Frequently Asked Questions

Q. What are the canisters or dampeners in my convertible? Can I take these out and install something else? Also ... My convertible has a bad vibration while going down the road what could it be?

A. On the corners of convertibles there are what's called "cocktail shakers" or vibration dampeners which were originally installed on every first gen convertible Camaro to help prevent vibrations. They were installed due to a very flexible body in the convertible models because of the lack of the roof structure. Some reinforcement was added to the convertible rockers and floors but it wasn't enough to prevent all vibration problems. The cocktail shakers are large cans with a suspended mass on a spring in a viscous fluid that are mounted on the corners - 4 in all. They were tuned to a resonant frequency of the convertible that caused the vibration problems. When the body was subjected to loading that would otherwise tend to make it oscillate, much of the energy was instead absorbed by the motion of the masses in the cocktail shakers - which reduced the vibration in the convertible body. The cocktail shakers weight about 25 pounds each.

It certainly would be possible to add a large amount of structural stiffness (subframe connectors won't be anywhere near enough) to the mid-section of the body to reduce or eliminate the vibration to the point of being able to remove the cocktail shakers. However that possibility would be very remote without a complete understanding of the Camaros stress and flex points. Another option would be to design and build your own vibration dampener. That, however, would require knowledge of the structural frequencies of the Camaro convertible body not to mention knowledge of how to tune the damper you are creating. The cocktail shakers are filled with automatic transmission fluid or ATF. The fluid is not subjected to friction, high heat or contamination as is the case with other fluid applications in the vehicle so it should not "wear out". The springs would be the only thing that could change or break, that would keep them from working properly. We have never found a "bad" one, if it still has fluid in it, only cars missing them which have the common 'cowl shake' much worse than normal. If your convertible Camaro has all four cocktail shakers and you still have bad vibration problems be sure to check that your tires are balanced properly and also new OEM body bushings can help reduce some of the vibration transfer. Be sure to check your springs and shocks as well. You should also try adding subframe connectors to help with flex and vibrations

If your original cocktail shakers are missing you would be better off trying to find an original set to replace them.

Cocktail shaker Part Numbers:

Years Location Part Number
67-68 Front Left 3909919
67-68 Front Right 3909920
67-68 Rear Left 3909927
67-68 Rear Right 3909928
69 Front Left 3950101
69 Front Right 3950102
69 Rear Left 3950109
69 Rear Right 3950110

Interchange information Pontiac Firebird (NOT CONFIRMED):
67 Rear Right 3909928 Dampener and bracket interchange with '67/'68 (same part number)
67 Rear Left 3909927 Dampener and bracket interchange with '67/'68 (same part number)

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