By on September 26, 2012

Apologies for the delay in getting the next article to ‘press,’ a few matters including a misbehaving back were needing my attention! Too much sitting, not enough exercise!


Now that most of the national championship races are over, people are starting to bench race on what setup to get for next year, what’s ‘best’, etc. I was responding to one thread on Miata.net and felt a slightly modified version would be appropriate for TTAC. I’d like to hear from people who have tested/tried different racing setups and what it was like to get, install, test, adjust and fine-tune those setups for the maximum result. I’ll have another article soon where we get back to the high-speed jacking down and display accelerometer data to support evidence of that behavior.

Buying expensive shocks or a ‘big name’ doesn’t guarantee they’re really tuned right, that the adjusters give you maximum grip, or that you’ll be able to integrate them seamlessly into your suspension without lots of head-scratching or potentially frustrating revisions to fix what’s wrong with the shocks.

Most people want to fall in love with whatever they buy – “it’s the best!” It’s natural (and probably a good thing when it comes to relationships!). But neither money nor love buy championships; intelligent choices (or bad choices leading later to better ones), measurement, testing and making effective changes in response to measured results does. Consider it the same as a lab experiment; following the scientific method is the only way to get worthwhile results.

Any number of the vendors that are considered ‘top shelf’ could give someone faster times. But why? and is that setup really ‘the best’? How can you tell if a suspension is really dialed in for maximum performance? That’s nearly impossible to answer. However, data acquisition doesn’t lie, nor do lap times. Combine the two and you have a powerful approach. If you’re able to create a theoretical model of your setup that relates to real-world test results, now you’re really cooking!

Knowing what to measure and then change is where the art and science of suspension tuning merge. I’m definitely still learning, but I’ve been paying attention to shocks from Stock class to XPrepared, street, backroads and track as well. Lessons learned in some areas factor in to others. I took National-level racer Bill Schenker’s advice when I met him for the first time at the Atwater, CA SCCA Solo National Tour in 2007. He slaughtered the very competitive C Street Prepared field. Incredulous, I asked him what made him so fast – ‘suspension!’ So I listened! Studied, tested, built, revised, paid attention to what I saw over the years. Stayed open-minded.

Maximum grip is one vital factor in getting exceptional results. Another factor is the car’s ‘feel’, how it communicates available grip to the driver. Driver ability and preference are the magical third and fourth parameters. From my calculations, actual shock dyno testing, and real-world shock potentiometer/accelerometer/lap time DAQ, I’ve been continually refining my understanding of how these interact.

Some setups will deliver more grip than feel. Others are more about feel than ultimate grip. I can tell what’s being emphasized by looking at dynos and how a car behaves on course . Without interviewing a driver before building shocks, how will the shock builder KNOW what kind of driver they’re working with? Does that builder actually know what creates grip vs. simply gives feel? That’s a subtle but important difference.

I’ve found that a builder usually ASSUMES everyone will want what makes that builder fast, or whatever philosophy that company espouses, or worse, what makes someone ‘feel’ fast. Something stiff and sporty – yay!  But there are enough sophisticated options and top-level results showing that ‘feel’ itself isn’t enough.

Does each driver at Nationals (or any race event) have the best setup? Maybe, maybe not. It usually depends upon how long they’ve been improving it. Many racers will readily admit they’re not master suspension tuners. Some can do both, or work with people who can assist in development.

So what kind of tuning will REALLY make you fastest? It’s a very important and oft-overlooked question at least in the amateur racing world. You hear it all the time in the realm of F1 though with driver preference. It’s a fairly big assumption that the shock builder really knows where grip comes from (definitely not intuitive) and that any adjusters present are able to get the maximum effective range for different surfaces or driving preferences.

Some people are faster with very stiff/tight setups, others like smoother/flow-y suspensions. An excessive preference for too stiff will cripple the ultimate grip. You can drive at 100% but if the setup is delivering 95% grip you’ll lose to a 98% driver with a 98% setup.

Low, mid and high speed damping all matter for autocross. Lincoln, NE, new home of the SCCA Solo National Championships, has seams between concrete slabs that induce high shock velocities (easily well over 10 in/sec) especially when taken at 50+ mph. Driver inputs are in the low-speed region. I’ve taken data at Lincoln last year (2011) in George Hudetz’s STX Mazda RX-8. It was about 95% dialed IMO and we were both in trophy position not having done more than a few practice runs in Lincoln. The first day, in searing heat and 90% humidity, I was in 8th (IIRC) out of 43 drivers. It was so easy to trust the car (yes, the RX-8 is an amazing platform!). With a clean run that first day (3 cheap/dumb cones) I would have been in 4th, only 0.6 out of first! Day 2, I slipped two spots to 10th by driving conservatively. I still took home my first trophy at Solo Nats and his car felt like a championship-winning machine! George’s FCM-tuned Street Touring Xtreme responded well, had so much grip (1.3g+ in sweepers) and we both knew we could drive it harder. I was better in sweepers, George faster through slaloms. The data helped show how much potential the car really had and it would have been enough to win the class.

I was glad that the data I’d taken at Packwood and elsewhere helped illustrate the value of our approach, plus further improvements we could make. Even though the data was on an RX-8, it helped me understand tuning as applied to a FWD coupe, RWD sedan, etc. Interconnectedness is a beautiful thing!

To anyone that really want to get a ‘dialed-in’ setup, simply having an adjuster won’t ensure you hit the sweet spot at every shock velocity range. Also, having seen some Penskes delivered without bump stops to a local autocrosser who was also told ‘you don’t need them’ and having a shock subsequently break, I really had to scratch my head at that glaring oversight.

There ARE subtle areas like bump stop tuning that play into a car’s poise and ability to be consistently taken to the limit and beyond (‘there and back again’). (I know certain National champions are making use of these and not just in Stock classes!).

I’ve talked a lot of  people out of buying more expensive adjustable options from us when it was pretty clear a well-tuned non-adjustable would do, at least until they really knew what they wanted. Most were extremely competitive right out of the box. I’ve also seen people with single and doubles make good use of the adjusters we’ve designed. They have an extremely wide ranges of forces and are concentrated in the 0-3 in/sec range, just where you want it for driver inputs/feel). We’ve made numerous design iterations on these high-end adjustable options, again tied to user feedback and test results. Suspension is one key part, interacting with our customers and being available for fine-tuning is another.

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21 Comments on “Suspension Truth # 3.5: The Danger of Paying Top Dollar for Big Name Shocks...”


  • avatar
    Robert Gordon

    Fortunately my car doesn’t have shock absorbers!

    • 0 avatar
      rpn453

      My buddy had a Chevette like that in high school. Once you got it bouncing, it just kept on going. I wouldn’t say there was anything fortunate about that situation though!

  • avatar
    dude500

    These “truths” are very informative, thanks!

    Are there any suspension kits that are generally good out-of-the-box, without the jacking down behavior you have focused on? E.g. Bilstein HDs, Koni Yellows, etc.

    Or maybe I should be thinking that “touring” shocks, having less need to “feel sporty”, may actually be better for ultimate grip? E.g Bilstein Touring shocks.

    • 0 avatar

      Thank you as well. Koni Yellows seem to work best with stock or soft springs and on softer damping settings. From what I understand of their design intent, they are meant to be stock-replacement shocks. Turning up the (rebound) adjuster will indeed increase jacking down. For autocross, smooth track or backroads that added rebound can give you more precision and reduce lap times. I’ve used Konis extensively in the past and many people do very well on them for performance driving. A down side is they typically have less displaced volume than a monotube, develop less bump force, emphasize rebound and therefore get crashy over rough surfaces. In a rough road environment, the softest setting you can tolerate, the better.

      Bilsteins can be hit or miss, depends upon what part of the world did the valving, US or Germany. Some HDs or Sports* work quite well, others have really severe jacking down. The good news is you can get them retuned. The Touring class Bilsteins I haven’t worked with. I believe most are twin-tubes and are likely softer than the (usually) monotube HD/Sport. If you ask for specs from Bilstein on the damping forces for all three version available for your vehicle, you can see what you’d be getting.

      I tend to like KYB GR2 for stock replacements, they often have pretty balanced damping curves. The AGX is a little more problematic, usually biasing more toward rebound so it’s in the ‘sportier’ direction which could be good or bad. Tokico often both rides and handles well. The D-Specs are well-designed for many applications, like the RX-8 and Mustang.

      As a general rule, I am very leery of most lowering spring kits because often you end up lower than you really want and often the springs sag pretty quickly. Some companies like Audi/VW and BMW have different OE springs packages so there’s more freedom to mix and match. Few and far between are those who say they love their Z-brand lowering spring 4 years after install.

      Note: Sport vs HD is usually the same shock, except the Sport has 1″ less exposed shaft. This may not always be true so you can ask your Bilstein rep to be certain for your application.

  • avatar
    Redshift

    This continues to be an excellent series. Thanks for it, and keep it up. I’m learning a lot.

    So, I think I speak for everybody when I say, who’s on board for a TTAC Group Buy? The dampers on my RX8 are getting very tired.

  • avatar
    drewtam

    http://books.sae.org/book-r-146/

    I found this text to be useful for those serious about suspension tuning. Serious tuning takes math to understand the data that is acquired on the track. Don’t be afraid of the math: learn it, use it. Or get a good mechanical engineer to help tutor you.

    • 0 avatar
      Athos Nobile

      And with powerful software like Matlab or one of the simulators available from Lotus Engineering… why would be ANYONE scared?

    • 0 avatar

      Solid recommendation and part of my library. There’s more in RCVD than I’ll ever learn about suspensions. However, it doesn’t replace testing, data gathering and adjusting a model accordingly. I think the Millikens would agree with that.

      For instance, the impact of sway bars (‘sta-bars’) on ride and grip is usually glossed over in favor the benefits but those negatives can be very important.

  • avatar
    imag

    Major exception to the above: Rally racing. Good rally shocks are absolutely worth the cost on any vehicle with pretty much any driver.

    • 0 avatar
      fiasco

      GOOD shocks are advisable anywhere, in rally something BIG AND BEEFY that will take repeated high-speed rough abuse is what you need. Something that keeps the wheels grippy for OtterCross and road racing… but eleventy-billion way adjustables?

      For 98% of the people out there (myself included), you might tell the difference between full soft and and full hard (that’s a Baruthian slip) on a given shock, but the other eighteen clicks are meaningless unless you have MANY hours of seat time in testing. I still fail to understand why OtterCrossers think they need $8,000 remote reservoir Moton shocks for five minutes a day of seat time. How can the oil get cooked that much that fast to need the remote??

  • avatar

    #*&$%#^@!!!

    Robert F#&%ing Farago would launch you out of a circus cannon into an industrial bacon-fermenter full of naked, butterscotch-be-pudding’d, 500lb. clown-sploshers for this, were he still here.

    You Hint at things, nail-down No specifics, and pose questions you Never answer.

    .
    You might as well cook the Entire Article down to the following:

    “Q: ???

    A: Well; it depends.

    END.”

    .
    Until you figure out something ACTUALLY CONCRETE TO SAY,

    ex: a framework of explicit numerical principles people can apply to their own data,

    Just have Jack Baruth Interview You instead, and then let Him write the column.

    +++And I am normally Completely-In-Love with this series! -So it’s a triple-disappointment!

    .
    It’s entirely possible I’m misunderstanding,

    and this is some kind of “State your specs + issues, and I’ll email you back an exact solution”-series.

    In that case, my apologies.

    • 0 avatar
      Greg Locock

      Yup, reads more like a promo than a technical article. Incidentally, the continual emphasis on shocks rather than springs/sta bars/ JBs/RSs and so on is a bit weird, never mind that tires are 70% of the whole equation. Good tires and middling shocks will hammer great shocks and middling tires.

      • 0 avatar
        GiddyHitch

        x1000 to both of you. I had to skim it a second time just to make sure that it was completely devoid of details except numbers that exist within a vacuum, without context. Yup, just feel vs grip and then … (my stuff rocks, buy my stuff) nothing.

      • 0 avatar

        @Greg + @Giddy: Ok, Thanks for the conf.! Thought I was going solo off-road there for a sec.

        -Because I reread this thing like 4 times myself trying to find The Kernel; and failed.

        .
        +Started getting that, “If someone’s setting up concepts but is vague about the deliverables: They’re Selling Something”-feeling,

        but it felt like I was being too cynical.

        .
        @Greg: AHA! Thank You. I didn’t know that thing about [viz.] Tires.

        SEE @Editors?!?! Value-Conveyed! BING!

        How come TTAC can’t get @Greg to write some pieces instead?

  • avatar

    Whoah, back up pork chops! Without writing a 10 page essay I couldn’t both give an overview and specifics in one shot.

    This *was* a ‘left field’ post that occurred spur of the moment while I was preparing a more thorough article #4. Looks like discussing racing shock buying experiences isn’t appropriate to this audience. It’s something I deal with it all the time.

    My intent was to offer a broader perspective on why spending lots of money won’t necessarily guarantee results. This was a ‘framework’ article more than “Top 5 Questions to Ask SpeedShopX Before Ordering.” That’s a valid topic which I’ll address in the future.

    I had originally posted the bulk of today’s content elsewhere as a response to a forum thread. The specific topic was ‘what shock to buy for XYZ racing class.” That’s why I focused on shocks. ‘Best’ tires are currently the Hoosier A6 in this case. In most racing series I’m aware of (if not on a spec tire) there are at most 3 top-level tires but typically a couple that stand out, so that was irrelevant to the discussion.

    Yes, there’s hard science at work that can deliver definite answers/numbers to sink your left-brain into. But without assessing the fuzzy-science of personal style and integrating many other subtle details, the end product often under-serves the customer. But because a lot of money was spent, the customer often blames themself for not being smart enough to understand how to use it.

    When creating a solution, the answer to many questions is often ‘it depends; what do you want to do?’ In my experience, maximum results begin when you ask and get asked LOTS OF QUESTIONS rather than being given LOTS OF FACTS. Anyone remember ‘How to Lie With Statistics’?

    The next article will be 4.0, returning to lots of graphs, data and facts *plus* subjective driving experience – for much-needed balance.

  • avatar

    “Best” depends totally on your usage. For example, when I go to a Rally, most cars have huge shocks with outboard coolers. This makes sense for a car with 2 feet of suspension travel, full roll cage and five point harness, on dirt.

    In the street world, what you get are shocks to a price. The OE shock will be decent, get loose around 50k, and be mostly trash at 75k. This is great with planned obsolescence, so when you get the loaner for your car’s 60k service, the loaner “feels tight”. Hondas are notorious for this, but on the other hand, they, up until recently, spent the money on the rest of the suspension.

    We’ve seen that half of all cars get to the boneyard with the first set of shocks, so most folks don’t ever re-up the car correctly. If you have 70-100k on your car, replace the sway bar bushings and end links, and you’ll be amazed. Do the shocks and your car will drive “new”. Geeks know this, but most folks won’t do this work, and most mechanics won’t suggest it, even if they do the shocks. Of those who do, many go the hard bushing route, which has its own set of tradeoffs for a street driven car. I’d rather do bushings every 60k and stay with rubber.

    I have a set of Bilstein shocks in my car that are far better than the OE BMW shocks. They aren’t “stiffer”, as that would destroy the compliance of the ride. You want the wheel to follow road undulation, not try to hammer it into submission. Bouncing tires don’t grip.

    You want to buy better shocks, not harder ones. This is easy for most Euro brands and the more tuner oriented Asian. Tougher for mass market cars. I can’t find shocks for my 2008 MDX other than OE or cheap replacement…no Koni or Bilsteins. Darn. I thought because it was a Honda, I’d have choices….now, if I’d bought an X5 instead….

    • 0 avatar
      JuniperBug

      It had never occurred to me that some mainstream cars wouldn’t have multiple shock options, but I imagine that could be true, and inconvenient.

      Both of my cars – a Miata and an old Jetta – have had a wide range of aftermarket shocks available. The Miata in particular has options ranging from $300 to $2,000. In general, all but the cheapest shocks seem to be of higher quality than what the OEM provides, and usually at a considerably lower price. I don’t know if that’s also the case on higher end cars, but it seems like an odd place for car manufacturers to skimp, given how much of a ride and handling improvement that better shocks provide.

    • 0 avatar
      joeveto3

      Shaikh, this is a great series. Thanks.

      And @Speedlaw — Thanks for your post. You really put into perspective, and answer a question I have regarding, mileage wear on shocks. Your point regarding rubber bushings vs poly and just replacing more often…I believe is spot on. It’s something I’ve suspected, but appreciate having someone else confirm it for a fellow geek.

      Good stuff!

  • avatar
    suspekt

    As punushment to TTAC, I shall withdraw my site attendance for 7 days. To all that disagree with this ban, do the same.

    TTAC benefits from the real passionate gear heads that visit this site and populate it daily with traffic and authentic commentary.

    Maybe my absence will do nothing. Not a thing. But I know that each of my visits is worth a few pennies and I have the power to withhold those pennies.

    Its too bad. Maybe this raises a larger issue… Is TTAC becoming too full of itself?


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