Home / Experts/Tech / I Led The Design Of The Tesla Model S’s And Ford GT’s Suspension. Now I’m Answering Engineering Questions For The Autopian. Where Did I Go Wrong?

I Led The Design Of The Tesla Model S’s And Ford GT’s Suspension. Now I’m Answering Engineering Questions For The Autopian. Where Did I Go Wrong?

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When I saw the Ford GT show car at the 2002 Detroit Auto Show, I knew right then and there I wanted to be part of its development. I, a Ford engineer with more than a decade of experience at the time, contacted the manager creating the team, and got the job leading chassis design. Wow! Talk about butterflies in my stomach! Here was the highest profile car the company had done in decades, and I was going to be in charge of the parts that make the ride, handling, and vehicle dynamics compete with the best the world has to offer. Over the next two years I lived and breathed Ford GT, ultimately helping create a car that was everything my team hoped it would be; it became an instant hit. If my career had ended there it would have been a dream for any automotive engineer, but fate wasn’t done with me yet. In 2009 — near the beginning of Model S development — Tesla called.

Hello Autopians! It feels great to be here with you all in this new venture David and Jason started. I’ve been a longtime reader of both, so when they called to tell me about the new website and ask if I wanted to be part of it I immediately said “No, who do you think I am anyway?” But then they told me about how they were building a place where car nuts would want to hang out, and that they’d let me get as nerdy as I wanted in a weekly blog called “Ask An Engineer.” What kind of engineer turns down a chance to get nerdy in public? So I gave in. 

So this is the plan: You folks ask questions, and I do my best to answer them. Every week I’ll choose a few questions and give the answers in the blog. I promise that the questions I choose will have nothing whatsoever to do with how easy they are for me to answer. No sir, nope, absolutely not — cross my heart, hope to die. Anyway, if I don’t know the answer then I’ll do some research to find it. It can be about anything, but since this is a car site, let’s keep it car-related. If you ask me what to get your significant other for Valentine’s Day then I can assure you they won’t be your significant other on Feb 15. You can even ask me about weird taillights, but I might let Jason take those. Actually, I don’t have a choice [points to taillight clause in contract]. 

So, who am I and why should you care about my answers to questions about cars and car-related topics? Well, I have been an automotive engineer for all 31 years of my career. Yes, I’m an old fart, but I’ve been a car nut from the moment I came onto this earth. As a little kid, all I wanted was a new toy car, and anything mechanical was fascinating to me. My favorite toys were Lego and Meccano, and I spent hours building contraptions and anything my mind could imagine. Did you know that you can build a gun with Lego train tracks and a rubber band? For a 13 year old, that’s way cool!

As I got older I got into engines, and of course the most accessible engine for a teen kid is a lawn mower. I had several over the years, and I remember one day I decided to take one apart as far as it would go. I wanted to know what made it tick, so I took everything apart  — the crank case, the piston from the connecting rod, the valves. I even stripped the carburetor down completely. My mother was convinced it would all end up in the garbage, but then I put it all back together. She never forgot the look on my 14 year-old face as I stood next to the fully assembled and running lawnmower an hour later.

A few years later I went off to college where I got my Bachelor’s Degree in Mechanical Engineering from Duke University. A few years after that I went back to school and got my Master’s in Mechanical Engineering from Georgia Institute of Technology. That got me my first job in the auto industry at Ford Motor Co. I spent 19 years there, with the majority of that time in the Chassis design and engineering departments. I learned all about suspension systems, steering systems, and brakes. My mentor, Manfred Rumpel, who had worked at Porsche as a young engineer, taught me well and instilled a passion for design excellence.

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Jaguar

As is normal in a company like Ford, I worked on many new designs that never got past the prototype stage, but then I became part of the D/EW98 platform, which became the 1999 Lincoln LS and Jaguar S-Type. As part of that project I spent two  years in England at Jaguar Cars doing the ride and handling development of the S-Type. I learned all about ride, handling, steering, vehicle dynamics, and about how to make a car comfortable but still fun to drive.

When I came back to Ford in Dearborn, I fell into the opportunity of a lifetime for any engineer — developing the Ford GT’s suspension. Seeing a GT still brings a tear to my eye. 

My team next to a 2012 Tesla Model S

As I mentioned in the first paragraph, in 2009 I got a call from a recruiter at Tesla Motors who wanted to know if I was interested in becoming their Director of Chassis Systems. I took the job, and at the end of that year packed up the family and moved out to California. This was right at the start of Model S development, and with a very small team of engineers we designed a completely new suspension, steering, and brake system from the ground up. 

Working for a silicon valley company might as well have been working on Mars as compared with a traditional company like Ford, and it took some getting used to (I may elaborate on this in a future blog). But it didn’t take long for my team and me to ditch all the old rules we had lived with for so long and design a world class chassis on a shoestring budget. What we did would have been impossible in Detroit, but we did it anyway. It’s amazing what you can do when your hands are freed from the shackles of too many rules and processes.

Lucid

I left Tesla in 2015 and went to work at Apple, where I stayed for 3 ½ years. After my time at Apple, I became the Director of Chassis Systems at Lucid Motors, where I worked with a stellar team that I still miss today. If anyone can design a Tesla killer, these guys can! For reasons related to family, I left Lucid and went to work for the Mahindra North American Technical Center in Detroit, but right as we were getting ready to move from California back to Michigan COVID hit and everything stopped. We unpacked our things and stayed in California with me working remotely from my home office like almost everyone else in the world. During those two years, changes at Mahindra and also family dynamics led me to decide I needed a change in direction. I decided to retire at the end of September 2021.

I loved my 31 years in the auto industry, and there is a lot I look back on with pride. There are many people who taught me so much, and to whom I am eternally grateful. I wouldn’t be here without them.

Well, now that I have all this time on my hands, it’s time to bring the things I learned to a wider audience. So fire away! Ask your questions, and I will do my best to answer them. Anything car-related is fair game, so send your queries to askanengineer@autopian.com. Let’s do this!

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54 Responses

  1. Topic suggestion for you, Huibert:

    Does the placement (leading edge or trailing edge) of the brake caliper affect the direction of torque from braking to the chassis?

    I’m no engineer and lack the proper vocabulary, but will attempt to explain my question. IF fore or aft placement DOES affect the torque vector, then it seems to me that placing the front calipers toward the rear, and the rear calipers toward the front ( as Porsche seems to do ) would lift the front of the car and squat the rear while braking which would help mitigate nose-dive and rear-lift due to weight-transfer.

    Of course, from weight-placement perspective, putting the heavy calipers as close to the center of mass as possible makes sense, but I’ve wondered about the torque vector for a decade or more after seeing a tire ( car on jackstands ) visibly move when brakes were applied while it was spinning.* Given that you noted learning about braking systems while at Ford-and especially that you worked on the GT, I’m betting that you know whether my theory applies even if the force is so negligible that it’s not part of design considerations.

    I’ve enjoyed your writing here so far, and will be looking for your byline every time I drop in: articles like the GT one feed my inner nerd and sooth my reading compulsion, so I’m very glad you’re here!

    *iirc, it was an early 90s Camry, and one major issue was the A-arm bushings were about non-existent; it would pull to one side when you braked hard. So scary I loaned her the money for the bushings & installed them for free. She carted 2 young kids around in that heap, and I was willing to do the work for free so they all didn’t die. Part of why I no longer do side-work…

  2. Welcome Heibert (I say as a fellow engineering minded auto / mechanical enthusiast on opening day of a brand new blog 🙂 )!

    I’d be interested in your thoughts on the advantages and disadvantages of common different suspension systems (torsion spring vs. mcpherson vs. leaf spring & live axles vs. inboard (think formula cars) vs. ID multi-link vs. Rear live axel & IFS. In fact I expect there would be more than enough material here for a multi-edition blog series!

    Other unique suspension ideas tried (prototyped (alpha, beta, pre-production)) though never making it to production, like Bose’s active hydraulic/mechanical/electronic (was in development for something like 20-30 years b/c Mr. Bose had a passion for racing) would be interesting to read about too.

  3. Consider an article on spring preload and how it effects ride height and geometry. And how it does not effect the stiffness of the suspension directly. I regularly find this is misunderstood! Everyone seems to think adding preload makes their springs stiffer.

  4. I’ve always been curious to pick a chassis designer’s brain on the topic of independent suspension in modern performance cars; my understanding of how independent suspension improves cornering grip is that you can build in a camber curve that tilts the top of the wheel inboard as the body rolls, and in so doing counter the tendency of the tire sidewalls to ‘fold under’, keeping the tire contact patch in its best shape for grip. Obviously impossible with a stick axle. But modern performance cars tend to be both extremely stiff in roll, and equipped with wide, very low profile tires which would be less prone to the fold under behavior. So the cars simply can’t roll very much, and the tires don’t need as much extra camber – is the tradeoff really worth it anymore?
    As someone who ‘gets every penny’ out of the cars I buy, I’d be more concerned about the compliance and degradation of all the extra suspension bushings that independent suspensions carry over the lifetime of the car, rather than a slight increase in ultimate cornering grip.
    Back in 2014 my daily driver was a 2005 Dodge Magnum, which has 4 wheel independent suspension. I love that car, but one thing that always bothered me about it was the fore and aft compliance in the suspension bushings – when you come to a stop that car ‘bobs’ back and forth once on the bushings, just a little bit, but it always nagged at me. That year I bought my current DD, which is a Mustang performance pack, and one of the reasons why I chose it was that was the last year the Mustang was going to be sold with a solid rear axle, the next platform was 4 wheel independent suspension. In the ponycar market it was the last holdout – the Camaro had been IRS since its rebirth in 2010-ish and the Challenger rode on the same suspension as the bouncy old Magnum.
    The Mustang handles great, though it rides stiff as a board (but that was expected). The 3 link rear suspension really works well, and doesn’t get upset over washboards like older solid axle cars I’ve driven (A 94 Z28 being a notable example).
    Perhaps because I like a challenge, or maybe just to be contrarian, I’ve always wanted to try and build a hot rod with solid front and rear axles to run autocross, and see if I couldn’t make the drivers of some modern cars cuss in their helmet… XD

    1. Save yourself some aggravation and research autocross S-10’s. Lots of quick ones out there. Start with the ZQ8 suspension. Easily upgradable in every direction. Drove the wheels off one for years, loved that truck. Still consider resurrecting it with a 4.8 LS, if I could find the time. Good Luck in your quest!

    1. There are many reasons why something might not make it into production. Sometimes the cost ends up to prohibitive. Sometimes other priorities take precedent. Sometimes after everything else has been included and packaged, the new feature just doesn’t fit anymore. And sometimes a new feature might simply turn out not to work very well. Nice idea but doesn’t work. That happens a lot.

  5. Awesome! Here’s something I’ve wondered about: in your experience, how much of a priority is serviceability when designing a car? I imagine it varies a lot between manufacturers and even individual models, but is it on the list at all? I know a lot of professional engineers are also amateur mechanics, so it must be on your minds somewhere, right?

    1. Hey Halftrack_El_Camino. Thanks for your comment. Serviceability is absolutely a factor in suspension design as it is everywhere else in the car. We always design things to last a long time but things happen. People drive into curbs, accidents happen. If we don’t design for service then the cost of fixing cars at the dealers increases and that just eats into the company’s profits. especially during the warranty period and any recalls that may happen. We make sure there is access to all the bolts and that you don’t have to take half the car apart to change a steering rack, for instance.

      1. Thanks for that quick reply! It’s good to know that engineers are thinking about this stuff, and sort of comforting that companies understand that poor serviceability eats into their bottom line. I guess the fact that so much on cars remains a pain in the butt to get to just goes to show how very many competing factors are in play when designing something as complex as a modern automobile.

        1. Frodo, I can’t speak for every automotive OEM but where I come from that would be unacceptable. Everyone has different standards though. I remember owning a 1981 Mazda 323. To replace the front brake rotor you needed to remove the knuckle from the vehicle and press the hub out of the bearing. This of course destroyed the bearing so you had to replace the bearing every time you replaced a brake rotor. Bearings are supposed to last the life of the vehicle so this was a complete surprise to me. Very disappointing and unacceptable in my book.

        2. I’ve always wondered about this one two, I know it was a thing for a lot of VW vehicles. I also remember that Mercedes used to sell bulb kits for their cars, the reason (if I remember correctly) being that if your were stopped by the police in Germany with a bulb out, you had to replace it there and then, if it was possible to do so. I wonder if the arcane bulb replacement processes would mean that you could justifiably claim that you couldn’t replace the bulb at the roadside and would be allowed to go on your way. It’s a damn poor justification for something simple being made complex, but I’ve always wondered if there was something like that at play.

  6. That’s pretty awesome to have someone like you around! Say, what’s the design process for a full car suspension? Let’s say, hypothetically, that someone wants to make a home made Lotus Seven but he has a mechanical engineering degree and access to CAD software. How do you make a GOOD suspension? What kind of input data and optimization criteria do you use? Asking for a friend 😉

      1. Awesome! I’m looking forward to this! Everyone always focuses on horsepower but I’m a firm believer in having fun with weight transfer in every direction rather than only in a straight line. And I have found very little litterature about how suspension design is done. “Race car design” by Derek Seward gave a nice introduction but I’d like to know more.

      1. Hypothetically, though, if you were working on something for a company from 2015-2018 that still hasn’t seen the light of day, would it be wise to assume that such an idea may have been scrapped, or that it just hasn’t come to fruition yet? 😉

  7. “What we did would have been impossible in Detroit, but we did it anyway. It’s amazing what you can do when your hands are freed from the shackles of too many rules and processes.”

    Truth. I’m convinced that processes at any sufficiently large company are designed to prevent complete failure, not to foster creativity and new successes.

  8. I’m sure this is a basic question, but it’s suspension related. Why is it that every time I go to a dealer, or even some other service center, they tell me that my car needs alignment? Wrangler, CR-V, Discovery, wife’s Volvo–doesn’t matter. “Looks like you need alignment, sir.” Sure, I might travel some rough city roads, but I’m not rock crawling. Can’t you design a car that doesn’t need constant realignment?

    1. Did they use one of those quick check machines?
      It could be possible their machines are off calibration.

      I bought a new car and before I took delivery I told them the alignment was off based on how it drove. They did a “quick check” using the quick check machines and the machine said it was good.
      I demanded they put it on the rack and the toe was off. So that’s a possibility.

      Now you can also get an idea based on the tire wear.

      They could also just be (wrongly) doing it as a “standard”.

  9. Hi! I would love to hear your take on working for traditional vs SV startup auto manufacturers, do you feel one way is better than the other? Did Tesla’s quality failures (I remember articles about Model S ball joints falling apart and other such issues) stem from the downsides of this lean and quick approach, or the people in charge being too aggressive with targets? Do you feel that the traditional OEMs can reinvent themselves to be more like Tesla in this regard, or this is the type of thing too ingrained to ever change without an epic overhaul of the company? Thanks!

    1. I believe (disclaimer: WAY amateur wrench-wielder –NOT chassis engineer– here) the shocks were put fore-and-aft to help control axle-wrap under acceleration.

      How To Make Your Car Handle by Fred Puhn is a great free downloadable pdf which I have found to be easily understood, and, though decades old, the basic concepts like weight-transfer, roll-center, corner-weighting, etc. still apply. I think I got the above answer from there. I highly recommend it to any fellow nerd interested enough to be reading the comments in this corner of my new favorite website.

      Seriously, people; go get it. I bet you learn something!

  10. Great intro/article to start!

    I’ve always wondered how does longevity is designed into vehicles. I’d love to know how Toyota can design the Land Cruiser to go 250k… anywhoo I’m looking forward to more of your insight on the backend of car design.

  11. So, you’re looking for column ideas? Here’s a question that’s been bugging me for a long time. (Maybe it’s elementary, but I’ve never seen it addressed.)

    Crossovers are clearly designed to *look* rugged. But in reality, are they actually more rugged or durable than the regular cars they are based on? Is a CR-V tougher than a Civic, or a Highlander more robust than a Camry?

    What inspires this question: I live in an urban area where the roads are full of potholes and 100 years of patching instead of repaving. Every daily drive is an exercise in trying to avoid the biggest impacts and gritting my teeth when I can’t. In winter, I imagine all my brittle salt-eaten suspension parts being smashed to within an inch of breakage. In one vehicle (a 2008 Mazda5), I actually endured four such breakages (shocks, mounts, bushings) in 8 years of ownership, but that car may have been especially fragile. My other cars haven’t needed similar repairs.

    I’m perfectly happy never to own a crossover, but if there is some actual – rather than just perceived – increase in ruggedness, then I’d like to take this advantage into account for future vehicle purchases. If not, then I will continue to wince in my low-riding cars knowing that the “on stilts” version wouldn’t be any sturdier.

    So, suspension engineer: what say you?

    1. I’d be interested in this. For example, my wife’s car is a 2020 Subaru Onyx XT. It certainly rides differently than her previous car which was a 2011 Nissan Murano which has the same chassis as the Maxima. Is the Subie’s suspension really designed to be more rugged and how can I determine that (by knowing the design or subtle cues in the ride or something else).

  12. Long time mechanic here. Two questions-do you know of an explanation of the euro fascination/decision to use lug bolts instead of nuts and studs? Is it some TUV thing?

    And can you speak to the process that vehicle components designs go through to reduce cost and how it affects reliability? In my years servicing and repairing cars I’ve seen what looks to be good component/system designs that become unreliable seemingly due to cost cutting. I have a hard seeing the final execution of the design being what the engineers had in mind.

  13. Ooh! Ooh! I’d lurve to hear what you think of this suspension geometry! I hacked one to make it seemingly drive well (I’m a fkn know-nothing amateur). But this is stock in a car that a decent suspension is sn insane surprise.

    Is it tolerably ok looking, dynamically?

  14. I am very curious about the pros and cons of different types of IFS. Mostly having driven trucks with torsion bars, I’ve wondered if they were chosen because they’re tough, cheap, or just easy to package.

  15. I would love a deep dive but in laymen terms on the electronic controls on modern EVs. I’m taking about the stuff between the battery and the motor I have limited experience in vfd technology that I believe is used in some cases, but my experience is in more industrial applications, and I don’t believe vfd tech is used on all (or maybe most?) Ev applications.

    Basically how is the battery output controlled to produce a certain power/speed?

    This would be particularly useful for those looking at aftermarket ev conversions

  16. As a hotrodder/truck guy, I’d be interested in an article on the biggest “bang for your buck” suspension mods that could be done as a base/second level mod to a street car. Great to see a professional perspective!

  17. You made the right choice, and you chose the right people. “Tracy and Torchinsky” will be a Broadway musical someday, and you’ll be in line for royalties.

    I can’t think of a better way to spend your days than writing about cars. (And perhaps talking Tracy off the ledge from that rusted out Tatra 603, as a purely humanitarian gesture.)

  18. “ Working for a silicon valley company might as well have been working on Mars as compared with a traditional company like Ford, and it took some getting used to (I may elaborate on this in a future blog)”

    Looking forward to it!

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