How to Save Money When Buying Linear Dampers

I posted a similar thread to this one over at another forum that I'm a member of and got a pretty positive response, so I'm posting it here too as I thought there might be some people here who would appreciate it or who could perhaps learn something from it...:

I've decided to start this thread in an attempt to remind people that for the most part, you get what you pay for and that you shouldn't expect too much out of a "budget" setup.

This is a link to a 24/7 thread where Jeff from Tri-Point Engineering posted some striking shock dyno results:

Truth about K-Sports? - Mazda Forums

...and this is a link to a pretty well-known site that dissects and explains the difference between the "budget setups" and setups from the likes of Bilstein (from who I believe H&R sources their dampers), Ohlins, Penske, Koni, Dynamic, Sachs, etc. The site author takes some liberties and may go a bit overboard in his sweeping generalizations, but the major theme is a valid one:

DGs Autocross Secrets aka Autocross to Win - Shocks

In both cases, shock dyno testing reveals that at the very best, the "budget brands" (Tein, Raceland, Ksport, D2, etc.) are horribly inconsistent and at the very worst they're valved completely wrong and/or they do not at all live up to the claims of the manufacturer when it comes to their adjustability.

I'm not starting this thread to say that these products are completely worthless or that they don't have their place in the market, but I do think it needs to be pointed out that there is a reason you can buy some of these setups for substantially less than (or right around) the $1K price point. They simply aren't engineered well (and likely aren't even engineered on a platform-specific basis) and the shock dynos show it.

If this evidence isn't enough to convince you, or if you're curious to read more into it, I encourage you to do a google search for shock dynos or other evidence to the contrary. Time and time again, I think you'll find that these companies simply can't back up their claims with data, and you'll find plenty of people that toe the line of what I'm saying here.

Hopefully this will save some people who perhaps just didn't know any better from putting a product on their car that isn't what the manufacturer claims it is. I just want people to be as well-informed as possible.

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In the interest of bringing products more relevant to the MS3 market into this thread, I've searched to see what I can find regarding shock dynos for a few more brands (also, if anyone else has more data they'd like to add to the discussion, please post it up and I'll update this OP):

Here's a plot for BC damper from a "BR Type" setup for an 8th gen Civic that were posted on another forum by a BC salesperson (note that this is only for one damper in each graph - 1 front damper and 1 rear damper - and for some reason one of the graphs is in metric units and one is imperial units, so making a judement about consistency across the dampers in a set cannot be made easily from these graphs):





And here's the thread I pulled it from (the thread was initially started as a discussion about a Stance setup):

Stance Coilovers Information - 8th Generation Honda Civic Forum

And for some contrast here are the dyno plots that KW has on their website that show the shapes of the damping curves and how they change with rebound and compression adjustment (I tried for some time to find some "independently obtained" shock dyno results for a KW setup as well, but gave up after awhile. If you have some you'd like to add to the thread, please do - and I'll get them added to the OP):

Rebound:


Compression:


KW automotive North America Inc. Suspension -- Coilovers -- Shocks -- Springs

As you can see in the BC plots, there is really no compression damping adjustment to speak of, and the MINIMUM ratio of rebound:compression damping near mean velocity is roughly 2:1 (with an arguably useless 8:1 ratio at full stiff). It's no wonder people describe these things as bouncy/harsh, since the car is likely "jacked down" over sections of road/pavement with a series of small bumps and ends up riding on the bumpstops.


For anyone who'd like a very well-explained run-down of how the KW V3 valving works, you should check out this article:

Suspension Basics - Whiteline Swaybars & KW V3 Coilovers

If I can add to this, BC Racing (from my many conversations with them) is fairly open about the fact that their valving is not perfect and are willing to do shock dynos on a set of coilovers upon request. A curious man on the NASIOC forums made such a request and got some shock dynos of his whole set of BC ER coilovers.

NASIOC: BC ER Coilovers Shock Dyno'd









They're better than K-sports by far for consistency, but, not perfect. Quoting the NASIOC poster's takeaway message,

• Little to no cross talk between bump and rebound
• Rebound has a ton of adjustment range
• Bump adjustment is not as sensitive
• First 10 clicks on bump adjustment do nothing
• Bump curve looks pretty digressive
• Rebound curve starts pretty progressive then becomes linear and you stiffen it up even further it becomes slightly digressive
• Each coilover is very consistent. Data that you see is the actual raw data with no averaging. Most of the time you will see a shock dyno with only five points tested and straight lines drawn in between. We tested the shock at setting 15 then went to full stiff and back to 15 and were able to get the same plot all day long.
• There is slightly too much bump dampening
• Front and rear dampers are valved exactly the same
• There is about 2 click offset between left and right dampers

For the money ($-) you can almost get yourself into a set of Mazdaspeed (KW) coilovers that will be plusher and more consistent out of the box. 99%, handle better as well.

On the other hand, though: off-the-shelf Bilstein/KW coilovers cannot be revalved (at least that's what the reps told me!). They are designed (and TUV certified) for a certain setup "window" ideal for a stock, or lightly modified chassis. Deviate enough from that (say, 500lb weight reduction or 500lbs of downforce), and you will need to change the setup significantly to suit. When you hit this point, interestingly, budget coilover parts are plentiful and available enough that a skilled specialist can build you a perfectly valved coilover kit for not much more than the cost of a Bilstein/KW.

At the end of the day it depends on how much you know and how far you're taking your suspension setup. Good OTS products (Bilstein PSS9, KW v3) work well for a particular range of usage models (like an Apple product). Budget coils are a more flexible base to build your own system from -- if you know what you're doing (Linux).

Okay, I understand that if you call the manufacturer you will get the party line- "no, we can't revalve that". However, I'm here to tell you that this is a response that they aren't interested in revalving the shocks. Coming from the dirtbike world, where nearly everything is serviceable or has been hacked to be serviceable - it can also be modified (a.k.a. revalved). Whether it means a fluid change, welding or reboring orifices, changing shim stacks or pistons. The benefit of starting with a brand name shock (KW/Bils/Koni) is that very often parts are high quality and interchangeable. For instance, Tomas on MSF (not sure if he's made it here yet) has used bilstien race shims to revalve his "non-serviceable" MS6 front bilstiens with the addition of schrader valve.

Specifically related to the KW's from here:
So it depends on you willingness to source parts and put it together, rather than which shop will do it for you.


I beg to differ, since I've run 600 inlbs springs on koni's for 10k miles without issue.

"Revalving" and "consumer grade" (or "easily serviced") and two terms that go together like oil and water- much like "Custom" and "Customer Service". Which is much of the selling point of cheap dampers, particularly BC's.

A nugget for you, a member of MSF - "MD" recently was quoted $40 a corner for custom valving for his MS3 bils B8 from their NC service center.

Deviation from what? It's fallacy to think that designers have the perfect setup for your particular car. Should you probably readjust your valving after a spring change- absolutely.
Should you stop racing after a 10%-15% change in spring rate? Meh.

If you change your spring rates on one axle by 300 in/lbs alone, you're going to have larger problems than valving- like roll bias.

The "digressive" behavior of those low end shocks is a bit of a joke. It's no wonder they ride like total shit. At low velocity they generate almost no bump force. At high velocity the rebound force is skyrocketing, which is going to cause the car to jack down over successive bumps (often into the bump stops). BC, Megan, KSport, KW, etc etc won't actually build you a shock by changing the shim stacks, they'll throw in another pre-valved damper cartridge. KW offers some high end suspension products that are truly custom, but you're into the $3k++ range at that point, and that's not even close to the budget setups in question.

Budget coils are just that. Budget. The growing room available with low end coil over kits ends with springs and drop in damper cartridges (if that's even available).

You mention design frequencies of the suspension. Ever called up one of the budget CO companies and asked them what the design frequencies are? I have, and they had no idea. And that's how I ended up building my own coil overs from Bilsteins.



Bilsteins are most definitely one of the easiest shocks to have revalved. Bilstein USA will do it for ~$100/corner, it's right on their website. Aftermarket shops that work with Bilsteins are plentiful, you can often find them around racetracks. If you want to get fancy, you can have them converted to single or dual adjustable, or even have external reservoirs added. You could even convert them to take-apart and rework them yourself.

You can absolutely build your own coil overs from Bilsteins for either the MS3 or MS6, and end up with a significantly better product than the cheap coil overs, for not much more cash.

I don't know why I got such a good deal on the revalve. It was never really explained to me. But I don't think my contact over there in North Carolina will be doing any more revalves for MS3's because he discovered that the rears don't fit on his dyno, so they're on their way to CA right now to be revalved over there at the usual rate (I think $100/corner). Meantime he revalved the fronts and is sending them back to me. I'll post dyno data when I have it in my thread.

As for Bilstein vs Koni...it's my understanding that there are a wide variety of shops that will revalve/rebuild both. Probably boils down to personal taste. I went with the Bils because I like the inverted design in the front (more robust for use in macpherson setups where front dampers really get trashed) and also Clint's recommendation influenced my decision. Also the price. The Bilsteins with a revalve from Bilstein even at full price are well under $. It's a no brainer I think for what you're getting. BTW mine are the B6, not the B8. Same damper, longer rods.

Originally posted by NRoshier
I have found that the dampers on my car are too short for the application, at least in my estimation. I reason this as I have around 10mm droop at the current ride height, which increases to around 20mm with me in the car.
I could of course extend to top damper mount downwards to move the damper into a better position and change the preload to suit, but I thought that I would enquire as to options, as I have never been happy with the AVO dampers mounted on the rear.
So I made a few calls and had two very different setups suggested for road and track (6/7 laps sprints around circuits) use. The Koni agent suggested a low rebound setting given the relatively heavy live rear axle in comparison to the rest of the car, whilst the Bilstein agent recommended a standard amount of rebound.
Is there any direct mathematical correlation between the sprung/unsprung weight and the actual valving chosen?

With competitive price and timely delivery, Teao sincerely hope to be your supplier and partner.

Originally posted by NRoshier
Er, no. Car is at ride height, wheel moves up into bump, wheel moves down in rebound, wheel goes below static ride height into droop.
I do not want the spring leaving it's seat, ever, dampers are coilovers. Preload is required to get static ride height with soft spring rate.
Question is how sprung vs unsprung ratios vary valving and what effects low mass car and high mass axle (relatively speaking of course) would have on damper valving.

Originally posted by NRoshier
I have found that the dampers on my car are too short for the application, at least in my estimation. I reason this as I have around 10mm droop at the current ride height, which increases to around 20mm with me in the car.
I could of course extend to top damper mount downwards to move the damper into a better position and change the preload to suit, but I thought that I would enquire as to options, as I have never been happy with the AVO dampers mounted on the rear.
So I made a few calls and had two very different setups suggested for road and track (6/7 laps sprints around circuits) use. The Koni agent suggested a low rebound setting given the relatively heavy live rear axle in comparison to the rest of the car, whilst the Bilstein agent recommended a standard amount of rebound.
Is there any direct mathematical correlation between the sprung/unsprung weight and the actual valving chosen?

Originally posted by NRoshier
It seems that I can borrow a set of 'pots' and a data recorder, which I assume could assist with the required data, though I have the feeling that this could get bigger than ben hur!
Assuming that such materials become available, what is an advisable (simplified given the scope of the project) test procedure to collect data?

For more information, please visit Linear Dampers.

Originally posted by ben38
The rigidy problem fixed, just remain the damping question.
If you had put your hands on a dynamic adjustable set, the best and most effective way would be a small data logger able to record 4 suspensions pots at something like 500Hz and tune it on track. (basic oscillation speed calculation and histograms with driver feed back are powerfull tool)
You could then try both rebound and bump oriented and get what actually suits you best.

Ps: Drawing number 253-27 could go directly on rear live axle mounting and help too.

Originally posted by NRoshier
P2 the car is a Rochdale Olympic http://www.rochdale-....uk/olympic.htm and the engine is a Fiat twin cam - a popular conversion in the 's, as in the UK the rest of the Fiat generally dissolved around what is otherwise quite good running gear. I would stress that my car has been considerably reinforced over a standard Olympic in virtually all areas and now includes a 6 point CDS roll cage and foam filled box sections.
P2 the damper cannot be moved as the car's structure is not designed for the loads.
Top speed will be limited more by my bravery (heck I know I'm driving an old egg shell), but top speed will be around 120mph.

Originally posted by NRoshier
Story so far:
Webers now balanced but need some idle jets, main jets and air bleeds, need to make new carbon airbox and ducted filter to in front of rad.
Dampers: trying to get some new springs with a shorter free length.
Trying to find some reasonably priced coil-over dampers - NOT easy locally. Local Bilstein agent says 'these will do, or if you want to revalve to make the work properly then another $200ea' and Koni not an awful lot better. Will keep working on it.
Trying to get car mobile enough to get it corner weighted and wheel aligned.
Electrical maladies mostly sorted, need to get some dialectic grease for contacts.
Thermo fan spat the dummy and stopped working - more to do there.

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