Civic change to timing chain

If I remember correctly, all Civic models from 2006 on have a timing chain. Pre-2006, it's a belt... except for the 7th-gen (2001-05) Si hatchback which had a chain.

Don't know about the Civics, but I recently bought a used 08 Fit. I had the dealer throw in a set of factory shop manuals.

Looking through the manuals, I was very surprised to find it uses a chain.

I would also like to know the reasoning behind this change. Belts kept the valve timing tack on till they failed, and eliminated 'internally lubricated component' from warranty coverage...

Erik

there are two main reasons for the trend back to chains:

1. some owners bitch about the cost of timing belt replacement. and probably with good reason since most dealers take the opportunity to really hose their customers when they do a belt job.

1. it's part of the general trend towards life limitation. you can keep a belted engine running for another 100k miles with a belt change. belted honda engines with 300k+ miles are not uncommon for example. but you're not going to get that out of a chained engine without a change. and since no chain change is specified, people will just keep it running, and by the time they've decided that the thing has worn enough to sound like a bag of loose gonads, they'll think the motor is dead and junk the whole thing rather than try to keep it running.

practically speaking, and to be fair, chains have improved a lot. modern wear rates are relatively low. tensioner strategies have improved. and they're cheap.

here is the important development that has made them more popular again: computerized design tools. in the old days, people designed stuff, and it worked, and that was that. today, designs are so minutely considered that what used to be wear points or noise points can be addressed and either reduced or eliminated. for instance, with gears, engineers now not only design the teeth profiles for maximum strength with minimum material, that profile is so intricate, it also takes into account the elastic deformation when loaded in operation! that helps reduce both noise and wear. to emphasize again, that is a BIG DEAL. applied to chains and sprockets, that design strategy also helps reduce noise and wear, thus removing a lot of the issues with chains that belts were used to avoid. additionally, one of the issues with cams is its tendency to change its angular velocity as it rotates because of the spring loading on the cam followers. with computer designed cam profiles, the worst of that has been reduced, and thus, so has chain loading, and thus also wear rate and noise. so, while a belt is inherently a better solution for camshaft drives because it not subject to stretch and doesn't cause the point loading that a chain does, a lot of the objections to chains have been reduced, and tied with #2 above, they're an acceptable compromise.

bottom line, we're going to see belts become a thing of the past. afterall, car companies are run by bean counters, not engineers and while belts may be technically superior, chains are now an acceptable mechanical solution, and their financial advantages are significant.

Eternal Searcher wrote in news:huejkj$7s2$ snipped-for-privacy@news.eternal-september.org:

This is correct. I checked on Techinfo.honda.com

Techinfo actually says that the "3-door" Civic had a chain from '01 to '05. I'm assuming all "3-doors" were Si's.

I believe you're right, although in Canada it was known as the Si-R.