GT Bob

Seriously guys... I see this on every stinking forum I go to. People moan and complain that companies don't understandwhat they want for their cars, or that they are just in it for the money and they don't care about our community... And without Fail, every time a guy like Sam comes along and not only tries to provide what the community wants but tries to be an active participant in it, they get flamed as soon as they mention the fact that a part they like and run themselves is one they sell. For god sakes guys, He owns a mustang himself... with his availablity of parts, I hafta think he's tried about every combo known to man, and then some..

I think Sam has contributed a great amount to the handling forum and posts like this one are only to show that his customers agree with him. Personally, when I have the money set aside to address my handling issues, Sam will be getting my money without question. Guys like Sam are the real deal and are the one's you should be taking a lead from, not the "Internet Hero's" who autocrossed once with his Mom's Acura SUV and moans and flames when Sam posts info counter to his.

It's crap like this that make manufactures lurkers on car forums, and not active members...

doc stang

newbie, here,
just my 0.02 worth,
i do not yet know a lot about suspension and handling, but am trying to learn as much as i can before i make any purchases,
i was/am strongly considering d-specs, but this thread has me now considering the koni's strongly as well,

i need to learn more about : adjusting the rebound only (a la koni) vs coupling (single) adjustability ( a la d-specs) of both simultaneously.
to that effect, i am going to give sam a call,
partly because of his horn tooting,
partly because of his wins,
partly because of he seems to deal with things in a forthright manner, (at least by his described examples)
partly because a lot of folks here seem to really respect his opinion, and, lastly . . .
partly to reward his advertising effort, (at least with some traffic, and potentially some business)

yes the o.p. was partially self serving,
yes it was to report an observation from someone who has tried both, ( as i doubt many people have had that oppotunity)

like rodeoflyer said, . . . [u][[/u]b]I[/b] am Joe Schmoe ( not to say sam's customer is)
and i don't yet understand all the jargon, so hearing it in less technical terms is somewhat valuable,
knowing what else is on the car ( i realize there is a partial list) wouuld help paint a fuller picture.

i see nothing wrong with the post,
it did seem to spiral out in left field,


i certainly do value teh opinions of vendor's and shops whos hands and butts are in it, rather than just selling stuff.
fwiw, (which probably aint much)
doc

Norm Peterson

I can maybe help with some of this.

About bump damping - it works with the spring in resisting wheel upward movement over bumps, and for any given car there's some sort of limit to how much force this travel should be resisted with. It's not supposed to be a major player in controlling roll, just provide enough control of the upward wheel travel so it won't overshoot and enough to avoid allowing the car to "jack down" over rough surfaces.

Ride-wise, it's obvious that too much bump will simply ride harder all the time.Way too much bump will make the tires go airborne over bumps (read: zero grip in any direction). Performance-wise, too much total force means that at least that wheel is not contributing as much cornering force as it could be. And the combination oftoo much force on the rise of a bumpfollowed by going light down the backside = greater tire force variation, which equals overall less grip as you travel that distance. Tire are not "constant coefficient of friction" devices; grip increases more slowly than downward load is applied. Particularly up front in a front-heavy RWD car, that's not the hot tip for getting the thing to maintain front grip.

I'll stick my neck out a little and suggest that D-specs might tend to work slightly better with springs toward the "soft" end of the range of readily available springs, and that Konis might be better with the heavier springs.


Norm

doc stang

so when you say heavier springs favor the koni's, is that to say PROGRESSIVE RATE springs?
and the "lighter" springs to go with tok.'s means LINEAR?

F1Fan

Hi Norm!

Thewaywe used to change thedamping rates on the Porsche (and BMW and VW) race cars we worked on was generally that asspring rates got higher (all else being equal, sprung and unsprung mass) the bump damping rate got softer and the rebound damping rate got higher. This was pretty easy to achive because all you had to do was tweak the externalrebound or bump adjusters on the dampers and send the car back out. Relatively speaking in effect the Koni Sport dampers are doing this exact same thing and it works pretty well as long as theinital bump rate is reasonably well selected and theproject car's specs is not too far off in terms of sprung and unsprung mass as selected by Koni. That said if you don't like what comprssion valving Koni has selected for you you can easily change the bump and/or rebounddamping rangefor a small fee by sending thedampersto Koni'sracing service department, talking to an engineer anddescribing where you want to go with the re-valve. We used to do this all the time early in the development ofcars with single adjustable dampers and for street cars without the budget for Koni D/A dampers.

As to the D-Specs working better with softer springs thishas not been my experience. I've been playing with springs, spring rates, ride heights damping, camber, toe and bumpsteer settingsfor a few months with the Steeda Adjustable Suspension setup on my car.I have put everything from a 165lb. spring to 250lb. springinfront and 165lb. to 200lb. spring on the rearof my car and the D-Specshave worked very well if not perfectly with all of them. I have also had the most amazing ride quality out of them for a given spring rateand have also tried some very different wheel and tire setups and found that the D-Specs work well with a VERYwide range of spring ratesand wheel/tireweight combinations too. I have not seen any reason to go to a higher spring rate for a street car and even if this were a dedicatedtrack car assumming it was stripped for weightI could not see going to more than a 375-450lb. front spring or more than 225lb.-250lb. at the rear, it's just not necessary. If I was going to builda serious racecar for the streetI would skip the Tokicosand go with Konis not because of anyissues on the part of the D-Spec dampers butfor the depth of services Koni's racing services shop has to offer and the ease of access to that technical tallent pool. Of course I would not bother to buy the Koni Sport dampers either. I would skip rightpast them and build up a set of Koni Race double adjustable inverted coilover struts andKoni Race double adjustable coilovers for the rear and save all the fuss of going back and forth to Koni racing services to revalve the dampers looking for what will work right for the car with a single adjustable Koni Sport damper everytime I made a change to the car that changed the sprung and/or unspring weights of the car.

HTH!

<< EDIT: OBTW all of the springs we use to use onPorsche, BMW and VWrace cars were straight rate springs as were the springs I have been playing with on my own car's Steeda coilovers. >>

F1Fan

Hi doc stang,

Progressive rate springs are a marketing hype thing. In reality all of the so called progressive rate springs arehit or missfor production vehicles. If you find a set that works well on one car the next set frequently don't work on the next car due to weight differences between the carsand the way the springs got made that day. The progressive springrate feature ofthe popularsport springs are not really so muchprogressive once the car is on the ground. The springs are wound with coilscloser to each other on one end and farther apart on the other end of the spring. Once the spring is installed much of that softer rate is used up by simply installing the spring to keep pressure on the spring seatsso the spring can'tcome out of the seats. The rest of the soft coils areused up as the car is loweredonto the spring and they take up the weight of the car. Once the car is being fully supportd by the springs if you stick your headunder the car you will see that the softer coils are pretty much inspring bind and acting as a solid at this point. In other wordsalmost all of the softer coils are no longer actively supporting the carand the stiffer part of the spring is doing most of thework now. There is a very fine balancebetween the softer coils and the firmer coils andwhich are active depend entirely on the weight being loadedon the spring which can vary by hundreds of pounds even on the same model due to the stuff people thinkthey need in their cars these days.

What I have found withEibach Pro-Kit springsaccross many different applicationswas the springs were too low and allowed the car to bottom out too often. Well gee, isn't thisexactly what the progressive rate spring design was supposed to prevent in the first place? Well yes that was the idea anyway and what the marketing geeks keep pumping out in print and on their websites. What was happening here in the real world though was the heel of thespring rate curve was well past the point wherethe increased spring rate could act to prevent or reducebottoming out because the car was already staring to bottom before the increased spring rate could take effect. I've seen this many times with many different brands of progressive spring and I just was not going to put up with it or try to find a progressive rate spring design that was designed to work properly on my car. Hence the Steeda coilovers even though I swore I was not going to go this route again on a street car and certainly not on this carmy daily driver. Oh well such is the state of the art in street suspension these days. If you really want it done right you still really have to do it yourself OR hire someone like Sam or find a local guywho has similar setup expertise. Of course you could just ask me and I'll tell you what I found and I don't charge you a thing unless you want to come over and use my garage and tools. Then you just have to bringover a couple of cases of beerto keep the garage gods happy.

HTH!

Norm Peterson

No. When I use terms like "lighter" or "heavier"with respect to springs, it's just synonyms for "softer" or "stiffer", respectively. I'm only looking at the spring rate at that point. Sorry.

FWIW, I'm not crazy about progressive rate springs either. To me they're useful as devices for improving the ride for mild to moderate drivers for whom handling = I can turn the car into the parking space easily (yay!). And it's a gimmick to let people lower their cars without sacrificing all of the ride quality. A band-aid, if you will. My opinion, of course.

Chip has described much better the point that I was trying to make. As you increase the shock setting to "match" a stiffer spring, the D-specs are theoretically going the wrong way with their bump damping, while the Konis are at least remaining constant on the 'bump' side of things. Hence it appears to me that as you select stiffer springs the Konis increasingly become the better choice.Assuming that their bump damping choice suits you, that is.

This bump damping issue isn't a pass-fail thing in a street car, BTW, just one of the little percentage things that win races or auto-X's for you once you get serious. A sensitive driver might notice a difference in the ride (noting here that some folks don't even notice the difference in ride firmness when you replace totally dead shocks with new ones). The increase in bump damping in the D-specs may not even be very much. (I'd really like to see some shock plots, hint, hint . . . Chip?).


Norm

F1Fan

Hi Norm,

There used to be some D-Spec charts on the webbut I don't now where they are any more. As I recallthe bump damping changes are fairly small and amount to no more than maybe 20% or so the the total working bump compression rateat the fully firm setting for a given piston velocity. This is in strong contrast to the rebound adjustability range which I recall being really wide somwhere about 200%withsharply increasing damping rates at slower piston velocities as the rebound damping increased. Somewhere around the lower 1/3? or soof the damping range thedamping curves goflat or linear for both bump and rebound damping rates. I think this is why the D-Specs ride well when set at their lower settings and yet when turned upcontrolincreasesso much more quicky than ride degrades. I also think this is why they work so wellwithlinear rate springs, the damping rates and the ratio betweenbump and rebound rates are were wellselectedfor the car so you can have a pretty niceride and still achive a high level of transitional control even at lower settings. It's weird to me but it works well enough. I think that on th smoothest pavement the type of valve Tokico used is not as refinedor as responsive as the valves used in the Koni Sport dampers.I think the D-Spec valving is morerugged compared to the Koni Sport's valve metering system as we used to get a lot of blown Koni Sport dampers back from the VW rally racers. Of courseas I recall they were using the Koni FIA stuts and rear dampers but AFAIK Konihas always used the same basic valve metering system in all of the top adjusted singleadjustable dampers.

HTH!

<< EDITED for clarity >>

Sam Strano

The "chart" of the D-specs is available on Tokico's website... but it's a generic chart that just gives an idea of what's up. Does not tell you what car they are for,or if theyare fronts or rears. Basically it's a very, very generic example. And it's here, right on Tokico's site: http://www.hitachi-hap-la.com/Tokico...roducts/dspec/

As for which is more durable. I have way, way better luck with Koni's than Tokico's where durability is involved. While F1Fan might have seen a lot of blown VW units, Rally is not what they are intended, or designed for. All I know is that so far I've had 3 blown D-specs and no blown Koni's. Doesn't mean thatbreaking onecan't happen but over the years in my experience, regardless of the car, Koni's don't have as many issues in comparison. What's more is that there are at least 3 different "Sytles" of Koni single adjustables, and they are not all the same. They adjust in different ways. Some you have to compress fully to adjust, some you extend fully to adjust. And then some use the ****, like the S197's do. They are not all the same mechanism.

I'm on record as stating the D-specs are a big improvement over previous Tokico's and I'm notanti-D-Spec. While the bump doesn't make the same kind of increases as the rebound, it shouldn't. There is generally about 2/3rds more rebound in a typical shock as there is compression damping, and if the D-Specs increased the compression in an equal amount vs. an equal ratio, that'd be big trouble. But as it stands, compression damping and rebound damping do different jobs. I just feel that compression damping need to be right, and critically damped. Not overdamped. The compression job is to control the movement of the unsprung weight. It does not deal with how the car takes a set, or how it generates roll or pitch. Those are rebound items. If you get too little compression that's bad as the tire bounces like a basketball. Too much and the ride becomes too harsh. The issue I have with the D-Specs, and the biggest reasonthat I personallychanged and recommend Koni's is that you can't have one without the other. And I've been boxed by that system of adjustment. There have been times I wanted more rebound control in the car, but getting it meant the accompanying increase on compression, which on not perfect roads makes for a more "heavy footed" response to impacts. Sure, we can turn the shocks down and make that better... but then you soften rebound damping and that in turn makes the car generate roll and pitch more quickly, and in extreme instances might cause enough drop to not deal with the spring rate well enough.

What started this thread was my posting of a customer's findings (not my own). Remember the car is on a set of Steeda springs. The man had both D-specs and the Koni's and his findings illustrate the phenomena I'm talking about above with regards to compression vs. rebound. He called me complaining the car didn't deal with bumps well. While he could turn the shocks softer and it helped, the car then felt too vague. This was a classic case of wanting to adjust rebound alone.... which is how we ended up getting him Koni's. The only change he made this time around was the dampers. He asked about changing springs, but I told him to wait, as I knew the Koni change would have a good effect. I didn't know if it'd be perfect for him or not, that was something we had to find out (and a reason I recommend incremental changes and not massive ones). I should also note that our first conversation revolved around what settings he was using in D-Specs. The second was a report on different settings and his findings. Only then did we make the decision to change him over, and clearly his happy with the switch.

I do think the Koni's are superior dampers. I also don't hate D-Specs. I think if money is truly an issue, the D-Specs are good bang for the buck. However, I find that folks often say money is an issue but go spend as much or more on things that matter much less. That's a mistake. Good dampers rule so much, and will be in place for so long that they should not be skimped upon.

Can you do worse than D-Specs? Sure, and I sell them because I believe they work and work pretty well. However, I don't feel they are the best thing around, and like most "options" you can get on a car, when you opt for something that doesn't cost as much, you tend to give up something. Here it's the combination of ride quality vs. performance and just now finely you dial in the car. I heard a great line the other night, and it's true.... "You can't know what you don't know". Those that have been able to back to back the two dampers know both sides. Those that haven't been able to, or can't have to rely on what they hear and can learn. Like anything you will get different opinions. This is why I spend time with folks and do my best to explain the differences. Something that is not my favorite doesn't equal that thing sucking. It might, but the two are not mutually exclusive. I don't think D-Specs suck, but they aren't Koni's IMO.

F1Fan

Hi Sam,

There was an S197D-Spec #DSP12 specific chart very early on the website when they were announced but this has been replaced with the generic version as you mention.

Durability wise when used on a smooth surface and maintained well I have no doubt thatD-Specs will lastjust as long as a Koni sport dampercan but inthe real world this is a big variable and with D-Specs being relatively new only time will tell in this application Absolute numbers are deceptive, there have been more D-Specs sold than Koni Sports I assumme this istrue evenat your relatively new shop. It is not the absolute number of returns but the percentage of units sold and returned actually failed (not caused by external forces)that shows reliability.

Historically I agree with you Koni are very reliable dampers but like everything else they do break on a regularbasis. The place I used to work atused to sell thousands ofKonidampers every year and the return rate of Konidampers that were actually broken was higher than the number of Bilstein dampersin the same condition at that time.Actually theKoni VWrace struts we soldwere supposedly built and designed for just for rally use and would blow the valves in the pistons out not the seals and not the foot valves. Based on the problems folks had with the Koni dampers at the time a lot of people switched to Bilsteins and had very few problems not caused by putting the car into a ditch or tree. Koni and Bilstein use very different valving methods and the Bilsteins justworked more reliablyfor the rally folks than the Konis at the time. Stuff changes all the time though so who know what works now for the rally folks? This was just an example and my experience with a problem that Koni did not overcome before people jumped toBillies.

The interesting thing is that if you look at even the D-Spec'scompresiondamping rateI think the percentange of change is much smaller than the increased rebound damping effectively giving you the same sort of adjustment we used to do on the 2/3-way dampers in use at the time. How the D-Specs and Koni Sports curves differ mightshow us better how they differ and why they can feel so differently with different springs and unsprungweights. I may be ableto call andget the specfic shock dyno charts for the DSP12 dampers from Tokico. Or if you have half a set of D-Specs you can send me for a couple of weeks so I cango and have them put on a shock dyno send them to me and I'll give you a copy of the shock dyno charts I get when I send the dampers back.

As I've posted before Koni's do very well undera narow range of conditions and for a track car or a high-performance road car will be a great option as long as the driver canaccept the additonal ride harshness and potential mismatch in compression damping for hiscombination. For the most part I aggree that Koni'sare a goodchoice as long as that driver isfocused on road racing, soloand autoX events. Long tours, rough roadsand drag racing have very different needs in terms of damping traits and Koni Sports simply cannot meet these needs as well as a D-Spec damper does. You will never get a car with Koni Sportsto transfer weight on the drag strip as quickly as a D-Specequiped S197 all other things being equal, you will never get a Koni Sport equipedS197 to ride as softly as a D-spec equiped S197. So as any one cansee you canjust as easily be boxed in with the Koni Sports if you happen to want to run at the drag strip or needa softtouring quality ride, it's no different. It's just the nature of the different valving systems and the reasonfor the existance of 2,3,4 and 6-way dampers. Given a choice IMO and experience on the street more people are willing to trade some finetrack control forpotentially better ride and a wider range of acceptable use. Sure you can buy better drag dampers, QA1 makes some nice strutsand the Koni Sports IMO make a better low-end road racing damperbut the D-Specs can and doperformas well as the dedicated road or drag strip dampers just look at the people using them onroad courses and drag strips. If winning racesis the measure of success then D-Specs are doing a lot more than just being the best bang for the buck dampers out there they are killing Koni at the moment.As you can see I don't disagree with your assessment that Koni makesthe better road racingusedampers but this is a bit narrower thanmost people are willing touse their cars.

HTH!