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  • My thoughts on wheel hop.

    Well, I've seen a lot of wheelhop threads lately, so I decided to write up my thoughts on it. Take 'em or leave 'em. Mods feel free to move this to whatever section you feel best.

    Ok, your Saturn has wheelhop, and clearly you are not alone. But before you go spending your hard earned monies on such goodies as the "earthshaker" mount, SDA dogbones, or filly things with 94a poly, do a little thinking. I believe the following misinformation is being spread on the subject of wheel hop: The cause of wheel hop is engine mounts that are too "soft". First of all, the only direct link between your powertrain and suspension is the driveshaft. While it is possible that your engine rocking back and forth could cause this motion, it is highly unlikely. How many rear wheel drive cars do you see cure wheel hop with engine mounts? Despite being RWD, they also have a driveshaft connected directly to the powertrain.

    So how do I fix it?

    There are a few things that contribute to wheel hop, but the basic premise behind all of them is your cars inability to control the up erratic movement of one or both of the front tires during low traction situations. There are several connections in the front suspension where this can come from: LCA bushings, swaybar-cradle bushings, struts, strut mounts, springs, and engine/trans mounts. The first thing you should do if you have wheel hop is check your struts. Why? Struts are direct control of the up and down motion of the wheel. Unlike most components in the front end of the saturn, they provide damping. When a strut is blown, you lose almost all control of over this motion, and regardless of the rest of your suspenion, your wheel will bounce up and down in the fender all day long.

    The next thing to check: Front end bushings. Why? Because as bushings wear, they provide far less gross motion control than in their new form. They also get softer, lowering the wheelhop frequency. Engine mounts also get softer, but pretty much only the TAM mount loses motion control as it wears. Most people don't think about it, but a lot of wheelhop is the result of the wheel moving fore/aft as well as up down. I've experienced this first hand... after I did the auto to manual swap on my 93SW2, you could see the wheels walk forward almost an inch inside the wheel wells. This is with all brand new components up front except swaybar-cradle bushings. Replacing those fixed the problem in a heartbeat.

    Other causes?

    Unsprung weight will magnify all of the above problems. Your saturns factory suspension (and most aftermarket suspension components for that matter), were not designed to control the motion of your 18X8 Chrome plated wheels. Adding a fair amount of unsprung weight puts tons more force on each rubber connection in the front end. And remember, its not just wheels, its balancing weights, tires, rotors, calipers, etc.

    So what about engine mounts?

    I'm not going to say replacing mounts wont help... it will. Be do they need to be hard as a rock? No. Having a super hard engine mount increases the dynamic rate a tremendous amount, resulting in higher wheelhop frequency (if it still occurs), more vibration (and we all know saturn interiors need all the help they can get), and they can also break shit. Believe it or not, the shape and durometer of a stock mount is finely tuned to dampen the motion of the powertrain fairly well. And the less vibration you can feel from your engine... the less vibration reaching your wheels.


    I don't want a shitty interior, but I still want to control engine movement, what should I do?


    My recommendation: Get a 1991 center engine damper setup. Its an air piston incorporated into a mount. It has a static rate of almost zero, but a provides quite a bit of damping, especially at wheel-hop frequencies. You could also make your own very similar setup. Several vehicles use this style damper to control start up vibrations.

    Anything else I can do?

    As I stated earlier, bushing compliance is a big factor... consider poly bushings, or even replacing swaybar to LCA bushings with steel washers. If this fails, or you feel its not enough, lower control arm to cradle ties may be effective.

    Also, learn to drive it without causing hop. A simple change in driving style can easily cure hop. And its free [img]{SMILIES_PATH}/smile.gif[/img]

    Lastly....

    If you are running a drag-tire setup, the above stuff still applies, but it may not eliminate hop completely. Obviously when you double the traction of stock tires, its a whole new ball game. But I can offer this... on a hard launch, allowing you engine mounts to have a lot of travel lessens the impulse of the clutch-dump, having the same effect the a "wrinkle wall" drag tire does. So once again, eliminating all compliance in the front end is not always the best solution. But, these thoughts are purely theoretical... I have never run drag tires.

    Anyways, those are just my thoughts on the matter. Take them or leave them.

    -Travis

    P.S. If you are wonder about credentials... I did spend 2.5 years doing NVH (Noise Vibration and Harshness) development of hydraulic engine mounts and bushings for Goodyear Engineered Products, along with writing a senior thesis on an actively controlled multi-stage damping hydro mount.
    ilostmysocketwrench | Bentra Motorsports Blog | Bentra Motorsports Videos

  • #2
    re-post this in the DIY section...
    [img width=600 height=150]http://www.sixthsphere.com/storage2/images/wejag665buljx09mu77e.jpg[/img]<br />99SL2 w/97SC2M Engine/Trans Swap, CAI, 2.25 Custom Exhaust

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    • #3
      Doh. So thats what the "tech articles" section is for [img]{SMILIES_PATH}/smile.gif[/img]
      ilostmysocketwrench | Bentra Motorsports Blog | Bentra Motorsports Videos

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      • #4
        [img]{SMILIES_PATH}/00550694.gif[/img]
        [img width=600 height=150]http://www.sixthsphere.com/storage2/images/wejag665buljx09mu77e.jpg[/img]<br />99SL2 w/97SC2M Engine/Trans Swap, CAI, 2.25 Custom Exhaust

        Comment


        • #5
          Very good information here.

          As the designer of the "earthshaker" mount, I agree with everything he says. I designed the unit for off road, drag use only......and thats what I use it for.

          ProDarwin : For drag use, what about using rotating/twisting motion bearings (sorry if I don't know the name of them) instead of the rubber mounts where the swaybar mounts to the subframe......this would remove alot of the flex. I like your idea of washers in the swaybar to LCA connection. Although I don't get wheel hop in my drag car, I am always looking for ways to get better traction off the line.

          Jer
          Daily : 2011 Subaru WRX wagon
          Ex daily driver : 2000 SW2 5spd, First S-series w/Hein's true A-arm front suspension, First sedan/wagon w/coupe front end conversion, boxed in rear subframe, SPS 3-way rear swaybar, Corado 11" rotor swap w/Wilwood superlight 2 front calipers, rear disk swap, Deeb's built engine w/dual intake cam's, OBX header, High flow cat, Thermal exhaust, MSD wires and coils, AEM CAI, OBX rad hoses, custom short throw shifter, black leather swap, black interior swap and there's a stereo somewhere in there.
          Ex daily driver : 86 Fiero GT, 3800SC 4spd manual *SOLD*
          Project : 85 Fiero GT, with the heart and soul of a 04 ION redline

          Check out my project car "Fierion"

          www.coppertopautosports.blogspot.com

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          • #6
            Yeah, a fixed bearing would work, but it would be almost impossible to get around the swaybar.

            A better option would be to machine 1/2 of a mounted bearing, similar to those pictured here: http://www.mcmaster.com/nav/framework.a ... =2D&size=2, with a zerk fitting and all. Unfortunately hard launches would probably distort it overtime if you machined it out of billet AL, but I'm not sure. The zerk fitting would definitely keep rotational wear to a minumum if properly greased.

            Even easier yet.... Just machine the front bushings out of alumnum, but make them a split bearing with a polished stainless center. Cap them with the stock brackets.

            If anyone decides to create a new front bar... design it as a system to incorporate something like this. Contact me and I'd be glad to help.
            ilostmysocketwrench | Bentra Motorsports Blog | Bentra Motorsports Videos

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            • #7
              Sounds like you guys need to look at installing a "stock car" tubular sway bar. Could be done. I've been looking at machineing up some solid sway bar bushings for awhile just need to get some projects out of the way.

              http://www.stockcarproducts.com/susp21.htm
              http://www.stockcarproducts.com/susp22.htm
              http://www.stockcarproducts.com/susp22a.htm

              Tim
              Collecting parts soon bitches soon........

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              • #8
                It makes sense, but a lot of the suspension related stuff is gibberish..

                Where can I find all the parts I need that were mentioned here?
                - Justin [s]99 Blue SL2 - T3/T4 14psi[/s] (dead)


                FS: Pimped lower trans mount, TiAL 38mm Wastegate, Gauge Cluster, Oil Drain

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                • #9
                  What parts do you want?
                  ilostmysocketwrench | Bentra Motorsports Blog | Bentra Motorsports Videos

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                  • #10
                    LCA bushings, swaybar-cradle bushings
                    - Justin [s]99 Blue SL2 - T3/T4 14psi[/s] (dead)


                    FS: Pimped lower trans mount, TiAL 38mm Wastegate, Gauge Cluster, Oil Drain

                    Comment


                    • #11
                      I found my wheel hop was from the bushing between theLCA and the sway bar. You can't order just the bushing. You have to but the whole LCA..gay.

                      I do believe it comes with a unrathane upgrade...if not, take some off and junked car and double them up.
                      -6S Resident Mechanical Forensics member #001.
                      1995 SC2 Turbo 3.6L DOHC, 6sp manual, Ford 8.8 rearend running on MS3x.
                      1998 F-250 5.4L triton...stock.

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                      • #12
                        I think you can order the front control arm bushings from Summit. They are Energy Suspension.

                        http://store.summitracing.com/partdetai ... toview=sku

                        That's the front set for our cars. Has for the sway bar lca's and the inner bushing.

                        --Adam
                        2002 Subaru WRX - 2012 Yeti SB66 MTB

                        http://www.facebook.com/adam.koback

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                        • #13
                          mine went away after I filled the front transmission mount in my ion

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                          • #14
                            ProDarwin : I know this might be alittle too simple, and redneck/cheapass way todo it, I was thinking about getting a bearing around the sway bar......what about cutting it in the middle (I would only do this on a drag car, not a daily driver) weld plates on the two cut ends, with bolts to join it back together........it might be alittle too simple, but it might just work.

                            Jer
                            Daily : 2011 Subaru WRX wagon
                            Ex daily driver : 2000 SW2 5spd, First S-series w/Hein's true A-arm front suspension, First sedan/wagon w/coupe front end conversion, boxed in rear subframe, SPS 3-way rear swaybar, Corado 11" rotor swap w/Wilwood superlight 2 front calipers, rear disk swap, Deeb's built engine w/dual intake cam's, OBX header, High flow cat, Thermal exhaust, MSD wires and coils, AEM CAI, OBX rad hoses, custom short throw shifter, black leather swap, black interior swap and there's a stereo somewhere in there.
                            Ex daily driver : 86 Fiero GT, 3800SC 4spd manual *SOLD*
                            Project : 85 Fiero GT, with the heart and soul of a 04 ION redline

                            Check out my project car "Fierion"

                            www.coppertopautosports.blogspot.com

                            Comment


                            • #15
                              I wouldn't use a bearing as soon as you cut the race it would jam. We used to make "split blocks" for the race cars back in the day.



                              The ones in the pics are NOT "split blocks" for sway bars. Those are tube holders I use for mitering tubes BUT you get the idea. First get 2 pieces of steel. and drill/tap/ counterbore for screws. Drill/counterbore for mounting holes. drill/tap for zerk fitting. Bolt them together then bore out the size you need for your sway bar. Groove the inside for the grease (make sure you line up with the zerk fitting hole) Pull your old swaybar mounts off and toss them. Bolt the new mount in place. Grease. Drive

                              Tim
                              Collecting parts soon bitches soon........

                              Comment

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