: Prop shaft= canadian for drive shaft
(1) Raise the vehicle.
(2) Clean all the foreign material from the propeller
shaft and the universal joints.
(3) Inspect the propeller shaft for missing balance
weights, broken welds, and bent areas. If the propeller
shaft is bent, it must be replaced.
(4) Inspect the universal joints to ensure that they
are not worn, are properly installed, and are correctly
aligned with the shaft.
(5) Check the universal joint clamp screws torque.
(6) Remove the wheels and tires. Install the wheel
lug nuts to retain the brake drums or rotors.
(7) Mark and number the shaft six inches from the
yoke end at four positions 90° apart.
(8) Run and accelerate the vehicle until vibration
occurs. Note the intensity and speed the vibration
occurred. Stop the engine.
(9) Install a screw clamp at position 1 (Fig. 1). Screw clamp = canadian for hose clamp
(10) Start the engine and re-check for vibration. If
there is little or no change in vibration, move the
clamp to one of the other three positions. Repeat the
vibration test.
(11) If there is no difference in vibration at the
other positions, the source of the vibration may not
be propeller shaft.
(12) If the vibration decreased, install a second
clamp (Fig. 2)and repeat the test.
(13) If the additional clamp causes an additional
vibration, separate the clamps (1/4 inch above and
below the mark). Repeat the vibration test (Fig. 3).
(14) Increase distance between the clamp screws
and repeat the test until the amount of vibration is
at the lowest level. Bend the slack end of the clamps
so the screws will not loosen.
(15) If the vibration remains unacceptable, apply
the same steps to the front end of the propeller shaft.
(16) Install the wheel and tires. Lower the vehicle.
#15
12 Second Club
They may be out of ballance with the car. The best way to ballance a driveshaft is when mounted but very few shops have the correct tools.
The above procedure does several things for you. First it eliminates the wheels and tires so if there is no vibration you know where the problem is. Second you can visibly inspect the rear brakes. If the vibration is coming from the axle flange you'll see it.
The above procedure does several things for you. First it eliminates the wheels and tires so if there is no vibration you know where the problem is. Second you can visibly inspect the rear brakes. If the vibration is coming from the axle flange you'll see it.
#18
I first noticed the problem when I swapped my old rear (the current one) back into the car. That's when it started the shaking nonsense. Maybe something is loose in the rear suspension?
also,
I don't believe I have Z rated tires on the car. But it never did this before.
also,
I don't believe I have Z rated tires on the car. But it never did this before.