A timing belt is very important parts to drive camshafts with a crankshaft.
On old vehicles, a chain type has been to use, a belt type becomes popular
for silent and cost save in now.
But belt type is easy to be elastic, and suddenly snaps on street as the serious
trouble.
The recently every engine power is becoming more powerful, so some ones are
adapted a chain type again for keeping the endurance.
When a belt breaks at the moment, camshafts stop rotating.
But a crankshaft
still rotates with a vehicle moving.
Then pistons hits valves and in the worst
case an engine receives very hard damages.
We would like you to understand that a timing belt is very important.
As so important, a timing belt is put into a timing case to protect from
others. However, it spurs on high-temp in a case,
and rubber of belt would
change in quality.
In addition, there is an auto tensioner on Miata, we have to check belt tension
or have to maintain basically.
An auto tensioner has a mechanism which a roller always pushes a back of a belt with oil pressure or springs to keep a suitable belt tension.
This maintenance free system is easy for us ( work shops and dealers), it is
not so good for a high rpm engine,
because a belt starts vibrating at high rpm
and an auto tensioner can not make a belt be stable.
According to the
situations, belt vibration would be an engine trouble.
A timing belt is composed by mainly belt surface, rubber and core.
Belt surface
Belt surface is to protect from cam gears.
Generally Nylon material is used, but Maruha heavy duty belt is more strengthen
with Nylon plus Kevlar,
and able to improve the endurance and reduce to wear.
Rubber
A timing belt case to protect a timing belt sometimes gives heat harms to a
timing belt with increasing temperature inside a case.
And with proceeding tunings, an engine power becomes more powerful. The load and
heat harm to a timing belt increasing more.
On rubber part of the recent timing belt, usually H-NBR as STD is used.
Maruha timing belt is not H-NBR as STD level, but high strengthen H-NBR for
racing engines.
Middle core
A core is to protect from elastic of a belt.
Glass fibers are used for STD belts, but more fine glass fibers are twisted to
be strength for Maruha belt.
The following is the data of comparing STD belt with Maruha heavy duty belt
by a manufacture.
Please refer to them for your reference.
There are two patterns of the causes of belt elastic.
It is elastic of middle core and another is belt cogs dropping into tooth of cam
gears.
Maruha timing belt is designed against these two cases, and able to keep the
correct valve timing with high performance.
When change timing belt, please care about water pump ,too.
Because water-pump is the behind of timing belt, and this is to be changed
together.
If you find water leaking from a water-pump after changing timing belt,
you have to do same work again, it is lost money and wasting time.
