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  #1  
Old 28-07-17, 04:47
sprite sprite is offline
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BE Chain length and distance between sprockets

I'm building a zx12r powered open wheeler bec for track days (20 minute sessions) and the odd hillclimb. I've been told that the chain shouldn't be too short as it might overheat and that distance between centres of sprockets should be at least 300mm (12inches UK speak :-) to prevent chain slipping over teeth.
Sprockets are approx 18t frontage 56t rear. I have a distance between sprocket centres of approx 250mm but if required, with much hard work , could take it out another 50mm though would MUCH rather not. Your thoughts would be appreciated.
Thnkyou
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Old 28-07-17, 07:59
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Quote:
Originally Posted by sprite View Post
I'm building a zx12r powered open wheeler bec for track days (20 minute sessions) and the odd hillclimb. I've been told that the chain shouldn't be too short as it might overheat and that distance between centres of sprockets should be at least 300mm (12inches UK speak :-) to prevent chain slipping over teeth.
Sprockets are approx 18t frontage 56t rear. I have a distance between sprocket centres of approx 250mm but if required, with much hard work , could take it out another 50mm though would MUCH rather not. Your thoughts would be appreciated.
Thnkyou
I would say that's a load of rubbish. Depending on the car some are much closer than that and as an example I run 15/52 sprockets on mine. Just fit it where it works but make sure you get the correct ratio for what you want to do or at least leave enough room to change both at a later date.
I could well be wrong so am sure someone will be along to correct any mistakes
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Old 28-07-17, 08:00
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Sprocket spacing

Well, I'm sure there are some "Rules of thumb" with regards designing the perfect chain-drive setup, but my car gets away with this;

It's less than 18cm between centres. It does stretch chains, but never had one break, overheat or jump teeth - even with the tiny front sprocket I have to run.

Sure you'll be fine!
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Old 28-07-17, 08:08
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I would be more concerned about the driveshaft angle coming out of the diff.
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Old 28-07-17, 13:30
sprite sprite is offline
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Thanks for the input guys. Will stay as is. As for drive shaft angle, should be fairly straight if my calculations are correct.
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  #6  
Old 28-07-17, 20:40
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I ran a Hitech that had about an inch between the teeth of the front and rear sprocket. Then again they were 78" wheel base.
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Old 28-07-17, 20:45
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Originally Posted by SteveSlowboy View Post
Well, I'm sure there are some "Rules of thumb" with regards designing the perfect chain-drive setup, but my car gets away with this;

It's less than 18cm between centres. It does stretch chains, but never had one break, overheat or jump teeth - even with the tiny front sprocket I have to run.

Sure you'll be fine!
I'd forgotten how nice your car is Steve!
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Old 29-07-17, 01:00
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Forget it Nick I'm sure it's a car that money can't buy!
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Old 29-07-17, 18:22
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I'd forgotten how nice your car is Steve!
It sure is a superb car, beautiful design.
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Old 29-07-17, 20:06
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Originally Posted by Nick Skidmore View Post
I ran a Hitech that had about an inch between the teeth of the front and rear sprocket. Then again they were 78" wheel base.
Damn shame the engines don't have a clockwise output - you could use intermeshing gears!
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