Posted on 09/17/2017 11:07:40 AM PDT by Michael.SF.
Question for old car experts: Last year, on the passing of my father-in-law, my wife and I inherited his 1948 Packard. The car was in excellent shape but had not been driven for a fee years. We now have the car back in full working order and have noticed something very cool:
At about 60 MPH the car occasionally sets into a rolling motion (clockwise from wheel to wheel, front to rear). The motion is subtle, but very cool.
I asked the mechanic about it and his comment was: 'Congratulations, enjoy it!'
He did not elaborate.
Can any freepers shed some light on this?
Sounds like the beginnings of Death Wobble to me.
“Harmonics of a perfectly balanced machine. Like the hum in a Hotpoint washing machine in spin cycle. Hint, I was a builder and rebuilder of these machines. When they are right they have a song they sing. I think this is so with all mechanical things.”
I’m a mechanical engineer. These are known as mass-spring-damper systems. You can do some really elegant analysis of these systems with something called Laplace Transforms, shows all the sinusoidal movement. As long as you are in bounds, enjoy it. I have a 57 Bel Air I drive, I enjoy all the squeaks and bumps. Our cars will still be driving 100 years from now.
For starters get those front wheels spin balanced. See what that does for it.
My first thought as well.
If its initials were "H.D." this would be a KYAGB moment.
But with 4 wheels, it's probably just a fun diversion.
well, if you’re not rolling at 60mph, you have a flat tire
Bookmark
Hah...that’s funny. I just visited the Lemay Family Collection museum in Spanoway, WA yesterday. Saw more Packards than you could throw a stick at. GREAT place to visit BTW.
The car’s suspension system has many parts and many degrees of mechanical freedom; each has its own resonant frequency.
It sounds like you’ve found a vibrational mode that is similar to nutation in a rotating object; in nutation, one axis makes a circular motion around a center line.
I think that resonance of that sort could only occur if insufficient energy is being dissipated by the shock absorbers.
The rolling motion is most likely not by design, but as a common consequence of the spring rates and damper settings. I’d say that the mechanic was just confirming that the car was in good, roadworthy shape. If the suspension bushings and shocks were all new, the rolling motion would probably be less noticeable. Leaf and coil springs weaken a bit with age, too.
That’s not desirable, nor by design. Probably need to rebuild the shocks.
‘Congratulations, enjoy it!’
I have a 1960 willys wagon. I enjoy every rattle and gear whine.
As to the mechanic, yes, he is a bit of a codger. Does not say much, specializes in Packards and Studebakers and other vintage cars.
I agree, if it had been a concern, he would have said something.
Thank you. I travel to Seattle regularly on business. I will have to stop in on a future trip.
Ever hear that?
You mean steering left to right without your input? Tie rods.
A friend of mine’s car did that.
Just replace everything if you can. If you don’t, before long your wheels will be pointed in opposite directions.
I’d make a wild guess and say, his “enjoy it” referred to the car itself, and that the sensation you’re detecting is nothing serious.
My folks had a ‘48 or ‘49 Packard when we were stationed in Japan.
My mom took dad to the airport one morning in April and left the car parked in the street overnight.
The next day was May 1st. The local communist anti- Yankee demonstrators snake danced past our house in Yokohama and someone spotted the Packard.
A group of about 20 kids began rocking the car and flipped it over on its top and set it on fire. A final gesture was a hammer and sickle painted on our front door.
Dad got home three days later. He walked right past the big scorch mark on the pavement and his first words were,”what the hell happened to the Packard ?”
LOL!
Haha, not 30 minutes ago we were in hubby’s work truck and he said it was just like a washing machine in the spin cycle and out of balance.
I have an ash tray from Packard electric.
No clue about the car though.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.