"J Brockley" > wrote:

>"Leon van Dommelen" > wrote in message
.. .
>> "J Brockley" > wrote:
>>
>>>
>>>"Zog The Undeniable" > wrote in message
...
>>>> zenmartini wrote:
>>>>> I know the timing belt is supposed to be replaced at 60k. My 2000 is
>>>>> at 75k but the belt is in good condition... no nicks etc. Money is
>>>>> tight at the moment... how much longer can I go before this has to be
>>>>> replaced... I know that I'll be stuck wherever I am but there is no
>>>>> damage that can occur right?
>>>>>
>>>> The biggest risk is that it fails halfway through an overtaking
>>>> manoeuvre.
>>>> However, and for reasons I don't understand, the Miata/MX-5 belts
>>>> normally
>>>> fail when the engine is first fired up.
>>>Inertia. The two I had fail (not in MX5) occurred at startup and in one
>>>case
>>>when warm. I guess when started there is a sudden change in lateral
>>>tension
>>>on the teeth from nothing to something high before it calms down and
>>>everything gets moving. I guess the only other time the rate of change is
>>>approached is when you put your foot down hard.
>>
>> Did they fail when you were cranking the engine or when it started?
>>
>> Leon
>> --
>Cranking. Never seen one snapped but seen where teeth start to part company
>with belt.

Stress concentrations would likely be larger when the rubber is cold.

Leon
--
Leon van Dommelen Bess, the Miata Bozo, the Miata
http://www.dommelen.net/miata
The only thing better than a white Miata is two white Miatas