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Hagerty
Hagerty Employee

Car Design Fundamentals: The A-pillar

Now that we've covered how cars are designed, it's time to review some of the terms designers use when talking about car design. Some of these words and phrases are referenced on a regular basis, even if they seem rather obscure. With that in mind, consider this your go-to reference series for car design lingo.
https://www.hagerty.com/media/car-design/car-design-fundamentals-the-a-pillar/
18 REPLIES 18
CitationMan
Gearhead

Thank you for the fascinating detail. We design challenged folks like or dislike certain car designs but we usually don’t know exactly why. We tend to focus on the car in its entirety, not on a specific detail like an A-pillar. When I used to go to auto shows, I would always look at the base of the A-pillar to see how the designer integrated the hood, front fender, door, and A-pillar. This must be a really difficult area to design cleanly, as there seem to be many awkward compromises made there. But unlike a C-pillar, the view of the A-pillar as one is standing over it can be very different than the side view from 10 feet or so. The side view can really hide a compromised A-pillar base.
AdrianClarke
Instructor

Thanks for your kind words.
A well designed car looks 'right' because it's proportions, stance, surfacing, overhangs and details are considered as a whole, appropriate to the type of car it is. Keen visual sensibility is needed to finesse these things and a designer should be able to say why a car looks right or wrong. But as you say, that's not the whole story. Once the overall form is frozen it's important to take that same care and aesthetic sensibility into the shut line management, the finish of parts and how it all fits together. You're right in that the base of the A pillar is a tricky one. You've got the fender, hood, door and A pillar all coming together in one place, they all have different tolerances and may be made from different materials (for instance the doors on my car are aluminum).
Our competitor evaluation department had an Aston Martin Vantage in (man what a chore that job must be!) and we had a good look over it. The way the side vents lined up and the fit of the hood was appalling. The catfish grille at the front (before they facelifted it) was literally a piece of chicken wire mesh.
You get seduced by the outward appearance, but how well the details are resolved is just as important.
hyperv6
Racer

Some real factors today also include what materials are being use to construct the roof. Some companies will incorporate more expensive materials like Boron steel that it tougher and can help reduce the size of the pillar.

As for Windshield to front axle that over history has varied. The Grand Prix in 69 the Lincoln Marks grew longer front ends. They rode better and still drove fine you just needed to adapt to having more out there. Even some sports cars today have had to have longer noses for the larger engines. Mercedes did this on some AMG cars. It also made the engine more mid sitting back farther,

I feel at times while it has made life easier we lost some of the varied styling that made many cars more interesting.
AdrianClarke
Instructor

Yes cars with longer wheelbases ride better. In older body on frame cars it was relatively easy to alter the wheelbase (for ride quality and perceived prestige).
I would agree we have lost a lot of aesthetic variety, certainly in mass market cars. There’s so much more competition now and the margins are much tighter, so mainstream manufacturers tend to follow each other.
Scramboleer
Intermediate Driver

I would pay extra for thinner pillars. Bring on the Boron steel!
hyperv6
Racer

Unfortunately that is the Boron Steel.

Flashman
Technician

Reading your articles is like getting a free introductory course in auto design. Keep 'em coming.
AdrianClarke
Instructor

Thank you for your kind words. I’ll get everyone sketching yet. More articles coming!
relton
Advanced Driver

The A pillar is an important design element. A pillars that extend ahead of the front wheel centerline have never looked good to me. A pillars that extend behind teh front wheel centerline seem, to me , to add a bit of dignity and elegance, and perhaps a bit of display of luxury. Mercedes S-classes of recent years are an example. The newest Bentley Continentals have moved the front wheels forward and now have A pillars that extend rearward of the front wheel centerline. I think they look better for it.

Lots of people argue that roff crush standards drove larger A pillars, but I think the desire for mor torsional stiffnes is the real driver. Regulations get a bum rap for a lot of things. Plus, there is absolutely no excuse for thick A pillars on a convertible, since convertibles are completely exempt from roof crush standards, and the A pillars contribute nothing to the torsional stiffness o an open car. Large A pillars in open cars seem to be driven by cost cutting, to use parts from a closed cr version. The current Mustang is an example of that.

You can also make a good argument that the roof standards add cost and weight, while having no effect on safety. There are multiple studies, some even done by NHTSA, comparing teh open and closed versions of the same car. This started with the 1982 Chrysler convertibles, and has continued since. But no regulator or politician is ever going to relax standards, at the risk of being crucified.

Back inthe late 70s, when it looked like the roof standards might outlaw convertibles, the issue finally got to teh Supreme Court. The court ruled, essentially, that anyone sentient enough to sign the papers for a new convertible most certainly realized that the car had no roof. That's why convetibles are exempt from the roof standards.
AdrianClarke
Instructor

It would be uneconomical to design different A pillars for a convertible version of a car, even though as you say they are exempt from roof crush standards. You’re adding tooling costs and production complexity (which also costs money). And the gains would be minimal, you still have to package wiring, airbags and trim.
What manufacturers do is something called design protection; they will build the capacity for different versions into one body-in-white. if I remember correctly, the last gen GT86 had the capacity to have a convertible version but Toyota never built it.
Scramboleer
Intermediate Driver

I would love to learn more about the race for improved torsional stiffness and ever-thickening A pillars. The rollover standards are oft-cited, but is that really the primary reason?
gpsuya
Advanced Driver

These big fat A-pillars create massive blind spots. It may be safer for the car occupants in a crash, but as a Motorcyclist that gets hit, the standard phrase 'I didn't see him" more often than not is true.
AdrianClarke
Instructor

I’m a motorcyclist as well, and commuted in London on a bike for a number of years. I always say to people thinking about learning to ride that it’s when, not if, you come off (I’ve come off plenty of times, luckily in an urban environment it tends to be lower speeds - my most serious injury was a fractured forearm when someone U turned in front of me).
Here in the UK motorcycle training is exceptional as the test (it’s a separate from the car test) is pretty intensive. You get taught to look over your shoulder before doing any manoeuvre apart from braking and to look at cars front wheels to see if they intend to turn.
I’ve often thought  car drivers could benefit from some time on a bike, just to learn the observation skills and where a bike might be on the road relative to a car.

Scramboleer
Intermediate Driver

It's strange to me that the safety regs don't include some kind of blind spot spec.
ctaarman
Detailer

Unquestionably thick A pillars are responsible for many collisions and injuries, however their numbers are not measureable. When I purchased a modern SUV, I nearly hit a pedestrian on one occassion and another time didn't see a car coming in a traffic circle and jusy barely avoided a collision, both incidents my fault. I had to develop a sideways head bob to check from both sides of the A pillar, which I still do today. I hate the lack of visibility.
Scramboleer
Intermediate Driver

Right there with you. Seems like a gap on the system that blind spots seem don't matter.
DaveA
Instructor

Interesting article. I was recently reading a book about Lotus and how the original Esprit was designed. Apparently the designers struggled with the A pillar and how it integrated with the curved windshield. Several people, including the famous Italian designer Giorgetto Giugiaro and Lotus founder Colin Chapman worked the problem late into the night, drawing sketches and making plaster A pillar mock-ups until Chapman came up with the solution: leave the A pillar as is, change the windshield. And thus, the Esprit’s flat windshield was born.
Scramboleer
Intermediate Driver

"...long A-pillar heading toward the front of the car can cause blind spots—not exactly what you want in a commuter vehicle..."

One might argue that blind spots aren't wanted on ANY vehicle. As DLO shrinks, pillars thicken, etc., it would be great to see a car company design a car that actually had awesome outward visibility, yet still complied with the regulations.

By the way, why don't the regulations include blind spots?