Hey gang.
On my 1967 Coronet. I am getting a drive line vibration at 2750 rpm at road speed between 63 and 65 mph.
I have the 2:94 gear fed by the 3 speed 727 automatic.
My profession is vibration analysis!
So tonight I'm going to wire up some sensors to measure vibration. Amplitude and frequency.
At 65 mph. There is that
....
......
drone vibration.
I suspect: 1x or 4x drive shaft. 1x or 3x pinion gear mesh. Or lastly any multiple of axle rpm.
Without data it's hard to pinpoint.
Has anyone gone thru this?
Thanks
Many times..
Most of the times a vibration that sounds like that is U-joint or driveshaft balance related. it could also be excessive play in the pinion bearing (or a loose pinion nut, had that happen once). Another cause can be the pinion angle is off (pointing skyward most likely).
I'd start with pulling the driveshaft and checking the U-joints. Check to see if the driveshaft has thrown any weights to throw it off balance
All of that stuff has been replaced.
This "Vibraton" has been present for some time. It has increased in amplitude after I tightened the loose spring u-bolts from the junk in the trunk post.
I will re check pinion angles first!
Face angles should be the same? With offset no more than 2 deg?
Your test sounds fun to me, keep us informed and pics would be cool.
Will do!
I will re check the obvious stuff.
Then I will throw on the vibration sensors.
I'm setting it up in my database so I can track and trend amplitude / frequency at given mph and engine rpm.
Going to use drive shaft rpm as my trigger via reflective tape and a photo cell tach.
I will also perform a cascade / waterfall plot.
A cascade takes and stacks fft spectra showing frequencies changing with speed.
One thing to check is your springs. Does the front segment have clamps on them? if they don't, that can cause the vibration you're feeling, especially after some hard acceleration..
(all this talk of frequencies, waterfall's, amplitude is giving this old sonar tech a stiffy)
Boing!!!...^....Boing!!!!...^...Boing!!!! she's heading straight for us Capm !!!
LOL, with the exception of the last two posts, this thread is very interesting. I'd love to see some pics of your testing equipment and what you do with it. TESTING, Mike, TESTING, note the word before equipment...
Rich just wants to make sure you don't have any more loose junk in the trunk..
While you are at it, why not do a bump test to find the natural frequency of the car? A good big dead blow hammer to the front bumper should do it!
I like your approach...... Nothing like having data to solve your problem. I'm guessing driveshaft or wheel/tire related.