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Project STurdteen: Installing KW Clubsport Coilovers

by Rathyna Gomer

 

Many of you have been keeping along with Project STurdteen's progress and have been watching this ugly duckling transform into the beautiful, regal swan that she was always intended to become. In the last article, we overviewed some of the sweet Parts Shop Max suspension that we were planning on putting onto the S13.

Before diving into that installation of those parts, let's take some time to look at what other suspension upgrades will be addressed. With the renowned suspension engineer, Sensei Kojima around, there's no doubt that the best of the best will be going into this build. STurdteen's primary focus is to become a demo car and to be a grassroots-level competitive and reliable drift car. The car will see the streets on occasion, but it will mostly be track dedicated. Choosing the appropriate suspension is imperative. This is the exact reason why we decided to go with KW Suspension Clubsport coilovers. 

 

The KW Clubsports are incredible. The corrosion resistant stainless steel bodies, double adjustable damping, and sealed pillow ball mounts work together for ultimate functionality.  

The stainless bodies prevent the stainless steel reinforced thermoplastic spring seat from getting corroded and stuck. This is a problem nearly all coilovers eventually have. The pillowball mount eliminates the stock squishy rubber mounts. This makes every bit of wheel movement controlled by the damper giving more ride control and less tire shock. Consequently, his equates to more grip.

 

These coilovers showcased a gas charged double adjustable twin tube damper, which have some characteristics of a monotube. Being able to adjust both compression and rebound damping is great for this project so that we can fine-tune the suspension settings for any track layout!

By having the compression and rebound damping adjustable independently, the KW Clubsport allows the driver to finely adjust the shocks to the track and changing track conditions. This is critical in drifting.

 

KW makes other coilovers that are intended for track and street use such as the Variant II and III, but the Clubsports have a couple of more features that make them more friendly for track in for this car. These coilovers have stiffer valving and spring rates as well.  

In this case, we will be running an 8kg spring in the front and a 6kg spring in the rear. These spring rates have been proven to work well in most conditions and have been run in Formula D with a lot of success on the current FD tracks on the circuit. 

The front Clubsports have a camber plate with an oversized stainless spherical bearing that is sealed with a rubber dustboot. This should prove to be much more durable than the typical camber plate with an open bearing.

 

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Comments
warmmilk
warmmilklink
Wednesday, May 03, 2017 10:28 AM
I'm pretty sure you can't really call that thing a turd anymore...
MaysEffect
MaysEffectlink
Wednesday, May 03, 2017 3:10 PM
^IKR...What is the difference in spring rate, shock length and other important changes? Given the fact the HKS kit seems like a better design that is both rebuild-able and offers pressure adjustment, it seems like just changing the springs and possibly rebuilding them would have been cheaper and a better route. Unless of course the KW's were a "sponsored" upgrade.

And are those for sure tender springs? and not helper springs? They seem much too thin to be a tender.
czubaka
czubakalink
Wednesday, May 03, 2017 8:06 PM
Yeah, I'm with warmmilk as well. I'd expect a turd to be running leaky kyb's or monroe's or something. Not trick arms and clubsports.
czubaka
czubakalink
Wednesday, May 03, 2017 8:10 PM
Oh, and I'm not complaining, I absolutely love this build.

Off topic - are there many drift events at willow springs? I'm moving to Ridgecrest (blech) next week and am looking forward to finally meeting everyone.
Mike Kojima
Mike Kojimalink
Wednesday, May 03, 2017 10:38 PM
The HKS shocks are nowhere close to the performance and quality of the KW Clubsport. The KW's are totally rebuildable and the improvements were gone over with in detail in the article unless you don't understand the implications of wide range independently adjustable damping, stainless bodies, etc. The tender springs are 2KG in rate. Having a Schrader valve isn't really an advantage. Increasing the gas pressure increases the gas reaction force which is a little like adjusting the spring preload and only increases the initial force needed to move the shaft, not affecting the overall spring rate. It is not a very useful adjustment. The HKS shocks are street performance and the KW's are Motorsports grade. Whether or not they are sponsored or not is irrelevant to anything related to how they perform. KW Clubsports are dollar per dollar, some of the best dampers on the market.
8695Beaters
8695Beaterslink
Thursday, May 04, 2017 5:36 AM
Does spacing out the strut body up front affect tire clearance at all?
Mike Kojima
Mike Kojimalink
Thursday, May 04, 2017 7:34 AM
No, because the lower control arm is also proportionally much longer.
MaysEffect
MaysEffectlink
Thursday, May 04, 2017 10:57 PM
"The HKS shocks are nowhere close to the performance and quality of the KW Clubsport." This is an arguable statement. The HKS front strut is an inverted monotube, which is proven to be stronger than a twin tube shock, certainly on this particular suspension design. With regards to material, aren't they HKS coated steel as well? Without showing a shock dyno comparison, how are we sure there is a massive difference throughout the adjustment range or the actual compression/rebound curve? The only real benefits i noted is the better spring package and the independent rebound/compression adjustments. And as i was trying point out, a spring change could have been done to the HKS kit for a cheaper price. And being able to adjust the gas pressure could be beneficial, certainly if you are changing the spring rate and the effective shock travel length. Having the ability to change gas pressure is one of the biggest selling points from some of the most expensive companies like Moton or JRZ. Moton specifically made a point about being able to custom tune the gas pressure to compensate for a change in spring rate and overall load. Whether or not this is a relative performance gain i can't argue, but nonetheless they made a point to note this.

With regards to cost. It makes a huge difference, certainly considering this is basically advertisement. For people who would like to know the cost differences and potential upgrades. Changing the Springs and rebuilding the shocks can cost significantly less than buying one of the most expensive off the shelf or custom kit on the market. As such a rebuilt kit can net comparable performance over spending thousands of dollars more on a new coilover kit.

How exactly are we suppose to know the improvements from this kit was purely down to the difference spring rates, or the actual damper internals?

I don't understand how one kit being "street performance" vs "Motorsport grade" is a buying point either. Obviously the HKS kit has lasted and worked up until this point. Why would it not be capable of providing equal reliability?

I'm not trying to be difficult. My main concern was what exactly was the difference in spring rate and why exactly was it necessary to make such an upgrade. Most people don't have that type of money to do such an upgrade. If someone already bought a decent coilover kit with good options, why would they scrap it to buy a completely new kit.
MaysEffect
MaysEffectlink
Thursday, May 04, 2017 11:06 PM
I will admit I'm guilty of skimming through the article. I looked over the short paragraph of the spring rates. But no comparable information was listed between the two kits in this regard.
538
538link
Saturday, May 06, 2017 2:50 AM
@MaysEffect: I think the main advantage to the KW is the superior valving, which more than makes up for the monotube vs twin tube differences. It was probably also chosen by the MotoIQ crew because of their familiarity with KW products.

They have lots of development time with KW setups in 240sx chassis, and I am sure it is easier and more time effective for them to go with a setup that they know exactly how to get what they want out of it, than to rebuild the HKS and try a bunch of different adjustments and hope to end up at the same level. Any money saved by rebuilding the HKS would get cancelled out by the additional effort of developing that setup. In the end, it is better to have a well-known setup that you already know how to adjust it to do exactly what you want.

You are right that shock dynos would illustrate the differences, but I dont think that was what they intended with the article.
MaysEffect
MaysEffectlink
Monday, May 08, 2017 8:10 PM
I understand your point, but it still undermines the importance of having the ideal spring rate and load requirements for the intended use. The biggest change here i believe is still the springs. All other factors of piston size and valving dynamics are non-quantifiable factors given they are variable by design.

We can clearly see the difference in spring setup between the two. How would we honestly know the HKS wouldn't perform better or worse simply by utilizing the same spring change as offered by clubsport kit? And how do we know the "problems" with the HKS kit simply wasn't a flaw of improper spring rates for the intended use. People have been preaching the importance of shock dynamics without ever really stating how the spring setup play a important factor in subsequent suspension changes. The shocks regardless of valving dynamics are useless without being in the correct spring load window for the car and intended use.

I'm only harking this point because i went through the same dilemma with my upgrades now with my Bilstein kit. There was actually nothing wrong or significantly different between my Bilstein valving and what i had setup with JIC magic for their kit. What we did find was the springs were severely undersprung and absolutely useless for both street and track use given the weight of the vehicle. Before i fully upgrade to the JIC kit i had them give me a different spring kit to use with the Bilsteins and the difference was night and day. We are still in the process of upgrading to the JIC shocks, but just doing a complete coilover kit because of better "valving" doesn't mean much of anything without a spring change.

This issue is also compounded by the fact the HKS kit was replaced with a inferior twin tube design (no matter the valving quality). Even in several recent articles on Drift cars (most notably Asbo's IM build), Inverted Monotube struts are used religiously for the reliability and consistent feedback. This is almost standard across top drift and rally cars. And considering how much abuse these type of cars have, it is understandable why. Twin tube shocks with thinner piston shafts are more prone to damage and leaking no matter the material or use. Not to mention the shaft has to be hollowed out to allow for the valve adjustment guides which only further decreases strength.

Simple by having a more complex valving design will never be easier to setup than a simple one-way adjustable kit. Unless you are simply copying someone else or a previous setup and not straying far from that baseline. The benefits come from being able to set the rebound and compression independently from each other. This potential alone has nothing to do with the valving window alone but its design to allow independent adjustments.

And lastly about cost, i disagree still. Based on my own cost in actually doing both upgrades. Having the shocks rebuilt and buying new springs is still cheaper than going with a new kit. New springs can be had for under 600 dollars and having the shocks rebuilt is about the same. That's only about 1200 dollars. I don't believe there are any "clubsport" coilover kits for under 2000 dollars. From my car perspective, the Bilstein Clusport kit is well over 3000 dollars as is the KW and a comparative Ohlins kit. Both the Bilstein & Ohlins being inverted monotube front struts, upside-down monotube rears.


I'm interested to see the response to the upgrades none the less, i do indeed hope it works as intended.
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