What is this "Cowl Shake" thingey?

[cdornier]

I have encountered the term "cowl shake" many times while researching Spiders. Apparently it has to do with the stiffness, or lack thereof, of the car's unibody?? What are the identifying characteristics of this phenomenon? As a casual driver, and not a hot-footer (well OK, occasionally, maybe!) I am probably not likely to encounter it, but hey, I wanna know. I see a hood, I see fenders, but I do not see a "cowl" anywhere on the vehicle, let alone a shaking onel!!

[alfa63]

Largely because a Spider does not have a roof, the body around the mid-section tends to "shake" going over uneven pavement. Drive into your driveway at an angle and you'll experience this or even railroad tracks.

I believe the chassis stiffeners available help cure this problem. When I time-trialed the roll bar did a lot to stiffen my Spider.

Here's some "cowl" definitions:
A part of the vehicle's body, located between the engine compartment and the dash panel. Often the windshield wipers are attached here.

A removable metal scoop at the base of the windshield and rear of the hood that directs air into the air box.

Because spiders have no metal roof to add structual support, they tend to be flexible, there is a Frame Stiffener which may or may not solve this problem. I belive strongly that it does, but some disagree, I noticed that you joined the bb last month, so you missed the rather lenghty debate, hopefully other respondents will also note the join date before responding to a "redundant" question, but sometimes they don't, nothing personal, well at least not directed at you. If you can, hook up with a spider owner that has a stiffener installed and do a side by side comparision. even at legal speeds I think you be impressed.

[BKCowGod]

Basically, cowl shake is when your windshield is going one way, your dashboard is going another way, and your teeth are going every way.

In other words, it's a lack of structural rigidity that manifests itself as the entire car shaking every which way over railroad tracks and potholes, etc.