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Damn Shimmy

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  • #594786
    Kevin TrilloKevin Trillo
    Participant

      Hey guys and gals, haven’t been on the forum lately but hopefully can get some help on this, i have a 2007 Chrysler aspen with roughly 103,000 on it with the 5.7 Hemi. my wife and i purchase a set of Nitto Tera Grapplers 265/50r20 in size. a shimmy starts around 55 60 mph and continues to about 75, haven’t really gone past that because i dont feel like getting a speeding ticket. i have rotated the tires still same vibration/shimmy at the same speeds. i have had the tires balanced twice, ive checked my drive shaft, the u-joints, wheels hubs, rotors, parking parking to see if maybe they were a bit to tight, the shocks and everything in between. the vehicle was cruising at the above speeds and i put the vehicle in neutral and still had the shimmy/vibration. very little feedback through the steering wheel but a lot through the seat/whole vehicle, its particularly the worst at 62-63 mph. im getting the wheels and tired road force balanced tomorrow. if this doesnt seem to correct the problem do you guys have any other suggestions?

    Viewing 9 replies - 1 through 9 (of 9 total)
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    • #594799
      college mancollege man
      Moderator

        If the shimmy is in the seat. then I would suggest drive line.
        Can you put the rear up on jack stands and see if the vibration
        is there. if it does not disappear drive line.

        http://www.ericthecarguy.com/faq/determining-the-causes-of-vehicle-vibrations

        #594812
        Kevin TrilloKevin Trillo
        Participant

          Yes I have checked the drive line, and I have jacked the whole vehicle up, front and back supported with jack stands because its full time 4wd, as stated above I’ve checked drive shafts, u-joints, all that good stuff no play, I alsoput the vehicle in neutral while at the speeds when the shimmy occurs, even in neutral and engine off it still shimmies, that eliminates the engine and driveline, I appreciate the suggestion but its been done!

          #594815
          John HugonJohn Hugon
          Participant

            Probably the vibration is caused by inconsistent sidewall stiffness or maybe slightly out of round with the type of tires you got. The Road Force balancer will detect an out-of-round or out-of-true conditions. Make sure you get a print out of the problem area to give to the tire manufacture so they can repair your issue. After they get done and all tires are at specs, the only thing you should feel is the road pavement….no tire vibration on a smooth road.

            In my opinion Hunter has a very good “road force” tire balancer.

            If you can, keep us posted of the fix.

            #594825
            Kevin TrilloKevin Trillo
            Participant

              will do! and yes i called the tire manufacture and the place i purchased the tires from and they told me to get a print out and all that good stuff, the guy i talked to at the tire places seemed very helpful and i dont see that it would be a problem to get a print out from him. i figured the nitto terra grapplers would give me some road noise and vibration because of the tread but not a shimmy, i also adjust the tire pressure as specified from the door jamb sticker no change, then put 43 psi in after and no change, tires are rated for a max of 50 psi. im going tomorrow and will post results for you guys hopefully the road force works i have heard good things about shimmy at highway speeds and it getting rid of them

              #595017
              EricTheCarGuy 1EricTheCarGuy
              Keymaster

                Based on your description I would suspect you have a bad tire(s). Especially if the problem wasn’t there before you had them installed. Also, some tire balancers are better than others. It may have something to do with the balance machine they’re using, or they’re not using the correct weights for your wheels. The problem you describe indicates a tire balance issue. If they tires can’t be balanced, it’s a tire problem. If they’re not using a good machine, or know how to use the one they have properly, that could also be the cause.

                Good luck and keep us posted.

                #595175
                Kevin TrilloKevin Trillo
                Participant

                  Ok so went to the shop that had a road force balance machine, a couple of the tires were over one @ 42 and the other @ 38 for a LT all terrain tire, they didn’t rotate the tire on the wheel to get the best balance, but I did notice a little difference. So later I was thinking hmm I did do a brake job a couple months ago so I took it for a spin in a parking lot and went about 10 mph and slowly depressed the e-brake, I have the pedal type with rear rotors and the parking pads are on the inside of the rotor like a drum brake. I did this a couple times then drove in a circle at idle and you could feea slight lurching feeling and lthe vehicle would stop without hitting the brake. I took it for a spin and the shimmy was a lot worse through all speeds. So my question is do you the parking brake pads could be rubbing just enough or too much to cause that shimmy? Suggestions for a fix? Was think disassemble clean all the parts reassemble and adjust?

                  #595181
                  RyanRyan
                  Participant

                    35 is the usual max for LT tire force variation. Those tires also have a much stiffer construction compared to P rated tires, translating to less forgiving of road and tire construction imperfections. If they didn’t force match the tires to the wheels like you said then of course the vibration won’t go away. What positions on the vehicle did the 38 and 42 come from?

                    #595232
                    Kevin TrilloKevin Trillo
                    Participant

                      Not entirely sure on the position, they didn’t go into that much detail :unsure: I did however take a picture of the screen not sure exactly where I would find that info, if you could let me know that would be great. I also plan on tearing into the parking brake stuff today, I feel that may be the culprit plus I have another appointment Monday at a nitro deal so the can inspect the tires, figured I could take a look at the parking brake and see if that’s because before I go pending more money!

                      #595372
                      Kevin TrilloKevin Trillo
                      Participant

                        Ok so I disassembled the park brake, cleaned the piss out of it, PB blasted the springs let them soak then cleaned again. Then assembled and adjusted them, I’m glad I did this because now the vehicle rolls much easier in R and D with out tapping the gas to get it going. Still didn’t fix the shimmy, so Monday I will going to a nitto dealer to have theatre thoroughly inspected. And hopefully road force balanced right this time I.e rotating the tires on the rim to bring the road force down a bit. Will keep you guys posted! Any input on other possibilities of the shimmy are greatly appreciated!

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