Crank stuffing epoxy

does anybody have a good source for epoxy for stuffing a crank?

i would like to also know if you have actually done this.

i'm throwing together a sick a-3 right now and i cant be havin' big old chunks of epoxy flying off the crankshaft at 12k.

Re: Crank stuffing epoxy

I wouldn't trust any nonmechanical substance for that.

Re: Crank stuffing epoxy

i know the pros use some pink stuff, on ports and cranks... i've seen it in cylinders and heads before, but i dont know where to buy it... i think whats his name from ohio who races the mopeds.. uh ... xmopedracerx i think.. he said something about stuffing his cranks.

i might not do it now that the crank pin is owning my arbor press.

Re: Crank stuffing epoxy

I've heard of using cork to stuff a crank. It's relatively solid but extremely light weight. Whatever you use has to very light so it doesn't unbalance the crank. Heck, a regular cork from a wine bottle might fit perfectly. Then cut it off flush and expoxy over it. Or maybe use the new style synthetic corks they're using these days. Not sure if those are as light as natural cork though.

Re: Crank stuffing epoxy

this is a tomos crank... not quite the same. I will probably put at least a couple pins into the metal if i do end up doing it, or i might hold out for an engine in better shape and do the case reed induction.

Re: Crank stuffing epoxy

Are you sure it's not just Bondo? Auto body filler?

Re: Crank stuffing epoxy

yeah for sure, bondo wouldnt last past the first startup

Nylon & polyurethane

cranks are typically stuffed with a durable lightweight plastic with good compressibility. This is usually nylon, machined slightly oversized to fit the hole and then mechanically pressed into place. There is an epoxy, known as devcon-4 -which is kind of hard to find- that can be used inside a crankcase as a filler material. However, I know that JB Weld can be successfully used for this as well.

Re: Nylon & polyurethane

I have stuffed em with balsa wood and then JB Weld on the ends. The lightening holes are 1/2'' deep on a puch crank so I just double up 1/4" balsa. Glue and fill in with JB. I plugged a crack in the block of a 16-278A marine diesel once with Devcon and it went on to log many nautical miles w/o fail. JB is good for 600F.

Re: Nylon & polyurethane

sweet, jb weld i think will be the ticket. I might drill a bunch of holes in the thin part of the webs to lighten them more to account from the added weight of the epoxy.

Re: Nylon & polyurethane

the holes might also give it a better grip on the metal as well... like i said, i might do it after i blow this up and rebuild it.

Re: Nylon & polyurethane

if you dont rebalance the crank, be prepared to replace your crank bearings at much shorter intervals. there is a lot more precision to doing that PROPERLY than just finding something to "fill the holes"

Re: Nylon & polyurethane

Lance applewhite /

Sammy Sosa is good at corking.I think he uses something gray.Maybe google baseball bat corking?? :)

Re: Crank stuffing epoxy

Graham those pins for the crank are heat press fitted. you need to heat it up with a torch and then press it out. hope this helps. y did u split the crank anyway? bottom con rod bearing?

Re: Crank stuffing epoxy

ahh.... i've pressed the puch rods apart before, and it wasn't this hard... this crankshaft is pretty turbo rusted, but i'm basically building a shitbike loaner anyhow out of some junk i have laying around, so i'm not too worried about it going to hell.

the balance on stock crankshafts is really poor, adding epoxy and drilling holes wont make it noticeably different, because its so far off ideal already. if i do go the 'do it right' route with this engine at some point, it will involve pressing everything apart, possibly installing a puch needle bearing con-rod when my mop-shop order shows.

Re: Crank stuffing epoxy

jb weld does really poorly with gas over time.

Re: Crank stuffing epoxy

He is right, says so on the package.

Re: Crank stuffing epoxy

what about using it for the clutch pads. i redid my clutches with cork and made the friction pads full size on the shoes. i glued them with jb weld because i heard thats what people used for that upgrade. is this true? graham y are you whiching to a puch con rod/bearing? are they better or stronger? im debating on weather to split my cases again to do some more work i didn't know about when i did the previous rebuild

Re: Crank stuffing epoxy

I plugged my Garelli tank with bondo 2 years ago and it is still holding

Re: Crank stuffing epoxy

How about Great Stuff, lol. Just kidding. try talking to a good dirt bike speed shop. You know the ones that have a name like, so-and-so's racing. Not your Yami/Honda/Kawi shop.

Re: Crank stuffing epoxy

I dunno. Obviously you want to use the proper stuff, but! I've had a blob of JB Weld as filler inside my Vespa Racer's crankcase since 2003. I beat the crap out of that bike, and there have been no issues with the JB. Thus, in my experience JB works.

Re: Crank stuffing epoxy

thats the kinda thing i like to hear!

does anyone know if the con-rods swap from puch? I cant get the fucking thing out to measure it and i'm ordering a pile of puch con-rods from my buddy in germany.

the switch to a puch con-rod gets you a beefier rod with 12mm needle bearings, and in my case, it replaces the carbon-funked rusty ass needle bearings which i hope to not explode when i start pounding on it.

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