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- 2007 Mazdaspeed 6 Sport
The lightness of the rear end during heavy braking went away for me with the H&R lowering springs.
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Mazda/Mazdaspeed 6 Autocross Thread
- Thread starter Blendercloud
- Start date
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- 2011 Mustang GT
Looks like there's an event coming up in a few weeks at Mich. State, and I'm thinking of going. All these rules are confusing, which class do you think I'd fit in best? The suspension is obviously not stock, and several other parts have been changed. Suggestions?
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- 2007 Mazdaspeed 6 Sport
I didn't know which class to fit into either. They just had me write down my mods and said they would assign me a class afterward. I don't really care about competing outside of competing with myself so it was no problem for me.
I just saw this thread, so let me jump in with my observations. I was the one that drove Blenderclouds Speed6 at the event and the understeer was drastic. First, a bit of background - I have raced in an AWD car for 15 years, so I am very familiar with the characteristics of AWD platforms. In general they always understeer quite a bit especially under power, but tend to swing into oversteer when lifting off the throttle in a corner. Blender's car did not do this. It understeered under power, off the power, on the brakes - it didn't really matter what you did, it would always understeer and I am talking about massive understeer like the car wanted to just keep going straight ahead regardless of what steering you input.
Now I have never driven another Speed6, so I cannot comment on whether they all drive like this, but I really expect not because it was bad enough to be dangerous in my opinion. If someone pulled out in front of you on the street, you would never be able to swerve around them and avoid an accident. So if we assume this car is not acting normally, we need to look at what has been changed to effect steering and chassis dynamics. As far as I know, the suspension and alignment are totally stock with the exception of the H&R springs. Spring rates can definitely alter steering dynamics so the springs should be a focus of attention here. If you were trying to setup a car to understeer like this, you would use very soft springs in the rear and very stiff springs in the front. Blender - Is it possible that someone sent you the wrong spring rates for one end of the car?
Based on the amount of understeer present, I really don't think a stiffer rear sway bar and more front end camber are going to be sufficient to make this car handle properly.
Tires are the other big factor and running 51 PSI may be too much, but AWD cars generally need big pressure in the fronts to keep them from rolling over. I doubt you can safely come down much below 45 PSI and again, that just is not going to make enough change to straighten this handling problem out. High pressure in the rears is probably not required but if anything it should help balance the front / rear grip so lowering it is not going to help either.
I have raced in probably any kind of car you can imagine and I have never experienced understeer as drastic as this. The cars that I have driven with bad handling manners usually have had some kind of problem such as mismatched tires and suspension mods gone wrong. I would really like to know what is going on with this car, because it seems to defy logic.
Now I have never driven another Speed6, so I cannot comment on whether they all drive like this, but I really expect not because it was bad enough to be dangerous in my opinion. If someone pulled out in front of you on the street, you would never be able to swerve around them and avoid an accident. So if we assume this car is not acting normally, we need to look at what has been changed to effect steering and chassis dynamics. As far as I know, the suspension and alignment are totally stock with the exception of the H&R springs. Spring rates can definitely alter steering dynamics so the springs should be a focus of attention here. If you were trying to setup a car to understeer like this, you would use very soft springs in the rear and very stiff springs in the front. Blender - Is it possible that someone sent you the wrong spring rates for one end of the car?
Based on the amount of understeer present, I really don't think a stiffer rear sway bar and more front end camber are going to be sufficient to make this car handle properly.
Tires are the other big factor and running 51 PSI may be too much, but AWD cars generally need big pressure in the fronts to keep them from rolling over. I doubt you can safely come down much below 45 PSI and again, that just is not going to make enough change to straighten this handling problem out. High pressure in the rears is probably not required but if anything it should help balance the front / rear grip so lowering it is not going to help either.
I have raced in probably any kind of car you can imagine and I have never experienced understeer as drastic as this. The cars that I have driven with bad handling manners usually have had some kind of problem such as mismatched tires and suspension mods gone wrong. I would really like to know what is going on with this car, because it seems to defy logic.
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- 2011 Mustang GT
I just saw this thread, so let me jump in with my observations. I was the one that drove Blenderclouds Speed6 at the event and the understeer was drastic. First, a bit of background - I have raced in an AWD car for 15 years, so I am very familiar with the characteristics of AWD platforms. In general they always understeer quite a bit especially under power, but tend to swing into oversteer when lifting off the throttle in a corner. Blender's car did not do this. It understeered under power, off the power, on the brakes - it didn't really matter what you did, it would always understeer and I am talking about massive understeer like the car wanted to just keep going straight ahead regardless of what steering you input.
Now I have never driven another Speed6, so I cannot comment on whether they all drive like this, but I really expect not because it was bad enough to be dangerous in my opinion. If someone pulled out in front of you on the street, you would never be able to swerve around them and avoid an accident. So if we assume this car is not acting normally, we need to look at what has been changed to effect steering and chassis dynamics. As far as I know, the suspension and alignment are totally stock with the exception of the H&R springs. Spring rates can definitely alter steering dynamics so the springs should be a focus of attention here. If you were trying to setup a car to understeer like this, you would use very soft springs in the rear and very stiff springs in the front. Blender - Is it possible that someone sent you the wrong spring rates for one end of the car?
Based on the amount of understeer present, I really don't think a stiffer rear sway bar and more front end camber are going to be sufficient to make this car handle properly.
Tires are the other big factor and running 51 PSI may be too much, but AWD cars generally need big pressure in the fronts to keep them from rolling over. I doubt you can safely come down much below 45 PSI and again, that just is not going to make enough change to straighten this handling problem out. High pressure in the rears is probably not required but if anything it should help balance the front / rear grip so lowering it is not going to help either.
I have raced in probably any kind of car you can imagine and I have never experienced understeer as drastic as this. The cars that I have driven with bad handling manners usually have had some kind of problem such as mismatched tires and suspension mods gone wrong. I would really like to know what is going on with this car, because it seems to defy logic.
Seems like you and I have very similar impressions of the MS6. Very nice write-up.
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- 2007 Mazdaspeed 6 Sport
... Blender - Is it possible that someone sent you the wrong spring rates for one end of the car? ...
Hey Rick,
Thanks for stopping in and sharing your thoughts. Unless the springs were miss-stamped/labeled and they were for another car entirely, I received the correct springs. When I received the package, I very closely scrutinized the individual springs. The spring rates matched up with the included Mazdaspeed 6-specific documentation. My future father-in-law and I installed them on his lift and I have 100% certainty of the correct installation. I'm not saying I'm always faultless. I am saying that I'm certain that in this case they are installed correctly.
Is it possible that with the reduced spring travel and increased spring rate that stiffer dampening should also be part of the mix?
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- 2011 Mustang GT
Hey Rick,
Thanks for stopping in and sharing your thoughts. Unless the springs were miss-stamped/labeled and they were for another car entirely, I received the correct springs. When I received the package, I very closely scrutinized the individual springs. The spring rates matched up with the included Mazdaspeed 6-specific documentation. My future father-in-law and I installed them on his lift and I have 100% certainty of the correct installation. I'm not saying I'm always faultless. I am saying that I'm certain that in this case they are installed correctly.
Is it possible that with the reduced spring travel and increased spring rate that stiffer dampening should also be part of the mix?
How were your springs marked exactly? I had to call H&R directly to verify that mine were MS6-specific.
Is it possible that with the reduced spring travel and increased spring rate that stiffer dampening should also be part of the mix?
Unless you changed the shocks, the damping is unchanged. Damping rate is dependent on shock shaft speed only so stroke length being decreased by lower springs has no effect on it. Good thought though! Did you actually get spring rate sfor the H&R springs? Most of these aftermarket suspension companies tend to be tight lipped about details such as real spring rates. If you did get rates, mind quoting them up here just for discussion?
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- 2007 Mazdaspeed 6 Sport
I don't have the documents with me anymore. Nor can I look under the car (head's too big, car's too low). I remember them having a number painted on them that I verified against the instruction pamphlet that was included with the order. The number was different for the front than it was for the rear. Additionally, the numbers were labeled on the pamphlet as being for front or rear.
- :
- 2007 Mazdaspeed 6 Sport
Unless you changed the shocks, the damping is unchanged. Damping rate is dependent on shock shaft speed only so stroke length being decreased by lower springs has no effect on it. Good thought though! Did you actually get spring rate sfor the H&R springs? Most of these aftermarket suspension companies tend to be tight lipped about details such as real spring rates. If you did get rates, mind quoting them up here just for discussion?
Steve may know the actual spring rate. I don't really recall. I think they were labeled as being a percentage stiffer than the Mazdaspeed 6 OEM springs. The H&R springs were specifically designed for the Mazdaspeed 6 as well.
As for my comment about dampening, I wasn't very clear. Sorry about that. What I meant by my comment was "shouldn't we consider that since the spring travel is less and spring rate is increased, that a stiffer dampening strut should be used instead of the OEM?".
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- 2011 Mustang GT
I don't have the documents with me anymore. Nor can I look under the car (head's too big, car's too low). I remember them having a number painted on them that I verified against the instruction pamphlet that was included with the order. The number was different for the front than it was for the rear. Additionally, the numbers were labeled on the pamphlet as being for front or rear.
That concerns me. On mine, they all had the same number on each spring, but the color mark (spot) on the front and rear were different. They actually have the same # as the Mz6 springs, but the color marks indicate the MS6 springs, from contacting H&R.
Steve may know the actual spring rate. I don't really recall. I think they were labeled as being a percentage stiffer than the Mazdaspeed 6 OEM springs. The H&R springs were specifically designed for the Mazdaspeed 6 as well.
As for my comment about dampening, I wasn't very clear. Sorry about that. What I meant by my comment was "shouldn't we consider that since the spring travel is less and spring rate is increased, that a stiffer dampening strut should be used instead of the OEM?".
I don't know the actual spring rate over stock, but I do know they're one of the few actually designed for the MS6, and not a Mz6 spring that fits (as they all do).
Steve may know the actual spring rate. I don't really recall. I think they were labeled as being a percentage stiffer than the Mazdaspeed 6 OEM springs. The H&R springs were specifically designed for the Mazdaspeed 6 as well.
As for my comment about dampening, I wasn't very clear. Sorry about that. What I meant by my comment was "shouldn't we consider that since the spring travel is less and spring rate is increased, that a stiffer dampening strut should be used instead of the OEM?".
Well, actually you are opening a huge can of worms with this statement. Again, the spring travel is not relevant, but the spring rate change certainly is. Most people don't understand the physics of a tuned spring / damper system. When Mazda designed the original springs and dampers for your car, they specified the parameters so that the spring damper system which includes the mass of wheel, brakes, and suspension parts would be tuned for a critically damped condition. This condition gives the best possible handling and comfort for a given system design. When you change to a stiffer spring and do not change the dampers, the result is an underdamped system. The main drawback of an underdamped system is that the car cannot keep the wheels planted on the ground during transient manuevers and/or irregular pavement conditions. This can result in reduced handling performance, but the stiffer spring rates result in less body roll which in turns improves performance masking the reduction in performance from the underdamped system. The net difference is perceived as a gain to the cars performance, so most people are happy with this approach, but it is certainly not optimized. I hope that all makes sense! I am an engineer and sometimes what is black and white to me comes off as gibberish when I explain it to others.
Anyway, you are entirely correct that ideally you should use a stiffer damper if you switch to a stiffer spring. Unfortunatley, you will never be able to match the critically damped condition that comes from the factory unless you buy a spring/damper combination from a company that has properly tuned these parts to work as a critically damped system on your car. Once again I must say that based on my experience, having an underdamped condition because of using stiffer springs would not be sufficient cause for you car to understeer as much as it does.
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- 2011 Mustang GT
Well, actually you are opening a huge can of worms with this statement. Again, the spring travel is not relevant, but the spring rate change certainly is. Most people don't understand the physics of a tuned spring / damper system. When Mazda designed the original springs and dampers for your car, they specified the parameters so that the spring damper system which includes the mass of wheel, brakes, and suspension parts would be tuned for a critically damped condition. This condition gives the best possible handling and comfort for a given system design. When you change to a stiffer spring and do not change the dampers, the result is an underdamped system. The main drawback of an underdamped system is that the car cannot keep the wheels planted on the ground during transient manuevers and/or irregular pavement conditions. This can result in reduced handling performance, but the stiffer spring rates result in less body roll which in turns improves performance masking the reduction in performance from the underdamped system. The net difference is perceived as a gain to the cars performance, so most people are happy with this approach, but it is certainly not optimized. I hope that all makes sense! I am an engineer and sometimes what is black and white to me comes off as gibberish when I explain it to others.
Anyway, you are entirely correct that ideally you should use a stiffer damper if you switch to a stiffer spring. Unfortunatley, you will never be able to match the critically damped condition that comes from the factory unless you buy a spring/damper combination from a company that has properly tuned these parts to work as a critically damped system on your car. Once again I must say that based on my experience, having an underdamped condition because of using stiffer springs would not be sufficient cause for you car to understeer as much as it does.
So, based on your statement Rick, you're best bet would be coilovers, right?
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- 2007 Mazdaspeed 6 Sport
Makes perfect sense. Setting up dirt track cars is in fact very similar.
So, based on your statement Rick, you're best bet would be coilovers, right?
Possibly, but not necessarily. It depends on if the company that makes the coilovers actually does design and test to ensure a critically damped system for your specific application. Unfortunatley, the reality is that they probably don't.
If they can use the springs and dampers for different apllications, they probably do and therefore only certain combinations would end being critically damped, if any. What I mean by this is that if I bought a coilover setup for my 6i, it would probably use the same damper assembly as the coilover setup for a Speed6, but the spring rates would be different and therefore not critically damped for at least one of those applications and possibly not for either.
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- 2007 Mazdaspeed 6 Sport
http://farnorthracing.com/autocross_secrets.html
I found this chunk of great information in another thread here. Credit goes to Brandini for finding it.
I found this chunk of great information in another thread here. Credit goes to Brandini for finding it.
I need to check the alignment on my car. There is no way my car is the worst understeering car I have ever driven. I do notice that if I turn-in and then jump on the throttle too hard, the car will start to push, but it is not that bad. I have noticed that you need to be really easy on throttle after turn-in. If you turn-in and then allow the car to take a set, you can then roll into the throttle and the car will just turn. Again, I have never driven another MS6, but that is the way my car behaves. I think that my Dad (dquarasr) and I will be doing a MS6 autocross throw-down between his car and mine, maybe then I can drive another MS6.
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- 2011 Mustang GT
I'm starting to wonder now if the issue isn't the physical limitations of the car, but rather the electronic settings of the AWD system. Since the car is constantly monitoring the yaw, steering angle, and other steering variables and geometric values, turning the TCS/DSC off may give us more ability to rotate the car on the course.
Also, as I've said in another thread regarding the AWD system, is that we should try to get someone on board to more aggressively tune the system to apply more power and give more degrees of freedom when coming through a turn. Right now, it still has quite a bit of FWD bias. Even with my RSB, rear brace, and springs, the car will rotate a bit more under power, but not as much as I'd like it to. I'd almost prefer it to be on the edge of oversteer.
There are several companies that may be able to do this too, such as Cobb and the AP. Also, there are several companies that make aftermarket Haldex controllers for the VW and Volvo crowd. They may be able to work something out for us.
Also, as I've said in another thread regarding the AWD system, is that we should try to get someone on board to more aggressively tune the system to apply more power and give more degrees of freedom when coming through a turn. Right now, it still has quite a bit of FWD bias. Even with my RSB, rear brace, and springs, the car will rotate a bit more under power, but not as much as I'd like it to. I'd almost prefer it to be on the edge of oversteer.
There are several companies that may be able to do this too, such as Cobb and the AP. Also, there are several companies that make aftermarket Haldex controllers for the VW and Volvo crowd. They may be able to work something out for us.
