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Timing belts vs. timing chains

edited November -1 in General Discussion
Do all cars now have timing belts, instead of chains?



I suspect belts cost less than chains, so car companies skimp by using belts.



Belts typically are supposed to be replace at 60K miles and is an expensive repair.



Besides being cheaper than a chain, is there any advantage to using belts?



What's the life expectancy of a timing chain?

Are there any regular cars that still use chains?
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Comments

  • edited March 2011
    BMW engines use chains, as do many high-end European cars. Many Japanese cars use belts. Chains last longer (rarely need to be changed) but are more expensive. Belts are lighter, cheaper but need to be changed (50k - 75k miles). Neither is better or worse, only different.
  • edited March 2011
    The trend is the other way!!! Belts were used mostly by foreign car makers and some domestics because the were quiet and cheap. However, US owners have gottten into so much trouble because they were used to chains, which did not need changing, that they did not bother reading their manuals and "forgot" changing the belts. This often caused great engine damage or completely disabled the vehicle at the most inconvenient time. I've had midnight calls from friends and aquaintances stranded for some "mysterious" reason.

    Of course most of these problems were blamed on the car makers. So, now Honda and Toyota use chains in nearly all their 4 cylinder cars. As are many Mazdas. Hyundai still uses belts, but is expected to change over soon too. We have a Nissan and a Toyota and both have chains. In fact the only car with a belt I ever owned was a 1977 Dodge (Misubishi) Colt.
  • edited March 2011
    I don't know what the percentage is...but many cars still have chains. And some companies are now getting away from belts and going to chains.
  • edited March 2011
    Subaru is also in the process of going to all timing chains.
    The existing 3.0 and 3.6 liter six-cylinder engines have always utilized timing chains.
    The current timing belt-equipped 2.5 liter four-cylinder engine is being replaced with a new-design 2.5 liter four-cylinder engine that utilizes a timing chain.
  • edited March 2011
    Many makers are returning to timing chains, but I don't know if the reason is as altruistic as I'd like to believe. As manufacturers push gas mileage higher and higher to comply with tightening regulations, they're using complex systems now to vary cam timing, even switching lobes in operation. I suspect that there's an underlying increase in the stresses that the cam-driver (belt or chain) has to endure and perhaps the timing itself is becoming more critical.

    I've attached a link that shows how complicated the whole issue of cam timing has become. Perhaps these new systems are requiring a more durable and precise method of cam driving. This may be a reason that chains are coming back.

    Perhaps one day gears, much more expensive than chains or belts and rarely used on automobiles, will return.

    http://en.wikipedia.org/wiki/Variable_valve_timing
  • edited March 2011
    I suspect Doc is right that too many people haven't changed their belts and wind up stranded with a car that's needing a new engine and one too many people complaining to the manufacturer about it; never mind they couldn't tell you where the maintenance schedule/owner's manual is in the car and they've owned the car since new.
    Another thing is that many owners will be told they need to change their timing belt on their car, then get told it's $500-1000+, then they trade the car in so they don't have to spend "all that money"
  • edited March 2011
    Toyota and others have gone to chains several years ago in many of their models. According to local motor component subcontractor engineer, it's strictly an engineering decision that is only indirectly related to the cost of making the motor. It had to do with the motor's overall performance and planned life expectancy.

    The initial move to belts may have been for quietness but with the advent of variable timing and their varied approaches to increased efficiency and power and along with other such technologies the decision was made. It is not a simple, "which is cheaper/quieter" that the average consumer can only guess at. Maybe increase stress; who knows and it's only a guess for we non engineers.

    The chain in modern day cars is no more of a durability issue than a connecting rod for a non OHC motor. All internal parts that are not routinely replaced or serviced are engineered for compatible life expectancy by each manufacturer according to this engineer. Theoretically, a chain can be made to be the longest lasting component.
  • edited March 2011
    A timing belt is a very precise way to time engine parts that require it as evidenced by the successful use by VW for many years to operate diesel fuel injection pumps, the timing of which which is critical to good engine performance and fuel mileage.

    Another reason for the trend to timing chains from belts is that consumers have become more aware of the expense of changing a timing belt that can be avoided with a timing chain. As evidence for that, during the past couple of years I have seen many posts here on CarTalk questioning the need for and the expense of changing a timing belt.

    Timing gears have been used for flathead, OHV and even an OHC engine in at least one Honda motorcycle but the distance from the crank to an overhead cam is too large for just a pair of gears so several gears would be needed with consequent loss of timing accuracy due to backlash. Harley Sportster OHV engines use several valve timing gears, one for each valve that are manually selected for backlash to keep the gear noise down.
  • edited March 2011
    [b] Do all cars now have timing belts, instead of chains? [/b]

    No, if all cars had timing belts, there would be no timing chains. ?

    [b] suspect belts cost less than chains, so car companies skimp by using belts. [/b]

    No, they use belts for several reasons including being generally quieter.

    [b] Belts typically are supposed to be replace at 60K miles and is an expensive repair. [/b]

    Not all. Mine recommends replacement at 100,000 miles.

    [b] What's the life expectancy of a timing chain? [/b]

    Life of the car for most people.

    [b] Are there any regular cars that still use chains?[/b]

    I believe so.
  • edited March 2011
    Timing belts are quieter and lighter.

    The replacement interval for Acura and Honda is 105,000 miles or seven years, if I remember correctly, so very few owners will have to do it more than once. I think most other makes use a similar interval.
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