View Full Version : Chains vs. belts vs. shafts
06-10-2008, 03:45 PM
I've been wondering, what are the pros and cons for belts and chains in regards to motorcycle drives and car cams? (and shafts in the case of the former)
I know what the pros and cons are for gears in relation to cams (noisy, expensive, not suited to OHC engines...)
06-10-2008, 04:13 PM
Chains are heavier and noisier than belts in an engine but they rarely, if ever, break. Belts are lighter so they lower rotating mass in the engine and they are also quieter. The only downside to this is the added maintenance of replacing the belt periodically. On some engines, if the belt breaks while the engine is running it could cause catastrophic damage to the valvetrain or even the pistons.
On motorcycles, a chain drive system is much simpler and lighter and also delivers more power to the wheel. Shaft drive is more complex, heavier and of course more expensive. About the only real benefit to shaft drive is that they require less maintenance, a lot less, and they are a bit smoother.
Belt drive is great unless it breaks...then you are screwed. Chains are much stronger than belts.
06-10-2008, 10:12 PM
Motorcycle secondary drive:
Chain: Cheap. Strong. Relatively light. Needs lubrication periodically. Can be dirtier than other types due to throwing oil when freshly lubed. A little noisier than belts. Needs adjustment periodically.
Belt: Maintenance free. Lightest. Not as dirty as chains. Needs to be replaced more frequently than chains.
Shaft: Almost maintenance free (lube needs changed, but at much longer intervals than for a chain), never needs adjustment or replacement. Most reliable. Expensive to engineer. Does not absorb vibrations. Can be prone to "shaft jacking" where acceleration or deceleration resistance from the shaft causes additional suspension movement.
For cam drive:
Chain: Much longer life than belts (300,000+ miles). Noisier. Requires a constant supply of lubrication.
Belt: Cheapest to design because it does not require an oil supply. Least noise. Absorbs vibration the most.
Gear: Essentially infinite lifespan. Most expensive to design. Heaviest. Transmits the most shock to the valvetrain. Noisiest. Can accomodate OHC, but that makes it an even heavier setup. Takes up the most space.
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