broken rear motor mount stud help!!!

Discussion in 'Frame Mounted Engines' started by 2fast4u, May 6, 2008.

  1. 2fast4u

    2fast4u New Member

    idk but somehow i managed to brake the rear motor mount stud clean off wat i need to no is how am i guna get the rest of the stud out of the engine any ideas

  2. turkeyssr

    turkeyssr Guest

    The only thing I can think of is drill it out and use a heli coil. I really have not had much success with 'easy outs' or similar methods to get those things out. You can try those first, but be prepared to use the helicoil.

  3. sparky

    sparky Active Member

  4. stude13

    stude13 Active Member

    take it to a welder, tack a bolt to it and remove
  5. azbill

    azbill Active Member

    take a dremel and cut a slot in the stud
    back it out with a screwdriver
    I have done this a few times successfully
  6. KiDD

    KiDD Member

    More Sad Times

    I was just riding home then heard this horrible metal on metal slapping sound. I get off and check the bike over and the rear left motor mount broke below the surface of the engine.... I read and

    I don't have a drill... but I do live next to a lot of auto shops. Do you think the welding a bit to the bolt and unscrewing it that way would hurt the aluminum?


    P.S. Why does oil leak out through the motor mount holes?
    Last edited: Jun 2, 2008
  7. sparky

    sparky Active Member

    I haven't been here so much, because my gearbox was messed up, so i had to ship it back & get another one.

    The day I got the gearbox, I went for a 15 mile ride away from home since I hadn't ridden in almost 3 weeks. On the ride home, the stud didn't break.... but the "female" part of the mount - where the stud fits into - broke!! I don't have a Sad Time engine, so it might sound a little weird to you. Anyway, I have no choice but to buy an entirely new engine & gearbox for $120, since the part of the block that broke is gonna cost me $50+ itself. And I'm tired of shipping parts there, waiting, & waiting some more.

    I had definitely tightened the bolts & had never had problems within 20 miles worth of riding, but with this new engine... I'm honestly going to be taking my own advice - replacing all bolts with Grade 8 bolts, replacing all gaskets, & putting blue Loc-Tite EVERYWHERE!! That prolly won't help you out, KiDD, but hopefully it will help someone out.

    RATRODER Guest

    Shouldn't engine stuff be posted in the Frame-mount area? louis
  9. KiDD

    KiDD Member

    Well I called the local racing engine machine shop (which is just around the corner from me) and they said it would take about a half hour and cost me 25ish dollars. I borrowed a drill from work and will buy some small EZ outs tomorrow. I didn't loctite these studs in so I hope they will come out easy. Always try the cheapest option first. If that doesn't work I will go to the muffler/welding shop next door to my apartment and try the "tack a bit on and unscrew it with that" trick. I'm just afraid of damaging the threads, I don't want to have to buy a tap or helicoil it.
  10. fastboy9

    fastboy9 Member

    I just finished sorting this problem out. I didn't have a dremel to cut a notch in the end of the bolt, and couldnt get it out with a centre punch. So I drilled the bolt out, next I filled the whole with a really hard epoxy (same as JB Weld in USA) then tapped an M6 thread into the epoxy and this time put much stronger bolts into the rear mount. I wish I did this before I even mounted my engine, would have saved so much time. I brought the tap set off of eBay for a fiver and the epoxy I already had.
  11. GasKicker

    GasKicker Member

    I've broken several motor mount studs on my Huffy mountain bike. I've decided that the problem is that I cannot position the engine in such a way as to square both motor mounts to my bike's tubes. I'm just gonna pull the kit off and put it on a cruiser bike frame with a manufactured front mount. I haven't broken any studs on my cruisers.

    Anyway, getting the broken stud out has been pretty simple.
    I use a 1/8" drill bit to drill a hole in the stud to a depth of about 1/8". I then take a #2 square head screwdriver bit and tap it in with a hammer. (The kind that inserts into a screwdriver handle). Then I use a 1/4" socket to extract the broken stud.

    Once, this didn't work because I had used loc-tite on the stud. I replaced the square head with a small flat head screwdriver bit. It came out easily then.

    I don't know about the oil coming out of the stud hole. I haven't experienced that on my Powerking 49cc engines.
    Last edited: Jun 3, 2008
  12. fastboy9

    fastboy9 Member

    When I drilled it out I found that the thread goes all the way through, right into the crank casing :-s. So thats probably where the oil is coming out from. I had my engine upside down when I was tapping it though so didnt notice.
  13. KiDD

    KiDD Member

    If I have to drill it out, would I have to take the engine apart and clean the metal fillings out since it does go all the way through?
  14. KiDD

    KiDD Member

    SUCCESS! $11.28 later I got the bolt out
  15. GasKicker

    GasKicker Member

    It's very satisfying once you see that broken stud moving in the right direction. Isn't it?
    For what it's worth, you should make sure the rear mount fits squarely against the down tube when yoou put the motor back on in order to avoid future stud failures.
    I also try to dampen the shock force by putting a small piece (2-3 mm) of fuel line between the mounting nut and the metal mounting strap. The theory sounds good.
    Good luck!
  16. KiDD

    KiDD Member

    That is why it broke, it wasn't flush when mounted. I'm going to file it down till it is perfect.

    Also I am going to replace the studs... again.... with this steel of known high quality as to avoid any future headaches (hopefully)

    I went over to Mike Simpson's place the other day to pick up some gaskets for the job.