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Harmonic vibration?

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Hey guys,
What's with the drone that I hear when I am cruising down the highway? It seems to be most noticeable at about 2200 rpm. Must be coming from the engine. Is it indeed harmonic vibration and is it a sign of an impending problem?
Also, I was bragging on my new Michelin Hydroedge tires on my TR6. Still like them, but going across the metal grate common on many bridges is a harrowing experience, especially under wet conditions! Backing off the gas makes it worse. Must be because of the unidirection of the tread. Gave me new respect for seat belts....had to stop and get a quad cappuchino to settle my nerves.
In another post, a young man commented that he was seven years younger than his TR7. Whew!
I had been driving for twelve years before my TR6 was even made. The Triumph MAKES

Bill
 
Hello Dr. Bill,

are you certain that it is not a transmission generated noise? I'm thinking of drive shaft U\J's or propshaft U\J's. Can you feel it or just hear it?

Alec
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Piman,
I can hear it more than feel it. It is like a pulsating drone that usually manifests itself at 2200 rpm in my TR6. Sounds like it is coming from the exhaust note but sense it emanates from the engine harmony. If that makes any sense.

Bill
 
Too, it goes away upon heavy acceration from that rpm and lessens and goes away when decelerating. Methinks that would be normal, just a quirk of a straight six???

Bill
 
Hello Dr Bill,
I really don't know, and as I typically cruise at 3 to 3.5Krpm I can't say that I've noticed it.
As you say it may just be inherent.

Alec
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Hey, Dr. Bill, my GT6 has a similar harmonic sound at roughly the same rpm, around 2200-2400. It actually seems to make my ears "pop" sometimes, especially with the windows rolled up. It's prominent enough to keep me from cruising at that specific rpm.

I've been all through the entire car, engine and drivetrain during my restoration effort and I'm pretty sure there's nothing seriously wrong with the car that might cause it. But, I also have the notoriously loud Pacesetter Monza exhaust system (soon to be scrapped due to hearing loss!) which would seem to contribute to the problem.

Exhaust system seems like the culprit to me. Maybe going to wider exhaust tube diameter or a more/less restrictive exhaust would stop it?

Who knows?
 
Bill,
I the guy you responde to about the grabbing clutch. I was going to ask you about a similar problem noise in my '73 TR6. I get a bad vibration around 60 mph in the 3000rpm range. It's hard to pin point the exact location. Sometimes I think its coming from the clutch area, and other times I think it may be the wheel area. I did have the wheel balanced a while ago, but that didn't stop it. Maybe I'll try it again at a different place. Did you ever hear of a disc being out of round that might cause that. Any ideas? Did you find your problem yet? With my problem the vibration stops as soon as I go a bit faster, and it doesn't vibrate before that point.
Later,
Frank
 
Hey F. Basil, my bet on your vibration problem is your universal joints. Get under the car with the transmission in gear (and the brake on!), grab the propshaft firmly and try to rotate it: if there's play in it, there's your problem.

If so, it's potentially dangerous and should be fixed ASAP. Replace all the universal joints, not just the bad ones.

I hope this helps, let us know what you do.
 
Frank,
As per another post in this area, I am now convinced that my vibration problem is indeed the natural harmonics of a straight six engine, albeit at a different rpm range than yours. The loud exhaust system only amplifies the situation. I have dual Falcons with custom oversized tips that act as megaphones for the exhaust note. I presume that if I were running stock exhaust, I probably wouldn't notice a thing. I have, however, never noticed that noise (music) in the 3K rpm range. Like the guy with the Monza exhausts (more raucous a noise), my previous TR6 w/ Monzas gave me the same effect, and a headache to boot. I had forgotten about that. I don't think that your "vibration noise" is harmonic. Might check out your thrust washers for wear.

Bill
 
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