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whunter
Frequent User
Username: whunter

Post Number: 21
Registered: 10-2003
Posted on Tuesday, 11 November, 2003 - 01:28 pm:   Edit PostDelete PostView Post/Check IP

This one has me curious, I would suspect mounts, axle shafts or exhaust vibration.
Any suggestions or comments are most welcome.

Larry
Guest
Posted: Mon Sep 01, 03 4:14 pm Post subject: hum/resonance problem in '89 Spur
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I've had my 27593 LHD '89 Silver Spur for about 1.5 years, and have been trying to figure out this evenly pitched hum that you can feel in your feet, but not the steering wheel. As a hopeful cure, the front wheel bearings were replaced but this didn't work.

It occurs at about 35, then stops until about 45, and then stops until about 55, etc. Releasing the gas pedal, or accelerating doesn't affect it. Oddly enough, at one point turning to the right increased its occurance, and to the left didn't affect it, now it is reversed where turning to the right reduces it & left increases its occurance.

Obviously driving me nuts, does this sound like any of the typical Spur problems? The car has just turned to 60,000 miles and all correct maintenence is up to snuff. If you like, you can email me as well to tbird@consultant.com
Thanks,
Larry

Thank you.
whunter
RROC, Lake Michigan, Motor and Ohio region.
ASE Master Mechanic
Bloomfield Eurotech
45671 Woodward Avenue
Pontiac, MI 48341
Work Phone 248-334-6400 Fax 248-334-2363
asemastermechanic@juno.com
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William H. Trovinger II
Prolific User
Username: bill_trovinger

Post Number: 41
Registered: 8-2003
Posted on Tuesday, 11 November, 2003 - 03:22 pm:   Edit PostDelete PostView Post/Check IP

Have not had this problem on my SS. However, had the very same thing same speeds and everything on my 4x4 Jeep. We even tried wheel bearings first and replaced the whole front LH hub. In that case it turned out to be U-joint to front left wheel.
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Larry
Unregistered guest
Posted From: 68.195.74.199
Posted on Wednesday, 12 November, 2003 - 11:56 am:   Edit PostDelete PostView Post/Check IP

Well, its a tough thing to describe in words. If any of you guys find yourself in Long Island, NY - I'd love to let you drive it. (Don't know of ANY other technical owners in my area)

On that 4x4, being on the front wheel U-joint, didn't you feel it in the steering wheel? It wasn't more of a thumping vibration, rather than a resonance?

Thanks for your interest!

Larry
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William H. Trovinger II
Prolific User
Username: bill_trovinger

Post Number: 42
Registered: 8-2003
Posted on Wednesday, 12 November, 2003 - 03:07 pm:   Edit PostDelete PostView Post/Check IP

Larry;

No there was no feeling of it in the steering wheel at all. Also when I put the car up and played with the u-joint it seemed tight. Well as tight as a Jeep's suspension should feel, they are loose right from the factory, as they are designed for off-road use unlike so many of the SUV's out there today. This is how we ended up wasting the time and money replacing the hub first.

I would find this very unlikely, as you do not feel it in the steering. However, just to be sure you have had the tires (sorry tyres) checked for uneven wear and balance?

Good luck,
Bill
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David Gore
Moderator
Username: david_gore

Post Number: 141
Registered: 4-2003
Posted on Wednesday, 12 November, 2003 - 07:24 pm:   Edit PostDelete PostView Post/Check IP

Larry,

What brand and type of tyre [tire] do you have on your car?

Can you find another Spur in your area and try swapping the tyres to see if this has a effect.

Earlier cars were very susceptible to tyre induced harmonic vibrations - the NSW R-R service dealer apparently kept a set of known goood tyres for testing cars when the owner complained of vibrations and the owner's tyres were usually found to be at fault - the solution was to dynamically balance the wheel/tyre/hub assembly on the car - dynamically balancing the rim/tyre on its own as done by the trye fitter was not good enough.
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Larry
Unregistered guest
Posted From: 68.195.74.199
Posted on Thursday, 13 November, 2003 - 07:20 am:   Edit PostDelete PostView Post/Check IP

Hi David,

I originally had the Bridgestone Duelers, and changed them to Yokohama Aegis LS-4. The resonance characteristics seemed to be the same.

Here's some info on them:

http://www.tirerack.com/tires/tires.jsp?tireMake=Yokohama&tireModel=Aegis+LS4

Here they are on the car when its not resonating:

http://mutley.hypermart.net/VandMyRolls.jpg

They were balanced off the car, as I haven't found anyone I trust with equipment to balance them on the car.

Would those "tire induced harmonic vibrations" come and go in the intervals I have described?

Also, wouldn't I feel it in my steering wheel?

Thanks for your suggestions!

Larry
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David Gore
Moderator
Username: david_gore

Post Number: 142
Registered: 4-2003
Posted on Thursday, 13 November, 2003 - 08:09 pm:   Edit PostDelete PostView Post/Check IP

Hi Larry,

Good try but you are using a hub/wheel combination that is probably responsible for the problem - just changing the tyres [tires] is not sufficient; this why the R-R dealer had a known set of good tyres to exchange on the owners vehicle.

The harmonic vibrations have definite cycles as you describe; at certain speeds they reinforce each other and the vibration becomes noticeable, in between these speeds, the vibrations cancel each other out and no vibration is evident. If you can remember high school physics or ever been a serious musician, you will recall how standing waves interact to reinforce or cancel each other.

These vibrations are usually low enough to not be transmitted through the steering wheel as the damping in the steering system is sufficient to absorb the vibration.
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Richard Treacy
Prolific User
Username: richard_treacy

Post Number: 69
Registered: 4-2003
Posted on Thursday, 13 November, 2003 - 09:37 pm:   Edit PostDelete PostView Post/Check IP

Are you running Avon tyres ? They are notorious for being impossible to balance off the car. I bought 17" rims and Michelins for my Turbo R to overcome the rotten vibrations. I suggest you borrow a colleague's wheels and try them out. That may reveal all.
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Larry
Unregistered guest
Posted From: 68.195.74.199
Posted on Friday, 14 November, 2003 - 04:47 am:   Edit PostDelete PostView Post/Check IP

Hi Richard,

My post above shows exactly the tires I have. They are Yokohama, and there is a link to a site that rates them. Some on that site have called them "noisy" since the time I bought them.

Hi David,

I see what you're saying about harmonic vibrations/resonance. I thought that by changing tires (which I needed anyway), at least the characteristics of the resonance would change. Having not changed, I eliminated tires. Maybe I jumped to quickly to dismiss them.

Would a rear wheel bearing cause the identical symptoms?

Thanks,

Larry
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Bill Coburn
Prolific User
Username: bill_coburn

Post Number: 74
Registered: 4-2003
Posted on Sunday, 16 November, 2003 - 10:41 pm:   Edit PostDelete PostView Post/Check IP

One snippet on tyres. Spirits in particular had a nice little habit of spinning their rims in the tyres, so you balance and the tyre moves and it is no longer balanced. Worthwhile a tyre mark to keep an eye on this little foible.

As to the vibration I would be tempted to hoist the car on stands so that the wheel geometry is normal and run the car up to the speeds you mention observing the car from outside. It would be worthwhile to have a stethoscope handy.

You may be interested in a problem I had recently with a 1987 Spirit which had noticeable vibration at various speeds that certainly literally showed at the steering wheel. New tyres (I always use Bridgestone R375's)fully balanced - no difference. The frequency suggested tailshaft and I was getting ready to replace the rubber joints on the tailshaft but they showed no sign of breakdown. At that point the transmission failed (no reverse or top gear) and was removed for overhaul. Apart from the intermediate band having ripped itself from the box anchor,the most noticeable defect was the severe wear on the centre support and reaction carrier. The internal bush was grossly worn to the extennt that the intermediate Clutch was actualy striking the intermediate sprag assembly. All bits were replaced and the box replaced. Performance was to specs and guess what - the vibration had disappeared. A new one on me and apparently on the specialists who did the work.

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