huge wear on suspension

For the past few races my suspension has been wearing around 50-40% at first i thought it was because i was manufacturing my parts at 'balanced' so i put it to very high and now its still the same, also i noticed that my internats suddenly dropped about 40% this race.

It won't be related to your manufacturing, but probably because of your drivers.  If they're inexperienced, have low focus, or just are untalented then they will tend to make mistakes, and sometimes serious enough ones to mess up the suspension and other parts as much as 50% per race (potentially even higher).  I'll check this out specifically though to rule out if anything is going wrong.

What does manufacturing quality affect then if not this? I would imagine parts with greater quality last longer.

Thanks for giving out tips, Andrew. :)

Alin: by "inexperienced" I was meaning a combination of several other abilities ;).  Mart: The manufacturing levels affect the performance of each part.  Part resilience is not currently based on level.  I think you're right though; it should be.

I just checked this over Joe.  One other thing I should have mentioned that changed fairly recently (before launch) is that parts damage is scaled up for shorter length races.  This excludes tyre damage though. It seems that the system is functioning as intended here.