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Engine braking would be about 1/100 the force seen from an actual brake, unless it was a meth head teenager TRYING to break something. Sprotors are like power,power,power, brake, brake, brake, repeat until the bolts come loose. Smart riders know that motors cost more than brake pads, and ride accordingly, anyway. When I "engine brake" it's because I am not going to slow down beyond the bottom of the gear I'm already in, and only need a tiny bit of slowing. I certainly don't haul my bike down from speed by slamming down through the gears!
 

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It was the Perewitz vs. Yaffe, Yaffe built a decent bike and Perewitz built an easter egg. He thought that it was because he took some extra material out of the center of it for looks. Looked the same as yours, Now im thinking it failed then exploded.
 

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Mine only came loose on shakedown run after mochup ( no loctite). After full assembly it never did again. 130hp, 130mph and at least 6k or so.. The bike was run on the dragstrip a couple times. Every bolt was still locked in place under inspection before I sold it a couple months ago. Just to be fair, i replaced the button heads with 5 point grade 8 fasteners with crush washers ,red loctite. anything can be made to stay in place. Saftey wire even ???
 

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Had that happen an hour ago with my pm setup, bolt backed out and locked up rear brake as I was pulling in driveway after my maiden voyage. I would believe from my experience this evening that it was user error for not using enough or any loctite on the sprocket bolts becasue thats what mine would have looked like in another few revolutions if i hadnt pulled in the driveway. Thinking ill safety wire mine or use longer bolts w nuts on back sides and safety wire and of course mucho loctite
 

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I believe that using one disc as a sprocket and a rotor causes the bolts to come loose eventually, regardless of installation technique. With a conventional rotor or sprocket the bolts are pushed in one direction only. With sprotors, they get pushed one way for braking and the other way for drive through the sprocket. This is what causes EVERYONE who runs them to have them loosen up.

Now, you can double up on the loctite, chase and clean your threads, do what ever you want and all you've done is push it out further into the future, but it WILL come loose sometime. A standard rotor or sprocket can installed such that it will NEVER come loose, a sprotor cannot, IMO.
I think you need to back up a bit before you post multiple posts badmouthing a product. Large mud trucks and custom hot rods use pinion mounted brakes on the differentials that get used in forward, reverse, and put under stress loads the worlds most powerful motorcycle will never see. I have never seen one of the bolts securing those back off. This was not a product failure, a bolt came loose and tore shit up. If your theory was correct, bolts holding in driveshafts would be falling out of cars everywhere causing worldwide panic and killing the human species. Only the amish would survive. Maybe the sprotor is not a good idea to everyone, but routine maitnance and general looking over the bike once in a while would catch this before this destruction took place. Sprocket and rotor bolts coming loose in harleys is nothing new either. It happens when people do not use locktite or a torque wrench. It is also not a bad idea to install 6 point hex bolts, drill, and safety wire them when the application permits. And remember, lock tite doesn't do shit if you do not properly clean the grease and oil from the threads first.
 

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It is also not a bad idea to install 6 point hex bolts, drill, and safety wire them when the application permits. And remember, lock tite doesn't do shit if you do not properly clean the grease and oil from the threads first.
i just saw this problem happen first hand (bolts backing out then machining the bracket in half).
You can't use safety wire because the supplied bolts are flathead hex, thus flush against the rotor.
 

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if possible...try nord locks...if they will fit ...I just repaired a hawg halter brand sprotor..the bolts backed out and acted like a lathe(poor quality lathe) and left less than .250 worth of material on the sprotor mount..the repair turned out fine..and the sprotor is back in service...hope you get it resolved..
 

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I've been in this industry a long time (since long before there were sprotors). I'm only saying what I'm saying because I've seen so many cut loose. Hell, just on this thread EVERYONE had the bolts come loose! If you want to equate that to pinion brakes on whatchamacallits, I lack the first hand knowledge to dispute you. What I DO know is that almost every sprotor will loosen at some point. I had one come loose with immaculate clean threads and GREEN loctite! Granted, it was a big motor and a huge back wheel, but it came loose.

I have yet to see one that did NOT come loose at one point or another. If you talk to everyone you see with one, they either have not been run long or they came loose, period. If these things worked well, I'd run one and recommend them. I fixed a dozen of them personally. That alone tells me there's a problem. I haven't even had to replace half that many Crane Hi-4 ignitions, and they have been out twice as long and I've installed a hundred of them (vs maybe 6 sprotors)! I speak from experience.


If you must run one, I'd recommend taking the bolts out once every 6 months and cleaning and re-loctiting them. Maybe even more often than that (I know I'd do it if I ran one every thousand miles!) Personally, I warn my customers about the fact that these things loosen bolts and only install them if the customer insists. That is what a responsible mechanic does when faced with this kind of track record. So... NO I will not retract my statements and in fact add to them. Run these things at your own peril!
 

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Nord-Lock is a brand of lock washers..check out the web site..I really like the product...I've yet to have one back out...and....instead of using loctite..you can put anti-seize on the bolt during final assembly..
 

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Besides that,automotive pinion bakes are used in forward 90 percent of the time, AND have totally different mounting hardware schemes. Sprotors are like: power,power,power, brake,brake,brake, repeat until they loosen. They are CONSTANTLY being pushed to and fro by a brutal twin motor that beats up everything it needs to run. A hundred and fifty horsepower jap bike's clutch would be pounded to death in a week behind a 60 horsepower Harley.

Can you tell I'm opinionated and obstinate?
 

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is the taper on the bolts used to hold the assembly together the same as the taper on the sproter ? if the tapers are not an exact match the bolt "rocks" at the upper point at which it leaves the threaded hub , this lets the sproter move and works the bolts out or breaks them off
 
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