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General Information => General => Topic started by: the4ork on August 03, 2007, 12:04:53 pm

Title: how much to knife edge and balance a crank?
Post by: the4ork on August 03, 2007, 12:04:53 pm
want to get my crank knife edged and balanced... how much does that typically run?
Title: Re: how much to knife edge and balance a crank?
Post by: Kudagra on August 03, 2007, 02:04:29 pm
Quote from: "the4ork"
want to get my crank knife edged and balanced... how much does that typically run?


Really depends on the shop. Best to call around. You know when you balance your crank shaft you will need the entire rotating assembly (flywheel, pressure plate, crank, rods, pistons, front pulleys.) Atleast to do it correctly.

Give me a few weeks and Ill let you know what the local guy here is charging me.

Cept I need to get my flywheel and clutch kit from Dave at Pass. perf.
Title: Re: how much to knife edge and balance a crank?
Post by: subsonic on August 03, 2007, 06:12:25 pm
Quote from: "Kudagra"
Quote from: "the4ork"
want to get my crank knife edged and balanced... how much does that typically run?


Really depends on the shop. Best to call around. You know when you balance your crank shaft you will need the entire rotating assembly (flywheel, pressure plate, crank, rods, pistons, front pulleys.) Atleast to do it correctly.

Give me a few weeks and Ill let you know what the local guy here is charging me.

Cept I need to get my flywheel and clutch kit from Dave at Pass. perf.


Dude, your going with the knife edge :shock: .  I have read here that doing that will increase your shake enjoyment way up the loose teeth level.
Title: Re: how much to knife edge and balance a crank?
Post by: Kudagra on August 03, 2007, 06:54:03 pm
Quote from: "subsonic"

Dude, your going with the knife edge :shock: .  I have read here that doing that will increase your shake enjoyment way up the loose teeth level.


Personally Im just going to have my stuff balanced. I dont think Im going to see RPMs that warrent the cost. Besides...you dont even gain that much. Im not worried by maybe 1 hp loss.
Title: Re: how much to knife edge and balance a crank?
Post by: Mark(The Miser)UK on August 03, 2007, 07:35:37 pm
Quote from: "Kudagra"
Quote from: "the4ork"
want to get my crank knife edged and balanced... how much does that typically run?


Really depends on the shop. Best to call around. You know when you balance your crank shaft you will need the entire rotating assembly (flywheel, pressure plate, crank, rods, pistons, front pulleys.) Atleast to do it correctly.

Give me a few weeks and Ill let you know what the local guy here is charging me.

Cept I need to get my flywheel and clutch kit from Dave at Pass. perf.


Do you mean it's all bolted together and spun? Nah; I've just visualised a flailing machine :o) You must mean match each piston/ con rod and separately balance the bare crank with the flywheel attached and pulley attached.... I've got some ancient books floating around which gives the details of balancing steam engines in trains. IIRC you cannot balance a reciprocating engine.... Makes sense really thinking about it. No lump on a crank will match the  changing momentum of a  piston. Having said that I feel an invention coming on... What about a flat 4 for instance that had quite thin conrods and so almost opposite each other with large diameter narrow bearings arranged so that opposite pistons fling out at  the same time and fire at the same time effectively 2 parallel syncronised 2 cylinder engines... :roll:
Title: how much to knife edge and balance a crank?
Post by: Kudagra on August 03, 2007, 09:23:18 pm
you wouldnt want opposite sides of the flat 4 firing at the exact same time...it would lock up and probably break something.

Yea they balance all the rods/pistons and stuff then they attach bobweights to the crank and spin that and balance it. It looks wicked but its just bobweights spinning and not pistons. I really hope not...Ive spent some money getting those pistons coated.

(http://www.golenengineservice.com/assets/images/a1_13.jpg)

Quote
The crank is balanced with the rotating assembly by first weighing the connecting rods, pistons, wrist pins, rings and locks then constructing bob weights filled with metal shot to mock them. The four sets of bobweights are then placed onto the crank, alternating at 90 degrees.
It is then spun on a dual plane balancer, which measures where and how far out of balance the crank is.


http://www.golenengineservice.com/html/gmhtp_1c.html


If I could get some cheap extrude honing Id get the G60 intake worked over
Title: how much to knife edge and balance a crank?
Post by: Mark(The Miser)UK on August 03, 2007, 10:12:48 pm
Quote from: "Kudagra"
you wouldnt want opposite sides of the flat 4 firing at the exact same time...it would lock up and probably break something.



Yea perhaps you're right... ah well back to the harmonic vibrations :D
Title: Re: how much to knife edge and balance a crank?
Post by: hillfolk'r on August 04, 2007, 01:19:57 am
Quote from: "subsonic"
Quote from: "Kudagra"
Quote from: "the4ork"
want to get my crank knife edged and balanced... how much does that typically run?


Really depends on the shop. Best to call around. You know when you balance your crank shaft you will need the entire rotating assembly (flywheel, pressure plate, crank, rods, pistons, front pulleys.) Atleast to do it correctly.

Give me a few weeks and Ill let you know what the local guy here is charging me.

Cept I need to get my flywheel and clutch kit from Dave at Pass. perf.


Dude, your going with the knife edge :shock: .  I have read here that doing that will increase your shake enjoyment way up the loose teeth level.










um,yea
the engine shop i used to work at???
i used to take every word from the race engine builder dude like gospel
he said: itll be hard (read: pretty much impossible)to knife edge  a crank and get it in balance using stock rods+pistons(weight wise)
without using mallory(heavy) metal slugs welded/pressed in  to get it back in spec
Title: how much to knife edge and balance a crank?
Post by: Slave2School on August 04, 2007, 07:06:24 pm
What exactly is knife edging?  pardon my ignorance!

If you guys are looking for insane rods kerma has some listed on tdiclub for 800/set, not sure if they would fit a TD, they are intended for tdi's.  Supposed to take all you can throw at them except perhaps...incompressible fluids.
Title: how much to knife edge and balance a crank?
Post by: clbanman on August 05, 2007, 04:28:45 pm
I personally think you would gain more for the money with a well designed windage tray instead of the knife edging.  As mentioned previously, I don't believe you could do it without heavy metal slugs to replace the weight of the material removed.