Timing belts and chains

General Discussion
41

I don’t mind changing timing belts

I’m sure there are plenty of mechanics worldwide who also don’t mind

A timing belt job could theoretically be a lucrative repair order for a shop, if they also sell the cam seals, crank seals, tensioner, water pump, etc.

Therefore, I don’t see timing belts as being a disservice to the automotive industry

Heck, one could make the argument that a better engineer would design a car that doesn’t wear out tires, brakes, clutch disc, etc.

Please . . .

By the way, I know somebody that recently bought a new car with a timing belt

He said he’ll trade it in when it’s time to do the belt

I snicker behind his back, because the car will be barely broken in by then, and he’s going to take a massive hit when he trades it in. He won’t even have gotten his money’s worth out of the car

42

To claim that timing belts are designed by idiots, timing chains by geniuses is nonsense. How about the ‘geniuses’ at Mercedes that designed the timing chains on the 3.8 V8? Famous for falling apart, required a retrofit because of all the problems with the cam drive chains.

And the decision to go with belt vs. chain was made on day one (about) of an engine’s design process: 99% of the engineers involved from then on had nothing to do with the decision.

43

@texases‌

Ah, the infamous aluminum 116 engine

You forgot to mention the stripped out female threads in the block . . . when you remove the head, only to discover that you also pulled the threads. And now thread inserts are required

44

@texases …please explain to all of how graduating at the top of an engineering class makes you a genius and graduating at the bottom of the class makes you an idiot? I’m going to guess that your attempt to explain this will be nonsense…so don’t bother. I generally agree with you on just about everything but on this subject…we are diametrically opposed.

45

There are “engineers” like Dean Kamen, who see a challenge and, through endless hours of searching, researching, designing experiments, failing, learning, and designing even more experiments, bring the laws of physics together to create solutions that most of us can only dream about.

And then there’s me. Given a set of design goals and limitations, I’d do the best I can to create the best solution I can, generally as a member of a design team.

For every Dean Kamen, there are countless tens of thousands of me. I don’t claim to be a genius, but I like to think I’m not an idiot either. My ex might disagree, but that’s a subject for a different forum.

I have to say that I found it humorous to have read that the Vega entered into this discussion. I’d bet lunch that the guys doing the block design wanted to line the cylinders, the guys that did the idle stop solenoid bracket wanted a better bracket (they broke and fell into the accelerator linkage… there was a recall, but mine broke before the recall), the guys doing the sheetmetal design work wanted to use a thicker gage steel, and all of the engineers wanted to have far more time to do reliability testing. But, alas, the bosses wanted an answer to the Corolla and they wanted it NOW, and they wanted it CHEAP.

IMHO it’s really kind of unrealistic to think that geniuses use chains and guys like me use belts. I feel confident in saying whoever designed any particular engine (and I guarantee it was a team effort) did the best they could to meet the goals given them. And in most cases they did a great job. The years in the field simply exposed the weaknesses of belts… the biggest being not technical, but human, the fact that changing them too often results in operating problems. The designers cannot be held responsible for predicting how many times poor workmanship will occur.

And I have never in my life met a designer working for someone else who didn’t want at least three times the time and budget for testing that he/she got.

I don’t personally like belts for reasons I’ve already stated, but that doesn’t mean I don’t respect the designers. Designing something as complex as an engine to fit in a little space the size of the average econocar’s underhood space, to be cheap enough to manufacture to make the car competitive, and perform well enough to meet today’s driving environment takes many tens of thousands of hours of design work, and lots and lots of head-butting with management and marketing. Oh, and accounting. Engine’s aren’t designed by one guy alone in a room. It’s unrealistic to think belts come from bad designers and chains come from geniuses. Design doesn’t work that way.

Okay, now, about the Vega… I liked mine, piece of junk that it was. I still remember it fondly.

46

Let’s compare a 1990s era Corolla to a 1990s era Cavalier

One uses a timing belt, which some of you hate

The other uses a timing chain

But one of the cars holds its value much better, and was more reliable

I’ll give you a hint . . . it wasn’t the car with the timing chain

Would most people knowingly choose the less reliable car, that doesn’t hold its value, for the sole reason that it used a timing chain . . . ?

Obviously, you would have to think in the past

Let’s pretend this was around the year 2000, when none of these vehicles was particularly old

If you think in present terms, both of these cars are 20 years old and not worth squat

47

There’s far, far more to a purchasing decision than what’s turning the camshafts. I’d take the Corolla every time. I actually DID take the corolla!

48

What makes me mad is the electronic engineering geniuses that build planned obsolescence into computer hard drives so they crash.

49

There are definitely lifespan goals for designs, but I can honestly say that I’ve never seen planned obsolescence as most people understand it. Engineers will, if they want to keep their jobs, not spend more than is necessary to get a design to meet it’s lifespan goals in order to make it last even longer. But they don’t in my experience design in failure. I truly believe that’s a misunderstanding by the general public.

50

OK…I’m bowing out of this discussion. I don’t like it when words are put in my mouth…specifically “genius” and “idiot.” They are catchwords that more than one person is using now even though I never said them. My point was simple…timing chains are better that timing belts…that’s a given. @cdaquila … you can pull the plug on this one because it’s toast for me. @db4690 … I expected better from you and so I guess I was mistaken. Your arguments were beyond weak. As for timing belts…they are like broken watches…they have the correct time twice a day. I guess “twice a day” reliability is good enough for some people.

51

My arguments are strong

Millions of people bought timing belt equipped cars, and were happy with them

And then millions of people traded them in for a newer car with a timing belt

And they were happy with them, as well

Those cars were more than good enough for millions of people, for decades

I have millions of people backing me

Let’s not pull the plug, just because one person has had enough

And let’s remember . . . I’m not the one asking for it to be closed this time

52

OK, now, I say this with great regard for all of you. I also say this up front: I do not have fervently held opinions about the matter. I do know my way around an argument pretty well, though. :slight_smile:

@missileman, I don’t read the thread as texases putting words in your mouth. But to be fair, as I read it, you’ve staked out a pretty black-and-white opinion that at its core many people agree with (ie, pro chain). It seems to be one that the others don’t equal in intensity when it comes down to the engineers’ competence. I think it’s fair to leave it open, because it hasn’t devolved to verbal knife fight levels. @db4690 doesn’t seem to be tirelessly, mindlessly championing belts, though. He just seems to think they’re perfectly OK if you maintain 'em.

53

Belts, chains, and even gears all have advantages and disadvantages. An engineer selects the best option to achieve his/her design goals. It’s that simple. And that complex.

54

It isn’t just an engineer working alone. It is a team of people, some of whom are engineers, that make design decisions. I’m sure that is part of the complexity you mention, SMB.

55

It is. I should have said “design team” rather than 'engineer".

Designing complex systems like automotive engines takes teams, often more than one team, and nobody really makes a decision on his/her own. There’ll always be a design chief who makes the final calls, but the work is done as teams.

In the modern world, the teams may not even share the same home town. In the case of the Toyota FRS/Mazda BRZ, the block was designed by Mazda and the heads by Toyota. As a matter of fact, many bodies may be largely designed by specialized design companies like Bertone or Pininfarina that aren’t car manufacturers per-se. Many cars use brake systems by Brembo, etc. etc.

In short, the perception that some “genius” chose a chain and some “idiot” chose a belt is totally out of synch by the way engines are really designed. Design processes simply don’t work that way. Except maybe for clothspins. But that’s a different forum.