This much chem I do remember. Both UV and ozone break the long polymer
chains into shorter ones and also break the crosslinking between the
chains. As the years go by, the percentage of short vs. long chains
goes up, and the % crosslinking goes down, significantly weakening the
polymer. How much is impossible to tell without destructive testing.
If the belt is faded or over 20 years old replace it. If left long
enough, they will eventually turn into powder. Say, 500 years.
Someone must have stolen your lap belt from the Jensen. With only a
shoulder belt you will submarine under the dash in a frontal impact,
which can be hard on the knees. That was a big problem with the early
passive restraint systems that used a motorized shoulder belt or one
attached to the door but required you to manually hook up the lap belt.
Many folks didn't, rendering the "restraint" system next to useless.
WSpohn4@aol.com wrote:
>
> In a message dated 21/09/00 12:02:45 PM Pacific Daylight Time,
> owner-mgs-digest@autox.team.net writes:
>
> > I would like to make the point that the belts in most of our cars
> > are now too old to be considered safe. That way I can sell lots of new
> > belts to people and make my bosses happy. See I told you that Blatent
> > Commercialism was involved.
>
> I think that it depends on what the car has been doing. It is principally UV
> that kills the material, and if you have NOS belts that have been in a drawer
> for 30 years, they may be almost as good as new. Similarly, if the car has
> been in close underground storage for the same period, the should not have
> degraded nearly as much as if used (particularly in a convertible) out in the
> elements.
>
> I have no idea if ozone affects belt material, and would welcome the views of
> any polymer chemists on that issue and on the UV aspect.
>
> Bill S.
> (My Jensen CV8 has diagonal belts ONLY - has anyone ever seen that in any
> other car?)
--
Stuart MacMillan
Seattle
'84 Vanagon Westfalia w/2.1
'65 MGB (Driven since 1969)
'74 MGB GT (Restoring)
Assisting on Restoration:
'72 MGB GT (Daughter's)
'64 MGB (Son's)
Parts cars:
'68 & '73 MGB, '67 MGB GT
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