Custom Crankshafts ?

[Rdyno]

So...they spin the crank up on whatever device they have and then merely add or subtract with these bobs based on the paired weights of the pistons/rods/hardware ?

No a lighter bob means you need to lighten the counterweight a heavier bob means you need to add to the counterweight.

[10sec rx7]

Custom Crankshafts ?

When the counter weight is heavy they drill to lighten when they are light they add metal slugs called Mallory like this

[Motherfucker Jones]

The bob weights are the equivalent weight of your rod/piston combo that gets clamped onto your rod journal for spinning up on the balancer. Material is then added or subtracted from the counterweights of the actual crank for balance. Drilling to remove weight or welding in (heavier than steel) Mallory metal slugs

[Motherfucker Jones]

I'm a slow cunt lol

[Motherfucker Jones]

And if they add the Mallory perpendicular to the crank rather than parallel, run like fuck coz it's sawing your block in half if it ever comes out lol

[333pg333]

Thanks for all the pics. Instructional.

I have this concept that it would be best to go with someone that can build the rods, pistons and crankshaft all in house. Might be being a bit extreme as not all manufacturers seem to do this. That's why I was wondering if anyone had heard of those guys in Melbourne but doesn't seem like too many people know about them. http://www.pureperformancemotorsport.com/ Now their website doesn't seem to come up properly when I click into them. Same thing happened when I mentioned PAR. Do I have a curse....?

[Kris]

Does Crankshaft Rebuilders offer balancing services for motorcycle engines?

[ZammoTheCockroach]

oooh so much porn in here

[dave1600]

Question for the gurus here - what advantage does using the "bobs weights" give you ?

I'm aware of the balance factor for stuff that isn't "naturally balanced" (my uncle taught me all about that when we were rebuilding a single cylinder vintage bike engine and the new piston was considerably heavier than the old one), but for, say, a 4 cylinder crank what do the bobs do ? Assuming you get the weights for the rods / pistons matched, would you not be able to just balance the crank as-is without needing bobweights ? Or are the balancing machines good enough to balance at different places on the crank (ie ensure that although it is balanced, it isn't balanced "unevenly" (if that makes sense) - an example being pushbike pedals, they could be balanced as a whole but obviously each "side" is unbalanced.

[morerevsm3]

Thanks for all the pics. Instructional.

I have this concept that it would be best to go with someone that can build the rods, pistons and crankshaft all in house. Might be being a bit extreme as not all manufacturers seem to do this. That's why I was wondering if anyone had heard of those guys in Melbourne but doesn't seem like too many people know about them. http://www.pureperformancemotorsport.com/ Now their website doesn't seem to come up properly when I click into them. Same thing happened when I mentioned PAR. Do I have a curse....?

negative ghostrider has a BMW S38 4.2L stroker crank and rods from them, looks good but unused so far, Rob Braunes E30 has their rockers and driveshafts that are so far performing well

[chartreusehj]

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[333pg333]

So I was under the misguided idea that everything needed to be all balanced up together but of course everything needs to be balanced up independently. D'oh. Of course you need to be able to refit or replace parts without fear of throwing everything out of balance.

Thanks Morereves3. I spoke to Thomas this arvo and made some good initial inquiries. He's a bit cheaper than others at around $4k for the crank. I also want to improve on our stock bearings so need to do a bit more research to see what is available and what we can fit. Good learning curve.

[13bvw]

Thought this might interest some. Dave Butler races a VW beetle at Jamboree and he is currently making his own crank at home, he also make his own tooling. Billet VW Crank Roughing out #4 Journal: http://youtu.be/VldacGFecO4

Sent from my Nexus 5 using Tapatalk

[gxxr]

^^Seeing you drive a clubbie, this comes out of the Galloway, just after grinding to size and nitriding, also made "at home"....hated the sound of the interrupted cut on this one! Balanced out within a couple of grammes too.

Does Crankshaft Rebuilders offer balancing services for motorcycle engines?

Graham Wilkins should be able to do the job.

[BigMuz]

Nice one. What lathe do you have at home?