Instability in Convertible

[Guest]

My reatta is a 1990 convertible with 69,000 miles. On rough roads the car is very unstable. I'm wondering if anyone has noticed this and is aware of any after-market fix. I believe the term for the problem is cowling-shake??<P>

[Guest]

Check out the post on this board from 5-29-00 called "front end shimmy". It appears to be a design problem with the convertible. Even with all parts of the front suspension in perfect tune, there will be some cowl shake, especially on rough roads or at a speed of about 50 mph on smooth roads. There is a Service Bulletin a dealer can obtain that calls for installing shims in the REAR springs to reduce, but not eliminate, the problem.<P>------------------<BR>1972 GS 455 4-speed <BR>1990 Reatta convertible<BR>1990 Regal GS

[Barney Eaton]

It has been said that ALL convertibles has some degree of "cowl shake". That alone will not make the car "unstable". <P>Depending on the mileage and maintanance, it could be tires, struts, alignment, etc. <BR>Do a little more investigation.<P>------------------<BR>Barney Eaton Reatta technical advisor for BCA and keeper of the Reatta database.

[Rick Villeza]

I learned the hardway.<P>Having grown used to the ride of my '89 coupe, I had the same reaction that you had when I bought my '90 convertible. After verifying the firmness of the steering linkage and checking the body shock mounts, I bought new Monroe Stabilizer Shocks (I saw the commercial) and aligned the car. No change. So I bought new tires and stood over the mechanic as he balanced them. No change.<P>The "body shake" you get when you drive across an uneven surface has to be expected on a car with large doors, side panels, and a windshield that is not supported across the top. <P>

[Guest]

<P> The cowl shake fix refered to also requires the addition of mass dampers as well as the spring shims. This is an extensive modification, and the parts may no longer be available.<P> Not widely available in 1990, 4 wheel "thrust angle alignment" should be performed on the vehicle after the obvious mechanical checks.<P> Bob Rich

[Barney Eaton]

Interesting side note to this problem. While talking with a former GM employee, he claims that they went to a wrecking yard and purchased "dampers" from a Corvair. It either did not work or wasn't worth the effort to release new parts for the Reatta convertible. <P>In '65-'69 (late Corvair design)cylinderical dampers were put in each corner of the Corvair convertible. Each damper weighed about 50 lbs (looked like a sealed refrigerator compressor) May Corvair owners removed them because they could reduce the weight by 200 lbs.<P>------------------<BR>Barney Eaton Reatta technical advisor for BCA and keeper of the Reatta database.

[Guest]

after hearing all of this about the convertibles' shaking and shimmying, maybe i don't want one after all...<BR>could this be why GM/Buick "donated" so many '91 convertibles to training shcools. hmmm...<BR>doug wolfe<BR>breatta@webtv.net

[Hank]

those dampers also appeared on camero convertibles , only familiar with 1968 model, but Barny's description is the same as I found on a restoration project for a Son a few years back.

[Guest dperras]

A friend of mine just bought a brand new BMW 3-series convertible (3 weeks old), which he let me drive. Guess what..same "cowl shake"...going over bumps and get the disconcerting sensation that the body of the car is flexing apart. Maybe this is just the nature of convertibles...period. The only bona fide convertible I can say I've driven that had no such sensation is the MB 500SL. Too bad it'll be a while before I have the $100K to buy one.

[Guest]

I've owned 3 GM covertibles - Sunbird, Cutlass Supreme & now a reatta convertible. The all have "shaked, rattled and rolled." The Supreme had the stabilizer bar (like a roll-bar) which helped but it still would shimmy on uneven roads. I think as convertible owners you just have to accept it. My reatta is still an awesome ride.