Newbie question on sways, shocks, and braces
08-10-03, 01:14 AM
#1
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Thread Starter
Newbie question on sways, shocks, and braces
I've been searching the forum for these answers but i'm still confused. I'm not sure what the difference is between a sway bar, strut tower brace and braces.
I want to do the l-tuned shocks but i'm confused about the rest. I read a post saying a TRD STB is almost a necessary install for a gs4.
My questions are:
If I want to keep the ride smooth but still want good handling what should I do (in addition to l-tuned shocks)?
How easy are these to intstall? I read on a post TRD STB can be installed easily in 15min. What about the braces and sway bars?
I guess i'm not understanding the degree of "stiffness" they offer...like adding a sway bar is stiffer than an STB, etc.
I want to do the l-tuned shocks but i'm confused about the rest. I read a post saying a TRD STB is almost a necessary install for a gs4.
My questions are:
If I want to keep the ride smooth but still want good handling what should I do (in addition to l-tuned shocks)?
How easy are these to intstall? I read on a post TRD STB can be installed easily in 15min. What about the braces and sway bars?
I guess i'm not understanding the degree of "stiffness" they offer...like adding a sway bar is stiffer than an STB, etc.
08-10-03, 02:05 AM
#2
well, if you want performance, i would really suggest coilovers over just shocks. the tein CS or flex are very good stuff imho. and if you want the biggest handling gain, get sways, they help the MOST without much penalty. the trd sways are common but it makes the ride harsher. i changed to daizen sways and the ride is a lot better without any ride penalty.
the trd stb and lcb i have them, but seriously i don't feel much at all. i don't have any rear stb and braces though
the trd stb and lcb i have them, but seriously i don't feel much at all. i don't have any rear stb and braces though
08-10-03, 12:55 PM
#3
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Whole bunch of information here if you search. To make a long story short:
Shocks work with the springs. Originally they were to damp out the oscillation that occurs in any spring when it deflects and restores, reason why they are sometime referred to as dampeners. However, in the modern world, the shock is used to work with the spring quite a bit to provide a different response on both compression and jounce. When you go to new shocks from old worn ones, the ride inevitably gets harsher just because the worn ones weren't doing much. But the tradeoff is almost always ride harshness versus ride comfort. Many cars, and the GS for example is very prone to picking up a lot of ride harshness when you increase the stiffness to increase handling. I put bilstein sports on my GS4 and on my wifes new GS3. We both love them on the GS4 but they were just too harsh on the GS3. I just replaced them with bilstein HDs and it is much better.
Stabilizer bars are also called anti roll bars. Simply, the center of the bar is attached to the body/chassis and the ends are connected to the moving suspension at the wheel. When one wheel goes down, on an independent suspension, it goes by itself. A stabilizer bar will attach to the wheel that is going down and apply a force to the wheel on the opposite of the car to have it move down. The net result is that the body connecting the two stays flatter in the turn. The more rigid the bar, the stonger the connection, and the less indepedence there is in the movement of each wheel. If both wheels encounter the same phenomenon at the same time, meaning they both want to go up or down, the bar plays no role whatsoever. And in the early days you could have no bars, then a front bar, and now front and rear bars. If you watch NASCAR at all you can see that every once in a while somebody gets some whicked handling and will actually disconnect the bar at one end or another during the race. Everything just works together.
If the body is flexing, it can be difficult to get precision in the response of the vehicle. Many ads, particularly Oldsmobile, tout the stiffness of their structure by advertising the frequency it resonates at, lower the better. The various bars that guys are installing here are to reduce whatever flex is inherent in the GS chassis.
There is the thumbnail sketch of the components you asked about. Just remember there are more components, such as the springs (which almost always have progressive rates nowadays), the tires (which also act as springs), and the chassis stiffness. Increasing chassis stiffness isn't always better and the modern car maker CAD programs are trying to get a certain response with a lot of historical input. Like I said, if you spend some time and just search in this area, you will find a lot of data and inevitable reference to the buttometer. Why is the buttometer important? Because what one guy calls "smooth" another guy calls "soft and ill handling" and what one guy calls "good handling" another guys calls a "buckboard". Everyone is different with different response and desires as to what they want the car to do. Which is what modding is all about.
Shocks work with the springs. Originally they were to damp out the oscillation that occurs in any spring when it deflects and restores, reason why they are sometime referred to as dampeners. However, in the modern world, the shock is used to work with the spring quite a bit to provide a different response on both compression and jounce. When you go to new shocks from old worn ones, the ride inevitably gets harsher just because the worn ones weren't doing much. But the tradeoff is almost always ride harshness versus ride comfort. Many cars, and the GS for example is very prone to picking up a lot of ride harshness when you increase the stiffness to increase handling. I put bilstein sports on my GS4 and on my wifes new GS3. We both love them on the GS4 but they were just too harsh on the GS3. I just replaced them with bilstein HDs and it is much better.
Stabilizer bars are also called anti roll bars. Simply, the center of the bar is attached to the body/chassis and the ends are connected to the moving suspension at the wheel. When one wheel goes down, on an independent suspension, it goes by itself. A stabilizer bar will attach to the wheel that is going down and apply a force to the wheel on the opposite of the car to have it move down. The net result is that the body connecting the two stays flatter in the turn. The more rigid the bar, the stonger the connection, and the less indepedence there is in the movement of each wheel. If both wheels encounter the same phenomenon at the same time, meaning they both want to go up or down, the bar plays no role whatsoever. And in the early days you could have no bars, then a front bar, and now front and rear bars. If you watch NASCAR at all you can see that every once in a while somebody gets some whicked handling and will actually disconnect the bar at one end or another during the race. Everything just works together.
If the body is flexing, it can be difficult to get precision in the response of the vehicle. Many ads, particularly Oldsmobile, tout the stiffness of their structure by advertising the frequency it resonates at, lower the better. The various bars that guys are installing here are to reduce whatever flex is inherent in the GS chassis.
There is the thumbnail sketch of the components you asked about. Just remember there are more components, such as the springs (which almost always have progressive rates nowadays), the tires (which also act as springs), and the chassis stiffness. Increasing chassis stiffness isn't always better and the modern car maker CAD programs are trying to get a certain response with a lot of historical input. Like I said, if you spend some time and just search in this area, you will find a lot of data and inevitable reference to the buttometer. Why is the buttometer important? Because what one guy calls "smooth" another guy calls "soft and ill handling" and what one guy calls "good handling" another guys calls a "buckboard". Everyone is different with different response and desires as to what they want the car to do. Which is what modding is all about.
08-11-03, 07:53 PM
#4
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RON, good write up!
One thing, though; resonant frequency of chassis rises with increasing chassis rigidity, eg, the HIGHER, the better. 32 Hz is low as far as musical notes go, but relatively high as far as chassis resonance is concerned.
One thing, though; resonant frequency of chassis rises with increasing chassis rigidity, eg, the HIGHER, the better. 32 Hz is low as far as musical notes go, but relatively high as far as chassis resonance is concerned.
08-12-03, 11:55 AM
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You know, I almost regreted putting that in when I first wrote it. This topic could fill up many threads and probably not interest very many people. If you are talking about a solid piece of material, generally you are right. There are other ways I could progress with this as we are involved in molecular engineering nanocrystal composites that just about let you design what response you want without much coupling at all, but I doubt that would interest very many people here. An automotive chassis is made up of a considerable number of parts. The trick to getting chassis stiffness is not just using stiff materials in the individual components but careful design of the individual shape, attachment, etc., of the components. Smaller components put together into an assembly obviously have opportunities to become resonant cavities, regardless of the material of construction. The inherent stiffness of the material is almost always a help in dampening the vibrations but resonances obviously have the ability to take small amplitudes and make them a lot bigger. When a modern chassis is reported with a fundamental frequency of say 35 Hz, it isn't really important where this falls on the audio spectrum but it is meant to convey a sense of the total resistance of the design to not only the fundamental but harmonics that can build up in the individual components. It has been a lot of years since the auto makers have used beef to stiffen up a chassis but when they started to get smarter on design, other effects starting coming in, like those resonances. The sophistication of modern auto design should not be underestimated. Most of the auto makers are modeling the chassis resonances to determine where the nodes are and are using those points for things like engine mount, exhaust hanger, driveline, etc. attach points so there is minimum chance of unwanted vibration transmission into the passenger compartment. If you think about it, it is a lot less noteworthy that the makers can get chassis fundamental frequencies of 35 Hz or so, but that they can do such a good job suppressing the higher order resonances. Although sometimes they don't. Spend some time thinking about where and how these vibrations are generated in the chassis to begin with and you start to know why the automakers all have supercomputers. A lot of intake tracts are specifically designed to allow the fourth order harmonic to give a nice low bellow when you tromp it, but here is yet another story.
Now, having said all that. I have posted before that I really doubt anyone here, especially on street tires, is generating enough load to have the various braces make much of an effect. The GS chassis is quite rigid on its own and you have to be very careful when you start modifying the suspension components because the GS, like most modern cars, pushes over into annoying harshness very easily (think about increasing stiffness but affecting those resonant cavities so you easily permit much more annoying resonances to set up). The tradeoff is that increased lateral acceleration will inevitably come from component value increases that are going to increase ride harshness. The OEMs, and Toyota is one of the best, understand all of this a lot better than I do and believe me, they know the tradeoff. They could design a remarkably rigid chassis but surprisingly enough, it may not be what you want in a street car, especially a Lexus. As I have posted before, Doug are you listening, is that the remarkable thing about bimmers is the overall balance between handling and ride. Not that they are superior in either, but the balance they have is, or was, uncanny. As the bimmers try to outdo themselves with new models, I have noticed that they also are pushing more into the harshness realm, but here is also a different story.
There are certainly some places where stiffening is a help that you can see by just looking at the vehicle (open the doors on a convertible and look from the side at what is connecting the front and rear that give mechanical engineers nightmares and you will see what I am talking about). Strut tower connectors are a great idea but they should obviously be a triangle that connects the strut towers and then go to a further body/chassis area for two dimensional improvement. The GS braces just connect strut towers so they are really only a help if the towers want to move linearly closer or farther apart, in synchronous fashion. There definitely is an effect from adding the brace, just doubt most people could feel it. I have no problem adding them for looks but looks don't mean all that much to me, at least for suspension components. As for a newbie question, there is little chance of addressing the topic of the add on braces and links without addressing chassis stiffness. I also didn't think I gave all that good a response on shocks but I hoped it would at least give him some idea of what we are all talking about here.
The manufacturers have embraced the fundamental frequency as a benchmark whether I personally agree or not (almost as useless as 0-60 times). But the impact of these add on bars is somewhat questionable. The aftermarket guys can easily fabricate some bars out and bold them on but I don't think very many of them have data on what the change in the chassis was before and after. At least, I haven't seen it published. You would expect that at least they could get some lateral acceleration figures or lap times somewhere with and without, but, once again, haven't seen that either.
I am sort of up to my eyeballs in the final stages of billpaying work but I have some papers on chassis stiffness that I could post some sections of, if anyone is interested. Just give me some time to do it.
Now, having said all that. I have posted before that I really doubt anyone here, especially on street tires, is generating enough load to have the various braces make much of an effect. The GS chassis is quite rigid on its own and you have to be very careful when you start modifying the suspension components because the GS, like most modern cars, pushes over into annoying harshness very easily (think about increasing stiffness but affecting those resonant cavities so you easily permit much more annoying resonances to set up). The tradeoff is that increased lateral acceleration will inevitably come from component value increases that are going to increase ride harshness. The OEMs, and Toyota is one of the best, understand all of this a lot better than I do and believe me, they know the tradeoff. They could design a remarkably rigid chassis but surprisingly enough, it may not be what you want in a street car, especially a Lexus. As I have posted before, Doug are you listening, is that the remarkable thing about bimmers is the overall balance between handling and ride. Not that they are superior in either, but the balance they have is, or was, uncanny. As the bimmers try to outdo themselves with new models, I have noticed that they also are pushing more into the harshness realm, but here is also a different story.
There are certainly some places where stiffening is a help that you can see by just looking at the vehicle (open the doors on a convertible and look from the side at what is connecting the front and rear that give mechanical engineers nightmares and you will see what I am talking about). Strut tower connectors are a great idea but they should obviously be a triangle that connects the strut towers and then go to a further body/chassis area for two dimensional improvement. The GS braces just connect strut towers so they are really only a help if the towers want to move linearly closer or farther apart, in synchronous fashion. There definitely is an effect from adding the brace, just doubt most people could feel it. I have no problem adding them for looks but looks don't mean all that much to me, at least for suspension components. As for a newbie question, there is little chance of addressing the topic of the add on braces and links without addressing chassis stiffness. I also didn't think I gave all that good a response on shocks but I hoped it would at least give him some idea of what we are all talking about here.
The manufacturers have embraced the fundamental frequency as a benchmark whether I personally agree or not (almost as useless as 0-60 times). But the impact of these add on bars is somewhat questionable. The aftermarket guys can easily fabricate some bars out and bold them on but I don't think very many of them have data on what the change in the chassis was before and after. At least, I haven't seen it published. You would expect that at least they could get some lateral acceleration figures or lap times somewhere with and without, but, once again, haven't seen that either.
I am sort of up to my eyeballs in the final stages of billpaying work but I have some papers on chassis stiffness that I could post some sections of, if anyone is interested. Just give me some time to do it.
08-13-03, 01:42 PM
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Thanks, my wife might argue with that intelligent comment.
This is pretty much a hobby now although when the earth was still cooling I did race pro for a while. Learned a lot, and removed a lot of skin from nuckles. The state of automotive development is just light years beyond where it was in the 60's. But if I wanted to learn on a car, that was the time to do it.
Hope it helps. You can always search for a lot of info here and please, never be afraid to ask a question. Somebody will eventually answer it. Or at least give you an opinion.
Ron
This is pretty much a hobby now although when the earth was still cooling I did race pro for a while. Learned a lot, and removed a lot of skin from nuckles. The state of automotive development is just light years beyond where it was in the 60's. But if I wanted to learn on a car, that was the time to do it.
Hope it helps. You can always search for a lot of info here and please, never be afraid to ask a question. Somebody will eventually answer it. Or at least give you an opinion.
Ron
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08-14-03, 01:27 AM
#8
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RON, again, an incredibly good post!
I think your wife and my wife would like each other; they think along similar lines or, at least, have similar opinions of their husbands..........
Thanks, my wife might argue with that intelligent comment.
Last edited by mooretorque; 08-14-03 at 01:27 AM.
08-14-03, 10:11 PM
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Originally posted by RON430
You know, I almost regreted putting that in when I first wrote it. This topic could fill up many threads and probably not interest very many people. If you are talking about a solid piece of material, generally you are right. There are other ways I could progress with this as we are involved in molecular engineering nanocrystal composites that just about let you design what response you want without much coupling at all, but I doubt that would interest very many people here. An automotive chassis is made up of a considerable number of parts. The trick to getting chassis stiffness is not just using stiff materials in the individual components but careful design of the individual shape, attachment, etc., of the components. Smaller components put together into an assembly obviously have opportunities to become resonant cavities, regardless of the material of construction. The inherent stiffness of the material is almost always a help in dampening the vibrations but resonances obviously have the ability to take small amplitudes and make them a lot bigger. When a modern chassis is reported with a fundamental frequency of say 35 Hz, it isn't really important where this falls on the audio spectrum but it is meant to convey a sense of the total resistance of the design to not only the fundamental but harmonics that can build up in the individual components. It has been a lot of years since the auto makers have used beef to stiffen up a chassis but when they started to get smarter on design, other effects starting coming in, like those resonances. The sophistication of modern auto design should not be underestimated. Most of the auto makers are modeling the chassis resonances to determine where the nodes are and are using those points for things like engine mount, exhaust hanger, driveline, etc. attach points so there is minimum chance of unwanted vibration transmission into the passenger compartment. If you think about it, it is a lot less noteworthy that the makers can get chassis fundamental frequencies of 35 Hz or so, but that they can do such a good job suppressing the higher order resonances. Although sometimes they don't. Spend some time thinking about where and how these vibrations are generated in the chassis to begin with and you start to know why the automakers all have supercomputers. A lot of intake tracts are specifically designed to allow the fourth order harmonic to give a nice low bellow when you tromp it, but here is yet another story.
Now, having said all that. I have posted before that I really doubt anyone here, especially on street tires, is generating enough load to have the various braces make much of an effect. The GS chassis is quite rigid on its own and you have to be very careful when you start modifying the suspension components because the GS, like most modern cars, pushes over into annoying harshness very easily (think about increasing stiffness but affecting those resonant cavities so you easily permit much more annoying resonances to set up). The tradeoff is that increased lateral acceleration will inevitably come from component value increases that are going to increase ride harshness. The OEMs, and Toyota is one of the best, understand all of this a lot better than I do and believe me, they know the tradeoff. They could design a remarkably rigid chassis but surprisingly enough, it may not be what you want in a street car, especially a Lexus. As I have posted before, Doug are you listening, is that the remarkable thing about bimmers is the overall balance between handling and ride. Not that they are superior in either, but the balance they have is, or was, uncanny. As the bimmers try to outdo themselves with new models, I have noticed that they also are pushing more into the harshness realm, but here is also a different story.
There are certainly some places where stiffening is a help that you can see by just looking at the vehicle (open the doors on a convertible and look from the side at what is connecting the front and rear that give mechanical engineers nightmares and you will see what I am talking about). Strut tower connectors are a great idea but they should obviously be a triangle that connects the strut towers and then go to a further body/chassis area for two dimensional improvement. The GS braces just connect strut towers so they are really only a help if the towers want to move linearly closer or farther apart, in synchronous fashion. There definitely is an effect from adding the brace, just doubt most people could feel it. I have no problem adding them for looks but looks don't mean all that much to me, at least for suspension components. As for a newbie question, there is little chance of addressing the topic of the add on braces and links without addressing chassis stiffness. I also didn't think I gave all that good a response on shocks but I hoped it would at least give him some idea of what we are all talking about here.
The manufacturers have embraced the fundamental frequency as a benchmark whether I personally agree or not (almost as useless as 0-60 times). But the impact of these add on bars is somewhat questionable. The aftermarket guys can easily fabricate some bars out and bold them on but I don't think very many of them have data on what the change in the chassis was before and after. At least, I haven't seen it published. You would expect that at least they could get some lateral acceleration figures or lap times somewhere with and without, but, once again, haven't seen that either.
I am sort of up to my eyeballs in the final stages of billpaying work but I have some papers on chassis stiffness that I could post some sections of, if anyone is interested. Just give me some time to do it.
You know, I almost regreted putting that in when I first wrote it. This topic could fill up many threads and probably not interest very many people. If you are talking about a solid piece of material, generally you are right. There are other ways I could progress with this as we are involved in molecular engineering nanocrystal composites that just about let you design what response you want without much coupling at all, but I doubt that would interest very many people here. An automotive chassis is made up of a considerable number of parts. The trick to getting chassis stiffness is not just using stiff materials in the individual components but careful design of the individual shape, attachment, etc., of the components. Smaller components put together into an assembly obviously have opportunities to become resonant cavities, regardless of the material of construction. The inherent stiffness of the material is almost always a help in dampening the vibrations but resonances obviously have the ability to take small amplitudes and make them a lot bigger. When a modern chassis is reported with a fundamental frequency of say 35 Hz, it isn't really important where this falls on the audio spectrum but it is meant to convey a sense of the total resistance of the design to not only the fundamental but harmonics that can build up in the individual components. It has been a lot of years since the auto makers have used beef to stiffen up a chassis but when they started to get smarter on design, other effects starting coming in, like those resonances. The sophistication of modern auto design should not be underestimated. Most of the auto makers are modeling the chassis resonances to determine where the nodes are and are using those points for things like engine mount, exhaust hanger, driveline, etc. attach points so there is minimum chance of unwanted vibration transmission into the passenger compartment. If you think about it, it is a lot less noteworthy that the makers can get chassis fundamental frequencies of 35 Hz or so, but that they can do such a good job suppressing the higher order resonances. Although sometimes they don't. Spend some time thinking about where and how these vibrations are generated in the chassis to begin with and you start to know why the automakers all have supercomputers. A lot of intake tracts are specifically designed to allow the fourth order harmonic to give a nice low bellow when you tromp it, but here is yet another story.
Now, having said all that. I have posted before that I really doubt anyone here, especially on street tires, is generating enough load to have the various braces make much of an effect. The GS chassis is quite rigid on its own and you have to be very careful when you start modifying the suspension components because the GS, like most modern cars, pushes over into annoying harshness very easily (think about increasing stiffness but affecting those resonant cavities so you easily permit much more annoying resonances to set up). The tradeoff is that increased lateral acceleration will inevitably come from component value increases that are going to increase ride harshness. The OEMs, and Toyota is one of the best, understand all of this a lot better than I do and believe me, they know the tradeoff. They could design a remarkably rigid chassis but surprisingly enough, it may not be what you want in a street car, especially a Lexus. As I have posted before, Doug are you listening, is that the remarkable thing about bimmers is the overall balance between handling and ride. Not that they are superior in either, but the balance they have is, or was, uncanny. As the bimmers try to outdo themselves with new models, I have noticed that they also are pushing more into the harshness realm, but here is also a different story.
There are certainly some places where stiffening is a help that you can see by just looking at the vehicle (open the doors on a convertible and look from the side at what is connecting the front and rear that give mechanical engineers nightmares and you will see what I am talking about). Strut tower connectors are a great idea but they should obviously be a triangle that connects the strut towers and then go to a further body/chassis area for two dimensional improvement. The GS braces just connect strut towers so they are really only a help if the towers want to move linearly closer or farther apart, in synchronous fashion. There definitely is an effect from adding the brace, just doubt most people could feel it. I have no problem adding them for looks but looks don't mean all that much to me, at least for suspension components. As for a newbie question, there is little chance of addressing the topic of the add on braces and links without addressing chassis stiffness. I also didn't think I gave all that good a response on shocks but I hoped it would at least give him some idea of what we are all talking about here.
The manufacturers have embraced the fundamental frequency as a benchmark whether I personally agree or not (almost as useless as 0-60 times). But the impact of these add on bars is somewhat questionable. The aftermarket guys can easily fabricate some bars out and bold them on but I don't think very many of them have data on what the change in the chassis was before and after. At least, I haven't seen it published. You would expect that at least they could get some lateral acceleration figures or lap times somewhere with and without, but, once again, haven't seen that either.
I am sort of up to my eyeballs in the final stages of billpaying work but I have some papers on chassis stiffness that I could post some sections of, if anyone is interested. Just give me some time to do it.
nice write up ron! Its been awhile since I read anything like this. Well since, last semester in college lol. D.
Last edited by dvp; 08-14-03 at 10:11 PM.
08-15-03, 12:16 PM
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Obviously this is more of a hobby to me now than it used to be. Don't want to bore you guys but the state of trans am in the early days was primitive by today's standards and would probably shock most of you as to how things happened. But it was great fun and it was possible to make a difference. For example, I think it was the Monroe heavy duty shocks for the 68 Fairlane station wagon were huge and exactly 50/50 valving. If you ground out the lower A arms on a 69 Z28 you could fit those things in there and really improve the handling on the track. Shocks today are their own science and most of us just don't have the resources to do much research so this board is particularly valuable. Unfortunately, most of the posts just gush enthusiastic right after the bits are installed with little if any support as to how things really worked out. And shocks definitely change over time.
There are a lot of posts on how do you get a GS to handle like a bimmer. Well, the first thing that helps is to really dispassionately evaluate what it is about the BMW that you want. In the bimmers I had, the one thing I would never apply to the suspension was harsh. The bimmer has (or had, the new ones are definitely getting harsh and part of the reason why I am far less of a bimmer supporter) a remarkable combination of handling and ride. But, they are not the ultimate handling machines. They actually don't have a lot of roll stiffness, like a lot of european cars, but then will reach a point where they just quit rolling, until you get to the limit where every car can have exciting traits. It is amazing how easy it is to get the GS to ride harsh. To tell you the truth, my wife's new GS3 is far better balanced than my GS4 in handling and really did not like the bilstein sports. So we put bilstein HDs on it and I have Sportivo sways to put on and I have to tell you, my feeling is that that combination produces about as close as I think you will get to bimmer balance in a Lexus. Not sure if you can do it in a GS4 but then a 540 actually doesn't have the balance of a 530 which is the bimmer that CR really rates as the best sedan in the world, not the 540 if you look at their reviews.
Sorry for the long posts and some of the techno babble but my view is that the more we all can share and know, the better products we demand from Lexus and the after market, and the more we all benefit. Some of this is pretty sophisticated to get right and some of it isn't. Also worth noting that I came out of the "If it don't go, chrome it" world where looks never mattered much. Today, the "look" of the suspension and wheels and tires and engine bits means more to most people than how they actually make the car perform. Then again, the bimmers got me into the concours level detailers and that is just as deadly to your checking account as any other type of modding.
PS I have to say that mooretorque really did catch me on the stiffness versus resonant frequency issue. I just thought I would try to comment on it (poorly, as it turned out) because of the useless babble that some of the auto makers are using it for, to demonstrate how rigid their chassis are. I don't know who started that, I think it was Olds, but I wish people were smarter to catch the advertising glop that the manufacturers continue to try to foist on us rather than just build a good product.
There are a lot of posts on how do you get a GS to handle like a bimmer. Well, the first thing that helps is to really dispassionately evaluate what it is about the BMW that you want. In the bimmers I had, the one thing I would never apply to the suspension was harsh. The bimmer has (or had, the new ones are definitely getting harsh and part of the reason why I am far less of a bimmer supporter) a remarkable combination of handling and ride. But, they are not the ultimate handling machines. They actually don't have a lot of roll stiffness, like a lot of european cars, but then will reach a point where they just quit rolling, until you get to the limit where every car can have exciting traits. It is amazing how easy it is to get the GS to ride harsh. To tell you the truth, my wife's new GS3 is far better balanced than my GS4 in handling and really did not like the bilstein sports. So we put bilstein HDs on it and I have Sportivo sways to put on and I have to tell you, my feeling is that that combination produces about as close as I think you will get to bimmer balance in a Lexus. Not sure if you can do it in a GS4 but then a 540 actually doesn't have the balance of a 530 which is the bimmer that CR really rates as the best sedan in the world, not the 540 if you look at their reviews.
Sorry for the long posts and some of the techno babble but my view is that the more we all can share and know, the better products we demand from Lexus and the after market, and the more we all benefit. Some of this is pretty sophisticated to get right and some of it isn't. Also worth noting that I came out of the "If it don't go, chrome it" world where looks never mattered much. Today, the "look" of the suspension and wheels and tires and engine bits means more to most people than how they actually make the car perform. Then again, the bimmers got me into the concours level detailers and that is just as deadly to your checking account as any other type of modding.
PS I have to say that mooretorque really did catch me on the stiffness versus resonant frequency issue. I just thought I would try to comment on it (poorly, as it turned out) because of the useless babble that some of the auto makers are using it for, to demonstrate how rigid their chassis are. I don't know who started that, I think it was Olds, but I wish people were smarter to catch the advertising glop that the manufacturers continue to try to foist on us rather than just build a good product.
Last edited by RON430; 08-15-03 at 12:20 PM.
08-17-03, 12:45 PM
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Nope, I don't have any problems with the spring rates on the stock springs and have very little interest in lowering. Normally, you really want the ability of the suspension to to absorb bumps and follow the road to be handled by the spring rates. That was a pretty clumsy sentence but I couldn't figure out a better way to say it. The shock should work in concert with the spring but with the fundamental forces supplied by the spring. The original intent of the shock was to damp the oscillations that springs incur when they are compressed/extended and return to rest. But nowadays the shocks are used to almost become an additional spring force and that is where the problems lie. The bilstein sports on my wifes GS3 not only provided a buckboard ride but it was most pronounced in the rear end where it was not only very easy to have it break loose but developed some other annoying traits (a loud thunk over big bumps was one of them). I have never really seen this from bilsteins before and what is really odd is that the bilstein sports on my GS4 showed neither of these problems. But it was so severe, and I felt so guilty buggering up my wifes new GS3, that I ordered the HDs and we have them on for a couple of weeks now. While the HDs are still noticeably stiffer than stock, they don't really have too objectionable a ride and the rear end is solidly under control.
My wife definitely does not like "floaty" ride (which oddly enough is her complaint about Honda/Acura but that is a different topic) and she was pretty good natured about the Sports but I wanted them off as soon as possible. A couple of people pointed to the weight difference between the GS3 and 4 but I don't buy it. Especially because the most noticeable difference was in the rear end where the weight difference is almost non existent. So, there is something very different about the GS3 and 4 suspension IMO and the sports are definitely not the way to go. I have no numbers but I assure you, the car would handle on a road course slower, you have to keep that precious little contact patch of each tire. Once the tire is no longer in contact, handling ability is dramatically reduced.
Now, that long winded bit aside, I don't think there are any replacement springs for the GS that are lower rate than stock. The rear end hopping is the car encountering a bump and the suspension reaction is too slow to keep the rear end in contact. Does that make sense to you? It should and if so you can see where I am going in further suspension tweaking. Don't want to give anyone else anymore of a headache reading these posts but the stiffer you go in a suspension, the less "indepedent" the corners are and the slower the vehicle responds to external input (road conditions), which is neither fast nor comfortable. Most of the European feel in cars is due to cars that have relatively weaker springs and stiff traction - anti-roll components. And a fundamental difference in American iron is that they tend to go strong springs/shocks for "sport" suspension which degrades ride on everything except billiard table smooth roads. The only reason I could guess for the American approach is that, at least in the past, it was the quicker/cheaper way to increase handling. Japanese seem to be somewhere in between but still a work in progress.
For the above reasons, I doubt springs are going to help much with the hop, I think you are going to need less stiffness. About the only thing that would help for low bucks is to do nothing. Shocks, even bilsteins, are constantly wearing and the valving that dictates the stiffness will degrade somewhat over time but I know how distressing it can be to drive it now. Like I said, I was flabbergasted that the Sports, which my wife loves on the GS4, were really awful, still IMO, on the GS3. Now, if you want to see a suspension with awful rear axle hop, you need to go back to the good ol' solid axle muscle cars. Next time you watch "THE CHASE" in Bullitt, wait for the scene where McQueen throws the stang in reverse and winds those rear springs up and gets the rear axle dancing. Saw that one happen and anyone who raced the early TA cars was all too familiar with it and it was very annoying. A lot of the problem came from the fact that with leaf springs, the axle locating and springing were done by the same component. Not very desirable. So everyone got Traction Masters ( a brand name as I remember) which was a lower link that you welded to the rear axle housing and extended with a solid link up to the chassis, where you welded mounting bracket as well. These would now locate the rear end and you could start playing with the spring for its rate abilities and not worry about such nasty side effects as the spring actually winding as the axle wanted to twist under acceleration. But when you broke one, it inevitably broke up by the chassis mount and the car wanted to pole vault when it dug in.
And there's another story.
Ron
My wife definitely does not like "floaty" ride (which oddly enough is her complaint about Honda/Acura but that is a different topic) and she was pretty good natured about the Sports but I wanted them off as soon as possible. A couple of people pointed to the weight difference between the GS3 and 4 but I don't buy it. Especially because the most noticeable difference was in the rear end where the weight difference is almost non existent. So, there is something very different about the GS3 and 4 suspension IMO and the sports are definitely not the way to go. I have no numbers but I assure you, the car would handle on a road course slower, you have to keep that precious little contact patch of each tire. Once the tire is no longer in contact, handling ability is dramatically reduced.
Now, that long winded bit aside, I don't think there are any replacement springs for the GS that are lower rate than stock. The rear end hopping is the car encountering a bump and the suspension reaction is too slow to keep the rear end in contact. Does that make sense to you? It should and if so you can see where I am going in further suspension tweaking. Don't want to give anyone else anymore of a headache reading these posts but the stiffer you go in a suspension, the less "indepedent" the corners are and the slower the vehicle responds to external input (road conditions), which is neither fast nor comfortable. Most of the European feel in cars is due to cars that have relatively weaker springs and stiff traction - anti-roll components. And a fundamental difference in American iron is that they tend to go strong springs/shocks for "sport" suspension which degrades ride on everything except billiard table smooth roads. The only reason I could guess for the American approach is that, at least in the past, it was the quicker/cheaper way to increase handling. Japanese seem to be somewhere in between but still a work in progress.
For the above reasons, I doubt springs are going to help much with the hop, I think you are going to need less stiffness. About the only thing that would help for low bucks is to do nothing. Shocks, even bilsteins, are constantly wearing and the valving that dictates the stiffness will degrade somewhat over time but I know how distressing it can be to drive it now. Like I said, I was flabbergasted that the Sports, which my wife loves on the GS4, were really awful, still IMO, on the GS3. Now, if you want to see a suspension with awful rear axle hop, you need to go back to the good ol' solid axle muscle cars. Next time you watch "THE CHASE" in Bullitt, wait for the scene where McQueen throws the stang in reverse and winds those rear springs up and gets the rear axle dancing. Saw that one happen and anyone who raced the early TA cars was all too familiar with it and it was very annoying. A lot of the problem came from the fact that with leaf springs, the axle locating and springing were done by the same component. Not very desirable. So everyone got Traction Masters ( a brand name as I remember) which was a lower link that you welded to the rear axle housing and extended with a solid link up to the chassis, where you welded mounting bracket as well. These would now locate the rear end and you could start playing with the spring for its rate abilities and not worry about such nasty side effects as the spring actually winding as the axle wanted to twist under acceleration. But when you broke one, it inevitably broke up by the chassis mount and the car wanted to pole vault when it dug in.
And there's another story.Ron