rubin Posted February 13, 2006 Share Posted February 13, 2006 just wondering, based on opinions, which you thought would be better for a street motor and a race motor? had a discussion with another mechanic and thought I'd get more opinions. im not going to even consider gears since this could only be done on ohv engines with the cam close to the crank my opinion is belt for racing and chain for street Ive read that belts use less friction, therefore are better for hp, but chains are obviously more reliable even though belts are getting pretty good now too. chains are also noisy but i guess it can be solved with proper insulation. I am confused why every honda I've seen uses belts but the s2000 (the most performance oriented) uses a chain Quote Link to comment Share on other sites More sharing options...
260DET Posted February 13, 2006 Share Posted February 13, 2006 I suspect that some Japanese cars are going from belt to chain for reliability and serviceability purposes. Interesting query, I've no real knowledge of it. Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted February 13, 2006 Share Posted February 13, 2006 http://www.datrats.com.au/LZ20B_VS_LZ18_3.JPG Gear drive for L20 and L18s. Not only do you have to consider friction, and reliability, but you have to consider error. Chains and belts will both have spongy drive of the cam from the crank, that is, the cam will be a little bit behind the crank while the crank is accellerating, and a little in front when it is decellerating. The L chain drive is well known for chain `slap' which is commonly touted as the primary limitation to high rpm. Some food for thought I guess. Dave Quote Link to comment Share on other sites More sharing options...
rubin Posted February 13, 2006 Author Share Posted February 13, 2006 very interesting gear drive setup, never seen something like that for ohc engines hows the noise? any special lubrication needed? friction loss? why dont more manufacturers use such setups? it would completely eliminate piston to valve damage for interference motors Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted February 13, 2006 Share Posted February 13, 2006 My guess is its noisy as hell. The LZ engines were race-only I believe so they don't care. Oh and it'd be a lot more expensive as well. Hehe. Dave Quote Link to comment Share on other sites More sharing options...
rubin Posted February 13, 2006 Author Share Posted February 13, 2006 true, also they must be heavy compared to belt/chain system and might rob some power ps. i just read my first post and i accidently said belts are noisy, i meant chains. i edited that out Quote Link to comment Share on other sites More sharing options...
desert dog Posted February 13, 2006 Share Posted February 13, 2006 Longevity: chain Timing accuracy/quietness: belt Quote Link to comment Share on other sites More sharing options...
ZsRUSTIN Posted February 13, 2006 Share Posted February 13, 2006 I have hotted up a few Japanese 4-Cylinder motorcycle engines and have never seen a chain failure. Most of these 600cc sportbikes are redlining to 17,500 rpm in stock form. And the kids buy aftermarket rev-limiters to push them farther. When I ride these bikes my I hear a voice saying SHIFT, SHIFT, SHIFT, but theres still 4,000 RPMs left. The enclosed chains are not really noisy when properly adjusted. They use the HYVO type chain. The roller chains get noisy when really loose or worn, I think our Datsuns use a double roller type. I know the Honda VFR V-4 used gear drive to its 4 cams, pretty quiet except for a slight whine, which sounds pretty cool. And these gears are straight cut. I have never heard of one of those failing either. I have seen older Hondas where the cam chain was so loose it wore a hole through the front of the cylinder, still with no failure.(they would come in for an oil leak.) I have a 1999 996 Ducati V twin which uses belts, kevlar composit I believe. They have been a problem, and have been updated several times. When these belts let go, usually at high RPM, it's catastrophic. I changed mine at 4200 miles, just to be safe. If you keep up with the service, belts are OK, but do not push them to thier limits. Mileage or time wise. Doug Quote Link to comment Share on other sites More sharing options...
rubin Posted February 13, 2006 Author Share Posted February 13, 2006 so i guess my first opinion of belt for race and chain for race is wrong eh. kinda the opposite way i guess race engines would rather take the dependability oof a chain, even if there is slight friction loss. Does anyone know for a fact that chains have more friction then belts? it makes sense to me as each link must move against each other, even with a roller chain Quote Link to comment Share on other sites More sharing options...
rubin Posted February 13, 2006 Author Share Posted February 13, 2006 also why do all those chopper guys on tv use belts for their drive wheels? most street bikes use chains Quote Link to comment Share on other sites More sharing options...
AK-Z Posted February 13, 2006 Share Posted February 13, 2006 also why do all those chopper guys on tv use belts for their drive wheels? most street bikes use chains Maintainence. The bikes with exposed chain drive need to be oiled every so often where as a belt, if it wears out then you just need to replace it, plus rust. Even though stainless is rust resistent its not rust proof because of the small amounts of iron, now there are certain types of stainless that do not have iron mixed in the alloy but they lack strength in comparison and are less rigid (more flexable). Now chain in a car is self oiled and is pretty much sealed, for the most part, from moisture. Quote Link to comment Share on other sites More sharing options...
rubin Posted February 13, 2006 Author Share Posted February 13, 2006 makes sense but still doesnt really explin why everyday streetbikes wold use chains that require maintenance while choppers which are used once a month or never at all, and are probably stored well would use maintenance free belts but i guess thats a totally different issue anyways Quote Link to comment Share on other sites More sharing options...
AK-Z Posted February 13, 2006 Share Posted February 13, 2006 makes sense but still doesnt really explin why everyday streetbikes wold use chains that require maintenance while choppers which are used once a month or never at all' date=' and are probably stored well would use maintenance free belts but i guess thats a totally different issue anyways[/quote'] Also Choppers are usually custom made bikes, where different combination of parts do not always equal the same length for trans and such. For street bike, they are usually build by one manufacturer and there for have control over the design of certain parts. And again maintainence. bikes that have chain drive and are used everyday have less likely chance of the chain seizing, where bikes that are more likely to be stored that would have chain are morelikely to sieze. Edit: Forgot to add that for "chopper bikes" they usually have 2 belts, one for the crank to the trans and then the trans to the wheel. Quote Link to comment Share on other sites More sharing options...
ZsRUSTIN Posted February 14, 2006 Share Posted February 14, 2006 The belts are used on choppers to help dampen out firing pulses. A lot of these aftermarket "Harley" motors are up to 120 - 140 cubic inches. Thats over 1000cc per cylinder, firing at an uneven order. Thats a pretty big bang. (how about a 7.0 liter L6) Chain primary/final drive on these bikes would make them even more uncomfortable to ride. I have converted several British twins (infamous for vibrating) to primary belt drive and it really smoothed them out. The belt drives seem to be tougher on the bearings since they have to run a pretty high amount of tension, especially if the pulley is located far outboard of the bearing. Doug Quote Link to comment Share on other sites More sharing options...
rubin Posted February 14, 2006 Author Share Posted February 14, 2006 thanks for the great responses. much better understanding now Quote Link to comment Share on other sites More sharing options...
vashonz Posted February 14, 2006 Share Posted February 14, 2006 Most of those choppers use the belt as the primary drive, but still use a chain as the final drive. All the bikes I am familiar with have the transmission connected directly to the engine, and the primary drive is internal. Changing the length of a drive chain is REALLY easy, takes about 10 minutes. As for chain drive vs. belt drive it used to be that chains could handle more abuse, but newer belt technology means that chains are cheaper and narrower. Belts are smooth. There was a good discussion of this on vfrdiscussion.com Back on topic, I think the gear drive would be cool if someone made it with herringbone or double helical gears, it would be smooth, quiet, and able to take lots of abuse. But would be really expensive. Quote Link to comment Share on other sites More sharing options...
rubin Posted February 15, 2006 Author Share Posted February 15, 2006 i dont think it'd be that expensive sure it'd cost more than a chain or belt but it would never need changing. with some belt kits costing a 100bux or more a one time investment in a couple of gears shouldnt be that bad and because oil can flow to it it can get constant lubrication and the bearings would probably never go bad either how much friction loss do you think there would be with gears as compared to chains/belts? would there be any wear at all with proper bearing lubricaton and splash lubrication on the mating gears (if needed) Quote Link to comment Share on other sites More sharing options...
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