Broken motor mount..

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Train_Wreck

Train_Wreck

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Feb 9, 2015
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So I had something unfortunate happen yesterday. I had a motor mount bolt snap clean off the engine, it is now flush with the engine... It is the right hand bolt on the back motor mount (where the seat post tube is). I'm thinking that I need an extractor kit to get it out, which is something I am willing to do because I do not want to get a new engine. Any ideas on how I might do this? What size extractor piece will I need? What sized bolts go inside the engine? I was able to get one of the other engine bolts out just to prove to myself that its threaded inside, and to see that the bolts go into the engine about 8/10ths of an inch. any help would be awesome guys, hope I am able to fix it by the end of next week. Thanks

Igor, A.k.a Brian
 
bluegoatwoods

bluegoatwoods

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Jul 29, 2012
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Broken motor mount, huh? Sorry to hear it. That's the sort of thing that's pretty disappointing.

Replacing that stud won't be any trouble at all. A hardware store will have what you need.

One problem that I've had with extractors is getting a good grip on the head of the extractor. So you might ask the store people for advice there. Maybe it means buying a teeny, tiny wrench?

It's been a while since I've had to deal with such things. But I suppose it'll happen again sooner or later.
 
allen standley

allen standley

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Oct 22, 2011
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If you can - you need a dremel with a cut off wheel to cut a slot in the top of remaining stud (if broke off flush) and use a screw driver to un-screw it. It has worked for many of us.
 
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2door

2door

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allen standley said:
If you can - you need a dremel with a cut off wheel to cut a slot in the top of remaining stud (if broke off flush) and use a screw driver to un-screw it. It has worked for many of us.
Click to expand...
This method is the quickest and easiest. IF, you didn't use red Loctite on the stud.

You don't need studs and nuts. Most any hardware store should be able to provide Allen head cap screws. You'll need 6mm X 1 and you'll have to determine the length. Probably between 15 and 25 mm depending on your seat tube diameter but possibly longer or shorter.

Tom
 
fatdaddy

fatdaddy

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Take the good stud with you to the hardware store and have the guy help you get the right size drill bit and easy out, You very carefully drill a hole EXACT center of the broken stud, Then the easy out will screw into the hole you drilled with a left handed twist and turn out the stud. This will probably not be your only broken stud so hang on to the drill bit and easy out for later use. The most common reason for broken studs is loose motor mounts, so make sure yer mounts are snug at all times. The dremel method works if the stud is not below the case surface. If it broke off deeper then the easy out is about the only way.
fatdaddy.usflg
 
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allen standley

allen standley

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Oct 22, 2011
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You very carefully drill a hole EXACT center of the broken stud

As a last resort only! Very scary... take the motor off the bike and use a punch before attempting this. Otherwise you can make a terrible mess for yourself if you fudge it. One chance to do it right. Been there done that. yeah and blew it...
 
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Train_Wreck

Train_Wreck

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2door said:
This method is the quickest and easiest. IF, you didn't use red Loctite on the stud.

You don't need studs and nuts. Most any hardware store should be able to provide Allen head cap screws. You'll need 6mm X 1 and you'll have to determine the length. Probably between 15 and 25 mm depending on your seat tube diameter but possibly longer or shorter.

Tom
Click to expand...
Yeah I was talking to my friend yeserday and he actually recommended the allen bolts. Any particular advantage over the normal threaded bolts and nuts? And the seat tube is about 1 inch, I have a basic road bike frame. And is there any way to make a notch in the stud to take it out without a dremel?

Thanks you guys
 
G

gokart25

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Sep 26, 2011
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Wow same thing happened to me 4 days ago..I did the dremel cut, and used flathead, to back it out. Lucky there was no lock tite on it.
 
fatdaddy

fatdaddy

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allen standley said:
You very carefully drill a hole EXACT center of the broken stud

As a last resort only! Very scary... take the motor off the bike and use a punch before attempting this. Otherwise you can make a terrible mess for yourself if you fudge it. One chance to do it right. Been there done that. yeah and blew it...
Click to expand...
Yeah allen, SORRY. I forgot to metion the punch. Ya GOTTA center punch it to stay center of the stud. I've tried to do it without a punch with disasterous results. Thanks for catching that bro.
fatdaddy.usflg
 
allen standley

allen standley

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Oct 22, 2011
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BOYGOFAST said:
Use the self tapping screws relocate the mounting block .
Click to expand...
Yes please do explain! you are gonna rely on hardened screws prone to breakage under variable stresses to replace bolts designed for the application at hand??? never heard of such a thing. Prove me wrong. Have you done this? I wouldn't trust that for 25 yards. Most of us avoid "The Highway to the Danger Zone"
 
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2door

2door

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In my opinion the advantages are the cap screws are usually grade 8.8, metric, and the threads are more precisoin than the kit studs. Also you'll only have one set of threads to worry about instead of two. Using an Allen wrench to tighten things will make it harder to overtighten them. (Unless you use a cheater.)

Some folks say that using bolts instead of nuts is better because you don't wear out threads after multiple assembly and disassembly. I guess that might be true, if, you're constantly taking things apart but I say, "do it right the first time and you shouldn't have to be taking things apart so often." :)

Tom
 
fatdaddy

fatdaddy

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allen standley said:
Yes please do explain! you are gonna rely on hardened screws prone to breakage under variable stresses to replace bolts designed for the application at hand??? never heard of such a thing. Prove me wrong. Have you done this? I wouldn't trust that for 25 yards. Most of us avoid "The Highway to the Danger Zone"
Click to expand...

Sounds like he's suggesting that you move up (or down ) the block mount position, drill new holes and use self tapping screws. HUH!!! It's a lot less work to just replace the broken stud with a better grade stud.
fatdaddy.usflg
 
Train_Wreck

Train_Wreck

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Soo, the problem is fixed. Decided to go with the speedout extractor kit, worked very nicely. Replaced all the bolts while I was at it because I overtightened the ones I had in there to begin with and they bent a little. Used the same nuts with the lock washers and all that, put some old innertube between the frame and the bracket to reduce some vibration. I did not go with the allen bolts unfortunately, but I made sure not to overtighten. Used blue loctite on the first nut, then put a locknut on with more locktite so now there are 2 nuts per bolt (no pun intended). I dont think this thing is goin anywhere anytime soon, but I will be sure to check my bolts ever so often to make sure this whole thing doesn't happen again.

Thanks for all your help guys, I was really bummed yesterday but now I know its gonna work, just have to let the loctite cure for a day.
PS I highly recommend the speed out extractor kit, it only took me a few seconds to get it out, the rest is history... dance1
 
2door

2door

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Get rid of the rubber. It won't reduce vibrations but it will allow the vibes to be transferred to the metal parts of the mount and fasteners. It will cause fastener failure and more vibrations than you have now.

This subject has been discussed and thrashed over on the forum for years and any experienced builder will tell you to mount the engine solid to the frame, metal to metal with no rubber or resilient material between the engine, mounts and frame.

Good luck and glad you got that broken stud out. We always suggest using a torque wrench. Those 6mm fasteners should only be tightened to about 60 inch pounds. That isn't much when you're pulling on a wrench. Be careful.

Tom
 
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