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Thread: Front End Shimmy

  1. #1
    Join Date
    Aug 2010
    Location
    Dayton, NV
    Posts
    18

    Front End Shimmy

    Hi, all. This is my first post and want to say hi to everyone. Bought a Unique Cobra a month or so ago (#4279477) and have spent most of the time getting the bugs out of it (even though the previous owner said it was "perfect"). It has a Southern Automotive 406 in it and seems to run OK after I re-jetted it. I'm at 5500 feet just outside of Reno and the car came from Georga, near sea level. I do, though, need some advise. I've had all four wheels balanced (they were all off a little with one being way off) but I still have a front end shimmy at between 55 and 60 mph . Could it be alignment and not just balance? Any experience in this area would be appreciated. I'll attach photos when I learn how to do it.

  2. #2
    Join Date
    Jan 2003
    Location
    Gadsden, Al , USA.
    Posts
    1,543
    Welcome to the forum. More than likely it is a balance issue, you might have to put weights outside the wheel and not just on the inside, that is the only way to totally balance your wheel. You might want to check to see if the tires are flat spotted from sitting in one spot too long, this will also cause a shimmy.

    Alan

  3. #3
    Join Date
    Jan 2003
    Location
    Shepherdsville, KY, USA.
    Posts
    1,725

    Tires

    Could very well be the tires, even thought they balance up they may have excessive road force variance. See who has a balancer in your area that can check for road force variance. You can go to the the Hunter Mfg. Site and they will list where the machines are. Anything over 20-25 is really not exceptable on the steering tires (front).
    Rick
    427 S/C , 427 Side-oiler, 4 Speed Close Ratio Top Loader, 3:73 Gear
    #4279405

  4. #4
    Join Date
    Jan 2003
    Location
    Dacula, GA, USA.
    Posts
    450
    Scotty, it's likely the tires. I have a local shop do my alignment and balancing that is precise beyond the typical tire store. They've had to spin my new tires on the rims to get them to balance half way decently. They also spin the tires on the car after the machine balance to get the last little bit of vibration worked out. Makes a big difference.
    427SC, Torch Red / white stripes
    427 Windsor Stroker from Southern Automotive
    Delicious example of Beauty + Power.

  5. #5
    Join Date
    Aug 2010
    Location
    Dayton, NV
    Posts
    18

    Shimmy

    Thanks for the feedback guys. I had the balancing done at a shop in Carson City who used the good Hunter machine. They had to dismount, rotate the tire, and remount it before balaning the tire to get it into spec. May have to replace the tires to get rid of the vibration. Have BFG radial TAs on it now but, after doing some research, may buy some Yokohama Avid S/Ts (235x60x15/295x50x15, that is if I can find them. I heard they are no longer being produced but are still around. Any comments?

  6. #6
    Join Date
    Mar 2003
    Location
    Ridgecrest, CA, USA.
    Posts
    246
    Most of your problem is probably the BFG tires. I had two sets and it was impossible to keep them balanced. Switched to the Yokohamas about four years ago and they have been flawless but alas, they (Yokohama) are pretty much out of the 15 inch tire business for cars like ours. The selection of tires available is getting smaller and smaller.

  7. #7
    Join Date
    Dec 2007
    Location
    Southeast MS
    Posts
    331

    M/t

    Mickey Thompson is making tires in those sizes now. Local guy here bought their S/R Radial tires and loves em.

    http://www.mickeythompsontires.com/street.php

  8. #8
    Join Date
    Jul 2008
    Location
    Calgary
    Posts
    145
    Anybody running the Firestone Indy 500 tires? The consumers ratings seem to be better than most others.

    http://www.tirerack.com/tires/survey...ireSearch=true

  9. #9
    Join Date
    Nov 2003
    Location
    Mississippi Gulf Coast and Central Florida
    Posts
    2,153
    Tony ran the Firehawks for awhile... he'll pop in sooner or later to comment.
    Paul

    289 USRRC
    1964 289 5-bolt block
    Toploader and 3.31 rear

  10. #10
    Join Date
    Aug 2010
    Location
    Dayton, NV
    Posts
    18

    Tires

    Decided to bite the bullit and buy new tires to try to solve my shimmy problem. Just had a set of Cooper Cobra tires (245/60-15, 295/50-16) delivered to my door for $425. Heard that Cooper was out of the 295's and weren't planning on making any more for quite a while. Thought I better get a pair while they were still available. Anyone wanting the website, just ask. I'll have them mounted and balanced next spring. Have a nice winter guys. Scotty

  11. #11
    Join Date
    Apr 2005
    Location
    Newton, NJ, USA.
    Posts
    174

    Scotty - DO IT NOW

    My advice is Mount and Balance your new tires right away.
    I'm sure others have had this experience as well, but it's not uncommon to have brand new rubber that is so out of balance or defective that they cannot be balanced properly.
    Bought a brand new trailer (C rated tires) and two of the four needed so much weight my tire man said he wouldn't put that much weight on the rims to correct the wheel shake. Guess what - four new tires from same manufacture and it tracks straight as an arrow now. It happens.

  12. #12
    Join Date
    Dec 2004
    Location
    Prince Frederick, Maryland, USA.
    Posts
    1,561
    Quote Originally Posted by arrowdriver View Post
    Anybody running the Firestone Indy 500 tires? The consumers ratings seem to be better than most others.

    http://www.tirerack.com/tires/survey...ireSearch=true
    They are ok . A little shimmy at 60-70 range. Some auto crosses and they are now crap. Will not buy them again.

    We spend a lot of money on our cars so I say put some money in our tires. The big problem is no one makes a quality "street" tire for 15' RIMS. I am thinking of buying Avon DOT tires from Krause racing or Goodyear drag radials. Haven't heard any feedback in those yet. Heard guys running the Goodrich drag radials with great results. I am interested in the Mickey Thompson's SR but have not heard any feedback on them being run on a Cobra. Avons get great feedback from Cobra drivers. I have a set of Goodyear Billboards and they look great but are bias ply and until they are heated up are not very pleasant. I also have a set of Goodyear blue streak slicks. Awesome awesome awesome but they are racing slicks and are not good for everyday street driving. Very lightweight and absolutely no shimmy.
    Tony
    Unique 427 #4279480 Precision Engine Machine Company 427 s/o 483.47 stroker close ratio toploader 3.31 jag rear

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