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broken bolt-air cleaner to carb
Found my oval air cleaner loose today, and think the bolt that holds it on to the carb snapped down in the threads. Has anyone had this happen? - can't figure out exactly why this would happen... Any thoughts how to safely get the broken off portion of the bolt out of the hole?
Could anyone tell me how deep/long the treads are down in a demon carb? Thanks, Nathan http://lh6.ggpht.com/_syhYSKBtXpg/S3...0/IMG_0037.JPG http://lh6.ggpht.com/_syhYSKBtXpg/S3...0/IMG_0039.JPG |
on a Demon they go all the way thru if its a 5/16 thread----take the carb off, base plate off and drill from bottom side--the drill will catch and run the bolt piece back out the top
or ---use a left hand drill bit and do it from the top but take the carb off anyway so no chips go into intake |
What JC said.
Consider replacing the bolt with a stud threaded on both ends. Wipe a bit of Loctite on the end that threads into the carb. This way the AC can be secured and removed with a simple wing nut. |
Whatever you do, seal off the venturis with tape before you do it. A simple drill and bolt remover might do it.
Does your Demon have the Idle-Eze screw under the AC bolt? |
Nathan, I wouldn't pull the carb off. If it was me, I would tape around the little boss area that the bolt is broken off in, and then put masking paper completely over the carb so that only the boss is peeking through the paper and it is totally taped off. Then I'd use an Easy-Out tool while I held the hose from the shop vac on it as well. Normally I would heat it up with a flame as well, but not on the carb.:rolleyes: We don't need you blowing your car up.
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That looks like red lock tite in there. You should probably apply heat before doing anything.
Removing the carb is so easy, I can't think of a good reason not to do it. Be carefull with the drill. The metal of the carb is softer than the bolt. That loos like a grade 8 bolt. If so, that's the reason you're in this pickle. Grade 8's are extremly strong in tension. But in situatuions like this, they can break. As your did. I usually use a piece of All Thread, and a nice nut on top. I'v never had the All thread break. |
I seriously doubt Nathan, or anyone, would be d-u-m-m enough to use any kind of Loctite on a bolt intended to be frequently removed. Maybe change that to "I would hope that..." :D
It's also possible that the bolt is Grade 8, but I doubt that's why it broke. The nut or bolt on an AC can be tightened down until the AC is a crushed ruin before you reach anything like the kind of strain the fastener would need to break. There's a huge amount of rubbery compression ahead of that, from the air filter between the housing plates. I'd say it's just a flawed bolt that took all the vibration it could. I'd second using a good piece of all-thread and a nice decorative nut - I use a chrome washer and a chrome acorn nut on my long oval. If I press down a little on the lid, I can tighten it plenty much just with fingers. An easy-out will likely pull the stub out with no problems. Steel bolt in cast aluminum = next to no retention torque to worry about. |
How can anyone tell if that is a a Grade 8 bolt:confused:
Looks like SS to me? |
It may or may not be a Grade 8, but I can see how Bob thinks it might be - It does have that slightly golden zinc-washed sheen. It might be just the photo, same as the apparent trace of red in the bolt hole.
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If you dont feel comfortable doing this repair yourself take it to a mechanic or machine shop and have them do it for you.....the cost will be minamul.....
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When you complete the repair on the bolt check the sealing of your air filter assembly, there appears to be a lot of dirt visable.
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First I would try a good, small diameter center punch. Tap it in a counter clockwise direction off center of the bolt. Keep taping every 90 degrees. You may get lucky in getting it out.
If you drill it watch so the drill does not walk off and destroy the carb threads. |
Quote:
I've made the mistake of using grade 8 bolts in places where they don't belong. Like the air cleaner. Or as part of a stand off. Over time the vibrations will cause the bolt to fracture due to lateral stress. Don't say it doesn't happen, I'v seen it/done it. Then you get a "light bulb" revelation. Switch to a 5 or all thread, and they never break. Just one of little things I'v learned over the years. Good decisions come from experiance. Experiance comes from bad decisions. |
I couldn't really tell, but if there is 5 or 6 threads left on top of the broken piece [at least the size of the diameter of the bolt] you could loctite a stud right on top of the broken piece. It will hold an air cleaner.
Lou |
Grade 8 Bolt
Our believe a grade 8 bolt has 6 lines or marks on the head of the bolt and the others have 3. Hope this helps
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You should feel Lucky, that same issue cost a friend with a BD a complete motor rebuild, a cam and a head.
It was a stud, it broke and went thru the motor. Dcel |
Springin
I had the same thing happen while installing a brand new Demon. I was installing a stud for later removal and cut-off. Once I had the stud sized to the proper length, I couldn't remove it. It siezed and broke, luckily for me, it broke about an inch above the carb and I was able to install a coupling nut to it for a new short bolt.
I wonder if Demons grab a stud a bit more than they should,,,,, maybe some lube or teflon is the answer. |
Car repair 101!
1. Take the carb off the engine, take no chance of dropping metal shavings into the manifold or carb. DRAIN ALL FUEL. Tip it upside down, actuate accelerator pumps to exhaust ALL fuel. Let it sit for a short while to evaporate. DRAIN ALL FUEL. 2. Look at the bolt, 3 marks = grade 5 use HSS drill bit, 5 marks = grade 8, use cobalt bit . Mental note to self "Did I use locktite???" If so you will probably need to use a little heat, hence the need to remove ALL fuel. 3. Obtain an "Easy Out" stud remover from the hardware store and drill the correctly sized hole in remaining part. Insert the tool into the drilled hole & twist. the tool will have LH twist on it so it tightens into the broken stud. It's that simple. 4. Use a stud instead of a bolt for replacement. |
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