this thread is actually a continuation of my original "DIY High-End Suspension on a $1000 Budget" thread found here, so now that I've succumbed to the overwhelming responses I've received from that thread, due to popular demand & request, I'm now posting up a sales thread as an Official Vendor.
those who follow my contributions to this community know me as TWGURU or Tony. Whilst my time in this community has been relatively short, I like to believe I have contributed a fair amount of "suspension tuning theory" in this short time, especially when it comes to my area of speciality; pressure tuning.
This is an area that, afaik, has not really been covered much. This is probably likely due to most coilover manufacturers not even knowing what it is, or don't really pay much attention to (cough cough...Bilstein...). I know Shaikh @ FCM has briefly touched on the topic (I highly recommend watching his Youtube videos), but hasn't really expanded into the reasoning behind it like I have done in my original thread.
Those who have enjoyed my original thread and find it educational should now have a better understanding of the importance of proper QC techniques, why Hysteresis and Cavitation is bad and, most importantly, how a damper actually functions and the role it plays in the suspension system.
Taking these important principles and applying them in the real world is the basis and foundation of all the dampers that I spec, build and tune for both my students (I teach suspension tuning theory to various manufacturers/specialists across the globe) and now my paying customers.
It is from this, I am proud to announce the start of VST: Veritas Suspension Technologies. Veritas is latin for truth, with our aim being to Unveil the truth behind the suspension industry
Our Penske style valving:
Valving - Penske style* Double Digressive Pistons/Parabolic Needles/Rebound Jets. These are machined to within 99.9% of the tolerances of the off-the-shelf Penske components. Made in USA
Shims - Sandvik 20C Carbon Steel Shims. Imported from Sweden, these shims were developed specifically for damper valving and are not the cheap/generic shims that are commonly used by our competitors
Seals - We only use genuine Viton Low-Friction O-Rings and High-Temp BUNA Seals
Oil - We use genuine UK-Formula Silkolene RSF 2.5w high-VI shock fluid. This fluid will retain it's performance properties at extreme temperatures without breaking down
Monotube Bodies - We use 52mm OD, fine-threaded carbon steel bodies with zinc electro-plating for corrosion resistance. Internal surfaces are impregnated with an anti-friction compound using a proprietary lapping process. Our 4mm thick walls ensure your safety. Made in Taiwan
Piston Rods - We use 14mm OD (non-strut) and 20mm OD (strut) chromoly-steel piston rods. External surfaces are impregnated with an anti-friction compound using a proprietary lapping process. Made in Taiwan
Bottom Caps - The majority of coilovers on the market use standard self-healing rubber seals to charge their dampers. Whilst these serve their purpose, they are prone to leaking and, most importantly, make pressure tuning extremely difficult (these rely on Nitrogen Needles to charge, and will leak anywhere between 20-50psi as soon as you remove the needle). We use industry standard schrader valves (same as tire valves) that leak less (all high-pressure dampers will leak nitrogen pressure. Anyone that says otherwise don't know what they are talking about) and allow precise pressure tuning to within 5psi. Made in Taiwan
*If you are wondering why we say Penske style, it is because their default off-the-shelf components do not fit our piston rods without a lot of machining work, so instead, we sourced the machined components from elsewhere hence "style" as you cannot buy these directly from Penske
Our mounts (These ones are for the ND):
Upper Mounts - We use Hard Anodized 6061-T6 Aluminum with a genuine Japanese NMB Spherical Bearing for both Front & Rear Mounts. Made in Taiwan/Japan
Perches/Lower Mounts/Collars - We use Hard Anodized 6061-T6 Aluminum. Made in Taiwan
Springs - We use genuine Swift Springs which have a lifetime guarantee against spring sag. Made in Japan
Coil Rotation - We use genuine Swift teflon thrust sheets between the spring/mount surface to allow the spring to rotate independently of the damper body. These do not rust nor require maintenance like Torrington bearings do, and are self-lubricating. Made in Japan
Rebound-Only Adjustable Damping - By default, this is the setup we use and recommend. As compression damping is fixed, we will offer two different tunes for our customers to choose from; a "Street Tune" for general road compliance, and a "Road/Race Tune" for those wiling to sacrifice compliance for performance. Both of these tunes will be based on high performance street tires (not R-Comps), with the Road/Race tune offering compression damping at the upper limit of traction threshold
Simultanous Compression/Rebound Adjustable Damping - Whilst we highly recommend against this setup, we understand why some would prefer this and we can accomodate if required. This will use the same valving profiles as our Rebound-Only Street and Road/Race tunes; the only difference being you can adjust compression as well. Be forewarned though; lowering your compression will also lower your rebound, resulting in a softer but also bouncier ride. Likewise, increasing compression will also increase your rebound, resulting in a harsher ride
Independently Adjustable Damping - Via the use of external reservoirs, these will allow you to adjust the compression damping independently from the rebound damping. What this means is, if you want to lower your compression damping for road compliance, you can do so without having to worry about pogo'ing all over the place. Likewise, if you want to increase your compression damping (to the upper limit of traction threshold for your tires), you may do so without having to worry about your rear end skipping all over the place
Ride Height Adjustment - Although we utilize threaded/adjustable lower mounts, these are NOT used to adjust ride height (contrary to other manufacturers beliefs). The sole purpose of the adjustable lower mounts is to allow you to set your desired bump/droop travel; typically, you set this to a 1:1 ratio between Tire : Damper. You would then lower/raise your vehicle using the lower spring perch. As we use linear springs, pre-loading the spring while unloaded does not change nor affect the spring rate (unless pre-loaded higher than static spring compression which you'll never do). If you adjust ride height using the lower mount, you will change your Tire : Damper ratio which you do not want to do
Those who have been following my original thread (linked at the start of this post. If you've not yet had the chance to read it, please feel free to do so. You may (or may not) learn a lot from it) will have a better understanding of our views & philosophy when it comes to the intricacies of damper valving & tuning. To cut a long story short, we tune our dampers based on:
1) Pressure Tuning
This is one of the most important parts of damper tuning and, unfortunately, is lacking from the majority of coilovers currently on the market. The process consists of a combination of rod displacement, chamber volume and nitrogen pressure calculations. It is via pressure tuning you can fine tune:
- Hysteresis. Also know as valving lag, and is the valving delay between the opening (acceleration) and closing (deceleration) phases of the compression and rebound strokes. When looking at shock dyno graphs, it is important that you view the Force vs Absolute Velocity Graph as this clearly shows any issues with the valving as shown below
- Cavitation. This is when the damper oil pressure drops to zero and vaporizes, which results in decreased damping forces. In monotube dampers, this happens when there is not enough nitrogen pressure to overcome the pressure drop caused during the compression stroke. Consistent cavitation will result in the damper oil breaking down and leads to damper fade
- Damper Response. All monotube dampers are gas pressurized and have what is called an internal gas spring. This is the initial force that needs to be overcome before the damper can start functioning (i.e the rod moving). Too high an internal gas pressure will result in an increased gas spring force which results in decreased damper response
A competitors damper with bad/non-existent pressure tuning:
A VST Stage 3 damper with proper pressure tuning:
It is not difficult to determine which graph above is the better performing damper. Viewing only a basic single-line Average Force vs Absolute Velocity Graph (which simply averages the open & close phases) or Compression Closed/Rebound Open Graph (which only shows 50% of the results) are meaningless as they hide any potential issues as shown in the graph above. Unfortunately, those are precisely what most of our competitors will show you in their marketing materials.
2) Valve Tuning
Double Digressive Piston - We use this style of piston as it generates a quick ramp up of damping pressure at low damper speeds (user-controlled input) allowing increased responsiveness and stability, and "blows off" damping pressure at higher damper speeds (bumps) allowing increased comfort and control
Critical Damping - This is described as the damping force required to control the oscillations of the suspension (i.e the energy stored in the spring) and return it to equilibrium. Too little damping force (underdamped) and your damper is unable to control the energy released from the spring, causing a bouncy or floaty ride. Too much damping force (overdamped) and your damper overpowers your spring, causing harshness and loss of traction. We generally valve all of our dampers to within 65-70% of Critical Damping @ 3"/sec damper velocity (Between 0-5"/sec is where the average vehicle will spend the majority of it's time). To calculate this value, we use a 2 DOF (Degree of Freedom) model which utilizes Vehicle Sprung & Unpsrung Weights, Damper & Spring Motion Ratios and Tire Spring Rates
3) Natural Ride Frequencies
Before we can tune the valving, we need to determine the spring rates required. Unlike our competitors that choose their spring rates (this can be inaccurate, as what feels soft on one car may feel harsh on another), we calculate the correct spring rate balance using natural ride frequencies with a ratio of approx. 1:1.2 (front:rear). Typically, these frequencies are (but can vary slightly):
Street Car - 1.0-1.5hz
Sports Car - 1.5-2.0hz
Track Car (Non-Aero) - 2.0-2.5hz
Track Car (Aero) - 2.5-3.0hz
4) Quality Control
Damper Bleeding - This is the process of bleeding/removing air from the damper during assembly. A monotube damper works on the premise of 3 individual chambers: Rebound Chamber, Compression Chamber and Gas Chamber. The Rebound & Compression Chamber must only be filled with oil, which is, for all intents and purposes, non-compressible. The Gas Chamber must only be filled with gas (usually Nitrogen) and is compressible. If there are air pockets inside the Rebound and/or Compression Chambers, then these turn from a non-compressible state to compressible state and Hysteresis occurs. Unfortunately, a large % of the oil in a bottle/drum is dissolved air. If, during assembly, this air is not removed from the oil, then you will have "compressible oil" inside your Rebound/Compression Chambers. Budget manufacturers don't care about this (or even know the reason why). Most good manufacturers will spend 20+ minutes manually pumping the piston rod up/down the damper body to bleed the air. Unfortunately, this only gets you 90% of the way there. The proper way to do it, and the only way to bleed 100% of the air out of the damper is to use a process byy which air is vacuumed out of the damper body and oil is vacuum-filtered via an automatic Vacuum Bleeding process. All VST Stage 2-4 dampers are Vacuum Bled
Dyno Testing - In addition to dyno tuning, all VST Dampers are individually tested on industry-standard MTS Shock Dynamometers to check for valving inconsistencies and issues. All Stage 2-4 customers will, during our build process, be updated with live dyno results showing them the progress of their dampers. There is zero excuse for any coilover manufacturer not to offer you these results.
Put simply, if a coilover manufacturer cannot supply you with a Force vs Absolute Velocity Graph for your exact damper, then they are usually a trading company selling cheap mass-manufactured coilover kits from the Taiwanese-Trio with non-existent QC. If they will not supply you with one for your exact damper, or want to charge you money to do so, then they have something to hide.
The one question that will always be asked is Where are these manufactured?. That is a good question and the answer to that is globally. Why do I say this? The reason is because:
1) All of our components, as described above, are imported from several different countries: USA, Japan, Sweden, United Kingdom and Taiwan
2) Although I am from Walnut, CA, my job requires me to travel the globe. However, because my job is in this exact same industry, it means that I can build and tune dampers to the exact same specifications no matter which location I am at (due to all of my clients & students having the proper equipment/facilities). A set of dampers could be shipped from USA one week, then shipping from Australia the next!