Side Effect of changing SPRINGS only
05-22-2004, 01:31 PM
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Originally posted by fietguy
...so the aftermarket springs installed will not blow out the shocks significantly earlier than the factory springs would...
...so the aftermarket springs installed will not blow out the shocks significantly earlier than the factory springs would...
...how about the people who have installed aftermarket springs and have concluded the ride is the same? in fact, in this forum, besides the guy who said his ride was bouncy, most people have said their ride is 'feels much like stock' yet with a great reduction in bodyroll in the twisties.
do these people not feel that with their new springs, the dampening is now not adequate?
do these people not feel that with their new springs, the dampening is now not adequate?
For actual handling, braking, and accelerating performance, remember that the goal is to keep that optimim tire contact patch, and keep it consistently. If you change springs, and the new spring/shock combination is not as well matched, you won't keep that patch as consistently. That's a fact. The question is how much of a difference is that going to be.
Now, is it going to be so different that a driver can tell a difference? Probably not. And when you are putting on most of these springs, you are lowering the car. The simple matter of dropping the COG an inch or more will make a significant difference in the handling and roll, even if the new springs aren't stiffer. And that improvement in handling will normally be much greater than the decrease in the optimum tire contact patch. It's that low center of gravity that really makes a difference in how nimble a car is.
My point is, even though you won't have perfectly matched shocks/springs, you will still improve handling by installing most aftermarket springs. It's just that it will be even better when you can match the shocks and springs.
On a side note, this is one of the ways that a coilover setup is better than most aftermarket spring/shock combinations. It is very hard for someone to match a set of springs and shocks from different companies on their car. I know a little bit about suspensions, more than the average Joe, but I know that even if I had a chance to test all sorts of combinations of springs and shocks, I would have a heck of a time finding the optimum combination. With coilovers, they are already matched by people who have the equipment and knowledge, and they've already done the work for me. Now, if you can get a package of springs/shocks from a company that are already matched (like the set from Mazdaspeed), then you're ahead of the game there too.
---jps
05-24-2004, 08:53 AM
#28
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From an engineering standpoint, my opinion is that changing out the springs without installing properly matched shocks could possibly shorten the life of the OEM shocks. However, all anyone can do is speculate or call upon past experience without knowing the design specifications (fatigue life, rated dynamic load, etc.) of the OEM shocks. It's very possible that the shocks will be just fine with stiffer springs, but it's also possible that life could be severely shortened.
Manufacturers specify damping rates for the shocks to achieve the desired damping ratio for the bounce mode of the vehicle. This is the dominant mode of vibration response when a vehicle goes over any sharp discontinuity in the road surface. The higher the damping ratio, the more rapidly the bouncing mode decays, and vice versa. A very rapid decay of bounce feels harsh, however it is better for handling. For this reason, sports cars are tuned with higher damping ratios than luxury vehicles.
If you consider the vehicle sprung mass and springs as a mechanical oscillator, the damping ratio, which I'll call Zeta, can be written as follows:
Zeta = c / (2 * (k * m)^0.5)
where c = shock damping coefficient, k = spring rate, m = sprung vehicle mass.
It's obvious that with a stiffer spring (higher k), the damping ratio decreases, and a lower damping ratio means that the vehicle will oscillate or bounce more. Therefore, there is no doubt that with stiffer springs, the OEM shocks will experience more cycles in a shorter amount of time. And since the durability of suspension components is measured with fatigue life, or number of cycles until failure, it is logical to conclude that the shocks will fail in a shorter amount of time.
The only question is how robust are the OEM shocks? Will the life of the shocks decrease on average by 1 year? 2 years? or more? We'd have to get some input from the Mazda suspension engineers to answer these questions.
Manufacturers specify damping rates for the shocks to achieve the desired damping ratio for the bounce mode of the vehicle. This is the dominant mode of vibration response when a vehicle goes over any sharp discontinuity in the road surface. The higher the damping ratio, the more rapidly the bouncing mode decays, and vice versa. A very rapid decay of bounce feels harsh, however it is better for handling. For this reason, sports cars are tuned with higher damping ratios than luxury vehicles.
If you consider the vehicle sprung mass and springs as a mechanical oscillator, the damping ratio, which I'll call Zeta, can be written as follows:
Zeta = c / (2 * (k * m)^0.5)
where c = shock damping coefficient, k = spring rate, m = sprung vehicle mass.
It's obvious that with a stiffer spring (higher k), the damping ratio decreases, and a lower damping ratio means that the vehicle will oscillate or bounce more. Therefore, there is no doubt that with stiffer springs, the OEM shocks will experience more cycles in a shorter amount of time. And since the durability of suspension components is measured with fatigue life, or number of cycles until failure, it is logical to conclude that the shocks will fail in a shorter amount of time.
The only question is how robust are the OEM shocks? Will the life of the shocks decrease on average by 1 year? 2 years? or more? We'd have to get some input from the Mazda suspension engineers to answer these questions.
05-24-2004, 05:27 PM
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thanks members, the last two answers were brilliant...and puts into perspective many assumptions
the missing factor just seems to be how robust the OEM shocks are...
hmmm, $150 for springs, $2000 for coilovers....if we get the coilover setup how do we know as consumers its the right dampening set up for the car? will coilovers life span be shorter or longer than OEM?
the missing factor just seems to be how robust the OEM shocks are...
hmmm, $150 for springs, $2000 for coilovers....if we get the coilover setup how do we know as consumers its the right dampening set up for the car? will coilovers life span be shorter or longer than OEM?
05-28-2004, 08:16 AM
#30
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great responses sputnik and buckeye.
Sptunik: based on ur last statement which would you think is the better option to go with..
JIC Coilover or MazdaSpeed Spring/Shock Setup.
I am not looking to just drop the car for looks, I would like to get rid of the bodyroll when autox.
also for those AutoX experts will changing springs and shocks change my class from BStock?
Sptunik: based on ur last statement which would you think is the better option to go with..
JIC Coilover or MazdaSpeed Spring/Shock Setup.
I am not looking to just drop the car for looks, I would like to get rid of the bodyroll when autox.
also for those AutoX experts will changing springs and shocks change my class from BStock?
05-28-2004, 12:16 PM
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It sounds like a cop-out, but it depends on who we are talking about.
First, I don't know about JIC themselves. I'd have to look at the different coilover setups available for the car, and see how they were put together, and how stiff the spring package is. There are some companies that make good coilovers for one make/model, and not-so-well-thought-out for others.
Second, it would also depend on how much suspension travel you lose with just the spring/shock setup. Even on relatively smooth surfaces, you do need to keep some suspension travel (for ride, handling, accelerating, and braking), and alot of aftermarket spring/shock packages have you either bouncing off the bump-stops, or setting the shocks too stiff (some people also adjust their coilovers too stiff too). I would look into it, but I expect that the Mazdaspeed setup will be okay in this aspect.
Third, if you are planning to go as far as coilovers, you have to plan on changing other suspension components to get the most out of it. You will need to consider replacing all of the suspension bushings, swaybars, upper shock mounts, adding effective strut tower bars (not just shiny pieces that go from tower to tower, solid bars that also connect to the firewall). At this point, lightweight wheels become a major factor, and even replacing the brake hardware with lighter calipers and two-piece rotors (even if you do not increase braking effort) makes a difference. Otherwise, you won't get that much more of a benefit from installing coilovers over mere spring/shocks. You don't have to do it all at once, but you need to eventually to get all of the benefits of a coilover package.
So in short, if you're just looking for a basic upgrade, the MS spring shocks would be the best bet. It would only be worth getting a full coilover package if you plan on doing the other mods too.
And I'm not an SCCA rule expert, but I do know that springs will put you into Street Prepared. Shocks might be considered "consumable" items like rotors and brake pads, and could be changed, but I could be completely wrong on that.
---jps
First, I don't know about JIC themselves. I'd have to look at the different coilover setups available for the car, and see how they were put together, and how stiff the spring package is. There are some companies that make good coilovers for one make/model, and not-so-well-thought-out for others.
Second, it would also depend on how much suspension travel you lose with just the spring/shock setup. Even on relatively smooth surfaces, you do need to keep some suspension travel (for ride, handling, accelerating, and braking), and alot of aftermarket spring/shock packages have you either bouncing off the bump-stops, or setting the shocks too stiff (some people also adjust their coilovers too stiff too). I would look into it, but I expect that the Mazdaspeed setup will be okay in this aspect.
Third, if you are planning to go as far as coilovers, you have to plan on changing other suspension components to get the most out of it. You will need to consider replacing all of the suspension bushings, swaybars, upper shock mounts, adding effective strut tower bars (not just shiny pieces that go from tower to tower, solid bars that also connect to the firewall). At this point, lightweight wheels become a major factor, and even replacing the brake hardware with lighter calipers and two-piece rotors (even if you do not increase braking effort) makes a difference. Otherwise, you won't get that much more of a benefit from installing coilovers over mere spring/shocks. You don't have to do it all at once, but you need to eventually to get all of the benefits of a coilover package.
So in short, if you're just looking for a basic upgrade, the MS spring shocks would be the best bet. It would only be worth getting a full coilover package if you plan on doing the other mods too.
And I'm not an SCCA rule expert, but I do know that springs will put you into Street Prepared. Shocks might be considered "consumable" items like rotors and brake pads, and could be changed, but I could be completely wrong on that.
---jps
05-31-2004, 02:42 AM
#32
I disagree. I think you will get plenty of advantage with a set of matched coilovers. The ability to independently set height of the car is very valuable - you can choose the ride height that matches your roads & driving style (the value of suspension travel should never be underestimated). Additionally, the ability to change the amount of damping can be easily utilized if you autocross - nice & stiff while competing, and nice & comfy while commuting. While the other things you list certainly go into making a top-notch car, I'd say you can extract the majority of the potential benefit of a set of coilovers simply by installing them, choosing a good combination of ride height & alignment settings, and installing a set of sticky tires (say, 245 section Kumho MX).
Another nice benefit of the stiffer springs is that they reduce body roll without the use of stiff sways. I know there is much controversy on this, but after fiddling with my Miata for 5 years I've come around to the idea that, for sways anyway, the smaller the better (with stiff springs, anyway). I'm still watching the market, but for my RX-8 anyway, I think the car will be best served by a nice set of coilovers with about a 50% increase in (linear) spring rate, a broad range of damping adjustment, a moderate height reduction (at my discretion, of course), and stock sways. Yes, this does sound a bit like the MS setup, with the exception of ride height & damping adjustments. I really want those.
And yes, non-stock springs, or spring mounting methods, bounce you out of B stock (but shocks do not). Just run STU instead - no reason to run SP, unless you really want to run R-compound tires, in which case you end up in ASP (good luck).
George
Another nice benefit of the stiffer springs is that they reduce body roll without the use of stiff sways. I know there is much controversy on this, but after fiddling with my Miata for 5 years I've come around to the idea that, for sways anyway, the smaller the better (with stiff springs, anyway). I'm still watching the market, but for my RX-8 anyway, I think the car will be best served by a nice set of coilovers with about a 50% increase in (linear) spring rate, a broad range of damping adjustment, a moderate height reduction (at my discretion, of course), and stock sways. Yes, this does sound a bit like the MS setup, with the exception of ride height & damping adjustments. I really want those.
And yes, non-stock springs, or spring mounting methods, bounce you out of B stock (but shocks do not). Just run STU instead - no reason to run SP, unless you really want to run R-compound tires, in which case you end up in ASP (good luck).
George
05-31-2004, 03:14 AM
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Correct me if I'm wrong here. My region has no STU class, so with my only mods being a cat back, springs, and a front sway, I should be running ASP, yes? I did my first event a week ago and got classed in SM (that was without the sway as well). Didn't seem right to me, but I didn't know enough at the time to say anything. I do plan on getting a dedicated set of auto-x wheels, and probably will slap R-compound tires on them. Save a little wear and tear on the lovely RE040's.
05-31-2004, 10:35 AM
#34
Yes, with those mods you are legal in ASP. Funny they put you in SM, the RX-8 is technically in SM2.
And you may want to petition your local region to allow STU. Show up at a commitee meeting and ask - usually they will add it without much fanfare. Of course, if you are the only person in the class, it's not much fun, but then again it's not much fun in SP unless there are several other "under-prepared" cars in your class to compete with ("real" SP cars are very fast). The nice thing about STU is you get a better PAX factor, so you'll place higher overall, and you can buy a special set of street tires, which will last longer than Kumohs or Hoosiers.
And you may want to petition your local region to allow STU. Show up at a commitee meeting and ask - usually they will add it without much fanfare. Of course, if you are the only person in the class, it's not much fun, but then again it's not much fun in SP unless there are several other "under-prepared" cars in your class to compete with ("real" SP cars are very fast). The nice thing about STU is you get a better PAX factor, so you'll place higher overall, and you can buy a special set of street tires, which will last longer than Kumohs or Hoosiers.
05-31-2004, 03:09 PM
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Originally posted by GeorgeH
I disagree. I think you will get plenty of advantage with a set of matched coilovers. The ability to independently set height of the car is very valuable - you can choose the ride height that matches your roads & driving style (the value of suspension travel should never be underestimated). Additionally, the ability to change the amount of damping can be easily utilized if you autocross - nice & stiff while competing, and nice & comfy while commuting. While the other things you list certainly go into making a top-notch car, I'd say you can extract the majority of the potential benefit of a set of coilovers simply by installing them, choosing a good combination of ride height & alignment settings, and installing a set of sticky tires (say, 245 section Kumho MX)...
I disagree. I think you will get plenty of advantage with a set of matched coilovers. The ability to independently set height of the car is very valuable - you can choose the ride height that matches your roads & driving style (the value of suspension travel should never be underestimated). Additionally, the ability to change the amount of damping can be easily utilized if you autocross - nice & stiff while competing, and nice & comfy while commuting. While the other things you list certainly go into making a top-notch car, I'd say you can extract the majority of the potential benefit of a set of coilovers simply by installing them, choosing a good combination of ride height & alignment settings, and installing a set of sticky tires (say, 245 section Kumho MX)...
---jps
05-31-2004, 04:52 PM
#36
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I wanted to add that unlike many other cars I've had the RX-8 with stock suspension is already on the verge of being "bouncy".
I personally would not do any spring swap without doing the shocks as well.
That is my opinion and it is based on doing spring upgrades on my last two cars. I do not have any actual experience with this on the RX-8 and I don't plan too for another few years. When my factory shocks wear out, I'll do something then.
-Mr. Wigggles
I personally would not do any spring swap without doing the shocks as well.
That is my opinion and it is based on doing spring upgrades on my last two cars. I do not have any actual experience with this on the RX-8 and I don't plan too for another few years. When my factory shocks wear out, I'll do something then.
-Mr. Wigggles
06-02-2004, 01:20 AM
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Originally posted by GeorgeH
Yes, with those mods you are legal in ASP. Funny they put you in SM, the RX-8 is technically in SM2.
And you may want to petition your local region to allow STU. Show up at a commitee meeting and ask - usually they will add it without much fanfare. Of course, if you are the only person in the class, it's not much fun, but then again it's not much fun in SP unless there are several other "under-prepared" cars in your class to compete with ("real" SP cars are very fast). The nice thing about STU is you get a better PAX factor, so you'll place higher overall, and you can buy a special set of street tires, which will last longer than Kumohs or Hoosiers.
Yes, with those mods you are legal in ASP. Funny they put you in SM, the RX-8 is technically in SM2.
And you may want to petition your local region to allow STU. Show up at a commitee meeting and ask - usually they will add it without much fanfare. Of course, if you are the only person in the class, it's not much fun, but then again it's not much fun in SP unless there are several other "under-prepared" cars in your class to compete with ("real" SP cars are very fast). The nice thing about STU is you get a better PAX factor, so you'll place higher overall, and you can buy a special set of street tires, which will last longer than Kumohs or Hoosiers.
06-08-2004, 04:59 PM
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i have had my tein s techs installed for several hundred miles with no complaints. as far as hurting the oe strut life well if they lasted 2yrs i would think that would be plenty even if i didnt change the springs.
as for a coilover setup im waiting on the flex system and edfc from tein to come in and match them with tanabe front and rear sways. ive installed the flex and edfc on a sti and it was unbelievable how they felt. stock the sti comes with a 39mm shaft in the strut and they ride wonderfully.
in my opinion, anyone who worries about hurting the oe struts by puttin aftermarket springs in should either save up and buy the coilover setup or just leave it alone.
as for a coilover setup im waiting on the flex system and edfc from tein to come in and match them with tanabe front and rear sways. ive installed the flex and edfc on a sti and it was unbelievable how they felt. stock the sti comes with a 39mm shaft in the strut and they ride wonderfully.
in my opinion, anyone who worries about hurting the oe struts by puttin aftermarket springs in should either save up and buy the coilover setup or just leave it alone.
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