1970 Monte Carlo assembly line photos

[Keith Seymore]

Originally Posted by Nasblu

Also notice in the body drop picture of the blue Monte Carlo the driveshaft dampner attached to front yolk looks like a harmonic balancer only smaller. Also on the Cranberry Red body drop picture looks like the car has redline tires which I have never seen before on any of the 1970 Monte Carlo built sheet I have ever seen.

Good eye.

You may already know but that is to control rear axle whine (as a result of "non conjugal meshing action" of the ring an pinion). The resulting disturbance is transmitted up the driveshaft, causing it to wind up and relax like a rubber band, the order of the disturbance being commensurate with the number of teeth on the pinion gear. The damper is tuned to attack the resonant frequency of the shaft. You can put them on the rear axle companion flange as well, but they are not as effective because the amplitude of the disturbance is bigger the farther forward you go.

We used a lot of those on the old Astro/Safari vans, and on GMT400 pickups with the aluminum one piece shafts.

K

[Nasblu]

Originally Posted by Keith Seymore

Good eye.

You may already know but that is to control rear axle whine (as a result of "non conjugal meshing action" of the ring an pinion). The resulting disturbance is transmitted up the driveshaft, causing it to wind up and relax like a rubber band, the order of the disturbance being commensurate with the number of teeth on the pinion gear. The damper is tuned to attack the resonant frequency of the shaft. You can put them on the rear axle companion flange as well, but they are not as effective because the amplitude of the disturbance is bigger the farther forward you go.

We used a lot of those on the old Astro/Safari vans, and on GMT400 pickups with the aluminum one piece shafts.

K

I had a feeling that was its intended purpose but was never 100%. Thanks for for the explanation.

[Nasblu]

More Flint Production.

[Kurt S]

Originally Posted by Keith Seymore

You may already know but that is to control rear axle whine (as a result of "non conjugal meshing action" of the ring an pinion).

We used a lot of those on the old Astro/Safari vans, and on GMT400 pickups with the aluminum one piece shafts.

Why is it only a problem on some carlines? Is it an axle design issue or something else?

[Keith Seymore]

Originally Posted by Kurt S

Why is it only a problem on some carlines? Is it an axle design issue or something else?

Usually it has to do with the interior volume. Vehicles like vans or Suburbans are particularly sensitive to all kinds of disturbances, since the body cavity can respond like a drum. An axle that would be ok in one vehicle would be "bad" in one of those.

The other consideration is if the "noise transmission path" is through the structure or is airborne in nature. Normally it finds its way into the vehicle through the rear suspension (you can actually detach the rear suspension and run the vehicle on a chassis roll dynamometer to verify the noise goes away). That is what was unique about the GMT400 project is that the noise would radiate off the drive shaft and was airborne - if you were standing outside the vehicle you could hear the axle whine as the truck drove by...

K