Date: 25 Nov 2002 04:22:28 GMT
Subject: Re: c900 harmonic droning?

Someone who looks an awful lot like Lance Morgan <> wrote: > I recently purchased a 91 900S (briefly had a 86 900T years ago), and > am really enjoying it. > I've noticed something I'd appreciate comments on: a harmonic type > droning - always starting at 70 mph up to at least 85 mph, and have > also sometimes heard it ~ 45 mph in 3rd, albeit a slightly different > tone. > The noise is moderate in pitch and, at high speed, has a repetitive > frequency of less than 1 second. It reminds me of riding in a twin > engine airplane Tires maybe? If it's the kind of noise I think you're describing, it's usually caused by two things that are almost, but not exactly, at the same frequency. Two tires that are just a *bit* different sized (could be just inflation pressure) might make the noise you describe. Never heard it myself, but I'd be interested to know if your tires are all the same size and pressure. > The noise completely abates when I push the clutch in, coasting at > high speed. Ah, well that shoots *that* theory down, I think. > Probable cause? Is there a twin engine airplane following you, except when you push in the clutch, by any chance? Unlikely, I know, but... > Thank you, > Lance > 5 spd 3dr 125K Hm. Pretty young for it to be inner drivers, which could be another possibility. How are the front two tires for match and pressure? Dave Hinz

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