# SuspensionTruth

SuspensionTruth

#400psi #FCMElite #HighPressureFail

A longer and more thorough video illustrating the response of a monotube Bilstein damper at a very high 400 psi fill pressure. The resistance to initial opening is about 96 lb! Then the cycle force is higher than the 200 psi case and the cycle frequency goes down. The higher the gas pressure inside the damper, the less the damper wants to be a damper and the more it approximates a SPRING! FAIL!

#TeamLowDamperPressure

#FCMElite #TeamLowPressure #RippleReducer #TeamNoJitter

The nitrogen gas pressure inside a standard monotube damper is necessary to keep the oil column supported so the shock piston can cycle through the oil and dissipate heat. However, too much nitrogen pressure creates excessive initial opening force - also knows as 'JERK' - which compromises the suspension's ability to track small surface changes as well as to keep the tires in contact with rough road surfaces. Jerk is a property that suspension engineers go to great lengths to eliminate or minimize to improve both ride quality and ultimate tire grip.

To understand these behaviors, it's important to realize introducing a gas charge at the bottom of the monotube damper creates some ... interesting results. In electrical circuit terms, you have added a capacitance in series with a resistance. This creates a delay in the system response while the capacitor charges. That's what my recollection of my circuit's analysis class and common sense tell me!

For the suspension analogy, this gas spring acts to block the smooth opening of the damper (while it also make it close or extend more easily). You can see this as I attempt to cycle the damper with 0 psi fill pressure, then 200 psi and finally 400 psi. The damper becomes harder and harder to open and also to cycle back and forth over very small movements. I do my best to demonstrate some of these behaviors in this and subsequent videos.

===

The gas spring creates an undesirable behavior within the damper - a frequency-dependent and amplitude-dependent spring. This is where the simple capacitor/resistor analogy becomes insufficient (any EE's please clarify my understanding if needed). The damper gas spring can increase in rate as the shock shaft goes farther into the damper. Also, if the nitrogen chamber is too small, the ramp in spring rate may be dramatic.

So, what may seem a simple 'preload' in a static situation ('you can treat it like spring preload') bec..

#SmoothIsFast

I love this slightly overhanging boulder problem; it has a good holds and reasonably spaced moves. While I do complete the problem, I've had friends and coaches encourage me to be more deliberate and smooth in my movements, which saves energy.

So I can climb the problem less dynamically and smoothly by keeping my feet on the holds and better-controlling my weight transfer. Many aspects of climbing apply to driving technique and suspension tuning!

#FCMElite #EliteConsult #RideHarmony #FlatRideMatters #Miata

Time is precious - yours and mine. Knowledge and experience are valuable to achieve a superlative result. This time, knowledge, and experience are worth paying for when they're proven to relieve confusion from information overload or from a buyer's inexperience. These are some reasons why I, Shaikh Jalal Ahmad, developed and employ a specific proprietary process I use when engaging with potential and existing customers to tailor the most optimized, harmonized, sublime ride for YOUR unique needs! I call this our 'FCM Elite Project consultation process.'

To better-illustrate how this process works, I wanted to record an actual Elite Project consult. Thankfully, I had an upcoming consult with Greg Wodark, who is a previous FCM Elite customer with his Audi S4 and now repeat customer with a Mazdaspeed Miata!

You can see and hear the detailed approach I take to listen and understand my customer's needs, engage in lively Q&A, and arrive at a specific suspension configuration to remove confusion and questions about 'what part(s) should I buy? how much do I need to spend to get the result I want?'

I've spent over 15 years developing and refining my understanding of suspension behaviors and suspension design to create a unique and valuable tool - the FCM Elite Project consultation process. With my experience building suspensions for over 1,000 unique customers and dozens of vehicle makes, models, and applications, I've developed my Elite calculation tools and step-by-step processes which take your questions, ideas, and desires and help me turn them into clear changes.

This Elite process, including the 'live' consultation, gives me an organized and accurate method to determine what suspension components should you change, buy, or modify to create 'Ride Harmony.' The sophistication, value, and uniqueness of this Elite process is why I charge customers for my time, so you get the best possible result while s..

I dropped more time on this last run though ended up in 2nd place about 0.4 behind Jack Chu's E46 M3. Next time!

Holy cow, the grip of the 285 BF Goodrich R1 S tires is amazing once you get some heat into them!

IMPORTANT NOTES: These prices are for our Elite labor and associated part upgrades. They DO NOT include the cost of the appropriate Bilstein monotube struts or shocks , which either you can provide to us or we can source for you at extra cost. Some older or damaged dampers may require additional parts to bring to working order, if repairable.

Expect to pay from \$450 up depending on the exact Bilsteins required for your application. In some cases, more extensive customization / modification of an aftermarket motorsports Bilstein may be required for your FCM Elite Project.

===

FCM Elite Stage 1 damper optimization of rebound/compression/gas pressure is \$325 per shock (or strut insert) and \$375 per strut. Cost for a front-strut and rear shock vehicle is \$1400 (BMW, Porsche, Mitsubishi, Subaru, Volkswagen) or \$1300 for a double-wishbone front/rear (Miata, S2000, Corvette, Lexus IS300, etc.).

Adding FCM Elite Stage 2 for our Ripple Reducer option is \$110 per corner, or \$440 for the entire vehicle. You need to add the Stage 2 price to the appropriate Stage 1 to find your total cost for Stage 1 plus Stage 2.

To create our top-end FCM Elite Stage 3 setup including our novel and proprietary Kerb Blow-Off valve (KBO) adds \$400 per corner or \$1600 additional for the entire vehicle.

Prices are cumulative, so for Stage 3, add Stage 1 plus Stage 2 plus Stage 3. Contact us for specifics on your vehicle as consultation fees vary based on the complexity of your Elite Project. Our standard consultation fee is \$125 for 30 min which we ask you submit along with your FCM Elite consultation form:

http://www.fatcatmotorsports.com/fcm_elite_consult_form.htm

For brief inquiries before you decide to Join the Elite, you can use our Elite Contact form:

http://www.fatcatmotorsports.com/contact_elite.htm

Thank you!
Shaikh Jalal Ahmad
Founder and Ride Harmonizer
www.fatcatmotorsports.com

DISCLAIMER: ALL OUR MODIFICATIONS ARE INTENDED FOR OFF-ROAD RACING USE AND CARRY NO WARRANTY O..

#LowDamperPressureFTW #RideHarmony #FCMElite

Greetings, class! This is Professor Shaikh with a demonstration video to illustrate how a spring and damper (also know as strut or shock absorber) are different. I made a video prior to this which was covering the 3 Crucial Elements of Sublime Suspension Design although I'm releasing this 'hands-on' video first. I trust you'll find it useful to help understand why the nitrogen gas pressure inside a damper is such a key factor in ride quality and ultimate grip, while also being easily overlooked.

#SuspensionTruthForum #STforum #AimSolo2DL #DecodingSuspensions

Please join us on our free FCM Suspension Truth forum to read and take part in discussions about suspension design and theory! Also, please share this invitation with anyone you know who is interested in how vehicle suspension work, who might have back pain or any special need that we can help address whether through education or an FCM Elite product!

http://www.fatcatmotorsports.com/forum/index.php

You can see work we've done and share your Elite project or goals to Harmonize your Ride. The more we can share, the more the community at large will benefit! More updates are on the way, expect lots of activity there especially as we integrate our new AiM Solo 2DL for data acquisition and analysis!

A big project I'm working on is a site where you can send anyone you know who wants to learn about suspensions and 'decode' how they're supposed to really work properly! The site's still in process but the URL is here:

http://www.decodingsuspensions.com

#NoKnobs #FCMElite #SCCA #FatCatMotorsports #YawMomentRacing

WOW, what a powerful win it is! Dave Ogburn III, of Yaw Moment Racing, was driving Deana Kelley's 2016 Mazda Miata, set up for C Street autocross at the National level.

http://www.fatcatmotorsports.com/img/portfolio/fullsize/SCCA_Pro_Solo_Nationals_2018_Dave_Ogburn_SuperChallenge_Win_Go_FCMElite.png

He's driven her car the past two years and has done exceptionally well, including multiple wins at Champ Tour events. This time, for the 2018 SCCA Pro Solo Finale, he took down multiple top-level and past National Champions to earn his win!

Dave has previously praised the smoothness and speed that our FCM Elite setup delivers. This includes our careful optimization of compression and rebound forces, nitrogen fill pressure for the damper, our Ripple Reducer enhancement, and Kerb Blow Off (KBO) technologies. A few videos from Dave and Deana are linked here:

https://www.youtube.com/watch?v=okwS5igbr2k

https://www.youtube.com/watch?v=aZn2xB3rr8g

https://www.youtube.com/watch?v=ysAIvA3w6Kk

https://www.youtube.com/watch?v=8G0M7KIji2o&index=48&list=PL9CC286CD2172A755

I'm very proud that Fat Cat Motorsports is an official sponsor for the Kelley / Ogburn Miata and we're able to bring home such a tremendous win!

Oh, and these National level WINNING dampers have NO KNOBS! They just don't need them, whether wet or dry.

Ready for your own FCM Elite solution? Contact us here:

http://www.fatcatmotorsports.com/contact_elite.htm

After warming up, I worked on a particularly challenging overhanging V4. Also worked with a fellow climber to improve our approach. I didn't send the route before they reset the wall, but it was fun to attempt (and tough on the fingers!).

#FCMElite #MinimizeJerk #QualityMeansCare #FluidityWithControl

"I'm remembering what it feels like to be driving Christina on Laguna Seca - how effortless the speed feels, how fluid the car is." - Shaikh, on the FCM BMW E46 330i at Laguna Seca Raceway

This is a video I made in 2016 and am finally releasing. I contrast what I see as a smoother, high-grip setup in our FCM Elite tuning to the jittery, constant sawing at the steering wheel due to lower Quality suspension tuning I observe in a less-well-optimized MCS setup:

My video through Laguna Seca Turn 6, dodging a squirrel:
https://www.youtube.com/watch?v=k-M_bZ_xKjo&t=3m10s

Chasing a '91 Acura NSXm driver runs 1:46s at Laguna Seca, from Turns 4 through Turn 6:
https://www.youtube.com/watch?v=62iT7ZjfUhs&t=7m28s

Andrie Hartanto @ Laguna Seca video (turn volume DOWN!).
https://www.youtube.com/watch?v=DNL9C8sUglc

In Andrie's video, skip to 3:00, 6:20, 9:40 for his approach to Turn 6. He's doing approx 75-78 mph peak speed mid-corner where I went a best of ~82 mph with less sawing at the wheel. He used Bridgestone RE-71R, I used BF Goodrich Rival S 1.5. These are comparable tires.

Read through ZMM pg 361-363

===
Analogy of a snow leopard chasing an ibex / etc. Fast and smooth and controlled!

The leading edge of experience. Nature knows no sharp edges. The damping curves of 'expensive' setups doesn't mean they're the highest Quality.

Jerkiness - Hard S video / prevents tires from following the ground / Brian S's Scion FR-S setup.

Dolphins in a pod, SURFING! Spy squid, spy tuna, spy baby (dolphin)

Setting up the car for using 285/30-18 BF Goodrich R1 S, WIDE and STICKY! Took Turn 5 at 82mph! Great feeling coming off the turn and tightening the line under throttle. Not herky-jerky...

Driving more calmly on the street .. I know she's more capable. Zen-like calm that's pervading, affecting my whole life. What a really connected suspension feels like it just informs everything..

Techne in Greek me..

Now you've got your motorsports-style Bilstein body, but it has a 1/2 inch ID spherical bearing - and your factory Miata lower shock bolt is 12mm! Can you use the bolt and not have issues?! I'd say NO, don't do that!

Why? The factory total clearance is about 0.40mm (0.015 inch) or 0.20 mm per side between 12mm ID shock bushing and 12mm OD shock bolt. You'd want to keep a similar tolerance when going UP in diameter to an effectively 12.7 mm ID bearing. In my estimation, you'll need to use a couple pieces of shim stock to cover the added distance between the 12mm OE bushing ID and the ~12.7mm motorsports bearing ID.

In this video, I demonstrate how I fit and position (2) 0.007" stainless shims I cut from shim stock to take up enough of the gap between 1/2 inch spherical bearing ID and 12mm bolt OD to provide a nice tight fit for the factory shock bolt.

I show the calculations and justifications for my shim stock choice, plus indicate this setup has a tighter bolt-to-bearing ID tolerance than the factory bolt to rubber bushing.

You can buy shim stock from McMaster-Carr:

https://www.mcmaster.com/#2317k56/=1eawu1i

So you're staring at a crimped rear Miata Bilstein that you want to get revalved - what do you do? While shortening the Bilstein HD is an option which I briefly outline in the first video, you may need to keep close-to-stock body length for various reasons.

In those cases, you could instead use a few of the motorsports style Bilsteins, such as the aluminum threaded body / Schrader-equipped AS2, the steel body / Schrader-equipped SN2, or the non-threaded / non-Schradered SZ series. Both the SN2 and SZ (digressive) shocks accept a sleve and spring perch for a 'coil-over' spring application such as the Miata has.

Very likely, for current and upcoming FCM Elite builds where we'd normally select the 90-97 Bilstein HD, we'll be switching to the S5Z-KIT and its related coilover hardware (threaded sleeve and spring perch).

To make the spherical-bearing supplied SZ damper work with a Miata shock mount, you'll need to machine the shock shaft to the NA Miata's profile. This modification to the shaft profile will reduce droop about 15-20 mm which is fine as long as the body length is comparable to the stock Bilstein. The S5Z body, from measurements in the Bilstein catalog, looks to be very similar to the standard Miata rear Bilstein HD.

https://cart.bilsteinus.com/Portals/0/BILSTEINMSCatalog-2018-WEB.pdf

qty 2 - S5Z-KIT (5" stroke 46mm steel body digressive piston), 16.25" extended, 11.25" collapsed (eyelet to eyelet), \$113 MSRP ea.

qty 2 - B4-BOA-0000117 46mm coil-over kit, 2.5 inch (for SZ steel bodies), \$62.75 ea.

Total \$351.50.

You'll also need to address the fit of the factory Mazda M12 x 1.5 lower shock bolt to the now-larger-ID 1/2-inch (~12.7 mm) spherical bearing vs. the ~12mm bushing. I suggest using some 0.007 inch stainless steel shim stock to do this. I give more info about the shim dimensions and clearances in the third video.

#StepIntoSmoothness #FCMElite #FatCatFootwork #MinimizeJerk #MaximizeGrip

'Too much oscillation - too much bouncing - causes a reduction of friction, a reduction of contact patch - both in terms of climbing up a wall as well as taking your car and going around turns,' - Shaikh

Segment of video from 'Neil Gresham Climbing Masterclass - Technique Introduction' used under Fair Use copyright doctrine:

"The doctrine that brief excerpts of copyright material may, under certain circumstances, be quoted verbatim for purposes such as criticism, news reporting, teaching, and research, without the need for permission from or payment to the copyright holder."

"If you want to fnd the secrets of the universe, think in terms of energy, frequency, and vibration." - Nikola Tesla

===

I've been thinking about how to draw more analogies between the various frequency and amplitude domains a suspension works within and how to relate it to real-world behaviors. While driving to get lunch (and thinking about climbing after work), I remembered a great training video I saw which described certain bad behaviors in climbing technique.

The video I've linked below and shown in my video helped me relate 'poor foot technique' when rock climbing (e.g. a bouncing foot when stepping onto a foothold) to 'poor suspension tuning' such as a having damper with too much gas pressure, or too much low-speed compression or rebound damping. In each case, there's BOUNCING present. You can also call it JERK! That JERKING or BOUNCING reduces the consistency of contact patch. BOUNCING reduces the friction you need to produce MAXIMUM grip! There's an inherent NERVOUSNESS which is unfortunately often expected with a 'sporty' or 'racy' suspension but it's demonstrably NOT the smoothest and fastest way!

Bouncing or jerking means less consistent friction and contact with the ground (or the wall!). Bouncing means less grip, less smoothness, MORE JERK. You don't ge..

“If you know the enemy and know yourself, you need not fear the result of a hundred battles. If you know yourself but not the enemy, for every victory gained you will also suffer a defeat. If you know neither the enemy nor yourself, you will succumb in every battle.” - Sun Tzu, 'The Art of War'

I got a call today from Aaron who is the new head of Motorsports Division in Bilstein East. He asked me about Spec Miata bump stop specs and behavior. I wanted to know what was going on. He said some people in the Spec Miata community have asked about shortening the Spec Miata shocks, apparently to get more suspension travel. I told him I feel that's unnecessary and potentially a bad idea, as there's a high likelihood of tire-to-fender contact up front. I also told him that the damping wasn't well optimized to which he agreed.

Later, after our conversation, I recalled the potential for metal-on-metal contact in the rear suspension, which is even MORE insidious and dangerous! This could happen between the upper-control-arm-to-frame if there was too much suspension travel in the rear. I noticed this years ago when using the Flyin Miata rear spherical shock mount setup. In this video, I point out that experience with the Flyin Miata rear shock mount that essentially shortened the shock body about 1 inch by moving the bump stop contact point upward.

Whenever you shorten a shock, it becomes even MORE important to manage the bump travel. That introduces more problems and places to mess something up on the Spec Miata. I'm all for improving the state of Spec Miata, but you need to understand the pros and cons of a change before diving in head first. Otherwise that change is taking you backwards instead of forward. Not every change is an improvement, folks!

It's important to understand what deficiencies may exist in any design before applying what amount to bandaids. The Spec Miata shock tuning is NOT ideal for race track use. By design the SM Bilstein shock tuning SEVERELY ..

Attention suspension nerds, this video is for you! I visualize (via shock dyno data) and quantify (via spreadsheet calculations for damping ratio, rebound to bump ratio, including influence of gas force) the differences between the Mitsubishi Evolution X GS-R (with KYB dampers) and MR version which has Bilstein dampers.

In summary, the Evo X GSR dampers provide a better-tuned setup, still with drawbacks but on an overall smooth surface will handle well and ride well. The Bilstein MR suspension is highly-biased toward rebound on the front strut and will aggressively pull you down into the front bump stops. Bilstein MR rebound to bump ratio (including gas) is about 3.2 : 1 on the front, compared to 1.9 : 1 for the front GSR KYBs.

o/~ Summertime and the valving's easy! o/~

Sharing some assembly and tuning notes for this B8 series Audi S4 FCM Elite Stage 2 build with H&R Street Performance coilovers.

The front spring adapter from H&R allows the spring to move a bit on the perch. I'd suggest gusseting up this gap with steel shims and possibly a thin section of rubber hose to prevent the spring from directly rubbing on a shim. I just don't like having springs move around on the spring perch!

Good news on the spring selection front is that per my measurements (I checked various Audi forums but I found the quoted value not very accurate) the spring provide Flat Ride with ride frequencies around 1.7 Hz front and 1.9 Hz rear.

On the rear, H&R says you need to re-use the factory upper mount and bump stop. If you wanted, I believe you could trim some of the rear bump stop at the upper end, but that's your call.

In terms of rebuildability, I asked Tire Rack to check with H&R whether their Street Performance kit for the B8 Audi S4 was a rebuildable monotube style. They said the fronts were but the rear were twin tube. With that information, I recommended my Audi S4 customer Jermaine to buy some rear B8 Bilstein Sports which were a monotube style.

Once I had the H&R Street Performance coilover setup in my hands, it turns out that the rears ARE a monotube, although the small body and 14mm diameter shaft. They may have assumed that the smaller body means twin tube, but Bilstein makes monotube in both 36mm and 46mm body diameters.

Given the high weight of the car, you end up with a bit of a dilemma (as I found) when attempting to valve the rear small body H&R for good grip, good ride without jacking down (meaning an excess of rebound damping compared to compression), and low surface reactivity (which comes from excessive nitrogen gas fill pressure and the associated gas force pushing upward on the shock shaft).

I'll go into this more in another video, but I saw more hysteresis when trying to..

4th and final part of Kevin Pankhurst's comprehensive track talk on Sonoma Raceway, recorded June 10th, 2018 at Edge Motorworks in Mountain View by Shaikh of Fat Cat Motorsports.

He continues from Turn 3 and finishes going over each turn and how to link them together for the best and safest lap.

Link to his 50% speed lap is here: https://www.youtube.com/watch?v=LYuGk4ahh3w

Continuing with Part 2 of 4 of an excellent track talk by Kevin Pankhurst covering Sonoma Raceway, recorded June 10th, 2018 at Edge Motorworks in Mountain View by Shaikh of Fat Cat Motorsports. He goes into what to bring to the talk and discusses the importance of choosing the correct brake fluid, dealing with brake fade, how frequently to flush your brake system, and more. We take a break after this session and return for parts 3 and 4.

There are two bump stops present on this Mitsubishi EVO X. One bump stop is a 29mm soft density stop that lives on the shaft of the strut insert and isn't viewable unless you take the strut insert out of the strut housing. I've never seen this style bump stop on any Bilstein strut except the Evolution X. It has a comparable density to the standard black soft density bump stop Bilstein sells in their catalog, p/n E4-B36-556A, Jounce Bumper, JOUNCE BUMPER,3RIB 40X32MM.

The second bump stop, which is visible resting on the strut, is ~77mm long and secures to the outside diameter of the strut insert. This bump stop also holds the dust boot in place and keeps the boot high on the strut tube. From driving observations (terminal understeer!), I feel the factory suspension travel on the Evolution X is is unnecessarily limited so additional bump travel up front will help smooth out the ride and reduce the understeer. With our Stage 2 revalve that has more 'rally style' damping profile, a slightly shorter bump stop will give more comfort on bigger road hits while still providing enough protection at full compression. I've tuned the damper to have more compression damping which resists bottoming out, and I've reduced rebound damping across the board to allow the tires to follow the ground better instead of the high rebound force causing 'jacking down' into the bump stops.

I'm going to trim the upper ~21mm section of the outer, longer bump stop to gain some additional suspension travel while still having the outer bump serve its function of retaining the dust boot. You never want to trim the lower portion of a progressive bump stop as that makes the bump stop spring rate increase quickly and leads to a harsher ride.

The standard shafts diameters are 11.0 mm and 14.0 mm, so know what you're working with and machine your brass or aluminum soft jaws / vise inserts accordingly. You could substitute a sturdy vise for the shop press though the press makes this SO much easier! We have 17.5T press and I use 3 tons of force.

I spray the shock shaft and soft jaws with brake parts cleaner and wipe clean to improve the friction on the chromed shaft. If your bushing housing is dirty, clean that but with a milder solvent, not brake parts cleaner.

If you have rubber or poly bushings, take care not to overheat the housing when applying heat. Also, remember to add a few drops of removable threadlocker upon reassembly.

To install a dust boot, slip the top of its cone over the lip of the bushing or bearing housing. I neglect to install the dust boot for our customer Brodey's rear dampers, hence making his video per his request as an intermediate DIY!

Checking out these Bilstein HD front our new VW Tiguan customer. Front strut inserts have pretty high gas force, about 70 lb! Rear gas force is 45 lb, also high. We'll get that down especially by incorporating Ripple Reducer which lowers the pressure created by the shock piston moving through the oil.

The front damper is a symmetric rebound:compression curve which is good to not jack down, but the forces are high. The rear has pretty good compression levels I'd say but the rebound is very strong so there's definitely jacking down happening.

Overall, the Bilstein HD dampers for the VW Tiguan look surprisingly like the PSS Bilsteins on the Mk6 Golf GTi we did a couple years ago. That's not necessarily good, but it helps me understand the ride complaints our customer have and also helps me toward a solution - FCM Elite damping optimization, reduced gas fill pressure (and lower measured gas force at the shock shaft), and Ripple Reducer. This will be a Stage 2 FCM Elite build, so no KBO but still will be very effective. It'll ride smoother and have better grip when we do our FCM Elite magic!

To get in touch to experience our vision of Ride Harmony, send us an inquiry here: http://www.fatcatmotorsports.com/contact_elite.htm

This one is kind of a heart-scratcher and I definitely intend to follow-up and seek more feedback from Porschephiles. What I know regarding Cayman vs 911 is there's some bad blood between the two on which is the better-handling car, which is more 'truly iconic Porsche', and who knows what else. I think they're both great sports cars, but I really had to wonder 'what were the engineers thinking?!' when I saw the factory rear Cayman damping forces!

It's very very VERY stiff on compression - to the point that nearly any mild bump (over 5 inch/sec, which is quite low speed) will cause the rear suspension to JUMP up and reduce contact patch with the ground. This will lead to a VERY BUSY ride, and an unforgiving suspension over any kind of broken or uneven road.

In stark contrast is the Porsche 911 (997), which is contemporaneous to the Cayman. The 997 rear shock (nearly a 1:1 motion ratio but just slightly lower) is supporting even more weight than the Cayman rear strut. So theoretically, the 997 rear should be a little stiffer but it's actually MUCH softer - or rather let me say, the 997 rear is less harsh. It's still overdamped on both compression and rebound, but not to the degree that the Cayman is.

If someone wanted to make the theoretically 'better-handling' Cayman suffer a ride quality penalty for outshining the 997, you can make that happen by overdamping the suspension. That's exactly what I see, and there's no good reason for it other than to make the Cayman ride worse than the 997 on rough roads.

What are your thoughts? Please pass this video along to any Porsche enthusiast you know, in case this information and dyno graphs aren't already available and have been discussed.

To get in touch for your own FCM Elite Project, send us an inquiry:

http://www.fatcatmotorsports.com/contact_elite.htm

In evaluate the Ohlins DFV coilovers for a Porsche Cayman. The dampers were loan by my customer Murat once he put our FCM Elite-optimized H&R Street Performance coilovers on.

Strangely, the front Ohlins have very limited extension or droop travel, and 2 inch total bump travel. So effectively you are riding around on the bump stops once the suspension is loaded. You can also see from the dyno test that the bump stop comes into play near the end of the 2 inch minimum required dyno stroke.

Also, Murat was running the dampers at FULL SOFT to get a decent ride. The front gas force on the Ohlins was 48 lb, which is quite high considering we could get down to 20 lb with the Bilstein-based H&R Street Performance coilovers using our FCM Elite methods.

The original spring rates were 70 N/mm front and 80 N/mm rear, or 399 and 456 lb/in, which he found FAR too stiff! He went down to 50 and 60 N/mm, or 285 lb/in front & 342 lb/in rear, which worked better but he was still missing the benefits of KBO and Ripple Reducer along with our gas pressure optimization.

He also complained of always scraping the front bumper's air dam going into / out of driveways and over speed bumps. We're adding a longer front shaft to the H&R setup to improve this further but having the ability to extend travel is a big plus!

This is another ready why I don't like the 'adjustable body length' feature because you can't use a long-enough strut tube or shock body length that allows enough extension / rebound / droop travel.

To begin your own FCM Elite Project, send us an inquiry here:

http://www.fatcatmotorsports.com/contact_elite.htm

For those who may be curious how you take a Bilstein apart, here's the process in all its glorious (gory?!) detail! We're using a customized Accu-Force shock fill machine with custom 36mm accessories / adapters. I show how to access the upper and low snap-rings, considerations for fluid overflow and maintaining as low stress as possible on the rod guide and seals when disassembling the damper. Oh, and you'll want to drain / wipe the inside of the damper body of excess oil once you're done 'cause there will almost certainly oil in there!

This procedure is useful if you want to set up the proper tooling to refill the damper without adding an external Schrader valve, which we don't do any longer. The OE-type nitrogen fill / shock assembly process gives better durability and more worry-free operation than you get with an external valve.

Keep in mind when you are servicing a Bilstein-based damper that you need to grind down any part of the nut / swaged end of the shaft otherwise you will ruin the threads. For newer builds, the nut is usually secured via a threadlocker so grinding isn't necessary.

If you'd rather have us take care of this for you, or want to begin an Elite Project, you can send us an inquiry here:

http://www.fatcatmotorsports.com/contact_elite.htm

SHOW MORE

Created 4 months, 3 weeks ago.

27 videos

 Category Education

In his seminal book 'Zen and the Art of Motorcycle Maintenance' Robert Pirsig wrote 'Quality eliminates Subjectivity.'

My goal is to eliminate the subjectivity, confusion, and mystery behind how a vehicle suspension works - and how we can make them work better.

I create videos based on Fat Cat Motorsports (FCM) Elite projects for my customers, HPDE (High-Performance Driving Experience) track days, autocrosses, personal thoughts, and how-to videos.

I'm happy to engage and answer questions within reason, however I cannot answer questions in great details specific to a particular vehicle. If you want my focused attention, please sign up for consulting here:

http://www.fatcatmotorsports.com/contact_elite.htm

I welcome your ideas, comments, support, and engagement! Let's explore this awesome area and pursue my goal of Harmonizing Your Ride!