KW Clubsport Damper Rebuild

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I traded my suspension setup to another forum member for his KW Clubsports that he believed needed to be rebuilt.

After contacting KW tech line I learned that they do not assist with DIY'ers who want to rebuild their dampers. They told me only KW authorized technicians could rebuild the dampers and they required "special tools".

So without spec cars or oil information gmitch and myself decided to tackle the project. Maybe some of you know this gmitch has a background in rebuilding and revalving motorcycle shocks.

First off it seems that KW underestimated that we have 908ssp who is a master machinist/fabricator (I mean c'mon just look at pictures of his car). 908ssp was able to machine out the damper rod clamps and the threaded cap (4 post).

From left to right: damper cap wrench, rear shock damper rod clamp, front strut damper rod clamp, and lastly a re-purposed Penske shock clamp

First the strut and dampers were taken apart.

Strut

Damper

Carefully remove all of the components (o-rings, spacers, etc) in the order they were removed.

All strut components on the left and all shock components on the right.

Using the clamps that 908ssp made we were able to separate the damper rod from the inner rod. The shaft assembly was disassembled because they chrome plated rods will be titanium nitride coated for a reduced friction mu and better thermal properties (reduce the amount the oil is heated up by the shaft). I will go into how KW's valving works later in this post/thread.

While dissembling the front and rear spring assembly (it is composed of both a tender and coilover spring) we noticed that the spacer was composite. You can see it was deformed due to the spring forces. Again 908ssp was able to machine a set of aluminum spacers to reduce the change for deformation due to spring forces.

After inspecting the springs that are standard from the KW Clubsport kit I decided that they were a bit much for a dual purpose daily driver (on nice Michigan days) and a HDPE/track day toy.

Springs that came with the KW Clubsport kit:

Front: 570 lbs/in
Rear: 340 lbs/in

With the street comfort factor in mind and referencing what both gmitch and 908ssp run on their coil-over setups, I decided to run the following:

Front: 60 N/mm -> 343 lbs/in
Rear: 50 N/mm -> 286 lbs/in

The new springs were yellow and I did not really care for that color all the steel parts were sent off to be powdercoated "race red". Also all the aluminum parts from the caster camber plates were sent off to be anodized gold. Just a little bling since we are already in there.

The shafts were dropped off to be Ti-N coated, so now it is a waiting for all the components to finish being coated.

That left one last question what oil should we use? We did measure the oil level of the damper so we did know that these dampers required for their internal air spring (these dampers do not have a bladder so therefore they are not gas charged, making them more similar to motorcycle/dirt bike forks).

After calling around a few places we found that KW uses a light oil. Luckily gmitch had some extra Ohlins light shock absorber fluid laying around, Viscosity 14,0 cSt at 40C.

I will update more as we rebuild the struts, including some technical information on the valving and how it uses a ZF Sachs style spring on the piston assembly.

 

[Napoleon85]

You, sir, are much braver than I. Good luck on the rebuild - I'm definitely looking forward to following this and seeing the results.

 

[Roadracer350]

AWSOME job on the machining!!

 

[Random Asshole]

Wow. Nice tech. Did you happen to ask what KW would have charged for rebuilding?

 

[Vorshlag-Fair]

Most KWs sold in North America are twin tube designs, but the KW Clubsports are monotubes - and pretty much anyone that can rebuild a monotube race shock can probably rebuild those. You'd be surprised how many rebuild parts can be and are often shared between JRZ, Moton, AST, MCS, Penske, Ohlins and other monotube racing shocks and struts. Shims, seals, O-rings, and sometimes even pistons and shafts.

Most shock rebuilders will have the various clamp blocks needed (these are blocks of machined aluminum that can squeeze the chrome shaft or strut body without damaging them), too. Your guy is quite industrious to make those from scratch!

If there are any KW-specific parts that are worn beyond re-use you might try contacting Bruce at PSI. If anyone has rebuilt KW Clubsports in the USA it will be those guys, so he might be able to source the parts. And there are tons of shock oils out their, but you look to have found what you need already. Again, you can run a variety of viscosities (which can change the shock's characteristics) but your motorcycle shock guy would know all of that.

RE suspensions also has a ton of shock rebuild tools, supplies and oils. It's usually not worth the cost or effort to gear up and rebuild shocks.... for one set. If you rebuild shocks for a living, or if you own a race team with multiple cars (that usually have multiple sets of racing shocks), then sure. The tools, supplies and shock dyno costs can add up...

Good luck,

 

[Roadracer350]

Most KWs sold in North America are twin tube designs, but the KW Clubsports are monotubes - and pretty much anyone that can rebuild a monotube race shock can probably rebuild those. You'd be surprised how many rebuild parts can be and are often shared between JRZ, Moton, AST, MCS, Penske, Ohlins and other monotube racing shocks and struts. Shims, seals, O-rings, and sometimes even pistons and shafts.

Most shock rebuilders will have the various clamp blocks needed (these are blocks of machined aluminum that can squeeze the chrome shaft or strut body without damaging them), too. Your guy is quite industrious to make those from scratch!

If there are any KW-specific parts that are worn beyond re-use you might try contacting Bruce at PSI. If anyone has rebuilt KW Clubsports in the USA it will be those guys, so he might be able to source the parts. And there are tons of shock oils out their, but you look to have found what you need already. Again, you can run a variety of viscosities (which can change the shock's characteristics) but your motorcycle shock guy would know all of that.

RE suspensions also has a ton of shock rebuild tools, supplies and oils. It's usually not worth the cost or effort to gear up and rebuild shocks.... for one set. If you rebuild shocks for a living, or if you own a race team with multiple cars (that usually have multiple sets of racing shocks), then sure. The tools, supplies and shock dyno costs can add up...

Good luck,

Terry that shim stack looks a lot like the Penske stack in the rear shocks on the bikes just a little thinner. Is that High and Low speed valves?

 

[Powered by Ford]

You, sir, are much braver than I. Good luck on the rebuild - I'm definitely looking forward to following this and seeing the results.

Thanks! I was hoping to put them on a shock dyno, but due to some upcoming events it does not look like I will be able to. Maybe over the winter I will pull them off and have them tested.

AWSOME job on the machining!!

That's Alex or on here 908ssp. He does an excellent job alright!

Wow. Nice tech. Did you happen to ask what KW would have charged for rebuilding?

Thank you! Yes, I did it was about $600+shipping both ways to have them rebuilt by KW. With Ti-N coating the shafts, new springs, and coating the parts I am still well under that cost. Believe it or not I found a Ti-N place local to me and they did all 4 shafts for $94. Not bad at all. If any is interested in getting some parts Ti-N give them a call.

http://www.ticoating.com/index.html

 

[Powered by Ford]

Most KWs sold in North America are twin tube designs, but the KW Clubsports are monotubes - and pretty much anyone that can rebuild a monotube race shock can probably rebuild those. You'd be surprised how many rebuild parts can be and are often shared between JRZ, Moton, AST, MCS, Penske, Ohlins and other monotube racing shocks and struts. Shims, seals, O-rings, and sometimes even pistons and shafts.

Actually not all of KW's Clubsports designs are monotube. For the S197 chassis they are still a twin-tube design, but have compression and rebound adjustability as the lower V-series only have rebound or are non-adjustable. You can see the inner and outer tube before and after cleaning.

Before cleaning:

After cleaning and inhaling more brake-kleen then I ever want to again. What a headache it can cause!

image7 by matthewatitus, on Flickr
Notice gmitch's suspension table? Trust me he knows his suspension.

Most shock rebuilders will have the various clamp blocks needed (these are blocks of machined aluminum that can squeeze the chrome shaft or strut body without damaging them), too. Your guy is quite industrious to make those from scratch!

If there are any KW-specific parts that are worn beyond re-use you might try contacting Bruce at PSI. If anyone has rebuilt KW Clubsports in the USA it will be those guys, so he might be able to source the parts. And there are tons of shock oils out their, but you look to have found what you need already. Again, you can run a variety of viscosities (which can change the shock's characteristics) but your motorcycle shock guy would know all of that.

RE suspensions also has a ton of shock rebuild tools, supplies and oils. It's usually not worth the cost or effort to gear up and rebuild shocks.... for one set. If you rebuild shocks for a living, or if you own a race team with multiple cars (that usually have multiple sets of racing shocks), then sure. The tools, supplies and shock dyno costs can add up...

Good luck,

Thanks again Terry for the contacts, all the components right now look great and re-usable.

Yes, we do understand that changing the viscosity changes how the damper's characteristics, after calling and asking around I think we are close to what KW specifies for their clubsports. However, I do have to say we really do like how KW uses nearly the same architecture (atleast in the s197 units) from front to rear in the dampers.

 

[Department Of Boost]

Most KWs sold in North America are twin tube designs, but the KW Clubsports are monotubes -

We were told that these were Clubsports. The person we got them from got them used too. I guess they are “mystery” dampers, LOL. They are definitely twin tubes though. Whatever they are they were had for a ridiculous deal. If Matt had 5x the money in them they would still be worth it.

and pretty much anyone that can rebuild a monotube race shock can probably rebuild those.

I was wondering what we were going to find in there. Ends up not much. They are dead simple. They are a 2 on the damper difficulty scale (1-10). Not nearly as complicated as the twin piston (not twin tube, twin piston) Motocross shock I have sitting on the bench. They are good dampers for Matt to learn on. And it means I can just provide “moral support” while he does most of the work.

Most shock rebuilders will have the various clamp blocks needed (these are blocks of machined aluminum that can squeeze the chrome shaft or strut body without damaging them), too. Your guy is quite industrious to make those from scratch!

I’ve got a toolbox full of custom clamps, tools, etc for doing suspension stuff. Off course nothing in these shaft sizes though. 908SSP to the rescue!

 

[Wicked GT]

This is an awesome thread, nice work! You need special tools to work on our struts/shocks... meh, we will make our own! Love it!

 

[ArizonaGT]

Interesting.

 

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We were told that these were Clubsports. The person we got them from got them used too. I guess they are “mystery” dampers, LOL. They are definitely twin tubes though. Whatever they are they were had for a ridiculous deal. If Matt had 5x the money in them they would still be worth it.

I did confirm the part numbers on the dampers are clubsports for an s197 when I first contacted KW.

I was wondering what we were going to find in there. Ends up not much. They are dead simple. They are a 2 on the damper difficulty scale (1-10). Not nearly as complicated as the twin piston (not twin tube, twin piston) Motocross shock I have sitting on the bench. They are good dampers for Matt to learn on. And it means I can just provide “moral support” while he does most of the work.

I’ve got a toolbox full of custom clamps, tools, etc for doing suspension stuff. Off course nothing in these shaft sizes though. 908SSP to the rescue!

Exactly I have enjoyed learning so far. Yeah of course you had so many different sizes. You just made 908SSP to be like a superhero machinist/fabricator. LOL

This is an awesome thread, nice work! You need special tools to work on our struts/shocks... meh, we will make our own! Love it!

You just summed it up! KW presented us with a challenge and we were not about to shy away from it especially with their attitude of only "we" can do it. C'mon...lol

 

[5.0_SD]

I suspect gmitch could make some coin from people in the forum here that need shocks rebuilt...hmmmm...side business for us here gmitch?

 

[sheizasosay]

Nice job! That's killer not having to pay $680 for a rebuild. Having the skill-set of everything you need to do that job has paid off. Hope they do you right on the track!

 

[Thekid760]

Dude!!!!

First off, awesome job, making the tools and tackling it!


But I am in serious need of a rebuild for mine, I have V3's, and I got quotes 200 each for everything even if the shaft was trashed.

Hook it up!

 

[sheizasosay]

But I am in serious need of a rebuild for mine, I have V3's, and I got quotes 200 each for everything even if the shaft was trashed.

Hook it up!

What ??? The Clubsports I know don't have a warranty, but the V1 and V3's were supposed to.

 

[Department Of Boost]

I suspect gmitch could make some coin from people in the forum here that need shocks rebuilt...hmmmm...side business for us here gmitch?

I used to do suspension stuff for a living, hence the dedicated suspension box/work area (also custom made).

I’m sooooooo glad that I don’t do it anymore. I really, really enjoyed it. But mostly it was the setup, custom work and trackside testing I enjoyed. Going through dampers, even if it was to do a bunch of custom stuff got real old, real fast. The chemicals are a killer. I get headaches, my skin gets screwed up, your covered in a thin film of fluid all the time no matter how careful you are, etc.

I like the testing and technical challenge, but the “grunt” work is rough on the body.

 

[jayel579]

After inspecting the springs that are standard from the KW Clubsport kit I decided that they were a bit much for a dual purpose daily driver (on nice Michigan days) and a HDPE/track day toy.

Springs that came with the KW Clubsport kit:

Front: 570 lbs/in
Rear: 340 lbs/in

With the street comfort factor in mind and referencing what both gmitch and 908ssp run on their coil-over setups, I decided to run the following:

Front: 60 N/mm -> 343 lbs/in
Rear: 50 N/mm -> 286 lbs/in

How accurate and/or comfortable are you with that 570/340 spring rate? Did you test that? I was given very vague springs rates on my KW Clubsports but never confirmed what they actually where. I was told they were 400 lbs/in in the front and 290 lbs/in in the rear. I always felt I had too much spring in the car, this would confirm my suspicions.

 

[Powered by Ford]

How accurate and/or comfortable are you with that 570/340 spring rate? Did you test that? I was given very vague springs rates on my KW Clubsports but never confirmed what they actually where. I was told they were 400 lbs/in in the front and 290 lbs/in in the rear. I always felt I had too much spring in the car, this would confirm my suspicions.

I would believe it is accurate those were the rates that were on the spring. According to their website and processes their rate tolerance is 3 - 5%.

For instance, what many believe is a part number on the spring is actually the "rate" - "freelength". Please note the rate is in N/mm and the freelength is in mm.

The springs that came with my clubsports said the following:

FRT: 100-170 -> in English units it would be: ~575 lbf/in; freelength: 6.69 in
RR: 60-200 -> in English units it would be: ~345 lbf/in; freelength: 7.87 in

As you will see KW does not use the English standard of spring lengths that you can get from Hyperco, Eibach etc. Yes you could use similar length springs, but you could run into a situation of coil contact depending on rate (direct correlation to wire size, larger wire = higher rate), etc. So I decided to go with KW springs (you can call their sales line and order springs). They vary by 10 N/mm increments.

The ones I ordered were:
FRT: 60-170
RR: 50-200

Just so you can quickly calculate the conversion between N/mm to lbf/in is: 1 N/mm = 5.70595 lbf/in

And if you are a nerd like me, you derived it and here is the derivation:

SI to Standard Derivation Rate by matthewatitus, on Flickr

Then 25.4 mm = 1 inch, but most people know that.

- Matt

 

[jayel579]

Fantastic Matt, thank you!

Actually I believe you are right. Its been two seasons since I put the Clubsports in my car but I want to say I remember seeing those numbers on there and we assumed it was a part number.