Piston Slap: When to Step Away From the Drawing Board? REVISITED

Sajeev Mehta
by Sajeev Mehta
piston slap when to step away from the drawing board revisited

After our last installment, I feel nothing but regret for [s]misrepresenting[/s] butchering TTAC Commentator Arthur Dailey’s query. Because people do get in their car to warm it up before beginning the process of rooftop snow removal. And they’d prefer to remove roof snow, not snow that fell into power window switch pods.

So after multiple emails, a promise to try again. To which Mr. Dailey’s reply was:

“OK. But perhaps you could expand that to explain something related to car design? Which is why I sent the question to your attention.”

  1. Aerodynamics resulted in the sloped roofline: However my 1962 VW Beetle had a roof that was sloped more than most current vehicles. But the VW didn’t have this problem because it had a built in gutter.
  2. Styling results in the elimination of gutters: when did building autos without an integrated gutter become de rigueur? Who was the stylist/manufacturer that started this trend?
  3. Some research into whether their removal even improves aerodynamics or is it merely a design or a cost cutting feature too.
  4. We haven’t addressed the issue of what passengers are supposed to do. With gutters they could just enter the car. Now are they supposed to stand around in the cold and snow until you get the roof and side windows cleared?
  5. And maybe you can address the rain issue as well as snow?

Sajeev answers:

1. No argument here.

2. This was a slow moving trend from the 1970s-1980s: take the gutter integration from first-to-second generation Renault 5. The more I search Car Design Archive’s Facebook Page, the more I believe this timeline. The odds of one person/automaker being responsible is unlikely, everyone was thinking the same way: it’s only a matter of who had the nerve to put it into production first. On a global scale, which is impossible to Google for you.

Every North American Pistonhead knows the 1986 Taurus ushered an era of clean styling, complete with hidden gutters (behind wraparound door sills) and a covered gutter near the C-pillar (a la 1983 Thunderbird). The Audi 5000, designed in the early 80s (late 70s?) was a Taurus styling influence, yet became the precursor to modern vehicles: adding two integrated gutters stamped into the roof (probably). While finished better than your average modern sedan/CUV (i.e no plastic strip, hiding unfinished body seams?) the 5000’s success might have been everyone else’s excuse to ditch ugly exposed gutters or complicated-Taurus-hidden-gutters for what we see everywhere today.

Ironically, the other Taurus influence, TTAC’s Ford Sierra has slightly-wrapped door sills with an exposed gutter. Too bad roof rainwater enters the gutter, runs to the A-pillar and — thanks to tumblehome — pours straight into the floorboard. Snow might fare better, but exposed gutters are NOT a guaranteed design success.

3. Research, in order to be valid, needs a database far more accurate than Google. Which is impossible for mere enthusiasts to possess. All I can say is the theory: removing exposed gutters isn’t making a big impact on aero. But, considering modern air curtains, we need every fractional improvement working together in hopes of rounding up a positive EPA rating. And if eliminating an exposed gutter gets you that fraction of a percent to move the needle, why not?

You are on to something when it comes to cost-cutting, along with the obvious aesthetic improvement.

But I suspect A-pillar wind noise reduction is a very significant benefit.

4. Yup! Either they stand around, or they help you. What this implies is asymmetric design ensuring passenger-side occupants are happier during foul weather: that’s the stylistic equivalent of reverse Viagra.

5. Let’s think about the cars presented in above. While both exposed/hidden designs can fare well with rain, they both can be terrible! (cough, Ford Sierra) Houstonians should have no comment, instead letting the B&B give their opinions on snow.

[Image: Shutterstock/Paul Vasarhelyi]

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

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2 of 16 comments
  • ToolGuy VW (marque not group) and Tesla very nearly switched positions on a YTD basis.
  • RHD Inexpensive gasoline appears to be a thing of the past. ILO is correct - we have enough sunlight, wind and emerging ocean wave energy to power the entire country and then some. Clean air is nice, and being free of the whims of OPEC, geopolitics and hugely profitable oil companies will do all of us a world of good.
  • Raymond Segura Can you tell me where I can get the rear bumper for 69 impala?
  • Art Vandelay some of the crazy numbers I get. Percentages look bigger with any fluctuations with low volume makes and brands leaving the market will see massive month over month changes. But what’s with Buick? I still see the occasional ad on TV and yet the drop is disproportionate even compared to all the other GM brands.
  • Master Baiter "There is no mandate for consumers to buy EVs, not in any country or state. That’s made up."Right. And you are not mandated to purchase a toilet that only uses 1.6 gallons/flush. You could choose to not have a toilet--just go in the woods, like the bears do.