Characterization of the OE Suspension Springs
12-16-2015, 01:17 PM
#131
Thanks so much Twohoos.
I think the link i left for the Honda japanese web page a couple posts above is the one you got that info from, cause a lot of the translated words are the same. But, i cant find a pic of the shocks.
I think the link i left for the Honda japanese web page a couple posts above is the one you got that info from, cause a lot of the translated words are the same. But, i cant find a pic of the shocks.
12-18-2015, 03:28 PM
#132
Thread Starter
Well! Here's an interesting plot, and one which I think really drives home the evolution of the S2000 spring rates.
Here's the idea: Each tire experiences a certain "normalized" load, which is just the weight on the tire divided by its tread width. This is the load per mm of tread. In the last table of my earlier post, I estimated the *ratio* of front normalized load to rear normalized load at 1.0g. However, this ratio varies for different cornering forces, since the lateral load transfer distribution is not generally the same as the car's static weight distribution. (For example, at rest, 50% of a car's weight might be on the front tires, but when cornering, only 40% of the weight transfer might be at the front.) So as cornering forces build, the car's "normalized" load distribution can change (sometimes dramatically). All else equal, the higher the F/R load ratio, the more understeer the car will exhibit.
Now, "understeer" and "oversteer" are only meaningful at the limit of adhesion: when there's plenty of grip, this F/R ratio is irrelevant. But grip limits change - tire sizes and compounds are an obvious factor, but even with the same tires, the grip limit depends on many things: track material, temperature, surface conditions, degree of banking, fuel load, and even driver weight, just to name a few. (In icy conditions, the lateral limit may be 0.1g or less!) The point is that if a car's F/R load ratio *changes* significantly at different cornering limits, it's possible to experience a dramatic handling change from one day (or one morning, or even one corner!) to the next. So ideally you'd like to see the F/R ratio be a constant value for all lateral loads. In fact, for an extra measure of safety, you might even want the ratio to increase somewhat at higher g's, so that the car's handling would tend to get more stable as cornering loads increase.
With all of this in mind, I offer the following.
Wow.
Now, obviously there are a bunch of caveats here - it's very much a first-order model, this is only steady-state (damping neglected), etc. Maybe the most important assumption here is that every mm of *rated* tread width is equal, i.e. can support the same load before it loses grip: Front/rear tread patterns can be very different (*cough*OEM AP1 S02s*cough*), compounds might differ slightly, and different F/R tire profiles can cause different response characteristics. And of course, alignment or inflation pressure can load the tread unevenly.
Still. If the *relative* trends are anywhere near accurate, it's pretty clear that the AP1's "tricky" suspension is not just due to roll steer. (Alignment and alignment change vs. load are also neglected here). These numbers suggest that, for '02-'03 especially, the AP1 could be a completely different animal in low-grip versus high-grip situations, simply based on the change in steady-state tire loading. Moreover, if we accounted for roll-steer, the downward slope of the AP1 curves "should" be even steeper - the AP1's tendency toward oversteer at higher loads is even *worse* than shown here!
By comparison, the AP2 curves are much flatter and, as we'd expect, shifted more towards understeer. In fact, the '08-'09 curve is absolutely flat! That's because the load transfer distribution ended up being identical to the at-rest weight distribution. However, this is actually a bit of a coincidence: they'd be different if I used a different driver weight and/or fuel load.
What I get out of all this is a real appreciation for the subtleties of suspension design, and how tricky it can be to account for the huge variety of conditions people will experience. And who knows, perhaps this ever-changing nature of the S2000 -and AP1s especially- helps explain why so many owners seem never to get bored with it: an S2000 is never the same car twice! (And if it is, it's easy to change!)
So the next time someone asks you how your S2000 handles, tell them: "It depends: How do you want it to handle?"
Here's the idea: Each tire experiences a certain "normalized" load, which is just the weight on the tire divided by its tread width. This is the load per mm of tread. In the last table of my earlier post, I estimated the *ratio* of front normalized load to rear normalized load at 1.0g. However, this ratio varies for different cornering forces, since the lateral load transfer distribution is not generally the same as the car's static weight distribution. (For example, at rest, 50% of a car's weight might be on the front tires, but when cornering, only 40% of the weight transfer might be at the front.) So as cornering forces build, the car's "normalized" load distribution can change (sometimes dramatically). All else equal, the higher the F/R load ratio, the more understeer the car will exhibit.
Now, "understeer" and "oversteer" are only meaningful at the limit of adhesion: when there's plenty of grip, this F/R ratio is irrelevant. But grip limits change - tire sizes and compounds are an obvious factor, but even with the same tires, the grip limit depends on many things: track material, temperature, surface conditions, degree of banking, fuel load, and even driver weight, just to name a few. (In icy conditions, the lateral limit may be 0.1g or less!) The point is that if a car's F/R load ratio *changes* significantly at different cornering limits, it's possible to experience a dramatic handling change from one day (or one morning, or even one corner!) to the next. So ideally you'd like to see the F/R ratio be a constant value for all lateral loads. In fact, for an extra measure of safety, you might even want the ratio to increase somewhat at higher g's, so that the car's handling would tend to get more stable as cornering loads increase.
With all of this in mind, I offer the following.
Wow.
Now, obviously there are a bunch of caveats here - it's very much a first-order model, this is only steady-state (damping neglected), etc. Maybe the most important assumption here is that every mm of *rated* tread width is equal, i.e. can support the same load before it loses grip: Front/rear tread patterns can be very different (*cough*OEM AP1 S02s*cough*), compounds might differ slightly, and different F/R tire profiles can cause different response characteristics. And of course, alignment or inflation pressure can load the tread unevenly.
Still. If the *relative* trends are anywhere near accurate, it's pretty clear that the AP1's "tricky" suspension is not just due to roll steer. (Alignment and alignment change vs. load are also neglected here). These numbers suggest that, for '02-'03 especially, the AP1 could be a completely different animal in low-grip versus high-grip situations, simply based on the change in steady-state tire loading. Moreover, if we accounted for roll-steer, the downward slope of the AP1 curves "should" be even steeper - the AP1's tendency toward oversteer at higher loads is even *worse* than shown here!
By comparison, the AP2 curves are much flatter and, as we'd expect, shifted more towards understeer. In fact, the '08-'09 curve is absolutely flat! That's because the load transfer distribution ended up being identical to the at-rest weight distribution. However, this is actually a bit of a coincidence: they'd be different if I used a different driver weight and/or fuel load.
What I get out of all this is a real appreciation for the subtleties of suspension design, and how tricky it can be to account for the huge variety of conditions people will experience. And who knows, perhaps this ever-changing nature of the S2000 -and AP1s especially- helps explain why so many owners seem never to get bored with it: an S2000 is never the same car twice! (And if it is, it's easy to change!)
So the next time someone asks you how your S2000 handles, tell them: "It depends: How do you want it to handle?"
01-08-2016, 12:19 PM
#134
Thread Starter
Administrative note: I've changed the download link in the original post - I'm now hosting the PDF file on Google Drive. The old link will no longer work.
BTW, thanks to everyone for the interest and feedback. Based on some web statistics, I estimate that the paper has been downloaded at least 10,000 times. That's about 5 times per day; or if you prefer, about 1 download for every 11 S2000s produced worldwide.
BTW, thanks to everyone for the interest and feedback. Based on some web statistics, I estimate that the paper has been downloaded at least 10,000 times. That's about 5 times per day; or if you prefer, about 1 download for every 11 S2000s produced worldwide.
02-04-2016, 09:43 PM
#135
This is great stuff. Is there some way to use this information to consider what other shocks/springs to use? For example, Mugen (sold by Honda, so technically should be part of this list, right?) :-) They have fronts which are 7s and rears that are 11s. How do I compare that to my 2003 AP1 to know how it will fall on the charts here?
For what it's worth, I've been doing more research and found that interestingly that the Mugen version went stiffer in the rear than stock - contrary to the path the factory was taking, but Mugen looked to changing compression and rebound to dial in or out the understeer/oversteer - making this comparison certainly more difficult.
For what it's worth, I've been doing more research and found that interestingly that the Mugen version went stiffer in the rear than stock - contrary to the path the factory was taking, but Mugen looked to changing compression and rebound to dial in or out the understeer/oversteer - making this comparison certainly more difficult.
03-03-2016, 12:54 PM
#136
Wow is right. Amazing stuff Twohoos! Your charts and data just keep getting more and more insightful. Its like you started building a solid foundation, not knowing what sort of building would take shape on top of it, yet somehow knowing exactly what sort of foundation to build. Then as time went on you took that foundation that your raw data represented, and could clearly see what each new floor of the building should look like. Eventually leading to this. I don't think people realize yet what this all represents.
It seems like this goes a long way to explaining what Honda was chasing with the suspension changes that were made to subsequent model years. It wasn't just that they were dumbing things down and progressively moving the bias to more and more understeer. They were trying to achieve balanced, stable, linear response to cornering load. And it seems like they finally achieved it.
I think it would be tremendously eye opening and useful to be able to overlay the graphs of popular aftermarket suspensions. Coilovers, swaybars, etc.
What would be over-the-top cool is to be able to plug in our own spring rates, sway bar rates, etc, and it would plot our own custom graph and overlay onto the chart above, so we could see what our current combo would lool like, and to plan out mods we might want to consider.
Also could make driver weight an editable variable, as well as tire sizes.
What did you use to plot that chart?
Sent from my SM-G920P using IB AutoGroup
It seems like this goes a long way to explaining what Honda was chasing with the suspension changes that were made to subsequent model years. It wasn't just that they were dumbing things down and progressively moving the bias to more and more understeer. They were trying to achieve balanced, stable, linear response to cornering load. And it seems like they finally achieved it.
I think it would be tremendously eye opening and useful to be able to overlay the graphs of popular aftermarket suspensions. Coilovers, swaybars, etc.
What would be over-the-top cool is to be able to plug in our own spring rates, sway bar rates, etc, and it would plot our own custom graph and overlay onto the chart above, so we could see what our current combo would lool like, and to plan out mods we might want to consider.
Also could make driver weight an editable variable, as well as tire sizes.
What did you use to plot that chart?
Sent from my SM-G920P using IB AutoGroup
04-09-2016, 10:37 AM
#137
Any major differences in shocks?
Car is a 2002 S2000 AP1 with 17" AP2V1 wheels and unknown maker very firm lowered springs. Car has a broken front left spring.
Replacing both front springs appears to be prudent. Softening the harsh ride is desirable.
Here's the proposal.
Install 2006 springs all round plus a 2006 rear sway bar.
Reading the data in this thread leads me to believe the car will then handle like my 2006 AP2 car. The question is the shocks. Will the 2002 shocks, which seem to be in good condition be OK, or should I look for later shocks as well?
-- Chuck
Car is a 2002 S2000 AP1 with 17" AP2V1 wheels and unknown maker very firm lowered springs. Car has a broken front left spring.
Replacing both front springs appears to be prudent. Softening the harsh ride is desirable.
Here's the proposal.
Install 2006 springs all round plus a 2006 rear sway bar.
Reading the data in this thread leads me to believe the car will then handle like my 2006 AP2 car. The question is the shocks. Will the 2002 shocks, which seem to be in good condition be OK, or should I look for later shocks as well?
-- Chuck
04-11-2016, 11:36 AM
#138
Thread Starter
Car Analogy:
Thanks so much for the very kind words. You're a little too generous I think -- but I'll admit you made my day.
To your questions: It's all in Excel; everything is editable/customizable; and yes the tool allows for custom spring/bar/ride-height setups and compares them to the OEM configs. BUT it would be a mistake to make any significant suspension changes based only on this tool's results: spring rates and static load transfers play a surprisingly small part in real-world handling "feel". There are so many dynamic and non-linear effects that my tool just can't capture: damping curves, alignment changes with weight transfer... More than once, I've pretty well transformed my car's handling with nothing more than a tire pressure change in between sessions.
So these numbers will be misleading if you treat them as the complete picture. Take the CR for example: we know how great it is on track, but based only on my numbers, you'd expect it to handle like a snowplow.
Chuck S's question offers another example:
Chuck - I would keep your '02 shocks and reunite them with a set of '02-'03 springs. First, putting '06 springs on '02 dampers will raise the front and lower the rear of the car (relative to stock), which would cause both handling and, um, cosmetic issues. Second, you should really experience your '02 in stock form: I've driven all of the OE configs --on both street and track-- and IMHO the '02-'03 AP1 is the most satisfying OE setup overall. And yes, this is despite the glaring rearward spring bias predicted by my tool: in reality, the '02-'03 is fun and comfortable on the street, and immensely rewarding on track.
Thanks so much for the very kind words. You're a little too generous I think -- but I'll admit you made my day.
To your questions: It's all in Excel; everything is editable/customizable; and yes the tool allows for custom spring/bar/ride-height setups and compares them to the OEM configs. BUT it would be a mistake to make any significant suspension changes based only on this tool's results: spring rates and static load transfers play a surprisingly small part in real-world handling "feel". There are so many dynamic and non-linear effects that my tool just can't capture: damping curves, alignment changes with weight transfer... More than once, I've pretty well transformed my car's handling with nothing more than a tire pressure change in between sessions.
So these numbers will be misleading if you treat them as the complete picture. Take the CR for example: we know how great it is on track, but based only on my numbers, you'd expect it to handle like a snowplow.
Chuck S's question offers another example:
Chuck - I would keep your '02 shocks and reunite them with a set of '02-'03 springs. First, putting '06 springs on '02 dampers will raise the front and lower the rear of the car (relative to stock), which would cause both handling and, um, cosmetic issues. Second, you should really experience your '02 in stock form: I've driven all of the OE configs --on both street and track-- and IMHO the '02-'03 AP1 is the most satisfying OE setup overall. And yes, this is despite the glaring rearward spring bias predicted by my tool: in reality, the '02-'03 is fun and comfortable on the street, and immensely rewarding on track.
09-04-2016, 06:35 AM
#139
Regarding the Type S shocks pictured above, that nobody really knows much about.
A guy walked into Ballade Sports with appears to be a set of these, asking to have them installed.
Ballade thought they looked like they were made by Showa, which is Honda's usual OEM manufacturer.
He bought them from this source:
Japanparts.com
https://www.japanparts.com/parts/detail/2564
They appear to be the same pictures as above, and the manufacturer is listed as Modulo. Anybody know anything?
A guy walked into Ballade Sports with appears to be a set of these, asking to have them installed.
Ballade thought they looked like they were made by Showa, which is Honda's usual OEM manufacturer.
He bought them from this source:
Japanparts.com
https://www.japanparts.com/parts/detail/2564
They appear to be the same pictures as above, and the manufacturer is listed as Modulo. Anybody know anything?
09-04-2016, 07:00 AM
#140
Chuck S's question offers another example:
Chuck - I would keep your '02 shocks and reunite them with a set of '02-'03 springs. First, putting '06 springs on '02 dampers will raise the front and lower the rear of the car (relative to stock), which would cause both handling and, um, cosmetic issues. Second, you should really experience your '02 in stock form: I've driven all of the OE configs --on both street and track-- and IMHO the '02-'03 AP1 is the most satisfying OE setup overall. And yes, this is despite the glaring rearward spring bias predicted by my tool: in reality, the '02-'03 is fun and comfortable on the street, and immensely rewarding on track.
Chuck - I would keep your '02 shocks and reunite them with a set of '02-'03 springs. First, putting '06 springs on '02 dampers will raise the front and lower the rear of the car (relative to stock), which would cause both handling and, um, cosmetic issues. Second, you should really experience your '02 in stock form: I've driven all of the OE configs --on both street and track-- and IMHO the '02-'03 AP1 is the most satisfying OE setup overall. And yes, this is despite the glaring rearward spring bias predicted by my tool: in reality, the '02-'03 is fun and comfortable on the street, and immensely rewarding on track.
We were able to source a complete set of OEM MY2002 springs and replaced all the lowering springs. Reports are the car rides and, perhaps, handles much better. And doesn't scrape on all the speed bumps.
I use the term "we" in that I found the springs and he paid for and put them on!
The color coding of the OEM springs is a large plus in determining what springs are there.-- Chuck