Rubber Bushing on mounting brackets

Discussion in 'Performance Mods' started by Gimmick, Sep 6, 2007.

  1. Gimmick

    Gimmick Guest

    Vibration on these things is surreal, Ive had a bottom bracket come undone, everything not locktited come loose and more. So i thought, why not hollow a bit of space out of the mounting brackets and place a small flat rubber bushing in between the motor and frame. I scavenged some great rubber from our scrap bin at the railway, and Im ready to try that out, but then i read a post in here that described this as ill advised, any one experimented with this at all?
     

  2. StreetPlanes

    StreetPlanes Guest

    If you can get your hands on some urethane you might do better. Rubber slowly dissolves when exposed to gas or oil and rots from exposure to the sun. Urethane is used in high performance automotive bushings because it's not affected by oils and wears hundreds of times longer than rubber. A trip to the auto parts store might yield a bushing that could be cut into several smaller bushings.

    A concern of mine is leaving enough metal to keep the bolts from tearing out. Not being able to see your rig I can't be of much help there.
     
  3. Atriot

    Atriot Guest

    Try using skateboard truck bushings, they even come in different durometers of urathane.
     
  4. Gimmick

    Gimmick Guest

    I like the idea of usin urethane, but I guess what im trying to do is a thin layer between the bars and mounting brackets, but urethane would work there too, I just need to find thin strips.
     
  5. iRide Customs

    iRide Customs Member


    I used innertube on Brutus and it seemed to work okay. I didn't mount and run the engine without so I can compare the difference.

    I am experimenting with a rubber mount for the new iRide that has will have my Dax 70cc as a powerplant. Yes I am using rubber grommets and yes they will probably wear out quickly but they are only $.30 ea. and easy to replace. If it is a complete failure, I'll just have to figure something else out.

    Dan
     
  6. jdsidecar

    jdsidecar Guest

    Glazer supply has urethane

    My father owns a glass company. They use urethane strips for setting blocks. They come in several thickness. I took a 1/2" X 3/4" X 2 strip and made a mount. I will get some pics this weekend of the set up. It worked great. Any comercial glass company should have these and they should be cheap.
     
  7. Gimmick

    Gimmick Guest

    awesome advice, looks like ill be making a stop by City Glass today.
     
  8. davidsis

    davidsis Guest

    rubber bushings

    I used heater hose, and it dramaticaly reduced the vibrations. Still holding up strong on my bike and I have about 5 gal of gas through it, really it works great. Heater hose ya, know the one that goes on the radiator of your car just cut a c shape on each end of the clamp.
     
    Last edited by a moderator: Sep 7, 2007
  9. davidsis

    davidsis Guest

    Where did my picture go, having problems posting picture.
     
  10. DougC

    DougC Guest

    D*mn!
    I just ordered some vibration mounts from McMaster-Carr but I'll have to go around and look at the skateboard bushings.

    It's been my experience that general types of rubber (such as what innertubes and tires are made of) is basically ROCK HARD, compared to actual vibration-dampening materials.
    .....
    I had a mountain bike at one point (Girvin Pro-Flex) that used urethane bumbers as shock absorbers. After a number of years of no problems, the urethane bumpers turned partially to liquid while the bike was sitting inside a garden shed on a 100+F summer day. The bikes and parts were no longer being made, so I couldn't just go buy new bushings for it. Without good bushings the shocks sagged and the bike wasn't rideable at all, because the rear shock shaft (which ran all the way through the rear shock) would hit the rear tire, so I had to put something in there to use the bike at all.

    I tried a few different kinds of rubber in there, all of it felt rock-hard, with no "give" whatsoever. The best thing I found was I cut a bunch of "donuts" out of a knobby MTB tire and stacked them in there, but even that was almost rock-hard, it was nowhere near as soft as the original urethane bushings were.
    ~
     
  11. Gimmick

    Gimmick Guest

    well, i got some thin urethane from a mechanic friend of mine and placed it on the mounting brackets, but only on the ones outside the frame tubes ( in the clamps). I have not gotten up the nerve to remove metal from the motor side of the mounts in order to accomidate the bushing material...soon. However, i did notice some decrease in overall vibration levels...
     
  12. gauge

    gauge Guest

    also u can try putting insulating foam in the frame and the handle bars that helps also
     
  13. DougC

    DougC Guest

    I tried to use the vibration mounts I bought but couldn't figure out any way that I felt good about. The vibration mounts are really intended to be used only in compression and not tension or shear, and I couldn't find a way to mount them that would ensure that they'd not suffer any tension or shearing force.

    I've got a small sheet of 1/16" urethane from MMC and I'll use that in-between a few washers, and then a bolt going all the way through.
    ~
     
  14. during this week i noticed that the vibration increased. i'm suspecting it's because of the improper tension of the chain (as the sprocket isn't in the exact centre so the chain loosens and tights while turning) or the vibration can be coming from the engine 9which is not a good thing !!)
     
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