What determines auto manufacturers' decision to install timing belt vs. timing chain?

Question

Is it engine displacement or regardless of this? Why can't auto manufacturers stick to timing chain, as this is long-lasting and does not snap, unlike timing belts which are made of rubber? What is the rationale for the decision to use either belt or chain?

Answer 1

MONEY!

Answer 2

It's all a matter of cost and how anal the engineers are that design the engine.

Timing chains are more expensive to use, as you have a lot of parts to have manufactured and assembled (the chain is made of high-quality steel and each link has numerous tiny parts). And, come mfgrs use double chains on the same cylinder bank. Obviously, if this much effort is put into the chain, then the specifications on the chain mfgr will be tight and closely monitored. Companies like Mercedes-Benz and Porsche use chains on every engine. Chains can last years and many miles, before stretching and needing a link removed or replacement. Some engines even have chain tensioners that help keep the chain tight. What this all has to do with is valve timing with the stroke of the pistons. If anything is off, the engine can run poorly. Most racing engines use timing chains as they can generally rev to a higher RPM and keep perfect timing, than one similarly equipped with a belt. (This is not always true, as it depends upon the type of belt used and how much weight is a factor.)

In the case of a timing belt, it is a very inexpensive part to install in the engine and will need to be replaced on very regular (this is where the owner must get anal) schedule. It is usually made with some form of rubber that has steel bands in it. What usually goes first are the tiny teeth of the belt that mesh in the grooves of the camshaft and crankshaft. If the company designed a non-interference engine, then you are ok... no engine damage will result. However, if the company did not allow enough room for the valves to be open with the pistons at the top, then you have a very expensive problem. (This can also be the case with an engine with a timing chain, but the chain lasts much longer and dies not sheer any teeth, as it has none to begin with.)

Do not think that an engine with a timing belt is a bad engine. It will still perform very well and last a long time. You will just need to be very cautious and have the belt changed on the mfgr-prescribed schedule. Timing chains can last beyond the number of miles an average car owner keeps a car for.

Answer 3

Belts do have their advantages. They're cheaper, quieter, lighter and easier to replace. They're also better able to handle the longer run necessary for overhead- cam engines. In the old days, a timing chain only had to be a foot long. Now, with overhead-cam engines, it has to be 3 or 4 feet long, and for that kind of length, a belt is not only a lot quieter, but more reliable, too. When you use a chain for that kind of length, it's more likely to loosen up, slap around and eventually break.

Timing chains do last longer, but not necessarily the life of the car. And when they do break, it's a big job and a lot of money to replace them.

Answer 4

to make money on service. i do not buy anything with a belt.they will brake with age too.

Answer 5

easier to change