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Am I screwed??

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Old 05-31-2011, 07:12 PM
  #1
szusa071
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Default Am I screwed??



This is my first time ever trying to start any type of nitro engine. Ive been having some trouble hand cranking it so today I picked up a electric starter and a aluminum spinner.

Somewhere in there I crossthreaded thespinner and whal laaa.....

Is there any fix? Can i get away with it like this or do I need to buy another crankshaft??

Also am I tightening thespinner enough cause when I use the electric starter it basically loosens the spinner, I think the inside of thespinner is stripped as well. Not sure though

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Old 05-31-2011, 08:06 PM
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Default RE: Am I screwed??

The crank is fine, that is only aluminum from the spinner, which can be removed. Best bet would be get a new spinner nut, clean the threads on the crank, some times the point of a pick or knife can free the aluminum. Be careful it may take some force. Best to use a die/tap. Are you useing the prop washer that came with the engine? if so you may still be in really good shape, its not looking like the threads are bad very deep. Use lock tight. Do not use the washer that came with the engine, the spinner nut is made to apply force on the prop where it is needed.
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Old 05-31-2011, 11:06 PM
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Hesco Racing
 
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Default RE: Am I screwed??

This is another question. Looking at the prop spinner it looks from the pic that the thread is very course. You sure it is the right thread?

I like to use a prop spinner with a loose nut and a bolt holding the spinner on. What you have there would loosen every time you start it as the thread is right hand thread and the prop spins left handed so every time you put the starter on it would loosen, or am I loosing my mind here. Righty tighty Lefty loosy Nope I think I'm right. That looks like a spinner from a electric motor.

Cobus
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Old 06-01-2011, 03:05 AM
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szusa071
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Default RE: Am I screwed??

Mr Gator, Iwas using the washer that came with the nut so Iguess as you say at least the threads arent damaged that far up. It may be hard to tell but where the threads looks like the aluminum is stuck between them, they do feel kind of rounded off to me, but Iwill try to give ita cleaning and hope it is as you say only from the nut.

So I shouldnt be using the washer at all? It should be the spinner nut butted against the prop is that correct?

Hesco, I will have to take a look at the thread pattern as you say, Im not 100% it is the correct spinner. Ipurchased it from the LHS where I purchased the engine so I just assumed he was giving me the correct nut. Would a cone be a better option? or willa spinner work fine? Id really not want to chance damaging anything further if indeed it is stripped on the crank.

Thanks for your replys, helps a ton.
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Old 06-01-2011, 06:57 AM
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Default RE: Am I screwed??

I've used those spinners a lot. As Mr. Cajon Gator said, do not use any washers with that spinner. You must also tighten it as tight as you can get it and then some. If it is not super tight it will keep coming loose. Also turn the prop clockwise till you feel compression, then put the starter against the cone. Then hit the switch. Try not to bump the starter cone against the spinner. Keep it tight against it till the engine starts and it should stay tight. Remember not to run the starter too long. The brushes on most of these starters are mounted in plastic and the plastic will melt if ran under load too long ruining the starter. Dennis
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Old 06-01-2011, 10:04 AM
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Default RE: Am I screwed??

Crankshaft threads on these engines are of a finer thread than most "standard" bolts you'll find at the hardware store. Example - standard 1/4" bolts come with come with coarser thread sizes - 12-20 threads per inch whereas the crankshaft threads on a lot of engines are 1/4" - 28, or 5/16" - 24 is another common crankshaft thread size. You just have to make sure the LHS gives you the right spinner/spinner nut for that engine. You can't ever assume they will give you the right parts - verify for yourself. I've ended up with wrong parts and not know it until I drive 20 miles back home.. Many spinner nuts have a list on the back of the package of the various popular engines and their respective crankshaft thread size.

Personally, I do not like using full spinners on my engines. The one I bought and tried was so poorly balanced I couldnt get it to run true. I bought spinner nuts instead. I have several aircraft engines from .40 up to .90ci and I have done the same thing on all of them to prevent the spinner nut from backing off. Locktite alone did not do the trick, so I now use the drive washer and nut that comes with the engine and tighten it up as you would normally. Then just put the spinner nut on after and snug it up against the regular nut. This has never come loose on me, and it will also prevent the engine from chucking the prop should it misfire and run in reverse. (I have had an engine chuck a prop using only the nut and washer that came with the engine and thankfully the engine just quit. If it keeps running after chucking a prop, it could mean bad things for your engine)

I suggest using the washer, nut, and a spinner nut. Many 4-stroke guys have to double nut their props because they come loose quite often.

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Old 06-01-2011, 06:49 PM
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What is disturbing is that the Aluminum spinner has damaged the so-called hardened steel thread of the crank shaft. Must be a Chinese ST engine.[:@]
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Old 06-02-2011, 10:33 AM
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Ok, so last night I went ahead and tried to use the spinner nut with the washer but because of the thickness of the washer I was worried there wasnt enough grip for the nut because of the 4 strippled threads on the crankshaft so Itried without the washer and it felt alot better on there. Im not sure what kind of options that gives me other than the way I have it set up now. I didnt try to run it yet but if all goes well I will give it a try tonight.

Im trying not to let my impatient nature get the best of me as I am so close to finally finishing the boat and getting anxious to run it. Dont want to throw it all away now by doing something stupid.

Thanks for the replys, always good to learn from others experiences.
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Old 06-02-2011, 11:05 PM
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Show us your boat and setup. Love pics

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Old 06-03-2011, 07:47 PM
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szusa071
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Here is the link to my build log if you havent come across it yet:

http://www.rcuniverse.com/forum/m_10387948/tm.htm

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