Cb750 rotor stuck

Finnigan

Finnigan

Over 1,000 Posts
Trying to get the rotor off a ruined 750 crank. Got a gear puller, tightened the bolt with a long wrench and hit it with a hammer. Did this several times and she won't budge, here's my setup. Am I missing something?

Thanks all
 

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I actually watched that video....interesting man but useful information. Tried following it best I could but darn thing keeps laughing at me
 
Is it threaded inside?
I know most of my hondas have internal threads that you screw a M16 fine thread bolt into and hit it with an impact wrench and it pops right off.

The puller should work though. Use an impact wrench on the puller nut, its the quick smacking action that breaks it loose.
If you don't have one, use a box end wrench and a hammer.
 
My spare crank shows the threads are on the inside of the crank shaft, i'm using the loosened bolt as an anchor point for the puller. I double checked to make sure I wasnt just compressing the rotor onto itself ::)

I'll keep bashing it and see if it breaks loose
 
the puller threads into threads cut in the rotor and then presses against the crank

but the puller you have will get it off you just need to rap on the end of the puller once you have it under tension look at the vid
 
here is the puller

http://www.ebay.com/itm/NEW-HONDA-1969-1982-CB750-K-FLYWHEEL-PULLER-MALE-BOLT-18-X-1-5-CB750K-69-70-71-/141008268596?pt=Motorcycles_Parts_Accessories&fits=Model%3ACB750&hash=item20d4bf6d34&vxp=mtr
 
Why am I thinking the rear axle screws into the rotor and used as a puller? ::)
Might be wrong but think I remembered that from somewhere...
 
it will fit but it will scar both the crank and the end of the axle

i would only do it if i had a spare old axle

i would by a bolt from somewhere and use that

fastenall could get one overnight ect
 
Repeated several times with a small sledge, almost jumped off the crank but I still had to hit it pretty hard. Thanks guys
 
That must have been a relief.

Smarter people than me designed it, but I don't get why rotors need to be such a pain to pull. Is it the weight of the rotor that requires it to be so solidly mounted to the crank? Lot of other heavy assemblies spin at the same or similar RPM (clutch basket springs to mind) but simply slide on. Is it because the rotor is a 'consumable' and therefore they don't want to invest in complex machining to have a secure mount that is also easy to remove like the gears on the transmission as another example?
 
Thats a good point, i always just thought that such a large amount of weight required that much force to break the static friction of being pressed on. Either way its a PITA
 
as an engineer i have often thought that what happens is the retainer bolt provides inward tension (tightening)

and constant low level heating and cooling causes expansion and contraction

that must tighten it on the taper over time

JMO
 
cxman said:
as an engineer i have often thought that what happens is the retainer bolt provides inward tension (tightening)

and constant low level heating and cooling causes expansion and contraction

that must tighten it on the taper over time

JMO
Click to expand...
surely as an engineer you know that the crankshaft expands at excactly the same rate as the flywheel ? it is a very close to a self holding taper, that is what it is called in engineer speak,only a narrow range of tapers fits this description
 
Tim said:
That must have been a relief.

Smarter people than me designed it, but I don't get why rotors need to be such a pain to pull. Is it the weight of the rotor that requires it to be so solidly mounted to the crank? Lot of other heavy assemblies spin at the same or similar RPM (clutch basket springs to mind) but simply slide on. Is it because the rotor is a 'consumable' and therefore they don't want to invest in complex machining to have a secure mount that is also easy to remove like the gears on the transmission as another example?
Click to expand...
with a proper puller they come right off no issues
it is designed to be securely attached for years of continuous service and taper fits the bill nicely
 
the rotor when charging and under full load runs hotter than the crank end sometimes by as much as 30 degrees warmer

while running and may not equalize till hot soak

so it could be slightly expanded and over time tighten due to tension

as the rotor tightens onto the crank over time i would suspect i am correct

and it would be a easy thing to test i will see if i can find any data on it as i am sure its been done before
 
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