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Old 04-05-2009, 06:14 PM   #1
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Default crank drilling

I was curious as to the drilling of the crank shaft? why, how much, and then fill with epoxy?ramped? save weight? timing? How do you go about doing it?
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Old 04-05-2009, 06:19 PM   #2
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Dude thats a whole world of knowlege needed to get into that, by all means go for it. Someone out there should open up an online RC engine modifying school LOL.
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Old 04-05-2009, 07:24 PM   #3
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Quote:
Originally Posted by bigmatt View Post
I was curious as to the drilling of the crank shaft? why, how much, and then fill with epoxy?ramped? save weight? timing? How do you go about doing it?
Seriously, I wouldn't try it if you haven't done it before. leave it to a pro, or atleast take apart one done by a pro to see how it was done. but you need alot of tools to do it properly, drilling a crank with no prior knoledge can throw the balance off and cause more problems. Your car would shake off your starter box, but that would be the least of your problems.
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Old 04-05-2009, 07:36 PM   #4
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I was not going to try, just wanted to know the reasons why it was done.
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Old 04-05-2009, 08:43 PM   #5
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you drill out the bore of the crank, to remove weight, the putty is used to bring the crankshaft volume back to normal. Putty is not the only thing used also, anything lighter than steel will work.
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Old 04-06-2009, 02:08 AM   #6
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Mr. Bridge, Mr. Willams, hola Maxi, Mr. Houston, I think this one's for you.

Last edited by The Working Man; 04-06-2009 at 02:31 AM.
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Old 04-06-2009, 04:55 AM   #7
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You can't just randomly drill or you'll throw the crank out of balance...

You also have to know what you're looking for. Meaning if you don't know why you'd want to drill and epoxy fill then you shouldn't do it. There is a reason for this and what the motor mod'er is trying to accomplish.

In general if you aren't removing material to balance the crank and are instead trying to "lighten" the crank, you'll reduce mass which means the motor will spin faster, which means you'll have less torque, and if you aren't careful it will rev so much higher to the point where you'll blow a rod...

Modding a motor isn't just taking a dremel to a motor and look at the work others have done and replicate it...

In my motor modding biz, I used a computer to model first, then started working on motors. I did alot of R&D before I came up with my final mods. I've got a stack of toasted motors from when I first started....
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Old 04-07-2009, 03:51 PM   #8
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you can't "drill" a crank... show me a drill that will work on a crank shaft, I want to see that!

too many people mess with engines... in this day and age of modern day CNC and machining, if something isn't being done to your top level engine at the factory, it's bacause it doesn't work! lol

go put gas in your tank and have fun
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Old 04-07-2009, 04:01 PM   #9
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it can be done to increase bore of the crank intake shaft (more fuel less runtime), lighten the crank (btw , most all the new nova cranks are lightened and jp has been doing it for a while)to produce a quicker spooling engine . to do this properly you need access to people who have cnc lathes or manual lathes or cnc mills which cost money so it is not going to be cheap

happy motorin'
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there are much more minor "mods" that can be done to increase performance

pk has a good point
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Old 04-07-2009, 09:53 PM   #10
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Here's a pic of a crank I drilled and epoxy ramped. It's the new Go Titanium nitrided crank. Like Houston said they spool up faster and some high end motors come with it from the factory.

Rex

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Old 04-07-2009, 10:02 PM   #11
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so is that from a EB race prep (un modded) engine, i was under the understanding that the EB modded GO was the only one that had the coated crank, or does the race prep as well. are they selling the coated crank's seperate now.
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Old 04-07-2009, 10:10 PM   #12
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The Eb motor is the only Go motor you can buy with the hard crank. You can buy the crank seperate but I don't think too many are available yet.

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Old 04-12-2009, 02:59 PM   #13
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There is no problem drilling a crank. And you will not get it out of balance as a single sylinder engine is not in balance normaly. You have a balancing factor that modders use a lot of time getting right it is not difficult but it is time consuming and need a very good scale.

On some cranks it can be difficult to drill out because the "hole" in the crank is out of center ( some Novarossi engines ). You can use a smaller bore or if you have a lathe with a chuck you can adjust, you will be able to get the hole in the crank to me in center and the crank spinning slightly of of center, making drilling easy.

I can get drillbits witch can drill hardness of 64 vickers and that is harder than a steel file. You will ahve to get a lathe and you will also need to cool down the drillbit and crankshafts.

If it is really nessesary, i feel it is very good on the OS v-spec, but when you see the Losi guys always using steel flywheel, it makes me think i am vasting a lot of time..
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Old 04-12-2009, 03:09 PM   #14
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modding the crank may not make a noticeable difference, but if you start to run the entire drive train lightened up then you will notice the over all difference.
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Old 04-12-2009, 04:25 PM   #15
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I have done this to many cranks over the last few years... However IMO its not really worth the time and wear on my bits..Truth be told running a lightened crank offers very little to no real performance advantage in offroad racing.. In a all out drag motor where we are running a ultra light 2.5 lb car that spools to full RPM well under 2 seconds a lightened crankshaft can make a big difference...But in offroad racing the effect of the lightened crank will result in more violent wheelspin when the tires break traction, and under full traction the gains from the lightening will not be felt..In many cases most of todays engines make too much bottom end as it is, so running a lightened crank is only going to make things worse.... Sometimes when I bore a crank diameter I will use the filler to reduce the overall crankcase volume and milling the crank gives the filler a good place to seat into..... IMO there are much better way to modify an engine then milling and filling.....
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