Expected shock/strut life?

[Just_George]

What's been your experience with the life of the O.E. struts and shocks? My ZHP is now at 61K miles and I expect it's probably nearing the point where it's due for replacements, maybe already there. Anybody here tired the Koni FSDs on a ZHP? Koni stuff is on sale now, so that might be tempting...

[3ZHPGUY]

I did my first Driving School at 83,500 miles and got black flagged for the weekend due bad struts. Didn't notice it on street driving but, when the car got loaded up in the corners, the tire and steering wheel would shake like hell. My instructor, wiped his thumb across the strut tube and found it oily.

At 92,000 miles, I installed Koni Sports and have been very happy with them. I keep the fronts adjusted to the Max and leave the rears in the middle. The ride is slightly harsher than OEM but, it handles geat.

Current millage is 138,000 and I did see some moisture on my left front strut when I changed out my brakes last week. I cleaned it off and will re-check it in a month. Either way, their lifetime warranted.

[Simmsled]

It has been my experience that Sachs twin-tube dampers seem to lose their 'edge' around 40-60k miles.
The 'edge' is seen mostly in low frequency movement (transitional roll stiffness felt as 'platform' or that 'flat' cornering feel). The mid to high frequency movement (basically about 95% of all bumps) do not suffer as much, and is the reason why 3ZHPGUY experienced what he did with the stock dampers. BTW... its a perfect example! My ZHP is at 65k miles and I'm planning on replacing the stock dampers on all 4 corners this year, but only because I want it to be 'right'.

On any enthusiast vehicle, the discussion is as old as dirt... Koni vs Bilstein vs Stock.
For most of the cars I've ever had, the answer was Bilstein. When they get the damping "RIGHT", there is no need to even consider another option.
Unfortunately, it has been my experience that they did not get it right for the E46, at least with stock sport springs. Long story short, the problem is with the rears. The damper's shaft and piston diameter are not large enough to offset axial loads and fail. The remedy is to use the rear shocks from the E36 M3. They ride smooth, and do not fail.
SO, just had to get that out of the way as the question was in regards to the Konis. The FSDs are solid dampers that have what I would call a 'selectively digressive' damping characteristic. They are smooth as butter (smoother than stock) but they realize when they are being 'driven' hard and 'selectively' adjust damping to provide more platform (flat cornering feel). The ONLY problem with this is when you throw the car into a corner and that corner has a nice fat quick bump in the middle of it. At that point, the chassis becomes under-damped and the result depends on how much throttle you are applying at the time. If you are heavy into the throttle, it could be understeer (front tires lose the tactile feel of the road and slip) followed by oversteer (rear tires unload, spin, then gain traction... or maybe they don't). Just don't lift. LOL

Ok... so the FSD isn't without compromise, but it is an excellent damper if you are just knocking about your daily grind and possibly do some HPDE days on occasion because your track-rat buddy with a Spec Miata drags you out (or possibly one of the ZHP Imola Elitists). HA!
That being said, if you are a person that is a bit more in touch with your ZHP than the average enthusiast, consider the Koni Sports.
They are about the closest thing to an adjustable Penske or Ohlins damper that you can get right off the shelf. Consistent, adjustable damping is the name of the game. Whether you are using stock springs or go more aggressive with stiffer lowering springs, they work with a twist of a knob (or damper tube in case of the rears). How do you know if the Koni Sports are right for you? If you like a taut (not rough, not floaty) characteristic to the suspension that feels like its ready and willing to hit the corners at the drop of a hat... Koni Sports are the right dampers. If you want to tweak the way the suspension responds, Koni Sports are for you.

The Bilstein HD, Bilstein Sport, Koni Sport, and Koni FSD dampers will likely be the last ones you buy for the car. They last longer than stock, and each of them bring a different feel to the table. There is no wrong answer here, unless you feel that BMW got it right with the stock dampers. This car is one that BMW, IMHO, did get right. The only issue I have with the stock dampers is that they don't last longer.

Overall:
Koni FSD is probably the most mild of the 'sport' oriented options
Bilstein HD/Sport (e46 front/e36 M3 rear) is a super sweet setup, but has the highest cost
Koni Sport is for the enthusiast that likes to tune the feel to the way they think it should be
Stock is for someone that doesn't mind replacing the dampers a bit more often (no lifetime warranty, whereas all of the aforementioned have lifetime warranties)

I'm a suspension nut and love talking vehicle dynamics. Always love to help!
Good luck man!

Matt

[BMWCurves]

I've only ever experienced Koni Sports (yellows) in three different applications (Mazda NA Miata, BMW E39 540i, and a mid-90s Mustang GT), but I can say they've all been improvements over stock. Definitely a little is lost to ride quality, but not terribly so at all. They're most likely what I will replace my stock shocks/struts with when the time comes.

Matt seems to know his stuff. I've heard internet horror stories about the FSDs going out in 30k miles but those are just anecdotal and I don't hold too much stake in those. I have heard they are the least aggressive change compared to stock, and do sometimes have less road feel like in the instances that Matt mentioned,

[slater]

matt - excellent post, thanks very much. i've had the same experience with bilstein... some cars are just right, others are not. to be fair i've had the same experience with koni. i tend to feel like bilstein doesn't have enough rebound damping, and konis don't have enough compression damping.

to pick your brain a bit -

i will most likely be using eibach pro-kit springs as my rear springs are looking iffy (paint is bubbling and flaking off on the bottom coil). bilstein sells a 'B12' kit that is comprised off bilstein sports, with the eibach pro-kits - this seems like a great setup - but the rears won't hold up? what about the bilstein setup (E46 front/E36 M3 rear) do you like over the konis, and vice-versa? the car is a DD and corner-carver - no track days in the future at this point.

what would you choose for your car?

peter

[NoVAphotog]

It has been my experience that Sachs twin-tube dampers seem to lose their 'edge' around 40-60k miles.
The 'edge' is seen mostly in low frequency movement (transitional roll stiffness felt as 'platform' or that 'flat' cornering feel). The mid to high frequency movement (basically about 95% of all bumps) do not suffer as much, and is the reason why 3ZHPGUY experienced what he did with the stock dampers. BTW... its a perfect example! My ZHP is at 65k miles and I'm planning on replacing the stock dampers on all 4 corners this year, but only because I want it to be 'right'.

On any enthusiast vehicle, the discussion is as old as dirt... Koni vs Bilstein vs Stock.
For most of the cars I've ever had, the answer was Bilstein. When they get the damping "RIGHT", there is no need to even consider another option.
Unfortunately, it has been my experience that they did not get it right for the E46, at least with stock sport springs. Long story short, the problem is with the rears. The damper's shaft and piston diameter are not large enough to offset axial loads and fail. The remedy is to use the rear shocks from the E36 M3. They ride smooth, and do not fail.
SO, just had to get that out of the way as the question was in regards to the Konis. The FSDs are solid dampers that have what I would call a 'selectively digressive' damping characteristic. They are smooth as butter (smoother than stock) but they realize when they are being 'driven' hard and 'selectively' adjust damping to provide more platform (flat cornering feel). The ONLY problem with this is when you throw the car into a corner and that corner has a nice fat quick bump in the middle of it. At that point, the chassis becomes under-damped and the result depends on how much throttle you are applying at the time. If you are heavy into the throttle, it could be understeer (front tires lose the tactile feel of the road and slip) followed by oversteer (rear tires unload, spin, then gain traction... or maybe they don't). Just don't lift. LOL

Ok... so the FSD isn't without compromise, but it is an excellent damper if you are just knocking about your daily grind and possibly do some HPDE days on occasion because your track-rat buddy with a Spec Miata drags you out (or possibly one of the ZHP Imola Elitists). HA!
That being said, if you are a person that is a bit more in touch with your ZHP than the average enthusiast, consider the Koni Sports.
They are about the closest thing to an adjustable Penske or Ohlins damper that you can get right off the shelf. Consistent, adjustable damping is the name of the game. Whether you are using stock springs or go more aggressive with stiffer lowering springs, they work with a twist of a knob (or damper tube in case of the rears). How do you know if the Koni Sports are right for you? If you like a taut (not rough, not floaty) characteristic to the suspension that feels like its ready and willing to hit the corners at the drop of a hat... Koni Sports are the right dampers. If you want to tweak the way the suspension responds, Koni Sports are for you.

The Bilstein HD, Bilstein Sport, Koni Sport, and Koni FSD dampers will likely be the last ones you buy for the car. They last longer than stock, and each of them bring a different feel to the table. There is no wrong answer here, unless you feel that BMW got it right with the stock dampers. This car is one that BMW, IMHO, did get right. The only issue I have with the stock dampers is that they don't last longer.

Overall:
Koni FSD is probably the most mild of the 'sport' oriented options
Bilstein HD/Sport (e46 front/e36 M3 rear) is a super sweet setup, but has the highest cost
Koni Sport is for the enthusiast that likes to tune the feel to the way they think it should be
Stock is for someone that doesn't mind replacing the dampers a bit more often (no lifetime warranty, whereas all of the aforementioned have lifetime warranties)

I'm a suspension nut and love talking vehicle dynamics. Always love to help!
Good luck man!

Matt

This is incredible Matt. All questions I've been curious about! That said, I thought "a lot" of people go with coilovers as opposed to shocks/struts/springs for their suspension refreshes since the price starts getting pretty close with either of the "regular" setups? What are the tradeoffs with going that route (besides price) pros/cons, etc in your opinion? Specifically, the BC coil overs, KWV2's, Bilstein PSS9's/10's, etc?

[Simmsled]

Great feedback and questions!
Will respond tomorrow.

[Just_George]

Thanks Matt - information overload! In my case, I have no intention of tracking my car, just looking to maintain or perhaps slightly improve the sporting nature of it. Roads in Michigan are an absolute travesty, so I thought the FSDs might be an improvement in day-to-day use while still offering the sporty handling. I put Koni Sports on my '04 330Ci and I like them, just wondered if the FSDs would be an improvement in the way of a better ride in 'regular' day to day driving. Thoughts? Thanks for your input!!

[Simmsled]

...to pick your brain a bit -

i will most likely be using eibach pro-kit springs as my rear springs are looking iffy (paint is bubbling and flaking off on the bottom coil). bilstein sells a 'B12' kit that is comprised off bilstein sports, with the eibach pro-kits - this seems like a great setup - but the rears won't hold up? what about the bilstein setup (E46 front/E36 M3 rear) do you like over the konis, and vice-versa? the car is a DD and corner-carver - no track days in the future at this point.

what would you choose for your car?

peter

Peter, Pro-Kit springs are a solid choice. I am not the biggest fan of progressive rate springs, but they can be an ally on the streets.
Here is an interesting situation, check out ECSTuning's shock section for our cars. You'll notice how they don't have an 'all 4 dampers' price package for us, whereas all the Konis are available as a set. It isn't a big secret that the e46 rears are not as robust.
The only way I would consider Bilsteins for our cars is with the e46 M3 rears. Their warranty is rock solid, but who wants to spend all that time messing with removing and installing rear shocks? Not me.
The comparison, the way I see it with a few points...
1. Bilstein's monotube design with high pressure nitrogen is the fastest responding damper design available for our cars. Period. When the valving is 'right', it is sublime. The closest you get to perfect out of the box is with this setup... BUT you're going to pay for it. NOT cheap.
2. The high pressure nitrogen also contributes to what is effectively 'added spring rate'. This is evident by experiencing a slightly higher ride height after install. How much rate you say? It can fall in the realm of +10 to +20 lbs of rate. Not a bad thing, but it does raise the car if compared to a twin tube design like Koni Sports.
3. With the Konis, it takes a little bit of trial and error to get them where you want them... but really not much (unless you are completely OCD) When they are 'set', they feel very fluid and controlled.

Overall... I have never been able to perfectly describe the feeling between the two, but here is an attempt. The Bilsteins feel like they get better the more you throw at them; high frequency damping is lightning quick and precise. For low speed damping, there is a lot of 'feel' that has been described as harshness in many circles. Great response, great tactile feedback, but a bit much for some. Konis take the edge off, and have great feel without the same kind of harshness. BUT, the Konis are sometimes described as 'stiff'. They are, however, not harsh.

All of my aforementioned details are comparing Koni Sports, not the FSDs. FSDs literally ride like butter, but don't have the same kind of 'edge' that the Billys or Koni Sports possess.

As to what I would do? Quite honestly the spring question is easy... stock... and the damper question is a bit tougher. I'll explain a little bit of why I like the stock springs. GRIP. Without writing a novel, I would rather have softer (linear rate) springs (like stock sport springs) with slightly stiffer sway bars than stiffer springs on stock or aftermarket bars. Its all about compliance. A great example is setting up a car for a street circuit. If it rains... we always back the low speed compression and low speed rebound down by quite a bit... then we would fit softer springs. This allows the tires to saturate more gradually... and it does take away a bit of the 'platform' feel. But long story short, and simply, softer rate springs relative to sways is the formula.

SO... when Tire Rack compared the Koni FSD to the Koni Sport to stock (e46) dampers, it is no surprise that the FSD had higher lateral grip... but a lower score in the 'response' department. Koni FSD vs Sport vs Stock e46 Tire Rack Review

BUT... make no mistake, that comparison was done COMPLETELY on full soft (not dialed-in) Koni Sports. So the 'feel' gets even better with the Sports, it never gets better with the FSDs. SO, FSD for the street car that really needs compliance. Do they have the 'race car feel'? Not like the Koni Sport.

Getting back to which damper setup I would (will) go with... I haven't decided yet. I'm between getting the Bilstein setup with the e36 M3 rears, and Koni Sports. On an Audi 90 I had once, I had Bilstein Sports on the rear, and Koni Sports on the front. It is COMPLETELY acceptable to mix, even though most people will say it is crazy. At the end of the day, what a damper does is simply a function of resistance per given stimulus. I would throw Koni Sports on the end that didn't respond the way I liked... adjust them... and all was well with the world.
Not sure that the FSDs would make me completely happy because I like more feel than they can offer... and the roads around here aren't really bad at all. One thing is certain... the Meyle HD rear mounts with reinforcement plates are the way I'm going to go. The bushing in the shock tower NEEDS to be compliant. It helps alleviate axial loading, thus lengthening the life of the rear dampers.

This is incredible Matt. All questions I've been curious about! That said, I thought "a lot" of people go with coilovers as opposed to shocks/struts/springs for their suspension refreshes since the price starts getting pretty close with either of the "regular" setups? What are the tradeoffs with going that route (besides price) pros/cons, etc in your opinion? Specifically, the BC coil overs, KWV2's, Bilstein PSS9's/10's, etc?

SO... I love how people think that coilovers are magical. Coilover setups allow tuning cross-weight. If they are not being used for that reason, then they are simply ride height adjustable spring/damper combos. They will be exposed to the elements, the perches must be maintained so they don't seize, and take some time to get 'right' if you are looking for a handling advantage. They SOMETIMES reduce unsprung weight (a VERY good thing) but most don't. Most people don't know that the KW V2 is a Koni Sport based coilover. YUP. How many damper manufacturers are going to spend the time and capex to invest in building their very own proprietary dampers? Well simply, they don't. They tweak existing designs instead from suppliers such as Koni and Bilstein. Indeed, the same dampers we have been discussing!!!
The BC coilovers being a bit of an exception... but really have only 1 thing good to say about them. They don't change damping profile when lowered. Thats it. I don't like them for a handful of reasons, and they will never go on any of my cars. To those that have them, just make sure you are cool with a 1 year warranty. Thats all I'm going to say about that.
The Bilstein PSS9/10 are brilliant. Adjustable Bilsteins? Awesome. More advanced than what NASCAR uses.
Believe it or not... the cup cars actually use a version of what we can buy off the shelf, but with a Schrader valve welded in to adjust the nitrogen pressure and to aide in quick rebuilds. They are NOT adjustable once on the car.
But the PSS9/10 are expensive. I would buy them 10 times out of 10 over the KWV2s, though.

The case for coilovers, IMHO, is not warranted about ~90% of the time. Most entry and mid-level coilovers don't have a damper that comes close to off the shelf Konis or Bilsteins. Look at H&R's coilover offerings for example (a company that I have huge respect for). They offer a Koni based kit, and a Bilstein based kit. Why? Best dampers combined with superbly manufactured, matched springs.
Here is a bit of a secret, lol, FK is a German company that makes coilovers. They have a set called Konigsports. These are about the least expensive Koni Sport based coilovers on the market. They are basically a KW V2 without the stainless for HALF THE PRICE.
No idea why FK isn't a bigger name in the BMW world, but whatever.

Coilover pros? tune cross weight, occasionally lighter than stock, adjustable ride height, some kits have matched springs/dampers, when properly developed they can outperform a normal spring/shock combo, much easier to swap different rate springs if tuning for track days
Coilover cons? added cost, added complexity, added maintenance to preserve ability to be adjusted, and just because it is a coilover, doesn't mean it is better

Bottom line on coilovers... adjustable ride height (for the 'stance' guys) is about the only advantage if not being used to tune cross-weight. Much better bang for your buck to get some quality dampers and spend the rest of the money on HPDE and tires! More fun too.

Thanks Matt - information overload! In my case, I have no intention of tracking my car, just looking to maintain or perhaps slightly improve the sporting nature of it. Roads in Michigan are an absolute travesty, so I thought the FSDs might be an improvement in day-to-day use while still offering the sporty handling. I put Koni Sports on my '04 330Ci and I like them, just wondered if the FSDs would be an improvement in the way of a better ride in 'regular' day to day driving. Thoughts? Thanks for your input!!

My opinion is, if you have the Koni Sports already, that you let me tell you how to tune your existing setup before making the change to FSDs! Its free! But I do know how bad the roads are up there, and FSDs may just be the way to go. One thing to remember tho, just because FSDs are smoother, doesn't give someone the ability to hit potholes! It just means you bend rims without really feeling it. LOL

Great questions!

I just hammered thru that... may make revisions later after re-reading.

[Just_George]

Matt, just to clarify - 2 different cars, '04 330Ci (not ZHP) has the Koni Sports. '03 ZHP currently has the OE struts/shocks....that's the one that I think is due and for which I'm considering the FSDs. Ability to hit potholes? Shoot, it's all you can do here to miss them, there's just TOO MANY! Thanks for the help! By the way, I'd much appreciate your advice on tuning the Koni Sports - the 330Ci rides on original springs (sport suspension).