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Discussion Starter #1
Had a chance to get over 120mph this weekend. Coming up on 130 or 140 (I didn't want to look too closely at the speedo during this exercise), there's a vibration which cycles over about 10 seconds or so, buzzing the steering wheel at quite high frequency, without actually affecting the handling or the braking. I had the front wheels balanced last week, and the tracking lined up at the same time, so I suspect it's not that.<br> <br> Any suggestions?
 

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Discussion Starter #2
Did they balance the tires for 120+ MPH? Probably not...

Most tire shops get a good balance up to 65-70 mph and that is good enough for them...and most drivers. I would get them rebalanced and ask them to do a 'high speed' balance.
 

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Discussion Starter #3
I am no mechanic, but I test drove a 560 SEC once, and at around 95 mph I got a similar vibe. The car had bad motor mounts. If you drive your car hard off the line this is hard on mounts. This is easy to check if you have honest mechanic.
 

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Discussion Starter #4
Now, that's very interesting

The car has done about 57k, and I have been wondering whether the mounts are past their best: I had a very fast 3.0 Alfa Romeo which had half-ish broken mounts - it was OK at speed but not so smart at gentle traffic work. The car's in the shop and I'll ask them to consider the mounts while they're in there - thanks.
 

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Discussion Starter #5
I'll ask

These guys race Camaros in their spare time; they're normally in the habit of getting things right. I'm used to tyre vibration - what was odd about this was the way it came and went in a ten-second heterodyned wave, at a constant speed.
 

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Discussion Starter #6
Even crazier than that...

The garage called up: they have been checking over the whole problem and discovered that... the tyres on the front are TWO DIFFERENT SIZES!<br> <br> So the guy who balanced the front wheels got the balance right - but one wheel was actually bigger around than the other, fractionally, at speed.<br> <br> I'm having a few well-chosen words with the place that sold me the car; they really haven't been on the ball with this one, at all.
 
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