OzVMX Forum
Clubroom => Tech Talk => Topic started by: Paul552 on August 16, 2015, 05:52:26 pm
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Thinking about building a crank pressing jig. Before I do does anyone have one they wanna sell
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You Can Buy them I will Get back to you Sooon !
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You Can Buy them I will Get back to you Sooon !
OK cool please let me know
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Applied racing do one,bloody exxy though,It would not be easy to make though I guess ;) http://appliedrace.com/shop/index.php?main_page=product_info&cPath=47&products_id=1919
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Thanks smed
That's why im gunna make one. At that price I might make 10 ;D
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Factor in $100 for a copper hammer as well. After your second crank you will realise paying $50 for a rebuild isn't a bad price
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Do you really need to use a jig? That thing is a lot of money
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One Japanese company who make aftermarket cranks have a simple feature for getting the initial true of a rebuilt crank very close.
At 180 degrees to the pin bore and about 15 mm in from the edge they drill an 8 or 10 mm hole through each half. This allows you to use a rod of the right diameter to hold alignment as you press.
Given that you are still going to have to true a crank that is carefully pressed, the alignment dowell holes could save a lot of mucking around if they are drilled before disassembly.
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Old timers used a steel ruler to line the flywheels up and a copper hammer , as mentioned , for the final adjustment.
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Old timers used a steel ruler to line the flywheels up and a copper hammer , as mentioned , for the final adjustment.
This must make me an "Old Timer", as that is how I was taught to do it, with the only difference being the uses of a lead hammer instead of a copper one. This probably makes me even older since lead has been "dangerous" for years.
CJ
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Press,Vee blocks, dial gauge and copper hammer .
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Press,Vee blocks, dial gauge and copper hammer .
Also you should use vernier or micrometer to measure overal width of crank shaft when pressed together other wise crankshaft may be too loose or too tight in cases when instaled
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4' high,2' round hardwood stump,use the other flywheels weight to shift alignment,(i'm talking real flywheels, not them pissy 2 smoke/gokart pizza cutter thingys :o),as you get close,press them closer together,& repeat,dial guages between centres ,or V blocks for finished dimensions (hopefully),it's a bitch those last couple thou's, ::),& yeah i like the steel ruler,& a scribed mark across the wheels for intial setup,& of course measure the distance the flywheels are apart,
with two stroke cranks if factory alignment/endfloat adjustment shims are present,i tend to delete,the tradeoffs giving the big end more "oil" clearance ,i'm talking 10-20 thou at the most, (ossa's mainly), works for me, :P
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One Japanese company who make aftermarket cranks have a simple feature for getting the initial true of a rebuilt crank very close.
At 180 degrees to the pin bore and about 15 mm in from the edge they drill an 8 or 10 mm hole through each half. This allows you to use a rod of the right diameter to hold alignment as you press.
Given that you are still going to have to true a crank that is carefully pressed, the alignment dowell holes could save a lot of mucking around if they are drilled before disassembly.
Drilling holes in your crank would upset the balance factor.
Also they would need to be accurately bored to be square to the crank and be a tight fit with the dowels otherwise you would still be spending considerable time with the copper mallet getting it right, just as easy with the old ruler.
With that jig above you would still need another jig to press the crank apart.