Talk to me about Koni dampers

dps214 said:

californiamilleghia said:

back in the dark ages , "BI" before internet , you could send your old Orange Konis in and have them rebuilt , 

Is that still done ?

Yes but nobody in the US has the ability to gas charge them. And iirc there's only two third party shops left that do it, koni stopped doing in house service somewhat recently.

In the motorsports end of things, the Koni twin tube shocks/struts typically are de-gassed and not recharged.  I've been told by a Koni rep that's also a road racer, along with others that the twin tubes don't need gas pressure to work correctly.  I have a set of KoniSports that were converted from single adjustable to double-adjustable by one of the two shops in the US that still work on them.  They do not have a gas charge.

I've owned two sets of STRT but only installed one of them. Seemed like a stock replacement, more or less. I think they're a little more damped than the 'average' stock replacement shock, but they don't 'feel' like a performance part. My .02. Hoping i like my 2nd set a little better, but it's the best that's available off the shelf in that particular application anyway. 

Keith Tanner said:

Just get the Sports. They're more likely to have the correct valving and they're more reliable than the Str.T.

Do you have any data to back this up? This seems to be a common sentiment, but they have very similar valving to where most people run the Sports anyway and mechanically they are supposed to have the same construction/internals with the exception of the adjusters...And it's not like the adjusters on Sports are exactly precision matched.

I put FSDs on my R56 Cooper S, and it transformed the car.  It's not a track car, but they work great on the street.  These replaced a set of Bilsteins, but I am definitely not a fan of those.  As they get their "sporty" feel by running way too much compression, it would crash and jolt over even the slightest bump, while the Konis feel practically perfect.  It now takes in the bumps and it vastly more controllable.  The best way to explain it is that it feels more like a BMW instead of the neighbor's kid's Civic with 1000 pound springs and no shocks.

Driven5 said:

Keith Tanner said:

Just get the Sports. They're more likely to have the correct valving and they're more reliable than the Str.T.

Do you have any data to back this up? This seems to be a common sentiment, but they have very similar valving to where most people run the Sports anyway and mechanically they are supposed to have the same construction/internals with the exception of the adjusters.

I asked Koni :) We have a pretty good relationship with them - we had a car in their booth at SEMA a few years back. I asked about both the valving and the frequency of warranty claims.

So not "data", but the best possible source.

In reply to Keith Tanner :

Interesting. Did they happen to note any reason(s) why that would be the case, or what the magnitude of difference is?

They're produced in a different factory that's not in Europe. I forget where. But as seen here, price is a significant driver on the STr.T (I always forget what the correct capitalization is) and it's possible this is reflected in the product. I can tell you that very few of the Sports are bad out of the box, as our customers are very good at providing immediate feedback to us on products that do not satisfy.

I did not demand to see their books and do not have hard data to offer. We decided not to carry the STR.T because it didn't meet our needs at the time. Maybe we should revisit that. But this means that we don't have the direct customer feedback on initial quality.

Thanks for the feedback, Keith. When there is no hard data available, we pretty much have to take what we can get from best sources we have access to.

One general note for this particular application: The Eibach's have the same spring rates across all E8X 1-Series and E9X 3-Series BMW applications. While these are ~20% stiffer than is claimed for the E8X factory sport suspension, they are essentially the same spring rates as the claimed E9X factory sport suspension. So for dampers sharing part numbers across the E8X and E9X platforms, like Koni does, they should at least be nearly as well tuned to the Eibach's as they are the E9X factory sport suspension...And most shared part number products are developed primarily/initially for the much larger E9X market, that may generally be better than is often the case for lowering springs in other applications.

I've liked the Koni Sports on every application I had them on.  I've only had STR.Ts on one application and didn't like them.  The sports I had on my MX5, the back of my 309GTi, and my 406 V6.  The 406 also had the STR.T on the back for a short time before the yellows - I didn't find much/any improvement in the STR.Ts compared to the 130k mile Peugeot OEM dampers (though Pug knew how to make dampers back then).  I'd probably look at FSDs for this application.

I have put Konis on probably 30-40 cars, starting when I was 19 and working on a Shelby Mustang. Other brands have positive attributes, but Konis always make the car I am putting them on ride better and handle better and I have never had one wear out or fail that I have started fresh with.

Just want to thank everyone who'd contributing to this - even without a definitive mutually-agreed-upon answer, there's a wealth of information that will make me much more confident in whatever decision I eventually make.

Keith Tanner said:

For a car on Eibach springs, I'd want Sports. I assume they are lowering springs with a mild increase in rate, which means they're already into bumpstop territory. 
 

I can not stress enough how important it is to have the Koni bump stops installed on the strut/shock if you are using lowering springs.  They keep the valving in the strut/shock from hitting the bottom of the case and destroying the strut/shock.  Should this occur it is not covered by Koni warranty.  

dean1484 said:

Keith Tanner said:

For a car on Eibach springs, I'd want Sports. I assume they are lowering springs with a mild increase in rate, which means they're already into bumpstop territory. 
 

I can not stress enough how important it is to have the Koni bump stops installed on the strut/shock if you are using lowering springs.  They keep the valving in the strut/shock from hitting the bottom of the case and destroying the strut/shock.  Should this occur it is not covered by Koni warranty. 

Are these included with the dampers, or do they have to be purchased separately? If the latter, do you have a p/n?

02Pilot said:

dean1484 said:

Keith Tanner said:

For a car on Eibach springs, I'd want Sports. I assume they are lowering springs with a mild increase in rate, which means they're already into bumpstop territory. 
 

I can not stress enough how important it is to have the Koni bump stops installed on the strut/shock if you are using lowering springs.  They keep the valving in the strut/shock from hitting the bottom of the case and destroying the strut/shock.  Should this occur it is not covered by Koni warranty. 

Are these included with the dampers, or do they have to be purchased separately? If the latter, do you have a p/n?

I don't have the part number as there are more than one that they sell.  You need to check if they are listed with the specific shock or strut you are purchasing.  I know that the rear shocks in my 924s came with them while the front struts did not.  I then trashed the fronts by hitting a pothole and I bottomed the strut and it was trashed.  I ended up speaking with Lee at Koni and he was the one that gave me the in site as to needing them specifically on cars with lowered suspensions.  In my case I was running progressive Eibach lowering springs that dropped the front about 1.25 inches.  In my case the inserts I was using did not come with them and I had to purchase them separately along with the new set of strut carriages.  I was a bit miffed with Koni about it as no where was there a warning about this in the literature with the struts but this was MANY years ago.  They did give me a bit of a discount on the replacements but it was still a very expensive pothole.  It is important to note that this is only an issue in a lowered car.  There struts are engineered for stock ride hight and when used that way this is not an issue.

Photo of various Koni Bump stops.

We have never had any experience like that with Konis - and I'm speaking on behalf of our customers. We do, of course, recommend using good bumpstops in all situations because there is always a bump big enough. I do know they recommend leaving that white nylon split washer in place and I forget the specific technical reasons. 

When I think about it - it may be more of a problem in those Sports that have the adjuster built into the body. You compress the shock all the way and twist to adjust. You're obviously making contact with some mechanism inside. The Miata ones (adjusted via the top of the shaft) are built differently internally.

You said cartridges? I assume those were somewhat universal and so it's somewhat understandable that they wouldn't have come with bump stops. I don't think I've ever seen an application specific koni shock not come with a bump stop if it needed one. The 924/944 is a particularly bad situation in that the oe stops are made of an awful material that likes to disintegrate to the point where whatever was on the car was probably either unusable or just totally gone. For what it's worth 99% of the time it's a bad idea to run a suspension without bump stops at all. Certainly not at anything remotely near stock spring rates. As Keith said, I'm guessing those were also the old style compress to adjust shocks which are easier to bottom out and destroy than the current external adjuster knob style.

I've had Koni yellows in several cars and been happy with them.  They worked really well in the NC MS-R on the track/autocross and were entirely OK for everyday street driving.   I'm going to replace the bilsteins in my '94 Miata with yellows.

The bumpstop discussion is interesting.  I've got a set of Koni double adjustables that I'm going to install on my '10 Mazda3 next weekend and of course I don't have bumpstops.  Have some KYB sleeves and bumpstops on order, but now I'm wondering if just grabbing random bump stops is the best idea.

The fronts that were the cartridge/insert  type strut and are adjusted with the knob up in the engin compartment were the ones that I trashed with a pothole did not come with the bump stops. In either case I got my info from Lee at Koni. I called him as I wondered why my struts had failed and if it was a warranty thing as they were only two years old at the time. I  am sure he can clarify things if you call him. My new set is now 10 years old and  have more than 100k miles on them and are as good as the day I installed them. Koni may have redesigned things since then but they still sell the bump stops so I assume they are a needed thing for certain Installations of there struts. 

Just an FYI follow-up for anyone else considering buying one stimulus check worth of Konis - 20% off pretty much everything Koni until the end of June.

Keith Tanner said:

Special Active is a blowoff valve setup. It has a weak point in that it tends to hit the bumpstops hard if you're at all limited on travel. I did some comparison driving in a Mustang at the SEMA show and we did get into the stops hard a couple of times. Felt good overall, I'd use them for a car like the Tesla. Just be aware.

 Please forgive the bump (pun not intended but retroactively taken credit for).

Keith, if you're still here, could I ask you to elaborate on this?  I think I'm experiencing it on my Mazda 5.  I love the ride and handling with Special Actives on otherwise stock suspension, except that it takes big bumps weirdly poorly.  Do you know why this happens?  Can anything be done to mitigate it?

Still here :) And the Special Actives are going to be available for the Tesla soon, so I'll get a chance to put my money where my mouth is. There's a set coming my way. 

It's my understanding the SA shocks want to either be on the bumps all the time or have very minimal interaction with them. They basically "give up" on sharp hits to give that nice ride, but if the hit is big enough that means a fairly solid bumpstop impact. That's why they're not great for lowering springs from what I understand. I don't know the geometry of the 5, but changing bumpstops is probably the best place to change this - either shorter and stiff (less interaction) or longer and softer (more gradual transition). 

Also, the Miata STR.T shocks re now being made in the Netherlands instead of Argentina. You can tell by the box - if they have holes in them to act as handles, they're Argentinian. We do carry the STR.T now as a stock replacement shock. 

I put Koni STR.T's on my brother in laws Fiesta SE and they ended up blowing within 10k miles. Wasnt super happy with the longevity considering the somewhat easy life they had commuting to work on the highway. The stock dampers lasted nearly 5x that amount before they started leaking.

We ended up just throwing some Bilsten B4's since they were cheap. So far in 7500 miles i havent heard a complaint.

Yeah Koni qc is...interesting. Seems like they either die almost immediately or last forever. My fiesta konis have been on for probably 50k on the rears and like 10-15k on the fronts are don't have any signs of issues other than some rust starting on the rears.

I'm not sure the exact functionality of the special actives but what Keith said seems right. Basically they work by adding delay, so small inputs get almost no damping for better ride quality. But the flip side is they big inputs end up using more stroke. I'd probably tend towards the longer but softer bump stop option as the solution.

Keith Tanner said:

Still here :) And the Special Actives are going to be available for the Tesla soon, so I'll get a chance to put my money where my mouth is. There's a set coming my way. 

It's my understanding the SA shocks want to either be on the bumps all the time or have very minimal interaction with them. They basically "give up" on sharp hits to give that nice ride, but if the hit is big enough that means a fairly solid bumpstop impact. That's why they're not great for lowering springs from what I understand. I don't know the geometry of the 5, but changing bumpstops is probably the best place to change this - either shorter and stiff (less interaction) or longer and softer (more gradual transition). 

Also, the Miata STR.T shocks re now being made in the Netherlands instead of Argentina. You can tell by the box - if they have holes in them to act as handles, they're Argentinian. We do carry the STR.T now as a stock replacement shock. 

Thanks, Keith.

What you're saying really resonates with my experiences.  It's interesting because a Koni rep told me the FSD mechanism only kicks in on rebound, so compression damping should be roughly comparable to stock.  But my experience is much more like what you're describing.  It kind of reminds me of the Öhlins DFV on my M3: excellent ride quality until bump stop contact, at which point I kind of hate my life.  Hard for me to imagine FSD isn't blowing off on compression as well.

I also suspected that bump stops were the main tuning opportunity, so I floated the longer bump stop idea by the Koni rep.  He suggested that that'd be counterproductive because FSD doesn't play well with bump stop contact.  I'm not so sure.  But at this point IDK what to do.  It seems so weird to me that dampers like this would have this flaw.  Like, how did they sign off on this application when it has such an obvious tendency to crash into the bump stops?  Makes me feel like I'm missing something...

I'd love to know the technical differences between the Ohlins DFV and the Koni SA/FSD. I suspect they're pretty minor, the main difference is selling price and marketing. 
 

Are you running lowering springs on the 5? Your Koni rep sounds more like a reseller with limited tech knowledge, as that statement about "only on rebound" sounds exactly wrong to my understanding. Hit up Lee Grimes at Koni, he's a really helpful guy who knows his stuff.