Belts

Ask Volvo before you answer, Gus. Friend of mine had an old Volvo stop moving when the timing chain went. This was years ago, and the car was quite old then… That’s also the only car I’ve ever heard of with a timing chain instead of a timing belt.

Since when did disagreeing with a person on a technical matter and providing information and data to backup the disagreement become not GP…?

All Andrew said here is that your blanket statement of “we tried all forms of belts sizes and shapes and widths, and found that belts just aren’t going to cut it for the powerful drive trains my team designs” is false (specifically the “belts in general arent going to cut it for powerful drivetrains part”).

He also literally even said that he’s not disagreeing with you that chains can handle more load then belts. And you replied to that with a “well actually, chain can handle more load then belts”. Try reading more carefully next time, before you start throwing around the “not GP” card

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A perfect example

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Just to clarifiy, the serpentine belt is not the timing chain. The serpentine belt usually drives your accessories, AC, alternator, and sometimes waterpump. The timing chains are usually inside the front cover, and are what most over/dual overhead cam engines use. The timing chain connects the crank to the cams, which is what times the valves opening and closing.

The serpentine belt on almost all cars has a spring loaded tensioner. The timing chains usually have hydraulically loaded tensioners that run from oil directly off the oil pump.

Most of Ford’s motors use metal timing chains. I believe chains are on the majority of other cars, though some do use belts. In some cases, the timing chains even have to be specially coated or have a super-fine finish in cases like police cruisers where they idle for long periods of time.

Timing Chain:

Timing Belt:

Serpentine Belt and Tensioner

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Whether a car has a timing chain or timing belt, it will stop when the chain or belt breaks. My 84 Mazda 626 stopped when the belt broke. Many current cars use timing chains in their engine and they are supposed to last the lifetime of the vehicle. No system is perfect. The Nissan VQ engine series from the mid- 2000’s have a high probability of the timing chain guides failing and causing catastrophic damage.

25H is an 25% stronger than 15mm wide 5mm HTD belts according to specs from SDP-SI and DID. However, it’s very easy to simply use a 24t pulley (~1.5" pitch diameter) over a 16t sprocket (1.27" pitch diameter) and end up with comparable strength. Going to a larger pulley like 28t is possible as well.
Different tooth profiles such as GT2 or GT3 will beat 25H chain in 15mm width. In fact, 5mm HTD has the same strength as 3mm GT3 for the same belt width.

Backing up your experiences with theory is good practice.

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Let’s all take a breather and not take responses personally.

This can also be an excellent teaching moment to learn how to differentiate between anecdotal experience and objective facts when evaluating topics.

Both of these types of responses can have their place in [technical] discussions - if you understand their limitations and learn how to identify each one.

Some answers between “should I choose Option A or Option B” can have an easy and “better” answer on paper. But in reality, sometimes the “better” option may be harder to implement given the resources at hand.

To everyone with anecdotal experience: please just be cognizant that your experience may not be universally true. In fact, it may only be true for a small segment of use cases. It may even be isolated to just your own situation. But that’s okay, as long as you can accept this possibility and don’t try to pass off your personal experience as absolute fact. Perhaps you may even learn that the reason all your past attempts failed was because of an unknown or overlooked factor.

To everyone arguing with technical facts: just remember that sometimes the “better” answer can be a lot more difficult for others (in a potentially vastly different situation) to actually implement or follow. It’s also possible that the tone of a factually correct post can be off-putting to some, which can cause an emotional response to the tone, rather than content, of a message.

There’s a lot of “outrage culture” in the world now. Let’s try not to add to it.

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Is this where I can put my experience in the couple thousand plus matches I’ve FTA’d/FTAA’d? I can’t remember a single time that I’ve picked up a belt (broken or not) from the floor…but just this past weekend I picked up no less than 5 chains, one I noticed broken about 20 links away from a master link. That was a 35 Qual + 7 Playoff matches off-season.

I don’t have a dog in the fight, but I do have a robot barf box sitting on the table for every event.

I mean, it’s anecdotal still :stuck_out_tongue:

And in the interest of full disclosure - I’ve broken both chains and belts in varying applications over the years.

I can’t remember a single time that I’ve picked up a belt (broken or not) from the floor…but just this past weekend I picked up no less than 5 chains, one I noticed broken about 20 links away from a master link.

This may have more to do with the failure modes of each. Chains break at a link and come loose completely, whereas belts usually strip out and remain in place, just in shreds.

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