i bought the treats "budget" crank, i believe it is made by DMP.
as you'll see in these (probably wayy to big) pictures, the holes in the circular parts of the crankshaft are WAY to close to the edge of the circle. you can see how weak it must be at these points, it almost looks like it flattens out because of how close it is.
just check it out and tell me what you think. is this going to break apart as soon as it gets hot and wreak havoc on my engine insides?
and
I've never seen one of those budget cranks, but that does look a little like a manufacturing error. However, it doesn't seem like a problem to me as long as the crank is balanced, I don't suspect there is much load on that part of the crank, it is really more of a flywheel, right?
I wonder if those big holes are to compensate for a heavier than stock piston?
I got one and was wondering the same thing.
Hopefully someone can shed some more light.
grip it and rip it
it looks like really poor machining. are they all like this? i was going to order a couple. now i'm not so sure.
How much stress is actually going to that section of the crank?
I bought 2 of them and they were both like that.
are you running them brennan?
peter that is the best i've heard in a while
i say set it and forget it.
I've got one, works great...
think about it, how much weight load is on the crank webbing? Do you think your crank spins fast enough that it'll break right there?
That is ridiculous. Even if it does hold up...that's just poor quality.
No, good quality! These cranks are built, machined and balanced to be that way! The holes have to go all the way to the edge to lower the centrifugal force in the crank webbing (lightened). It's so the motor can spin up to rpm easier. It just looks weird because there's nothing in the holes (stuffed). Most people agree stuffed cranks don't offer enough performance benefit for the money anyway.
I'd love to see a crank that broke on the webbing from running on a moped.
I've been known to do unseen shit with moped parts.
Sealed my case yesterday, we'll see what happens! Hah.
isnt that just how they balance it from the factory? that would be my guess. it does look pretty flimsy tho. oh well, i guess youll find out.
I am putting a Metrakit on my Puch right now... is it worth getting a aftermarket crankshaft ?? I already have the case apart because im replacing seals bearings & case matching.
Just curious what people think.
yes. small end needle bearing instead of brass bushing = longer life.
yeah, you've got no worries on that, steel melts at way higher temps than you're ever gonna get in your case, even if you get remotely close to that temp you're aluminum piston would be so melted it would have blown completely outa your exhaust port, and cyntrifical force is only stronger enough to break apart a rim shape like that it there's something attached to it at it's weakest spot, on that crank it's only the mass of that thin slip of metal pulling on it so there's no way it's even gonna bow in the slightest, i'll bet even if you heated that up cherry red and spun it at full rpm it wouldn't even budge
I think it will be fine. Iv'e made things worse than that and it held up. there is not much load on that area anyway. and for the kit question, i think it would make a huge difference because these kits use larger, big bore pistons. I think a new performance crank is needed to counter balance the weight of it. and because of this, i think the holes are supposed to be like that. I will be fine. Say super ultra mega fast rpm 5 times fast :)
Man, where were those two, very reassuring posts three weeks ago when I made this thread? jokes, jokes. thanks hippy.
i installed the crank pictured above and rode it all of bombourbon run, some 100 or so miles round trip, plus to and from work most days since the beginning of november. its working great.
do you know anyone with the stuffed version? did it make a difference?
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