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This is a discussion on Suspension and Handling Technical Reference within the Suspension & Wheels forums, part of the Tech & Modifying & General Repairs category; This PDF chart from Whiteline is used to figure the percentage stiffness change from one size of bar to another. ...

  1. #16
    Moderator GV27's Avatar
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    Swaybar size chart

    This PDF chart from Whiteline is used to figure the percentage stiffness change from one size of bar to another. It is valid for any solid steel bar and also useful for converting a quoted percentage stiffening for a hollow or aluminum bar into the equivalent steel bar for comparison to other products.

    Thanks to Driggity for the link.

    http://www.whiteline.com.au/docs/bulletins/010barup.pdf
    "Inasmuch as ye have done it to one of the least of these my brethren, ye have done it to me." -Jesus

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  3. #17
    Moderator GV27's Avatar
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    STi Suspension Options Discussion

    STi has several (confusing) suspention options available. Here's a discussion with great insight from the resident expert on the subject, Big Sky WRX:

    Performance suspension kit at subaru help

    WRX suspension trivia
    Last edited by GV27; 04-21-2003 at 08:09 PM.
    "Inasmuch as ye have done it to one of the least of these my brethren, ye have done it to me." -Jesus

    1990 Alfa Romeo Spider Veloce
    1992 Toyota 4Runner SR5 3.Slow
    1993 Honda CBR600F2
    2002 WRX SportWagon *sold*

  4. #18
    Moderator GV27's Avatar
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    Koni Strut Insert Info

    An info thread:

    Koni Insert Info

    Install instructions:

    http://www.vfaq.com/mods/Konis.html

    Thread Search, Keyword = "Koni":

    http://www.clubwrx.net/forums/search...der=descending
    Last edited by GV27; 09-08-2003 at 03:45 PM.
    "Inasmuch as ye have done it to one of the least of these my brethren, ye have done it to me." -Jesus

    1990 Alfa Romeo Spider Veloce
    1992 Toyota 4Runner SR5 3.Slow
    1993 Honda CBR600F2
    2002 WRX SportWagon *sold*

  5. #19
    Moderating on the run! Big Sky WRX's Avatar
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    Labeled photo of the Group N bushings (not including strut tops, engine/tranny mounts/pitchrod):
    Attached Thumbnails Attached Thumbnails stibushings.jpg  

  6. #20
    Registered User Claudius's Avatar
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    Here's a brake pad performance comparison chart.
    Attached Thumbnails Attached Thumbnails pad performance2.jpg  

  7. #21
    Moderating on the run! Big Sky WRX's Avatar
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    With lot's of STi takeoff's on the market these days, here's a run down of many of the v7 setups available:

    PART NUMBERS
    JDM MY 01

    GDB(a) STi
    Right Front strut - 20310FE000
    Left Front strut - 20310FE010
    Right Rear strut - 20360FE000
    Left Rear strut - 20360FE010
    Front spring - 20330FE130 [pink above, orange and blue below]
    Rear spring - 20380FE670 [yellow above, 2 orange below][non-tapered, gray insulators at the top]

    GDB(a) STi RA
    Right Front strut - 20310FE000
    Left Front strut - 20310FE010
    Right Rear strut - 20360FE000
    Left Rear strut - 20360FE010
    Front spring - 20330FE330 [pink above, purple and green below]
    Rear spring - 20380FE690 [yellow above, orange and green below][non-tapered, gray insulators at the bottom]

    GGB(a) STi wagon
    Right Front strut - 20310FE020
    Left Front strut - 20310FE030
    Right Rear strut - 20360FE020
    Left Rear strut - 20360FE030
    Front spring - 20330FE130 [pink above, orange and blue below]
    Rear spring - 20380FE680 [yellow above, orange and red below][non-tapered, gray insulators at the top]



    JDM MY 02

    GDB(b) STi
    Right Front strut - 20310FE300
    Left Front strut - 20310FE310
    Right Rear strut - 20360FE300
    Left Rear strut - 20360FE310
    Front spring - 20330FE130 [pink above, orange and blue below]
    Rear spring - 20380FE670 [yellow above, 2 orange below][non-tapered, gray insulators at the top]

    GDB(b) STi RA spec C
    Right Front strut - 20310FE300
    Left Front strut - 20310FE310
    Right Rear strut - 20360FE300
    Left Rear strut - 20360FE310
    Front spring - 20330FE340 [tent: pink above, blue and green below]
    Rear spring - 20380FE790 [tent: 2 yellow above, 2 green below][non-tapered, blue insulators at the top]

    GGB(b) STi wagon
    Right Front strut - 20310FE320
    Left Front strut - 20310FE330
    Right Rear strut - 20360FE020
    Left Rear strut - 20360FE030
    Front spring - 20330FE130 [pink above, orange and blue below]
    Rear spring - 20380FE680 [yellow above, orange and red below][non-tapered, gray insulators at the top]

    If you wade through all the part numbers you will find the following things about the A and B revisions:

    A and B revision STis(sedans and wagons) used essentially the same struts and springs in both years based on model. Example: A and B revisions of the wagon used the same parts. [The revision B PNs for front and rear struts are listed as alternatives for Rev A vehicles in the part books, theyre interchangeable. These number differences can help identify which year your takeoffs are from tho.]

    The STi RA(a) and RA spec C(b) race-prepped models use the same struts as the standard STi sedans but use unique springs front and rear for each year.


    JDM MY 03

    GDB(c) STi
    Right Front strut - 20310FE300
    Left Front strut - 20310FE310
    Right Rear strut - 20360FE840
    Left Rear strut - 20360FE850
    Front spring - unknown [3rd coil down, 2 purple dots]
    Rear spring - unknown [3rd coil down, 2 green dots][tapered, gray insulators at the bottom]

    GDB(c) STi spec C
    Right Front strut - unknown
    Left Front strut - unknown
    Right Rear strut - unknown
    Left Rear strut - unknown
    Front spring - unknown
    Rear spring - unknown

    The C revision appears to carry through the same front struts as used on A and B revision. However the rear struts, springs and topmounts are quite a bit different from the previous models. The paint codes for the C revision models seem to be of a different format as well and probably shouldnt be compared to revisions A and B.

  8. #22
    Moderating on the run! Big Sky WRX's Avatar
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    Offset calculator

    This is kind of handy- offset calculator:

    http://toy4two.home.mindspring.com/offset.html

    Big Sky

  9. #23
    Moderating on the run! Big Sky WRX's Avatar
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    Thanks to Gary S pointing out this very good article on brake bias:

    http://www.stoptech.com/whitepapers/...erformance.htm

    Big Sky

  10. #24
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    Fender Rolling

    Thanks for posting that B.S.! (pun intended) I meant to and let it slip through the cracks.

    And thank B.S. for this fender rolling link:

    http://www.quickhonda.net/fenderRolling.htm

    C
    Last edited by Big Sky WRX; 01-24-2005 at 07:20 AM. Reason: updated url
    "Inasmuch as ye have done it to one of the least of these my brethren, ye have done it to me." -Jesus

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  11. #25
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    Another, nice simple, easy to follow suspension tuning guide

    Borrowed from Susquehanna Motors:

    http://www.rallylights.com/useful_in...ion_tuning.htm

  12. #26
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    Post Aftermarket Wheel Tech Info

    Thanks to Luke @ Tirerack for posting this info on another forum:

    Performance benefits:
    While many people choose alloy wheels for their beauty, there are equally important performance benefits to be derived including...

    Reduced Unsprung Weight Compared to Steel Wheels
    This is one of the most critical factors affecting a vehicle's road holding ability. Unsprung weight is that portion of a vehicle that is not supported by the suspension (i.e. wheels, tires and brakes) and therefore most susceptible to road shock and cornering forces. By reducing unsprung weight, alloy wheels provide more precise steering input and improved "turning in" characteristics.

    Improved Acceleration and Braking
    By reducing the weight of the vehicle's rotational mass, alloy wheels provide more responsive acceleration and braking.

    Added Rigidity
    The added strength of a quality alloy wheel can significantly reduce wheel/tire deflection in cornering. This is particularly critical with an automobile equipped with high performance tires where lateral forces may approach 1.0g.

    Increased Brake Cooling
    The metals in alloy wheels are excellent conductors of heat - improving heat dissipation from the brakes - reducing risk of brake fade under demanding conditions. Additionally, alloy wheels can be designed to allow more cooling air to flow over the brakes.

    What determines quality ?
    The Tire Rack’s quality standard for wheels is very high and the manufacturers that we represent in this market understand that we constantly monitor products to ensure that quality products are sold to our customers. But what determines quality?

    Manufacturing Process
    Manufacturing processes and levels of testing are critical to a wheel's structural integrity. (Read more in "Wheel Construction.") International quality standards such as ISO9001, QS9000, TUV of Germany or VIA of Japan, establish important production and quality standards that manufacturers must follow. In addition, dimensional tolerances based on strict, original equipment market standards versus the more “casual” standards allowed for many aftermarket products should be met. Even durability standards for finish are different between the original equipment market and the aftermarket.

    Proper Fit
    An accurate fitment is the difference between good, better and best. Critical wheel dimensions such as width, diameter, offset, center bore, brake clearance, as well as load factor and lug hardware are the basics when it comes to properly fitting aftermarket wheels. Installation also requires a high level of sophistication. Many new vehicles are available with features such as ABS, traction control and other features that create a more difficult environment for installing aftermarket wheels. Stability control systems, run-flat tires, large high performance brake systems and staggered wheel and tire sizes are also factors to be considered when establishing accurate fitments. Wheel manufacturers with product design, research and development teams work to determine proper fitment as part of the manufacturing process.

    Protective Finish
    The type and quality of protective finish on your wheel (as well as proper maintenance) will determine how your wheels look years from now. Check for finish warranties backed by manufacturers with outstanding reputations for quality.

    Reputation and Heritage
    The reputation of a manufacturer is a strong indicator of quality since it is quality upon which a distinguished reputation is built. It takes time to build a positive reputation and a commitment to maintain it is important. And know a wheel company's roots. Many wheel manufacturers first established themselves in the motorsports arena and apply that technological and philosophical foundation to their production of wheels for use on the street.

    Country of Origin
    Certain areas of the world bring to mind certain products and characteristics. For example, Germany is at the top in automotive technology and precision. Italy is the front-runner in design and exotic cars. Know where your wheels are manufactured.

    The Tire Rack's Commitment to Quality
    The Tire Rack constantly reviews wheel data from new vehicles to be sure that we are aware of the original equipment sizes and packages offered. We physically inspect many of today’s new vehicles and often supply technical data to some of the manufacturers outside the U.S. that may not have access to certain vehicles in our market. For many wheels that we import or represent, we specify certain dimensions that we require to ensure wheel fit and maintain our high quality standards.



    The offset of a wheel is the distance from its hub mounting surface to the centerline of the wheel. The offset can be one of three types.

    Zero Offset
    The hub mounting surface is even with the centerline of the wheel.

    Positive
    The hub mounting surface is toward the front or wheel side of the wheel. Positive offset wheels are generally found on front wheel drive cars and newer rear drive cars.

    Negative
    The hub mounting surface is toward the back or brake side of the wheels centerline. "Deep dish" wheels are typically a negative offset.

    If the offset of the wheel is not correct for the car, the handling can be adversely affected. When the width of the wheel changes, the offset also changes numerically. If the offset were to stay the same while you added width, the additional width would be split evenly between the inside and outside. For most cars, this won't work correctly. We have test fitted thousands of different vehicles for proper fitment. Our extensive database allows our sales staff to offer you the perfect fit for your vehicle.

    Torquing lug hardware:
    Proper installation requires that the wheel lug torque be set to the recommended specification for your vehicle. These torque specifications can be found in your vehicle’s shop manual or obtained from your vehicle dealer. Finish tightening the lugs down with an accurate torque wrench. Use a crisscross sequence (shown below) until they have reached their proper torque value. Be careful because if you over torque a wheel, you can strip a lug nut, stretch or break a wheel stud, and cause the wheel, brake rotor and/or brake drum to distort.

    NOTE: When installing new wheels you should re-torque them after traveling the first 50 to 100 miles. This is necessary because as the wheels are “breaking in” they may compress slightly allowing their lugs to lose some of their torque. Simply repeat the same torque procedure listed above.



    More Wheel Tech
    03 Cobra
    566whp/515wtq

    Pics
    & Dyno
    Pics

  13. #27
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  14. #28
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    Under carriage torque specs tutorial


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    Whiteline Chassis Talk 1 – The basic suspension modes.

    Preamble:

    This is the first part of an ongoing series of posts discussing chassis and suspension tuning as seen by Whiteline. By that we mean that it’s our perspective based on the facts, as we know them.

    This is not meant to form the basis of the definitive perspective or encyclopaedia on the subject as we have a lot more yet to learn. For example, our professional library has over 30 texts on the subject and that’s just scratching the surface. However, we hope that some may use this information to better understand the basics, the Whiteline world and why we do what we do.

    Physics is physics but just as there are theory’s that are taken as fact till they are disproved, we too are open to new ideas, techniques and theory’s that may change our view and position. This is not meant to act as a disclaimer but rather as a reality check to hopefully highlight the fact that this does involve science and that the industry as a whole is constantly learning and changing as a result.

    For example, front wheel drive race setup as a science did not exist 15 years ago. It’s only really in the last 5 years that the techniques and principles developed at the cutting edge of the sport have entered the mainstream suspension industry. This is not to suggest that someone’s discovered the equivalent of front wheel drive “gravity” but rather, enough thought and science has now gone into this area to properly understand the physics behind the very complex interactions involved.

    This has lead to some dramatic changes in setup theory overall. Equally, its safe to assume that this is not the last time it will happen and we need to be ready to accept new ideas, question our existing ones and be ready to accept change. However, there are some things that are as fundamental as gravity and a good understanding of them will help illustrate and provide clarity in understanding suspension and chassis dynamics overall.

    The 4 Basic Suspension Modes:

    The attached table was actually taken from Racecar Engineering magazine (1997) and is very useful in showing the various and distinctly different modes of suspension travel. This is important because it highlights that we need to break down all movement into its correct mode and try to deal with it using the correct tool (or component).

    Needless to say it will become increasingly obvious how much of a compromise any conventional suspension system and why “active” systems are so much more effective (and why they are banned in most motorsport). However, in the real world we have to recognise that the 4 main modes, in alphabetical order are Heave, Pitch, Roll and Warp. Some of these are obvious and some people will already know others but it’s worth going through each one separately in detail.

    Heave is defined as a synchronous motion of all wheels in one direction. In simple terms, the vehicle body moves up and/or down as a whole.

    Pitch is defined as front and rear wheel pairs move in a synchronous motion but in opposite directions. That is, the body of the vehicle rocks either forward or backward resulting in the front or rear wheels pairs compressing or extending as a pair but in opposite directions to each pair.

    Roll is defined as the synchronous motion of each left and right pair of wheels albeit in opposite directions. Body roll in simple terms with one side of the vehicle extending while the other side compresses on its suspension.

    Warp is a little trickier but is one of the most important to understand properly. It’s correctly defined as oppositional motion in opposite directions for either left and right wheel pairs or front or rear wheel pairs. Or, synchronous motion in opposite direction in the case of diagonal pairs. In simple terms, this describes what happens when one single wheel moves up or down independent of the others in response to a change in the surface. This may be a bump in the road or a pothole for that matter. However, it is distinctly separate from all the others and needs to be for better understanding.

    All these modes are occurring constantly at any given time while the vehicle is moving. No surface is ever perfect and every change will result in one or many of these 4 elements coming into play. Separating them however helps us look at what components are involved in each, what they are doing and what is the optimal or hypothetical ideal to best deal with each. But before we start, its useful to jump ahead and quickly summarise the critical role of the wheel and tyre

    Every performance outcome on a car is dependent on the tyres. Cheese cutters will not cope with delivering big power to the ground while the brakes will struggle to stop the vehicle. Big wide tyres set to toe-in or set to big negative camber settings will sit like boxes on an angle to the road effectively running on the edges.

    It’s obvious that the tyre needs to be appropriate for the job and so does the angle or alignment setting but even more importantly, it needs to stay physically connected to the road. This is one of the most misunderstood and overlooked elements of suspension and chassis setup but is absolutely critical to a successful outcome. You can’t have grip with out contact and the main role of a good suspension system is to keep the wheel in contact with the road surface. Not just touching it but maximising the size and quality of the contact patch. More on this in future issues so lets go back to suspension modes.

    Springs are primarily designed to hold the car up leaving some compliance to allow the wheels to follow the changes in the road surface. In which case, we can ask the question what is the ideal spring rate needed for “warp” modes? Many, including Whiteline will argue that the theoretical ideal rate is effectively zero, none, zilch! Why, because any rate that reacts against unimpeded individual wheel travel will result in a reduction in the quality and quantity of the contact patch.

    Note: Interestingly there is a model of a suspension system in existence that delivers just such an outcome using hydraulics. It is patented but is unlikely to reach mainstream production due to the relatively complex nature of the components. However, modern commercial examples surround us already. Racecars including F1 use separate springs for the various modes (done so for decades) while modern active dampers or shocks are designed to respond in different ways to different loads and modes.

    Roll is best controlled by swaybars. Why not springs, you ask? Consider what happens when the car is loaded into a corner in roll and one or both of the loaded wheels encounter a change in road surface through a warp mode? Remembering the law of equal and opposite reactions, a loaded outside front wheel encountering a bump will encounter a significant rate through the pre-compressed spring (car is loaded in corner) resulting in the spring passing on the load to the body that will move away from the road. Result? Lost contact, even if only for a moment but potentially disastrous from a handling point of view when you consider its doing a great deal of the cornering work at the time.

    Heave and Pitch modes need sufficient rate to stop the car bottoming out over uniform bumps or the front or rear axles running out of travel as this would have the same effects as excessive resistance on a loaded wheel as detailed above. Specifically, we run the risk of a tyre(s) momentarily losing contact with the road leading to loss of grip. In simple terms, this loss of grip is part of what you feel when the car understeers or oversteers. Understeer being a relative loss of grip on the front while oversteer is the relative loss of grip in the rear.

    Whiteline believes in using as little spring rate as absolutely possible for these reasons. We start from a small amount and increase, as we need it, not the other way round. As a full range suspension manufacturer, we believe in using the right component designed for each job to deal with its chief responsibility. That’s why we use swaybars and not springs to control body roll. We would no more design a swaybar to hold a car up in pitch or heave than we would try to get the spring to hold the body up in roll.

    If one accepts that the above modes are fair and logical, it follows that any increase in rate for a desired outcome must lead to an increase in other areas to maintain a balanced outcome. So how do we explain a 100 or 300% increase in the factory spring rate while leaving the roll resistance rate the same? For example, how could one justify using 400lb + springs on a road/race car while still using stock swaybars when the stock springs were only 200lb.

    We don’t, because it doesn’t make sense. Assuming we ignore any “bandaid” or short term tuning remedies, a balanced and inclusive solution that recognises the unique role of each component will always be far more effective.

    More in future issues but here's a quote from the head of one of the fastest touring car teams in Australia.

    "The Shocking Truth" - an article in Motorsport magazine, No 192.

    In this article, Larry Perkins is talking about their development program since the end of the '99 season, where he felt they were 3/4 sec off front running pace, to end of 2000, where the Castrol Team (his) were winning front row starting positions, races and setting fastest laps again.

    ... One major aim of all the changes was to be able to run very much softer springs, front and rear. They accept more roll in doing this, but the important thing to consider is the overall dynamic situation - if you've got the stiff chassis and suspension components, the suspension that is free to move without friction, carefull optimisation of the suspension geometry, and shocks that can control the chassis platform, it does work better.

    Jim Gurieff

    Whiteline Automotive


  16. #30
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    Whiteline Chassis Talk 2 – Piston volume, when size DOES matter!

    Preamble:

    A shock absorber is many things but chief in its multi-function is role is that of an effective energy converter. Remembering that energy cannot be lost, by dampening (hence the reason they are more correctly referred to as dampers) the springs or body’s oscillations, the shock converts kinetic energy largely into heat.

    This function has little to do with extended or compressed length, alloy or steel body construction or even spring rate used however it is just as equally overlooked by most consumers when choosing shocks. Equally, very few manufacturers quote or publish this information yet its arguably one of the most important aspects to consider when deciding what’s appropriate for each situation.

    Size IS important:

    So why is shock or piston size so important? Because it is the most direct measure of the rigidity of the unit and the oil volume. The biggest enemy of a shock is heat and lost of it is inevitable when it starts to work hard. With increased heat you have decreased oil viscosity, which means a dramatic drop off in damping performance leading to higher speeds leading to higher temps…... We are building a database of stock shock heat outcomes under test to demonstrate the outcome but you can understand why racecars use remote canister or reservoir designs to increase the volume of oil and gas.

    Not only does viscosity reduce with heat, gassing and aeration increases further reducing performance. With out being critical of any particular brand, many popular twin tube adjustable shocks simply can't go past 2 to 3 laps of a typical supersprint or short circuit race with out the driver complaining of the shocks "going off".

    As a tuner and fitter of many brands of shock absorbers, we recommend, use and fit many quality brands of shocks on a regular basis but it’s simply not fair to expect a 32mm piston twin tube to deal with spring rates in excess of 250lbs, high performance tyres and hard use. It may surprise some that during recent tests of an MY05 Sti, 3 high speed laps of a short circuit resulted in shock body temps in excess of 65 Deg C using stock suspension and tyres. You can imagine what would happen with intermediate tyres and/or higher spring rates

    A good way to see why piston size is so important is to use P x R2 to highlight what this means in terms of surface area and resultant oil volume.

    Lets first start with a stock front strut with a 30mm piston and 22mm shaft.

    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 sq mm. That’s the effective oil area below the piston (call it cylinder area), but we need to factor in the shaft and its displacement effects above the piston.

    That’s a 22mm diameter shaft which equals an 11mm radius, squared we get 121, multiple x P we get 380 sq mm. Take the cylinder area of 706 and subtract the shaft area of 380 and we’re left with 326 sq mm. Hence using this and applying the same process to some alternative sizes we get the following outcomes for comparison:

    Stock twin-tube strut with 30 mm piston / 22 mm shaft

    = 706 sq mm below and 326 sq mm above. Average of 516 sq mm

    Nominal “40mm” inverted mono-tube strut design using 36 mm piston / 12 mm shaft (most common configuration)

    = 1017 sq mm below and 904 sq mm above. Average of 961 sq mm.

    Group 4 non-inverted mono-tube strut design using 46 mm piston / 22 mm shaft

    = 1661 sq mm below and 1281 sq mm above. Average of 1472 sq mm

    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 Group 4 has 285% more than stock or 53% more than a typical “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. It is important to note that a twin-tube shock will have some additional fluid in the outer chamber however the working chamber is relatively small.

    It can also be assumed from this example that a mono tube will have better and faster heat dissipation properties than a twin-tube due to the oil chamber being closer to the atmosphere. (Refer to other section for explanation of different internal designs)

    Adding higher spring rates into the mix only complicates the problem. Increasing spring rate (fitting lowered coils that need to have an increased spring rate – refer to separate explanation) while using standard shocks is one of the best ways to shorten its life. It is not unusual for a car with 10,000kms of wear losing over 50% of its effective damping due to fitment of lowered springs from near new. This is due to excessive wear and heat as the damper is not designed to control the increased rate.

    Fitment of higher rate springs must be balanced with fitment of more appropriate shocks or dampers rated to control the higher rate. However, simply increasing the rate may easily overpower the capacity of the shock and its oil to deal with the higher rate. Maintaining control over the wheel/body oscillations (the main task of the shock) is dependent on a balanced relationship.

    This relationship must also factor in intended use such as motorsport or off-road driving. For example, a 32mm aftermarket shock with an appropriate valve spec to suit a 300lb spring may be OK for daily cruising but it’s unlikely that it will cope with any prolonged heavy use, even down to minutes.

    Please check my math and feel free to comment. Either way, I hope you can see why racecars use such large shock absorbers and why off-road racers will even use multiples per wheel with external reservoirs or canisters.

    Cheers

    Jim Gurieff

    Whiteline Automotive

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