Timing belts vs. timing chains

timing-belts
belts

#1

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?


#2

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.


#3

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.


#4

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.


#5

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.


#6

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.


#7

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”


#8

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.


#9

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.


#10

Do all cars now have timing belts, instead of chains?

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.

#11

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.


#12

I apologize for beating the same drum, but I can’t help but feel with the interrelated connectivity of the systems in the modern engine, that failure in one in particular has a bearing on the “Federally required emission control warranties” indirectly. It really could come down to engineering with this in mind as well.

I still feel that as a by-product of an effort to protect the environment, we get motors that perform better, and last longer, timing chains v belts not withstanding.

Just a believer in that if you do the right thing, regardless of immediate investment cost, it really is cheaper and beneficial in the long run. Does the govt. always get it right ? Heck no. But, here is a case where a debate about chains may be an example where environmental concerns are not removed from good economic policy when it comes to car design. And, we the consumer get to reap a few benefits as a result.

IMO, the biggest jump in overall reliability of cars may be directly attributed to these emission control mandates and the decisions to use chains then belts then back to chains is just an evolutionary process which benefits us all.

Feel free to completely disregard this “flower child, piece sign waiving” political thought.


#13

You make a good point, Dagosa. Before we had emission controls and their madatory 50,000 mile life, engine design left a lot to be desired. Ford was fined heavily years ago for faking the durability tests and handing fraudulant information to the EPA.

The exhaust system, up to the end of the cat coverter wast the first thing to be beefed up. Then the ignition system had to be made very reliable with long life plugs, no ignition points, etc. With better crankcase ventilation, the engine was less subject to sludging and ran cleaner. In addition the fuel mileage standards added to making engines run leaner and creating less soot. Lube oil and gasoline manufacturers had to provide better and cleaner products.


#14

I absolutely agree that better running, more reliable, longer lasting engines are a direct result of, for one, the technologies developed for emissions and mileage mandates. The evolution from carbs to multiport fuel injection is probably the biggest leap.

The evolution of computer technologies, “thinfilm” and resulting microchips, now used to control fuel metering and timing, is another huge contributing factor. And with that high-tech revolution came CAD/CAM software that even the science fiction writers could not have imagined. Nobody could have dreamed of the design power in these programs.

I’d add that there’s an additional “driver”: cost. The shift in manufacturing philosophies from focus on quantity shipped to focus on consistency and erroor-reduction drove concepts such as Design For Manufacture, Statistical Process Control, and Value Stream Analysis, all of which have dramatically improved quality and longevity, particularly in engines.

And, of course, there are wonders to behold in the materials area. Reverse gravity casting alone was a huge leap in the quality of castings.

Lots of good stuff converged over the last half of the 20th century to create engines that are truely amazing.


#15

Hyundai used to be a mix of chains on some engines, belts on others, but with the latest round of updates, I think they all went to chains. I have a 2010 Kia small car, 2011 Hyundai large car, and a 1995 Ford Ranger - all use chains.

I think my motorcycle uses gears :slight_smile:


#16

I disagree: belts are a pain in the rear, and the difference in price (in a new car) between a belt-driven vs chain driven motor is negligible. In fact, Subaru just started putting chain driven motors in the majority of their 4-cylinder cars (already offered in the 6-cylinder motors)… why? because owners complained about how much hassle it was to replace the belt at 105,000 miles (plus, the fact that if you have an idiot mechanic, he may “forget” to replace the belt tensioning pulley, which means another $1,000 replacement, a year or so later, when the pulley fails!),


#17

As an historic side note: BMW was one of the first companies to popularize the timing belt, after buying the technology from a smaller company, Glas, maker of the Glas GT (which later became the BMW GT). Originally, the technology was used because it was quiet, simple and cheap. http://en.wikipedia.org/wiki/Glas


#18

I think the old VWs used gears, and I know you used to be able to buy geartrains to replace the timing chains for some commonly-hotrodded V8 engines. OK4450 might have some current information.


#19

Seems to me it’s not so much an engineering issue as a profit driven perversely motivated practice designed to make more money for dealerships on the maintenance and repair side than they made on selling the car in the first place.

It is in the car manufacturers interest to repair and sell more cars. Designing a car that could actually run 400,000 miles with minor maintenance and wear would mean selling fewer cars…of course it might cost 20 percent more to make but the benefit to consumers would be enormously cost effective.

Glad to read belts are on the way out…people are wise-ing up…and competition can work.

Most people want reasonably priced reliable efficient long lasting transportation…period.

For example…why don’t all manufacturers make exhaust systems to last by using steel that won’t rot away?

The age of disposable cars must end!


#20

Kudos to you for reviving a 5 year old, totally dormant thread.
That truly constitutes a public service… :smirk:

In any event, I keep my vehicles for 10-11 years, and the last one of my vehicles that needed any type of exhaust system maintenance or repair was a 1974 Volvo.
Nothing that I have owned subsequent to that piece of automotive crap has required any type of exhaust repair, even after as long as 11 years.

:unamused: