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What is better when it comes to sway bars

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    What is better when it comes to sway bars

    A solid or a hollow sway bar

    The 1997 acura CL has solid front and rear sway bars

    16mm rear and 25mm front

    But it also could have a 27.2mm hollow front sway bar.

    Which is best?

    #2
    I'd rather have a solid bar. It just seems like it would be stronger.
    COUPE K24

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      #3
      Originally posted by '93CB7Ex View Post
      I'd rather have a solid bar. It just seems like it would be stronger.
      But is stronger what your looking for is what i want to know

      Or would a hollow bar be better because it could twist more to help the inner wheel get traction?

      Comment


        #4
        it depends on what you are wanting the sways to do. hollow or solid, it almost does not even matter, (almost just a weight saving thing), pretty much size is everything when it comes to sway bars

        i once read that a hollow bar, (not specific to sways), can actually be stronger than solid bars, which is why ALOT of tall flag poles and steel support beams in buildings are not just bars of metal, but hollow poles. our cars', (and many others'), chassis is hollow, many roll cages are made with hollow bars

        if you want the sways to eliminate understeer, get the progressive 22 rear sway and keep or upgrade to the ex 25.5 mm bar

        if you want race car feeling, absolutly no body roll, get the progressive bar in the rear, and the tanabe 30.4 mm bar for the 94-97 accord

        theres at least two members with that front bar, based on their mrt's, (and a third one had the bar but as far as i saw never installed it), i cannot remember who they were, and it was a pain last time i searched for them

        on another note, having a 27.2 in the front without an aftermarket bigger rear is not very ideal, as you increase understeer, that being said it WILL make the car feel more solid
        Last edited by KB7; 12-25-2010, 04:38 AM.
        _

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          #5
          Sway bars are a compromise between roll stiffness and mechanical grip. By adding a larger bar, you're decreasing mechanical grip because you're linking both wheels on that end together. However, in many cases, the increase in roll stiffness is enough to overcome the reduction in mechanical grip.

          The only way to really know is measurement and calculation. The CB7 does respond very well to a large rear bar though.

          As far as hollow vs solid, a solid bar is going to be stiffer, but it is also much heavier. The analogy about flag poles being stronger if they are hollow is a misconception. In some situations, the bar's own weight can work against it, making the part fatigue or break easier. This isn't the case with a sway bar though. I don't know of a hollow bar for the CB7, but if you do, probably go for it. Its lighter. Just make sure it isn't stupid large so that you have outrageous roll stiffness and you piss off your tires.
          Last edited by mndude07; 12-26-2010, 01:31 AM.
          There are no black and white suspension answers!!!!!!!!!!!

          Comment


            #6
            Originally posted by mndude07 View Post
            Sway bars are a compromise between roll stiffness and mechanical grip. By adding a larger bar, you're decreasing mechanical grip because you're linking both wheels on that end together. However, in many cases, the increase in roll stiffness is enough to overcome the reduction in mechanical grip.

            The only way to really know is measurement and calculation. The CB7 does respond very well to a large rear bar though.

            As far as hollow vs solid, a solid bar is going to be stiffer, but it is also much heavier. The analogy about flag poles being stronger if they are hollow is a misconception. In some situations, the bar's own weight can work against it, making the part fatigue or break easier. This isn't the case with a sway bar though. I don't know of a hollow bar for the CB7, but if you do, probably go for it. Its lighter. Just make sure it isn't stupid large so that you have outrageous roll stiffness and you piss off your tires.
            Im pretty sure the stock bar is hollow. I broke a 90 integra rear sway bar inhalf and it was hollow. I'd imagine it would be the same

            The weight is not much, maybe a few pounds. I don't care about weight that much. the car is heavy im ready to live with that.

            So anyways, should i get the solid or the hollow bar? Both are the same size.

            Comment


              #7
              mndude07- Im certain that hollow is stiffer than solid, its due to more surface area. Examples are given above. It also has more resistance to twist.

              Tippey724- However in this application is would make sence to stick to a solid rear bar, made by Progress or ST, as people have had success with them on a cb.
              Last edited by marcusv8thunder; 12-27-2010, 11:17 AM.


              UKDM 93 CB3 Page (1) H22A U2Q7 LSD
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              Comment


                #8
                So when it comes to sway bars do you want it to twist or not? Im really confused now lol

                And im not getting a progress or ST bar im getting a stock bar which is either solid or hollow and 16mm. It'll be cheap which is what im looking for.

                Comment


                  #9
                  There are way too many variables to determine which is stiffer. Diameter, metal hardness, wall thickness of hollow bars.

                  Given the same diameter and metal hardness, the solid bar will be a tiny bit stiffer and alot heavier. The material resisting most of the twisting force is the very outside of the bar. I would be willing to bet a 1.25" hollow bar with 3/16" wall thickness would be MUCH stiffer than a 1" solid bar of the same metal hardness.

                  Your best bet is to fasten one end to something and test the stiffness of each bar, preferably being able to apply the same amount of weight and measure the distance the other end moves. See for yourself which is stiffer.

                  I currently have the dx/lx front sway which is 22.4mm and is a bit too soft IMO. I'll be upgrading to the ex/se bar which is 25mm and should be a good balance.
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                  Comment


                    #10
                    Originally posted by marcusv8thunder View Post
                    mndude07- Im certain that hollow is stiffer than solid, its due to more surface area. Examples are given above. It also has more resistance to twist.

                    Tippey724- However in this application is would make sence to stick to a solid rear bar, made by Progress or ST, as people have had success with them on a cb.

                    Well....sorry but you're incorrect. If you look at the equation for the polar moment of inertia of a tube or bar, they are the same, except that the equation for the hollow bar has the inner diameter subtracted from the outer diameter. This means that the largest value for MoI is when the inner diameter is zero (a solid bar).

                    Now, since your torque applied to the bar remains constant, the length of the bar remains constant, the modulus of rigidity remains constant, then the bar with the larger MoI is going to produce a smaller twist in the bar.

                    T/J = GQ/L

                    T=torque applied
                    J=moment of inertia
                    G=modulus of rigidity
                    Q=twist in radians
                    L=length of bar

                    Doesn't a stronger bar twist less?

                    Hollow bars are not stiffer, given the same outer diameter and material. For some reason, people think they are because they are often labeled as a "race only" bar. If you look though, they are often much larger diameters. They are made hollow for two reasons. First, you can have a higher proportional torsional rigidity compared to total diameter, thus maximizing stiffness and minimizing the polar moment of inertia. Minimizing a moment of inertia makes the bar easier to move and since it is linking your suspension corners together, it has a similar effect as reducing unsprung mass directly. Also, they are hollow for weight. I don't think you realize how much of a total freak you have to be about weight when it comes to race cars. Yeah maybe its only a 2 pound difference....but what if you had that mindset for everything? You'd have a 4000lb race car and be very slow.

                    You can see that surface area has nothing directly to do with a bars' resistance to twist.


                    So, if you're set on getting an OEM sway bar, you probably want the largest one that will fit. They are hollow as far as I know and none of them are extreme high performance, so you don't have to worry about going TOO stiff. Yes, all sway bars twist to some degree. And yes, too stiff can be a bad thing because of what I said in my previous post about mechanical grip vs roll stiffness. Adding more bar will make the car stiffer all around, but its the proportion of the front to rear roll stiffness that dictates under/oversteer.

                    My plan before i wrecked the car was to use the progress rear and the largest OEM front I could find. Having the progress rear with the stock front made the car much closer to neutral, but I could have used some more roll stiffness in the front, but I didn't want to add too much and create more understeer.
                    Last edited by mndude07; 12-28-2010, 04:10 AM.
                    There are no black and white suspension answers!!!!!!!!!!!

                    Comment


                      #11
                      Originally posted by mndude07 View Post
                      Well....sorry but you're incorrect. If you look at the equation for the polar moment of inertia of a tube or bar, they are the same, except that the equation for the hollow bar has the inner diameter subtracted from the outer diameter. This means that the largest value for MoI is when the inner diameter is zero (a solid bar).

                      Now, since your torque applied to the bar remains constant, the length of the bar remains constant, the modulus of rigidity remains constant, then the bar with the larger MoI is going to produce a smaller twist in the bar.

                      T/J = GQ/L

                      T=torque applied
                      J=moment of inertia
                      G=modulus of rigidity
                      Q=twist in radians
                      L=length of bar

                      Doesn't a stronger bar twist less?

                      Hollow bars are not stiffer, given the same outer diameter and material. For some reason, people think they are because they are often labeled as a "race only" bar. If you look though, they are often much larger diameters. They are made hollow for two reasons. First, you can have a higher proportional torsional rigidity compared to total diameter, thus maximizing stiffness and minimizing the polar moment of inertia. Minimizing a moment of inertia makes the bar easier to move and since it is linking your suspension corners together, it has a similar effect as reducing unsprung mass directly. Also, they are hollow for weight. I don't think you realize how much of a total freak you have to be about weight when it comes to race cars. Yeah maybe its only a 2 pound difference....but what if you had that mindset for everything? You'd have a 4000lb race car and be very slow.

                      You can see that surface area has nothing directly to do with a bars' resistance to twist.


                      So, if you're set on getting an OEM sway bar, you probably want the largest one that will fit. They are hollow as far as I know and none of them are extreme high performance, so you don't have to worry about going TOO stiff. Yes, all sway bars twist to some degree. And yes, too stiff can be a bad thing because of what I said in my previous post about mechanical grip vs roll stiffness. Adding more bar will make the car stiffer all around, but its the proportion of the front to rear roll stiffness that dictates under/oversteer.

                      My plan before i wrecked the car was to use the progress rear and the largest OEM front I could find. Having the progress rear with the stock front made the car much closer to neutral, but I could have used some more roll stiffness in the front, but I didn't want to add too much and create more understeer.
                      You wrecked your accord?

                      Comment


                        #12
                        Originally posted by Tippey764 View Post
                        You wrecked your accord?
                        LOL its funny thats your only comment on everything I wrote. Yes I did, roughly two months ago I guess. Its drive-able, but the frame is totally ruined. I'll be betraying you all and going to a EF sedan. I plan to continue all my Accord's plans with the civic though. The civic is 500lbs lighter though is the reason...and parts are more common. The F22A and Prelude VTEC brakes will be going onto the civic. It should be quick out of the box.
                        There are no black and white suspension answers!!!!!!!!!!!

                        Comment


                          #13
                          Although barely touched upon, one thing you need to question is what metal is the bar composed of? My rear sway bar on the cobalt is a 1.25" hollow Chromoly steel bar which is the exact one on the SCCA Time Attack Cobalt. With no front sway bar there is way too much off throttle oversteer which can be dangerous.
                          Call me Travis.
                          2006 Cobalt LS/SC ~ "Burt the Bloody Bumble Bee"
                          1992 Accord LX ~ "Smoothie"
                          1991 CRX Si ~ Hellion
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                          Comment


                            #14
                            Originally posted by Cobalt View Post
                            Although barely touched upon, one thing you need to question is what metal is the bar composed of? My rear sway bar on the cobalt is a 1.25" hollow Chromoly steel bar which is the exact one on the SCCA Time Attack Cobalt. With no front sway bar there is way too much off throttle oversteer which can be dangerous.
                            Right. We were talking about keeping the metal constant for the comparison. The type of metal with determine the modulus of rigidity; the G term in the above equation.

                            4130 (chromoly) is especially good because it has a high strength to weight ratio, and responds well to heat-treat.
                            There are no black and white suspension answers!!!!!!!!!!!

                            Comment


                              #15
                              too much off throttle oversteer.

                              I haven't got to this stage yet. but I plan on only beefing up the rear for starters. rear strut bar and rear underbracing if it's available.

                              is this bad. then maybe ill get the weakest front bar i can find.

                              concentrating on getting as much oversteer as possible.

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