Thread: Strange Vibrations

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We have 1400 miles on the 32 and just got back from the Goodguys meet in Bowling Green. Still trying to get some kinks out. I replaced a bent axle, worked on the I-Pod set up, and installed a SoCal steering stabalizer.

The car has a vibration that starts at about 50 mph and does not go away at incresed speed. The shifter, which is long, the emergency brake, and the floor all vibrate. I have noticed it does decrease or stop if I let off the throttle. Everything in the drive line is new or rebuilt.

Looking for some things to check???

U-joints out of phase, loose spline, pinion angle, or just crappy u-joints, all possible causes. Sprung driveshaft from improper u-joint installation is another one. Loose or improper preload on the pinion bearings can do it, too.

OK, just read your other thread. My money is on the pinion bearings causing both problems.

guilld; Was it doing this before you replaced the bent axle?

tire going?

Originally Posted by vara4

guilld; Was it doing this before you replaced the bent axle?

Yes it was

Originally Posted by jyardgirl

tire going?

Tires only have 1400 miles on them.

Starts vibrating at 50 mph. does Not go away as you go faster?
You did replace the bearing in that bad axle housing.
I'm gonna agree with R. Pope U-joints need replaced, if
nothing got messed up in rear from bent axle.
Kurt

Place jackstands under the differential. Remove wheels/tires. Run motor up to identify or eliminate wheels/tires as the culprit. Vibe gone, balance wheels/tires. Still there? Remove rear brake drums/rotors and go again. Vibe gone, balance rotors/drums. Still there? Remove axles and go again. Vibe gone, straighten or replace axle(s). Vibe still there, remove driveshaft, use plastic cup to contains trans fluid at the splines of the output shaft and go again. Vibe gone, problem in diff or driveshaft. Take driveshaft to good shaft builder and have it spun up. If shaft in balance, problem is in diff. If shaft out of balance, have balanced, re-install and go again. Still there, problem in trans/converter/flexplate/engine balance. Prop up rear of motor, remove trans/converter and go again. Vibe gone, transmission/converter problem. Vibe still there, engine balance/flexplate problem. Replace flexplate with known proper balance item for engine balance system used (internal/external) and go again. Vibe gone, flexplate balance problem. Vibe still there? Internal engine balance problem.

Now, I've written this sort of "tongue in cheek", but it does show a process I might use of going through things to find a vibration.

Check the tires for Out-of-Round.

Happens now and then.

Jack the car up, place an indicating device close to it, spin tire by hand keep an eye on run-out.

Indicating device can be as simple as a pencil lying on a coffee can and the point close to the tire....

This type of problem can drive you nuts trying to find. It can be as simple as an out of round tire or a bent wheel to a torque converter that is out of balance or off center to the crank centerline to an out of balance engine rotating assembly. Use Tech's troubleshooting sequence and advice given in previous posts and you will find the problem. The u-joint "out of phase" can easily be overlooked. Letting off the throttle can unload a lot of things from pinion and bearings, to u-joints, to unlocking the torque converter if u have this type converter. Keep us updated.

i had a problem like this an it was the drive shaft out of time by 4 degrees was just enough that it felt like all four tires were flat spotted. an it was done by a drive shft shop. made me not want to drive the car. jonathan