Date: Sun, 29 Nov 1998 11:25:43 +0100 From: "Johan LAUWERS" <lauwers.sablonnopsam.be> Subject: Re: 99 strange noise
Hi chris, I had the same with my '83 900 GLi. The problem in my case was rather simple. If you know anything about Fysics you know that every single object is vibrating. Well at a certain RPM the vibration of the car became the same as the one of my exhaust. In that case the exhaust starts to vibrate a lot because the car's frequency is fortifieing the exhaust' s and that was the sound. In fysics this effect is called resonance. You can check if it is not possible to tighten it a bit more in order to make the self-resonance of the exhaust higher then the vibrations in your car (e.g. at 8000 RPM, an RPM you'll never reach). Johan. chris Baillies heeft geschreven in bericht <73q6dh$j1e$2nopsamreader5.core.theplanet.net>... >My '81 Saab 99 makes a strange tizzing/rattling noise at around 4000rpm that >disappears above or below that speed. The car only has 57000 on the clock >with FSH and is otherwise very smooth, looks and drives like a new car. I >thought maybe a piston ring, but it uses no oil, no excessive blow-by etc. >Any ideas? > >chris > > >
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