I have a '68 Camaro convertable that doesn't have cocktail shakers (body dampeners). From what I understand these distribute weight evenly compensating for a hard top. Is this correct? What would I expect if I added cocktail shakers? Do they give better handling or are they even necessary? Could the absense of these twist the frame? ashmeacn@hiscs.org

Hi there and Welcome,

The Cocktail shakers are there only absorb the vibration at higher speeds that the convertables generated. They had a cross brace for extra support. Many people removed these because of the extra weight they carries at all four corners.

Are they necessary...GM installed them because that was the only way they could stablize the car. After 30+ years, I can't imagine the car is stronger than when it was new ( unless you installed a roll cage ;) )

Again, welcome !

Timo

I always thought they put them on convertables to weight the ends on the car to help keep the car from pinching or closing up on the doors. Just my thoughts on it.
Roger

TGA,
I have been doing considerable research into these damn "cocktail shakers". (Many posts on the subject here.)I have a 68 convertible and after purchasing the car, discovered I have the rear but not the front ones...and here is what I've found out so far.
No one makes them. No reproductions. You have to find used ones and GOOD LUCK!!!! If you can find them, they are expensive! But here's the rub, they are model-year specific. Don't let anyone tell you that the 69's will bolt right in...they won't!
They are HEAVY...about 22 pounds each. They are basically a big can, filled with springs, weights and transmission fluid. They "sproing" when you tap them. They were originally called seismic dampeners. They have brackets welded to them and it appears you need to remove the headlight assembly and front grill to install them. (I'll let you know more after I install mine this weekend). They are supposed to quell front end vibration at all speeds, (especially going straight, hitting that small irregulatity in the road and feeling that little shimmy for a sec or two...you MUST know what I'm talking about, if you're driving your car without them).
When the top of a coupe is removed, you lose the structural integrity of the car, that why convertibles have specially reinforced rockers, X-bracing at the transmission tunnel, reinforced floorpans, door "wedgies" and the dreaded "cocktail shakers". The reinforcements add strength, and the shakers add weight to all four corners, and their 'guts" cancel out the vibrations inherent in the design. Chevy kept these for all 1st gen Camaros and Firebirds, as well as the Corvair convertibles. It seems that this unique piece of engineering was sort of an embarassment for Chevrolet, and not much is said about them. In the restoration books there is little mention, and no pictures of the fronts. Some pics of the rear ones, easy to see in the trunk. It seems that these things are neccessary, no one has come up with any kind of replacement brackets or bracing. Somes guys just yank 'em and try sub frame connectors (which I will be adding also)or just live with the little shimmy. Hopes this helps.

Actually - GM originally called them "Harmonic Dampers" and they are refered to as "Body Damper Assemblies" in the AIM (C4-1). They were shipped to NOR/LOS empty and filled with ATF at assembly.
They are there to dampen the 'Cowl Shake' that is inherent in Uni-body convertible design.
They were designed by Charlie Rubly of the Chassis Group and the idea came from the 58~59 Thunderbirds that used them for the same reason. Charlie's nickname for them was "Cocktail Shaker" which stuck and is what they are called today.
If you are missing them your car will have a 'Bent Wheel Rim" feel to it.
GM didn't like the fact they weighted so much but, the improvement in the ride of the car was so great they decided to use them anyway.

You can try Jim Dyer at Chevy Classics in Stockton, CA to see if he has any available right now ( www.jimdyerchevyclassics.com (http://www.jimdyerchevyclassics.com) / 209/941-2112 ) or see if D&R has them available ( http://www.drclassic.com/cgi-bin/database/database.cgi?action=show&c=Convertible&a=Z50036 ).
The 67~68 are interchangable but the 69 will not fit the earlier cars.

Hope this helps.

Vintage68,
You are the BOMB!!! :D

I've got a 68 convertible I'm ready to restore and I've only got 3 shakers. Does the battery take the place of the 4th one or do I need to venture on to e-bay for 1 more

You need all 4!!

Go to "Desperately Seeking Cocktail Shakers" in Camaro Tech 2003. All will be revealed! smile.gif

Thanks for all the replies. Your information was helpful. What if I welded sub-frame connectors and put a four point roll bar in? This should stiffen the frame but would I still get the shimmie without the cocktail shakers? TGA