treekiller

"OEM shocks are most often a compromise between ride, handling and cost, with cost sometimes dictating the quality of the ride and handing possible. Manufacturers usually view shocks like any other commodity which means that the low bidder gets the business. Things like manufacturing quality, engineering support and technical savvy also weigh in to the decision, but cost holds the big stick.
When an OEM engineer tunes the shocks for a particular vehicle, he has many competing interests to consider. This is necessitated by the nature of the average customer who will expect his vehicle to be comfortable on a long journey or city streets, loaded with cargo or empty, and still handle an emergency situation in a competent fashion. And that is just the beginning of compromise as there are many subtleties not even mentioned here.
What this means to the enthusiast driver or racer is that the original shocks often do not provide the desired level of handling, response and feel from their vehicle. This becomes especially true when altering the vehicle in other ways like stiffer springs, higher/lower ride height, anti-roll bars, tires etc. Many people fail to realize that having properly optimized shocks can vastly increase the performance potential of any vehicle but they must be matched to the components of the system. In many cases, just changing shocks to a high quality unit tuned to that particular vehicle will have a more profound effect on the performance envelope than any other component.
One more thing to understand: most so-called "high performance" aftermarket shocks are nothing more than shiny, highly marketed units manufactured with cheap components. Very few companies manufacture their own valving components. Even fewer actually do any on vehicle testing to optimize the control forces for the application. The manufacturer typically measures an OEM shock and adds 20% or so to the control forces just so you notice a difference when you bolt them on the vehicle. While this may be enough for the less demanding consumer, those who understand the importance of shocks need to investigate the company they are buying from and choose the one that offers the best engineering, quality, technical support and value."

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Shock Tuning, (Thanks Bob Tunnell)

1. When listening to advice, consider the source and the context. Many of the Internet special interest groups are a wonderful source of information. But one of the biggest drawbacks to all the advice you see on SIGs is that the authors are rarely qualified to offer SPECIFIC advice for YOUR car. It's easy to SOUND like an authority... it's rare to actually BE one. When reading their advice, pay particular attention to what make and model of car they own and drive, what modifications have they made that are truly applicable to your car, how experienced they are, what discipline are they tuning for (autocross, road race, street, track, etc.), and how closely their budget resembles yours.

2. Be specific in your analysis. If your car is pushing, pay particular attention to *when* it pushes. Is it on initial turn-in? Is it mid corner? Is it on corner exit? Or is it a combination of all three? For example, if a car pushes in mid corner, but not upon entry or exit, chances are the problem lies with alignment, spring, or bars... not the shocks. So it's critical to properly identify the symptom and isolate the true cause of the problem... the treatment needs to address the root cause.

3. Fix the end of the car that has the problem. If your car isn't turning in properly, don't adjust the rear of the car to try to make the front end work better. Conversely, if the car is extremely tail happy because of low rear grip, decreasing the front grip to compensate may make the car feel balanced, but it will ultimately make you slower. Often in Stock class autocrossing or road racing we're forced into adjusting the "wrong" end of the car because rules limit our ability to adjust properly, but these methods should be considered a last resort.

4. Don't discount driving technique as a big factor. Most drivers don't like to hear this, but it's true. I can't tell you the number of times I've been told by a driver, "My M3 pushes like a pig!" But when I get in the car it seems perfectly balanced to me. I'll ask the driver what his previous car was and invariably it was a Camaro, Mustang, Corvette, or other high horsepower RWD car. M3s were not built to handle the same as pony cars and they cannot be driven quickly with the same technique. Slow sweepers in particular need to be entered slowly, under control, and "carved"... not tail-out Dukes Of Hazard style. And the best part -- changing your driving technique doesn't cost you anything!

5. For the best results stick with one tuner. Professional high performance tuners know more than anyone else about how to make your car fast. We work on making cars faster and handle better day in and day out. We know which products perform best together and which ones don't. By mixing and matching products -- usually in an attempt to get the lowest price -- customers often end up with a car that doesn't respond like any of the advertising claims they've been reading. Put a pot pouri of components on your car and you'll likely end up with a mixed bag of results and wasting your money. Different tuners have their areas of expertise and their advice.... spend a little extra, discuss your needs and budget with a professional tuner, and you'll likely get far more value for your money.

6. "Compromise cars" will not do everything well. I am frequently asked how to set up a car that will be good on the track, but still plenty comfortable to drive on the street. Not everyone can afford to own enough cars to have one for a commuter, one for autocrossing, one for road racing, one for rallying, and another for concourse events. Most of us are forced to live with compromises... one, or maybe two, cars that have to perform a variety of functions. When asking a tuner for advice on how to set up your car, you must first determine in your own mind what compromises you'll be able to live with and be certain to communicate your needs. If winning autocrosses is more important than having a luxurious ride during your 5-minute commute, chances are you'll be happy having your car set up more for performance. But if you drive an hour to work over frost heaves and tar strips, you probably should set up your car more for comfort and leave the WRC Championship for another time. BMWs are amazing cars and can do a lot of things well, but don't expect a tuner to do the impossible.

And about the following Shock Tuning Guide in particular...

7. The following guide is for tuning shocks for road racing -- autocross tuning can be very different. Road racing maneuvers are almost always done "in phase," meaning the link between driver input and vehicle response is usually linear, or very close to it. In Autocross we frequently encounter "out of phase" maneuvers, meaning secondary inputs are often necessary before the vehicle has even had time to respond to the initial input... slaloms and high speed offsets are good examples of maneuvers rarely encountered in road racing. The suspension tuning is often one quite differently.

8. Guides like these almost always assume you are able to change all elements of the suspension. The guide below (and most guides like them) are based on the assumption that you have already optimized the spring rates and that you are dealing with a fairly balanced, competent, road car. For most of us we rarely encounter this "perfect" situation. In Showroom Stock road racing or Stock Category autocross, for example, we are faced with preparing a car as it comes from the factory and cannot change spring rates. We often deviate from these basic guidelines to "trick" the car into doing something that would make factory shock engineers cringe. <g>

9. Make the shocks do their job and let the other suspension components do theirs. The primary job of the shocks is to do two things -- affect ride quality and control the rate of weight transfer. Don't ask them to act as springs (unless you're stuck with the dilemmas I presented in #1 or #2). In terms of handling control, shocks do very little in the middle of a corner. Springs and sway bars have a much greater affect on handling in the middle of a corner. By paying particular attention to #4, you'll have a better idea whether the problem lies with your shocks or elsewhere.

And one last general guideline to keep in mind...

10. In general, stiffening one end of the car will reduce the mechanical grip on that end. In other words, when you raise the spring rate, increase sway bar size or stiffness, stiffen the bump or rebound of a shock, install firmer bushings, etc. you will reduce the grip on that end and decrease traction. To increase grip you must lower the spring rate, increase the sway bar size of stiffness, soften the shocks, use softer bushings, etc. (Tire pressure is another contributing factor, but that's a discussion for another day.)


KONI shock tuning guide
Suggested Adjustment Procedures For Road Racing Use
(from the KONI NA Factory Tuning Guide)


Adjusting The COMPRESSION (Bump) Damping Control (Very Important to do this FIRST!)
Bump damping controls the unsprung weight of the vehicle (wheels, axles, etc.). It controls the upward movement of the suspension as when hitting a bump in the track. It should not be used to control the downward movement of the vehicle when it encounters dips. Also, it should not be used to control roll or bottoming.
Depending on the vehicle, the ideal bump setting can occur at any point within the adjustment range. This setting will be reached when "side-hop" or "walking" in a bumpy turn is minimal and the ride is not uncomfortably harsh. At any point other than this ideal setting, the "side-hopping" condition will be more pronounced and the ride may be too harsh.
STEP 1: Set all four dampers on minimum bump and minimum rebound settings.
STEP 2: Drive one or two laps to get the feel of the car. Note: When driving the car during the bump adjustment phase, disregard body lean or roll and concentrate solely on how the car feels over bumps. Also, try to notice if the car "walks" or "side-hops" on a rough turn.
STEP 3: Increase bump adjustment clockwise 3 clicks on all four dampers. Drive the car one or two laps. Repeat Step 3 until a point is reached where the car starts to feel hard over bumpy surfaces.
STEP 4: Back off the bump adjustment two clicks. The bump control is now set. Note: The back off point will probably be reached sooner on one end of the vehicle than the other. If this occurs, keep increasing the bump on the soft end until it, too, feels hard. Then back it off 2 clicks. The bump control is now set.

Adjusting the REBOUND Damping Control
Once you have found what you feel to be the best bump setting on all four wheels, you are now ready to proceed with adjusting the rebound. The rebound damping controls the transitional roll (lean) as when entering a turn. It does *not* limit the total amount of roll; it *does* limit how *fast* this total roll angle is achieved. How much the vehicle actually leans is determined by other things such as spring rate, sway bars, roll center, ride heights, etc.
It should be noted that too much rebound on either end of the vehicle will cause an initial loss of lateral acceleration (cornering grip) a that end which will cause the vehicle to oversteer or understeer excessively when entering a turn. Too much rebound control in relation to spring rate will cause a condition known as "jacking down." This is a condition where, after hitting a bump and compressing the spring, the damper does not allow the spring to return to a neutral position before the next bump is encountered.
This repeats with each subsequent bump until the car is actually lowered onto the bump stops. Contact with the bump stops causes a drastic increase in roll stiffness. If this condition occurs on the front, the car will understeer; if it occurs on the rear, the car will oversteer.
STEP 1: With rebound set on full soft and the bump control set from your earlier testing, drive the car one of two laps, paying particular attention to how the car rolls when entering a turn.
STEP 2: Increase rebound damping three sweeps (or 3/4 turn) on all four dampers and drive the car one or two laps. Repeat Step 2 until the car enters the turns smoothly (no drastic attitude changes) and without leaning excessively. An increase in the rebound stiffness beyond this point is unnecessary and may result in a loss of cornering power. Note: As with the bump settings, this point will probably be reached at one end of the car before the other.
However, individual drivers may find it desirable to have a car that assumes an oversteering or understeering attitude when entering a turn. This can be easily "dialed-in" using slightly excessive rebound settings at either end

Outkasted24

Great Information, Stickied as requested

treekiller

A simplified guide to what component does what in the whole suspension chassis equation. Or, enough information to make you dangerous!
This is by no means the definitive guide as each sub section alone can justify a volume of books let alone all the components we have not covered yet. So, if you're interested in finding out more, let us know and we can recommend some other texts for you to read. Naturally this FAQ will be expanded as more questions are asked and we get round to answering them.
Dampers or Shocks

What do they do?
Isn't a gas shock better than an oil shock?
What about adjustables
Piston diameter - when size IS important
Monotube shock absorbers - to invert or non-invert?
Mono Tube Vs. Twin Tube comparison
Why should I buy Your shock, arent they just #$@% brand with Your sticker?

Dampers or shocks - What do they do?

A damper or shock absorber does not actually absorb shocks. Springs absorb shocks by compressing in response to vertical acceleration. The primary function of a shock absorber is to dampen the kinetic energy stored in the spring as the spring compresses. It converts this energy into heat which is one of the reasons we have gas shocks, but more on that later. When the force that caused the compression goes away, this stored energy releases and the spring extends with a lot of force. Imagine a pogo stick.

Now, before we confuse everyone too much. We'll refer to a shock as a damper and vice versa through out this explanation. Technically speaking damper is more correct, but shock is fine as long we keep in mind what its actual job is. It's also important to note that a shock's rate needs to match the spring and the swaybar. This is why tuned suspension packages are a good choice.
Shock absorbers are inherently velocity sensitive (despite the marketing hype). That is, the faster the piston moves (increased vertical acceleration) the more resistance or damping will result. This is due to one of the laws of fluid dynamics, which states that a fluid's resistance to flow through any given orifice will increase directly as the square function of flow velocity. The bottom line is the harder the damper works, the harder it works!
Because a shock absorber is velocity sensitive by nature, it has to be load sensitive because the velocity is produced by an acceleration, which is composed of force and velocity.
In order to maintain sensitivity at low displacements, valving has to be arranged so that little damping takes places at low piston velocities and conversely substantial damping takes place at high piston velocities. All fluid filled shock absorbers are therefore velocity sensitive, a good shock absorber will also be frequency sensitive. And this is often what separates the good from the average. Naturally its difficult to get a real frequency sensitive solution for very little money.
The current state of the art in racecar technology is to lower the spring rate as much as possible whilst increasing the swaybar rate as high as possible. This allows the tyre to follow the road surface maintaining the maximum grip possible. If the spring rate or bar rate is too high then it will hop from bump to bump losing traction. The bar controls the roll, the soft (relatively) spring deflects for the bumps and the rebound on the shock can therefore be set at a relatively lower/softer level.

So, next time your asked by a salesman to "pull his levers" and see how stiff their particular shock is, remember that stiff ISN'T always better. And, you can't possible simulate the high frequency of road bump deflection with your hand. No matter how well practiced you may be.
Isn't a gas shock better than an oil shock?

Yes and no. A popular misconception is that a gas shock works on gas where as an oil (normal) shock works on oil. All conventional automotive shocks work by forcing oil through a programmed set of holes, however a gas shock will use compressed gas to keep the oil under pressure.

This is done largely to minimize aeration or "foaming" of the oil which would reduce the effectiveness of the shock as air passes through the valves rather than fluid. To see what this is like, tip a conventional shock absorber upside down and pump the shaft a few times. You'll notice the movement become jerky and uneven as oil and air intermittently pass through the valves.

The gas also helps to dissipate heat which keeps the oil cooler and maintains the viscosity and therefore the shock "rate". Gas shocks are ideally suited to long travel applications like rallying and off road. In fact, this is where the technology was primarily developed in the first place as lots of spring travel over big bumps really tests a conventional hydraulic shock.

There are many types of gas shock, twin-tube, mono-tube and remote canister combinations for super heavy-duty use like rallying and off-road racing. Most of the economical gas shocks are of a twin tube construction (low-pressure) where as most performance or race gas shocks use a mono-tube (high-pressure) system. There is no such thing as an ideal system, it really depends on the application as mono-tubes may have advantages in some respect but the high-pressure gas can act as a spring complicating the suspension design process.

The main disadvantage of a gas-pressurized shock is cost; more of it compared with a conventional hydraulic. Which leads to a very simple rule of thumb to help avoid confusion. If faced with a choice of gas or oil for the same price, it's unlikely that the real working part of the gas shock is of the same standard and level of sophistication as the oil. You get what you pay for. And, choosing gas shocks generally mean you'll need to design the rest of the suspension system around that fact with spring and bar rates being affected.
What about adjustables?

Adjustable shocks, why use them? A lot of people have recently asked us this question. Specifically why do we so often use adjustable dampers in our suspension kits.

In simple terms, the adjustment of a damper allows for 3 things;

1. Initial adjustment to allow closer matching of spring to damper rates.
2. Fine tuning in response to changes to components like tyres or swaybar rates.
3. Subsequent adjustment to maintain rate as the dampers inevitably wear.

With out going into too much detail as to the types and levels of adjustment, suffice to say that most adjustable dampers allow for changes to the "rebound" rate. This is the extension component of the dampers movement cycle and is the principal force that controls the spring's oscillations. That is, correct damper rebound rate is critical to the spring damper relationship.

Other types of adjustable dampers for the street use a gross bypass adjustment that simply controls the amount of bleed or bypass around the main valve mechanism. This is a very coarse adjustment that is not really suitable for performance tuning as it often forces you to change the bump or compression characteristics when you might only need some extra rebound and vice-versa.

Now, being a hydro-mechanical device, the damper eventually wears out. The piston rubbing on the bore of the damper eventually wears the seals, the valve springs get softer allowing more oil to bypass the piston and valves, which control the oil flow and give the damper its "damping" characteristics. The more wear, the less "rate" you're left with.

With an adjustable shock we can compensate for this wear by increasing the rebound rate to bring us back to square one. Now before you start going off about your brand shock never wearing out, accept the fact that any hydro-mechanical device MUST wear out as its operation depends on friction, and friction is a natural wear component by definition. The only issue is how long it takes one damper to wear versus another.
The answer to this is almost directly proportional to the money spent. That is, the cheaper the shock, the quicker it will loose it's rate. This also means that an adjustable damper costing a little more than a non-adjustable will often be the superior choice for road use as it can be made to perform more consistently for longer.

Piston diameter - when size IS important

Why is this so? Because it is often a direct measure of the rigidity of the unit and the oil volume. The biggest enemy of a shock is heat and that is inevitable when it starts to work hard. With increased heat you have decreased oil viscosity, which means a drop off in damping performance and you can understand why race cars use remote canister or reservoir designs to increase the volume of oil and gas. Even multiple shocks with extra reservoir’s are sometimes used in applications like off-road buggy’s and rallying.


Not only does viscosity reduce with heat, gassing and aeration increases further reducing performance. Not trying to be critical of specific brands but many popular twin tube adjustable shocks simply can't go past 2 to 3 laps of a typical sprint race with out the driver complaining of the shocks "going off". We use and fit a lot of this stuff all the time and recommend it but it’s simply not fair to expect say a 30-32mm piston twin tube to deal with spring rates in excess of 250lbs, big swaybars, high performance tyres and hard use.


A graphic example of why piston size is so important is to use Pr2 to highlight what this means in terms of surface area and resultant volume.
Lets first start with a conventional twin-tube stock front strut with a 30mm piston and 22mm shaft and do a rough calculation.


Using “ P” (pie) at 3.14 we get 30 x 0.5 = 15mm radius. Squared = 225 then x 3.14 (P) = surface area of 706 mm2. That’s the oil area below the piston (call it cylinder area), but we need to factor in the shaft above the piston.


That’s 22mm diameter which = 11mm radius, squared we get 121, x P we get 380 mm2. Take the cylinder area or 706 and subtract the shaft area of 380 and we’re left with 326. Hence using this and applying the same process to some alternative sizes we get:


Stock twin-tube strut 30 mm piston / 22 mm shaft = 706 mm2 below and 326 mm2 above. Average of 516 mm2


A nominal “40mm” inverted mono-tube strut design uses 36 mm piston / 12 mm shaft. (Some brands use sizing in their model descriptors which relate to body/shaft rather than piston size).


= 1017 mm2 below and 904 mm2 above. Average of 961 mm2
non-inverted mono-tube strut design using 46 mm piston / 22 mm shaft = 1661 mm2 below and 1281 mm2 above. Average of 1472 mm2
You can see that the nominal “40mm” product will have around 86% more oil volume than the stock strut given the same body size where as a True Monotube has 185% more than stock or 53% more than a nominal “40mm”.


Needless to say, a 46 mm piston in an inverted design will have even more fluid as you can get away with a 12 mm shaft thanks to the body acting as a virtual main shaft but at the expense of the drawbacks of an inverted design. (See separate FAQ topic.)
Obviously this stuff is only important if you plan to get serious and top performance is important but there is no doubt that “bigger IS better” when it comes to piston size.
Monotube shock absorbers - to invert or non-invert?

The following is an extract of a post to NASIOC in December 2003 that discusses the issues relating to inverted vs non-inverted mono tube shock designs. Specifically it addresses the various differences and how the relate to driver and vehicle.


The issue of mono-tube vs twin-tube designs is quite complicated and involved. We are far from worlds leading expert in this field but we've assembled a bit of knowledge over the last 10 years and in particular in the last 2 years while we've been working on our own damper solution.


To avoid restating information, I'd like to suggest that anyone not entirely familiar with the mono vs twin tube arguments also look at the next topic in this FAQ headed "Mono-tube vs Twin-tube - ride characteristics". This was formulated and published at the time that some of you started experiencing a "bouncy ride" with particular brands of coil-overs.
Since that time, we have learnt a bit more and will probably expand the FAQ to cover this better. However, in the meantime we can add a bit more to this debate hopefully making things a little clearer for those with problems.


Any conventional mono-tube (relatively high pressure design greater than 6 bar) has to deal with the problem of shaft displacement. As Archimedes found out, adding his body to the bath forced the water to displace somewhere, in his case on to the bathroom floor. So it goes that as a damper compresses, the shaft entering the damper tries to displace the oil. In a twin-tube this is taken care of by the secondary oil chamber (twin tube) surrounding the primary piston tube that can take the extra fluid via a foot valve in the bottom of the primary chamber. The relatively low pressure nitrogen blanket on top (less than 2 bar) and the use of the foot valve means that there is little force to oppose the shaft displacement except for the valving itself but what happens in a mono-tune running in excess of 6 bar?


The basic design of a mono-tube has the high-pressure gas chamber directly inline with the oil/shaft chamber separated by an additional floating piston. The gas keeps the floating piston hard up against the oil to minimize aeration and cavitation keeping the fluid cooler at the same time, hence why they are fundamentally more appropriate for serious and motorsport use. Unfortunately, you can now see the potential for competing interests with compression and shaft displacement.


The first issue is that at relatively low shaft speeds (comfort range) the entering shaft forces the floating separating piston to further compress the gas delivering a noticeable reactive force. (Note: it is a well known fact that replacing twin-tube with mono-tubes will often deliver a noticeable rise in ride height using the same spring. However we are yet to see any shock manufacturer officially acknowledge this.) The static pressure increases and that is why initial gassing pressure of a mono-tube is so important and part of the shocks “tunning” setup.


Within this same characteristic lies the issue of “cracking pressure”. (Our terminology but called different things by some manufacturers that DO acknowledge its existence/ Sachs Motorsport for one as they have started using revolutionary constant displacement designs in F1). We use this term to describe the shaft velocity and resultant pressure required to “crack” the valves open on the main piston. You can imagine what might happen when the shaft starts moving into the main chamber, a light enough force would simply move the floating separating piston further compressing the gas and acting like a momentary spring rate increase. A little more force however and we actually “crack” the main piston valves open allowing fluid to pass thru the piston, basically letting the shock do what it was designed for. We do not have sensitive enough instruments to measure this but it is our belief (backed by the experience of our backsides) that this contributes noticeable to what a mono-tube “feels” like to drive.


Needless to say we are very aware of this characteristics and therefore went to great lengths to find ways to try to “tune it out” of our coil-overs. I believe we have gone 75% of the way to doing so but I guess it won’t be acknowledged until someone on the board actually fits a set and passes on some feedback.


The second issue is to do with inverted mono-tubes designs as mentioned already by many of you. There is no doubt that an inverted design HAS to have more friction than a non-inverted. One can argue till they’re blue in the face about how little extra friction their particular inverted design has but that can not overcome the physical fact that an inverted design has to have more due to the extra seals and guides necessary to make it work.
Imagine the entire body of the shock now operating as the shaft. The up side is that we can now use a 40 mm effective OD shaft (actual body) to give us greater rigidity and strength but we now need an extra oversize seal to interface between the shock and strut body. Secondly, we need extra guides inside the strut body to help the shock body move purely up and down with minimal side movement. Most contemporary struts operate inclined for caster and/or camber so poor guide or seal design and less than ideal material spec will lead to stiction as side loads are not directly transmitted to the vertical.


This is a particular problem for shocks originally designed for rally or gravel competition where the necessity for longer suspension travel means compromises in guide placement to allow long wheel “droop” and shock extension. I guess that’s one reason why our coil-overs are specifically designed for tarmac or non-rally use to avoid this compromise on relatively short travel requirements.


You can sometimes see the results of stiction as a dulling or blueing of the shaft chrome on one side to the point that you can start seeing lines develop in the chrome. The quality and hardness of the chrome is critical but even the best finish will degrade rapidly if the seals are of a poor quality or the guides are inadequate allowing the shaft/body to deflect or grab through its travel. (or you allow too much dirt in around the shaft)
Now we can throw in some other interesting side issues like the need for air vents in the strut body to stop the shock body acting like an air ram as it moves into the strut. Once you let the air in and out that means you can potentially let water and dirt in as well. This leads to a dramatic rise in effective spring rate to the point that we have seen cars in our workshop that CAN NOT be bounced in the rear. It's as if the rear coils were removed and replaced with wooden blocks, hardwood at that. This is why some brands say that your inverted mono-tubes need an annual service and frankly why so few cars are fitted with inverted mono-tubes from the factory.


The maintenance issues are a potential nightmare and are difficult to control within normal new vehicle warranty periods. A WRX Sti is one car that does have stock inverted mono-tubes and we have seen and know of cars that have required maintenance at less than 20,000 Miles but this is not that common as many owners of these vehicles replace the factory shocks with something more upmarket and/or expect “motorsport” problems and issues.


Remember that the inverted mono-tube design has its roots in motorsport and rally where extreme use highlighted the benefits of a more rigid strut with long travel and they could afford to dissemble, clean and re-grease each shock after every race.


All of the above issues further contribute to the nature and characteristics of mono-tubes and inverted mono-tubes designs. It is an area that is quite complicated and in our view made more difficult by performance “fashion” trends pushed by certain manufactures as they try to find an edge over their competitors. This is all quite normal and we are in the same race I guess but we decided early in the design process that we did not want to enter the same competition and would do what we thought was best for the market we service and that is, serious road performance right up to weekend competition.


As for the issues of tyres, tyre pressure and strut tops and the effect these have on mono-tube ride quality, most of what has been said already is pretty true. Specifically, one must always think of the total effective spring rate of each corner of the vehicle and what parts of it are damped or undamped. The effective spring rate is everything between the tyres contact patch on the road and the theoretical centre point of the chassis/body the splits the car into quarters. That is, the tyre itself has a spring rate (undamped), the control arms, mounts and mounting bushes have a spring rate (undamped), the actual spring will have a spring rate (damped) and finally the body and chassis will flex with its own springs rate which is undamped.


Any undamped or uncontrolled rate is universally “bad” unless its factored into the handling equation like F1 (or any serious motorsport) tyres are. Hence why we say that there is no such thing as too much chassis rigidity and why race teams go to extraordinary lengths to remove as much undamped or uncontrolled rate as possible.


With this in mind, we can speculate on what would be better or worse in each case of tyre/spring/damper/mount combination but there is no easy or universal answer as it depends on the precise interplay of that particular combination and the shocks valving. If higher tyre pressure works then fine, if softer mounts help then that’s OK too. We on the other hand use some internal valve mods to dramatically dampen (bad pun I know) this issue at low speeds with out sacrificing control.


Even then, there is a chance that a customer’s particular chassis combination will result in some negative behavior but I guess that’s why they’re rate adjustable.
Mono-tube vs Twin-tube - ride characteristics.

We've assembled some graphs showing the varying performance characteristics of mono-tube and twin-tube gas shocks. You may have seen arguments from time to time about how mono-tubes ride worse that twin-tubes or vice versa. There's also a perception that a mono-tube will tend to "bounce" more at low speed delivering a jiggly ride that some find uncomfortable. Whiteline argue that any high-pressure mono-tube design gas shock will deliver a certain "bounce" in the ride due to the inherent design of a mono-tube compared with a twin-tube. The accompanying information helps to explain why this is often the case.

The following graphs show a force/velocity trace line using a computerized shock dynamometer. Each pair of shocks within each graph was for the same application, using commonly available performance brands. They are "sport" valved for road use and are a good example of their "type". Please note the units of measure used and how they relate. Take particular note of the comment regarding the "Comfort Zone" which exists in the 0.0 to 0.15 m/s velocity range. It is also useful to note the relatively high amount of force in extension vs compression and that initial compression (bump) response is very important in analyzing perceptions of ride comfort.

The actual vehicle application and shock brands used are irrelevant for this example and will not be published. The mention of any specific shock brand and design configuration within this article is purely for illustration purposes and may not accurately reflect the brands actual performance across all models. (Sorry, standard disclaimer required.). We also make some generalizations on pressures used and it must be understood that the same manufacturer will use different pressures for different models within the same general configuration.

The first graph (blue vs red) shows a "lower-pressure" mono-tube design vs a twin-tube design. A "low-pressure" mono-tube is a relative description as we are still comparing a gas chamber directly behind the hydraulic chamber with a pressure of between 35-50 psi with a twin-tube with between 10-20 psi as a light pressure blanket in the outer tube. Examples of lower pressure mono-tube shocks include KYB, Tokico, Sachs and Boge. The second graph (green vs red) shows a "high-pressure" mono-tube vs a twin-tube. Pressures here are considerably higher with ranges between 75-110 psi. Examples of higher pressure mono-tube shocks include Koni and Bilstein.









In either case, with any mono-tube you will see a relatively sharp and significant increase in the amount of force required to get the piston moving at slow speeds such as larger road surface irregularities at low vehicle speeds. The classic "anti-example" to this would be the sort of ride you'd feel in an old Cadillac or similar. However an increase in vehicle speed will increase the piston velocity over the same given road surface with a relative "softening" of the initial sharp bump trait felt at slower speeds. As you can see, this symptom is much more pronounced in a higher pressure mono-tube.

Its obvious that the green trace represents a shock with an overall higher base rate that would be felt by any driver however the initial step is the key in how the shock will "feel". In the case of the blue line, the ultimate bump rates of the 2 shocks meet but it is the nature of the beginning of the blue curve that give this shock its particular "ride" character.

These graphs can't deliver a conclusive answer for something that is largely perceptual like ride comfort but an understanding of the differences will hopefully help the driver appreciate what they are actually feeling on the road.
Why should I buy a Your shock, arent they just #$@% brand with Your sticker?

If a customer was to buy a pair of coil springs from us that looked identical to another brand (from theirs point of view) would that mean that ours is simply a copy of another brand with a different colour? Lets assume not. Then if we acknowledge that we physically did not curl the spring wire into the coil shape with our own hands or equipment then are we somehow deceiving the customer? Is Our shock only Our shock if we physically made it in our factory?



we try to allocate a unique part number to any product that we have added some value to the outcome. This may be as a result of a slight valving change, body modification or even no obvious physical change but the fact that it is listed as a part of a kit means that it is designed to work as part of the kit.


In our experience, we regularly encounter situations where a supposed "high end" damper performs abysmally with a desired spring rate or design. This can also be true of cheaper dampers but just like buying shoes, as long as it is a reputable brand, the most comfortable one is arguably the best. KYB, Koni and Bilstein for example are amongst the best brands in the world for quality of manufacture and reliability. If their specifications for a particular damper is a good general fit with our package then we will use it as a base knowing that it will deliver a positive performance outcome and last. Equally, you will NEVER see us use certain brands of shock absorbers regardless of their valving appropriateness.


We do not publish exact composition details of our materials, designs or component interplay as that is the very essence of our value adding and is proprietary information. The testing, analysis and tuning process is what makes our product different and our kits so effective. Customers that choose to purchase our product believe in the value of this process and the positive outcomes it delivers. We do not expect everyone to believe us or feel the same way but we can not call a part something else just because it might look like something familiar.