Timing belts and chains

My first experience with a Belt was my Chevy Vega…But it wasn’t a interference engine. One time my belt broke while driving on the highway…I coasted to the next exit (about 100 yds away)…pulled into a side street…and found an auto parts store 1 block away. Put on the new belt in less then an hour and was on my way.

The first interference I ever saw was my dad’s 72 Toyota Corona…it had a chain.

LOL, yeah, I seem to recall that there was enough room to squaredance around the engine in my Vega! People used to pop smallblocks in the engine compartments. Cosworth sold a complete conversion kit. It was rumored at the time that Chevy had intentionally sized the engine compartment to accept a smallblock and planned to offer a V8 option.

I don t think many car buyers know anything about engine types at all. they buy what feels good to drive and trust that the car is well designed if it drives well

I am of the belief that timing chain engines were designed by engineers at the top of their class. Timing belt engines, on the other hand, were designed by engineers who graduated at the bottom of their class. I would say the same thing about aircraft engineers who would design an aircraft with cardboard wings.

If I’m not mistaken some Ferraris and Porsches used timing belts

I’d hate to be the salesmen who tells those customers that their engines were designed by engineers who almost failed the class . . .

Sorry . . . I don’t buy that argument at all

It’s just a different way of doing things . . . not better or worse, just different

I’m not concerned about having a timing belt in my V6 Accord. It’s the only time I’ve spent more than $500 at one time on the car, and it only happens every 105,000 miles. For me, that’s 8 years. $100/year isn’t all that much.

Missileman, it isn’t about engineering prowess. It’s about management mandates.

Even fools know better than to rely on a belt as an engine part. Engineers just try to get by. Now we don’t have to shave engine weight, we build engines that get better fuel economy.

mountainbike …I am well aware of management mandates and pencil pushers who watch the bottom line. In a better world…timing belts would not exist.

@db4690 …different would assume that timing belts are just as reliable as timing chains. They’re not so your argument is a moot point. @chunkyazian … you are welcome to disagree but at the same time remember…I give tit for tat.

I don’t assume that timing belts will last as long as chains

I change them according to the manufacturer’s specified intervals

Anybody that doesn’t do this is asking for trouble

Besides, I really liked the cars I had that used timing belts

The timing belts were not enough of a discouragement to buy a different car

With every single car, I knew before I bought it, that it used a timing belt

Many other people felt the same way as I did

And some of them have said as much . . . on this forum

Amazing that the cheap post-WW2 Crosley had a gear-driven OHC. Except for some Ducati motorcycles, it just never caught on.

Nice photo Insightful.
If memory serves, the old air cooled VW Beetles had gears too. Perhaps someone here who’s torn one down can confirm or correct me.

@missile , with all due respect, which engineering school did you attend? Engineering school is about learning how to identify the relevant facts of a problem, describe all known physical observation mathematically, and come up with a solution. A good engineer would call for a timing belt replacement reasonably before the belt failure, that’s accurate quantification of belt life. Whereas a bad engineer would specify a change interval way longer than the belt life.

since the average driver knows little about cars other than how to drive them the optimum design for the average driver would seem to be a car that required little maintenance and one that all components who s failure would be a major problem were designed to last an equal amount of time.

when I buy a pair of shoes I expect the sole and the leather upper to wear out at the same time. if one fails before the other, I don t buy those shoes again

@chunkyazian with all due respect in return…you are missing my point here. A good engineer would never come up with the “timing belt” in the first place. It’s engineered obsolescence at it’s worse. Coming up with a belt replacement before it fails is just a “workaround” of which I detest. I do have a degree in electronics engineering which allows me to point out faults in other engineering endeavors. +1 for @wesw .

Engineers have a set of conditions they must meet, including cost. Ignoring cost is a recipe for disaster. The good engineers at Saab produced an excellent automobile, with safety features that exceeded requirements. Unfortunately, the Saab was much more expensive than comparable cars and the public would not buy it. Then, they went out of business. Good engineers strike a balance between competing desires for the features that might be present and come up with a satisficing solution. Producing a product that does not meet requirements is bad engineering. Producing a product that far exceeds requirements can be bad engineering as well if it costs too much.

@jtsanders …I see your point as well but a good engineer would not design a sub par system like the timing belt system when there was already a better alternative available. I know cost is important but some engineer along the way threw caution to the wind and designed a weaker system for keeping the valves in time. They made a few pencil pushers happy and increased the bottom line but did a great disservice to the automotive industry at the same time. The least an automobile manufacturer could do is to provide free timing belt changes for the life of the vehicle. It’s their baby…they can change the diaper.

Just curious, @missileman, have you had a timing belt ever fail on your car?

No…but I’ve only owned one vehicle with a timing belt that I’m aware of. It was a 1973 Vega and a V8 was installed long before the belt had a chance to break. I know about the weaknesses of timing belts so why would I own a vehicle that had one? I bought the Vega not knowing that it had a timing belt.