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Which part needs replacing

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    Which part needs replacing

    So I am comparing my car to my moms TL with a simple bounce test, and her car is WAY stiffer than mine, I am wondering if it is the shocks or springs that are more responsible for anti-sway, and stiffness of the ride for more overall performace, cuz I think i can only afford to replace one or the other lol

    Thanks

    #2
    the stiffness is controlled by the shocks because they are the ones that absorbe the shock or movement. get what im saying?

    Comment


      #3
      Originally posted by Danielson
      the stiffness is controlled by the shocks because they are the ones that absorbe the shock or movement. get what im saying?
      Thats not really correct.

      Pirate, if you want to start making your car handle better then the things to consider are going to be tires, springs, shocks, alignment, sway bars, chassis stiffening.

      I'd suggest that you start w/ springs/shocks and get an alignment (you may also need a camber kit). You should do those things together because you'll need an alignment after springs/shocks/camber kit. However you can add sway bars, different tires... one at a time and you won't need to get the car re-aligned.

      Sway bars help to prevent "sway" but springs/shocks will also aid in the feeling of body roll. Springs/shocks will make the car feel stiffer/softer when you push on the fender, whereas sway bars won't change how that feels.

      Comment


        #4
        Originally posted by Colin
        Thats not really correct.

        Pirate, if you want to start making your car handle better then the things to consider are going to be tires, springs, shocks, alignment, sway bars, chassis stiffening.

        I'd suggest that you start w/ springs/shocks and get an alignment (you may also need a camber kit). You should do those things together because you'll need an alignment after springs/shocks/camber kit. However you can add sway bars, different tires... one at a time and you won't need to get the car re-aligned.

        Sway bars help to prevent "sway" but springs/shocks will also aid in the feeling of body roll. Springs/shocks will make the car feel stiffer/softer when you push on the fender, whereas sway bars won't change how that feels.
        Thanks Colin,

        That says it quite nicely, I guess I should have stated that I already invested in the tires, thats why im so angry, Im sure the tires would stick a lot better if the weight was dist. a little better on them. I really want to get the sway bars and all that jazz, I just dont know how much i want to get into it because most of the bushings mainly the rear lower control arms are shot..So i dont know how effective upgrades are going to be when placed on such a bad foundation...

        Comment


          #5
          Its all a problem of having "weak links" as soon as you replace one part, there will be another part holding you back.... but if you take it too far your car might not be as street friendly as you'd like it to be.

          if some of your bushings are completely shot, then I'd say do that stuff first. It'd be good to do maintenance type stuff first. Or, even better, just do it all at once. You could do bushings, springs and shocks, then get the car aligned. You'll probably have to wait longer to do it that way (cause it'll take longer to save the $$) but its probably your best bet.

          I know that on my car all the bushings were mediocre, but only the rear trailing arm bushing was completely shot. Thats the one I'd worry about the most. Especially since replacing the other ones w/ oem bushings is very expensive. And depending on your preference.... the poly bushings may be stiffer than you'd like.

          Comment


            #6
            So I dont think that I can quite afford a sping/shock combo, but I have been reading up on sway bars to be one of the best bang for the buck suspention upgrades, is that true? Ans also I would like to know what the advantages are to getting front and back vs just front or just back.

            I also read somwhere on here that sway bars can decrease wet weather handling, but that doesnt sound right to me, is there any disadvantages to sway bars like braking or bad weather handling?

            Thanks

            Comment


              #7
              Originally posted by pirate252
              So I am comparing my car to my moms TL with a simple bounce test, and her car is WAY stiffer than mine, I am wondering if it is the shocks or springs that are more responsible for anti-sway, and stiffness of the ride for more overall performace, cuz I think i can only afford to replace one or the other lol

              Thanks
              "Stiffer" is a highly subjective word. Is the chassis stiffer? Are the anti-roll bars thicker? Are the spring rates higher? Are the tires' PSI higher? Do the tires have a higher spring rate, and less tire distortion in the sidewall?

              As stated above, these factors contribute to a "stiff" car:
              Front and rear sway bars
              Spring rates
              Chassis stiffness. (which can be increased with a roll cage, and/or triangulated strut bars, tie bars, traction bars, and chassis braces.)
              Stiffer suspension bushings
              Suspension linkages made from materials with less elasticity. (And a stiffer contruction)
              Tires with higher spring compression rates, higher PSI, less sidewall distortion, and a lower profile sidewall
              Wheels made from material with less elasticity. (I.e., stamped steel wheels VS. Billet AL, and a stiffer construction.)

              (There are perhaps are more factors which I am forgetting.)

              Also, if your car has the original springs, and you've got high milage, the springs tend to "sag" over time, and the spring rate will become lower over a matter of 15 years of usage.

              You mentioned that your rear LCA bushings are shot. That has a BIG affect on the "stiffness" and "responsiveness" of the car. (IMO, fix your car before you start modifying it.)

              In terms of anti-roll bars/ sway bars decreasing the tractive capacity of a car in wet weather conditions, this depends on a few things:
              If the front anti-roll bar is stiffer in the front, this will cause the car to "push" or understeer, because of less delay of time of weight transfer to the outside front tire. This makes the tire reach its' total tractive capacity limit sooner, and break traction thereafter. (Thus causing a loss in front tire traction.)

              If the rear anti-roll bar is stiffer than the front, the rear tires have a greater tendancy to reach its' tractive capacity sooner, and break traction sooner. When the rear tires break loose before the front tires, this is known as "oversteer." Depending on the situation, even in wet conditions, some oversteer can be helpful in making the car easier to turn, although more "twitchy" near the traction limit.

              I hope this helps.

              -Andrew

              Comment


                #8
                Originally posted by Danielson
                the stiffness is controlled by the shocks because they are the ones that absorbe the shock or movement. get what im saying?
                The reason why Danielson is incorrect here, is because the shocks don't absorb the "shock" from bump travel. The springs are the primary components which absorb the shock/force from bump travel. A higher spring rate will contribute to a reduction in body roll also.
                The only purpose of the shock/strut/dampener, is to slow the springs' rebound rate as the spring exerts a force on the chassis, pushing the chassis back up to ride height.
                Also, another purpose of the shock, is to limit (or control) the total amount of total suspension travel.

                -Andrew

                Comment


                  #9
                  Wow, thanks for the great reply...

                  I do have one question though, you say that the front sway bar being stiffer will make the car oversteer, and the rear bar being stiffer will make the car understeer. So how come in sway bar kits, and OEM sway bars (cars that have them front and back) the fronts are always bigger? Isn't a little oversteer better for handling, like why RWD is better than a FWD...Why dont they make preformance sway bar kits with a bigger one in the back and a smaller one in the front to make a nice controlled amount of oversteer?

                  Thanks again for the extremly informative reply.

                  And its my rear control arm bushings that look shot, there way worn and cracked, I have looked and they look like they need to be profesianally replaced since you need a press...any guess on labor cost??

                  Also just to shoot this question out there...A while ago, when it was nice and warm outside still I took a nice twisty high speed joyride and was going along fine for the whole way../except one slip up where I was coming around a corner at about 60 and this freakin truck was way over the line, so I pressed gently on the brakes in fear of causeing the tires to brake loose, and the car kinda jerked, thats the only thing I can think of to describe it...the car felt like all the weight transfered and then came back again when I let off the brake, felt like I lost control for a split second, but no tires made a noise or anything, just scared the crap out of me, could that be related to the LCA bushings?
                  Last edited by pirate252; 10 Jan 2005, 22:15:52.

                  Comment


                    #10
                    Originally posted by pirate252
                    ...you say that the front sway bar being stiffer will make the car oversteer, and the rear bar being stiffer will make the car understeer. So how come in sway bar kits, and OEM sway bars (cars that have them front and back) the fronts are always bigger? Isn't a little oversteer better for handling, like why RWD is better than a FWD...Why dont they make preformance sway bar kits with a bigger one in the back and a smaller one in the front to make a nice controlled amount of oversteer?

                    Thanks again for the extremly informative reply.

                    And its my rear control arm bushings that look shot, there way worn and cracked, I have looked and they look like they need to be profesianally replaced since you need a press...any guess on labor cost??

                    Also just to shoot this question out there...A while ago, when it was nice and warm outside still I took a nice twisty high speed joyride and was going along fine for the whole way../except one slip up where I was coming around a corner at about 60 and this freakin truck was way over the line, so I pressed gently on the brakes in fear of causeing the tires to brake loose, and the car kinda jerked, thats the only thing I can think of to describe it...the car felt like all the weight transfered and then came back again when I let off the brake, felt like I lost control for a split second, but no tires made a noise or anything, just scared the crap out of me, could that be related to the LCA bushings?

                    Re-read my first reply. A stiffer front anti-roll bar (in relation to the rear anti-roll bar) will induce UNDERSTEER. It will not induce oversteer.
                    Front factory OEM anti-roll bars, on front wheel drive cars, are larger in diameter, or "stiffer" (as in they resist the twisting forces more), is to make the car understeer before it oversteers (if it ever does oversteer), because for the semi-beginner/novice driver (soccer mom level), understeer is an easier condition to control. To bring a powerful RWD car back from an unstable oversteer condition, the driver would have to countersteer, reduce of cease throttle inputs, and coerce the rear wheel to pass the centerline point, centered in between the front wheels' track. After it passes this point, the car will then change direction.
                    As for aftermarket sway bars, these usually are an aftermaket manufacturers' "best guess" at a cars' suspension system. An aftermarket manufacturer cannot economically build several varieties of stiff and soft anti-roll bars, to suit a variety of suspension configurations.


                    As for your joy-ride, try not to. (And if you do, please get sticker/wider tires, and do it on a dry, bright, sunny day, at slower speeds than you mentioned, and also, try to aim for a time which generally has less taffic congestion.)

                    In terms of your cars' condition when it "kinda jerked," the only way for me to tell you what it's doing, is for me to see it, because there are MANY factors which are going on. Although from what you've detailed, here's my hypothesis:
                    Initially your car was in steady state turning, as you were in mid-corner. (As in there were no sudden changes to your tires' slip angles, and neither heavily understeering nor oversteering.)
                    As you saw the truck infront of you, you slammed on the brakes, causing front tire load transfer, which caused the front tires to completely brake loose, and slide. (No, tires do not need to make a screeching sound if they slide. For example, in the rain, sliding tires generally make a "xxsshhhhhhssshhsxxx" type of sound.)
                    When your front tires locked-up, the car is now understeering and following the path of the rear tires. The front wheel lock-up, caused a "winding-up" or twisting of the front supension linkages. The lock-up reduced your speed sightly, and when you let go of the brake, the wheel then began to roll/hop, and your suspension linkages jolted forward, from back-to-front, (from perhaps energy stored from cocking your LCA's and other linkages back) causing a change/disruption to the chassis. (Hence the jerking motion, or perhaps rearward pitch, after the brake release.) So that's my guess.

                    As for FWD vs RWD, the short answer: RWD is better for performance. Think of rearward weight transfer. Nonetheless, FWD race cars, have beaten RWD race cars before, and both had the same power-to-weight ratios.

                    (Also, pick up a Race car engineering book. Or pick up one of Carroll Smiths' books. Either that, or Valkenburgh's race car engineering book. I'm trying to get my BS in Mechanical Engineering, with a focus in Automotive Engineering right now, and I've found these works to be quite helpful, as side texts.)

                    -Andrew
                    Last edited by UCSlugRacerX; 11 Jan 2005, 00:02:39.

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