adinini wrote:My car starts shaking around 50-55mph and I can't find what's causing it!!! I've did the following:
-changed tires
-alignment (4 wheel x2)
-changed front struts (actually got worse after this)
-checked front wheel bearing (good)
-wheel balancing x 4
-checked engine mounts
-checked tie rods
Any ideas before I take it to the dealer and let them charge me an arm/leg and still not fix it.
Thanks...
First. I'll write that alot of things can make a car shake.
Balance would be the most common.
I see you've done that with a new set of tires.
Hopefully it was at a quality shop. Take it back and, have them balanced and, rotated. Also, ask them to check for a bent rim.
I could use a little more information, too.
Does it get worse on rough roads. If it shakes the steering wheel when hitting bumps. And, I know it will normally. The question is excessive shaking from bumps. Excessive shaking from bumps indicates bushings and, ball joints. Even loose tie rod ends. Visually check your lower control arm bushings. Jack it up by the frame. Not the control arm. You check the ball joints unloaded. Let the control arm and, wheel hang free. Grab the tire at the top and, bottom. Give it a good shake. Looseness indicates wheel bearing and, or, lower ball joints. Repair as needed. Then realign. But, here's the kicker. Most shops will not align an auto with loose front end parts/ OK. So, you've probably eliminated anything but a bent rim or a drive axle. I'd have to recommend a 4 wheel alignment BTW.
If, you have the balance redone. Ask them to check for a bent rim.
Drive shafts. This is a complicated deal.
First, inspect the boots. For damage. And, also to see if one has been replaced. Sometimes people will reboot a damaged driveshaft. You may have a bent drive shaft. Inspect the shaft for visual impact damage. Dents, ect. Drive the car in a parking lot. Make tight slow turns accelerating. Listen for clicking noises. If the driveshaft clicks in sharp turn while acclerating. It needs repaired/replaced.
Sometimes drive shaft joints fail. For no seeable reason. These are hard to diagnose. The easiest way to find this is to accelerate hard. See if you get a wobble from hard acceleration. The next way is tricky. You need the auto on a lift and, a big long prybar. Make sure there is nothing behind the car. Start the car. Have somebody put it in drive and, bring it up to speed. Watch the drive wheels for shake. See if the shake is in the drive wheels. The shake could be comming from the back. Stop the car from spinning the wheels. Put it in nuetral. Manuelly spin each wheel and watch to see if they are out of round. If the tire is not truely round you have a problem. Feel the surface of each tire. For any roughness, choppynesss, or lumps and, flat spots. Replace any tire or rim that is not true. This will not verfie rear wheel balance or, a bad drive shaft. Back to the drive wheels. If you drive wheels appear good. But, you have a shaky wheel during the rack drive test. Remove the shaky wheel. Put the wheel nuts flat side in down on the rotor to hold it in position. Tighten down all wheel nuts flats side/top to 20 ft. lbs. Run the car again. See if the hub rotor and bearing shake at your known problem speed. If, the shake is gone. Rotate a different wheel to this hub. Repeat rack check. See if a different tire shakes.
If, the hub rotor axle assembly shakes without the wheel. Well. You still have to determine why. Rotors are balanced. check for the rotor balance weight. Remove the rotor. Recheck. See if rotor removal makes the shake go away. If it does. Replace rotor. If, not. Inspect wheel bearing. A little looseness doesn't mean it's bad. Turn it and, feel for roughness. If you feel roughness. Remove the bearing. Check the wheel bearing for roughness off the car. Any roughness or, excessive looseness indicates a worn/damaged/rusty bearing. Well. you are down to the drive shaft. Check it for side to side looseness. All driveshafts plunge. So, pushing it in and, out will be normal. Don't pull it out to far. Or, you may pull the tripod out of the plunge joint. And, you'll have the pull the boot off and, put the tripod back into the plunge joint.
OK. If, you can't find anything by making these checks. Reassemble. Drop the car till it's about a foot off the ground. Have somebody bring the car to the shakeing speed. This is dangerous so be careful. Make sure there is nothing behind the car for a little ways. Like at least 50 ft. While the drive wheel is going 55(Speed stated) Slide you bar preferable at least 10 long on the ground under the wheel about 1.5 ft. Hang on to the other end of it tight. Slowly pick up your end of the bar making contact to the wheel while spinning in drive(Going forward wheel movement) Careful now. If you apply to much friction. The wheel will yank the bar out of you hands and, shoot it out behind the car. Hitting anything in the way. As, you do this test. If the applied pressure makes the car/wheel start shaking. It's the drive shaft.
That test is a advanced check for a acceleration wobble test. Most bad drive shafts will wobble on semi hard acceleration.
You also need to check engine mts. Make sure the engine doesn't have a shake from missing, or bad cylinder or bad valve. You may have a engine misfire at 2500 rpm (estimated) or, at the speed you are experienceing it.
If, it shakes when you brake. It's rotors and, or, drum that aren't true. Except, bent rims and, seperated out of round tires can cause this.
So. It can be caused by alot of things. And, even a combination a several things.
Like, I wrote. A better description might help. Like in curves. Are the tires inflated properly? Are all the tire the same size and, brand??
God Bless,
Chris
