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Tvättbjörn
Samba Member
Joined: May 07, 2004
Posts: 1431
Location: SoCal
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 Posted: Sat Sep 08, 2007 7:52 pm Post subject: counter weights on cranks |
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| does anybody know if the companies are pre-heating crankshafts befor they weld the weights on?? |
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1432
Samba Member
Joined: October 08, 2006
Posts: 399
Location: so cal
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| Posted: Sun Sep 09, 2007 8:06 am Post subject: |
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| Very unlikely a preheating cycle, but tack welding at different points prior to finish welding I would think may put some preheat to offset stresses from cold shrink. If thats what your getting at. |
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GregZA
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Joined: August 25, 2005
Posts: 75
Location: South Africa
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| Posted: Sun Sep 09, 2007 8:35 am Post subject: |
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I don't know the answer to the original question, however I have a couple of questions myself:
How do they calculate the weight necessary for an effective counter weight.
What type of welding process is used, i.e. arc, submerged arc, mig, tig?
Sorry about the hijack... |
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nsracing
Samba Member
Joined: November 16, 2003
Posts: 9479
Location: NOVA
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| Posted: Sun Sep 09, 2007 9:22 am Post subject: |
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| GregZA wrote: |
I don't know the answer to the original question, however I have a couple of questions myself:
How do they calculate the weight necessary for an effective counter weight.
What type of welding process is used, i.e. arc, submerged arc, mig, tig?
Sorry about the hijack... |
That is a very interesting question. Who knows?
But adding counterweights do improve performance and longevity if properly balanced after.
The welding question is ..some companies actually do some pre-heating before full welding on the counterweights. I do not think they do post heating or heattreatment after.
The heat-affected-areas are on non-critical portions...outside of the rod journals and quite some distance. Unless you cook the hell out of it adding the counterweights with a TIG welder is a good question. |
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1432
Samba Member
Joined: October 08, 2006
Posts: 399
Location: so cal
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| Posted: Sun Sep 09, 2007 11:11 am Post subject: |
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| The earliest welded cwt cranks were developed by Bob Dickson out of San Diego in the late 60's and were originally sold thru Berg & Pauter. Being a pretty innovative engineer Bob developed his own formula for required amounts needed to offset rotating/reciprocating weights for use within a predetermined rpm range. It was initially designed for use in his super V programs and based on parts available for that time. The process was soon picked up by others and found a broader use in drag racing and offroad. All Berg & Pauter earlier versions were Tig welded, stress relieved & nitrided, no preheating was done, but stress relieve and nitriding operations, which are both heating cycles, were accomplished at completion as well as shotpeen and balancing. I have no idea if current manufactures use any type of formula for present day components. |
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Tvättbjörn
Samba Member
Joined: May 07, 2004
Posts: 1431
Location: SoCal
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| Posted: Sun Sep 09, 2007 3:03 pm Post subject: |
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| GregZA wrote: |
I don't know the answer to the original question, however I have a couple of questions myself:
How do they calculate the weight necessary for an effective counter weight.
What type of welding process is used, i.e. arc, submerged arc, mig, tig?
Sorry about the hijack... |
Good question. As an example. It looks like that the weights DeMello puts on are much bigger weights on compared to China cranks or DPR crankshafts. DPR work looks much cleaner compared to DeMello`s, As long as they stay within factory tolerances it really does not matter how they look, but a little bit cleaner work on DeMellos side would not hurt either. |
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