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Discussion Starter #1
Had my car in for what I thought would be a wheel bearing swap today. But they checked and found no noise from the bearings, albeit without any load on them spun with the car on the lift. They did find some cupping to the front tires, but also did an alignment check and found everything within spec. So, any ideas where this rumbling sound is coming from? It is definitely rotational with the tire rotation frequency, not engine or driveline (it's there also when coasting w/clutch in or trans in neutral, with no brakes applied), but what else could it be? It sure sounded like bearings. Is it possible they only make noise when under load but not on the lift? My indy is super and basically talked me out of a bearing swap rather than take my money. He doesn't have suggestions other than possibly going to different tires in the future (presently using Goodyear F1 GSD3s). I have heard that the Goodyears can get noisy after a while. Also, I recently installed new rotors, but can't see how these could cause noise.
 

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I would guess it is tire noise, especially if it is a low rumbling sound at slow speeds.
 

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+1
 

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Differential bearings?
 

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its either a bad tire or a sturt... if you have weak strut or a bad strut mount you will definatly get cupping of the tires... but from the sound of it, it's most likely a tire with a belt shift, both situations will cause cupping of the tires... get the tire and the struts checked out... im calling a tire with a belt shift!!... good luck!
 

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. They did find some cupping to the front tires, but also did an alignment check and found everything within spec.
Then something else is amiss. I would suspect worn shocks if all the bushings are good.

So, any ideas where this rumbling sound is coming from? It is definitely rotational with the tire rotation frequency, not engine or driveline (it's there also when coasting w/clutch in or trans in neutral, with no brakes applied), but what else could it be?
I am trying to think if it could be guibo, it is rotational. If you think tires (perhaps because of the cupping), swap left and right and remount inside out so they are facing the same way, but the cupped side ( I assume outside) is now on the inside. If the noise is different, then it is tires.

Good luck.
Regards,
Jerry
 

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Had my car in for what I thought would be a wheel bearing swap today. But they checked and found no noise from the bearings, albeit without any load on them spun with the car on the lift. They did find some cupping to the front tires, but also did an alignment check and found everything within spec. So, any ideas where this rumbling sound is coming from? It is definitely rotational with the tire rotation frequency, not engine or driveline (it's there also when coasting w/clutch in or trans in neutral, with no brakes applied), but what else could it be? It sure sounded like bearings. Is it possible they only make noise when under load but not on the lift? My indy is super and basically talked me out of a bearing swap rather than take my money. He doesn't have suggestions other than possibly going to different tires in the future (presently using Goodyear F1 GSD3s). I have heard that the Goodyears can get noisy after a while. Also, I recently installed new rotors, but can't see how these could cause noise.

it is possible but not probable or not likely that the bearings only make noise under load.. if its on a lift and you spin a wheel or a hub of a bad bearing you will hear and feel the ruffness of a bad hub bearing...
 

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and if you say ur indy is super... and he is as good as i am, lol, then hes more then likely right and u should trust him... i can't know 100% without seeing the car, but im tellin you what i know...
 

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Discussion Starter #9
Thanks for the replies, guys. I'm thinking tires, too, but not struts. While it is possible a strut went bad, these are Koni FSDs with less than 15k miles on them. I have another pair of wheels/tires in the garage (my OEM rears which I used to run up front; yes, another story - gotta go find where I put those spacers and longer lug bolts now), so when I get time I'll mount 'em up again and see if the noise goes away.

BTW, interesting alignment readout (I asked them to check it out b/c of the cupping). Ride height is spec'd at 573mm rear, and the measured height was 583mm, 10mm taller than stock with FSDs and stock rear springs. Ride height front is spec'd at 600mm, and measured at 590mm with H&R springs and Dinan camber plates, so it sits 10mm lower in front for a +20mm rake front to rear (compared to stock). Yet, visually the front looks much lower than just 10mm lower than spec. Must be the rake. Front camber with Dinan plates and H&R springs comes out to -1.9 degrees. I wonder if the rake or neg. camber has anything to do with the cupping?
 

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Had my car in for what I thought would be a wheel bearing swap today. But they checked and found no noise from the bearings, albeit without any load on them spun with the car on the lift. They did find some cupping to the front tires, but also did an alignment check and found everything within spec. So, any ideas where this rumbling sound is coming from? It is definitely rotational with the tire rotation frequency, not engine or driveline (it's there also when coasting w/clutch in or trans in neutral, with no brakes applied), but what else could it be? It sure sounded like bearings. Is it possible they only make noise when under load but not on the lift? My indy is super and basically talked me out of a bearing swap rather than take my money. He doesn't have suggestions other than possibly going to different tires in the future (presently using Goodyear F1 GSD3s). I have heard that the Goodyears can get noisy after a while. Also, I recently installed new rotors, but can't see how these could cause noise.
check ur rack opini:M5eyes:eek:n
 

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Interesting, I had a noise like this 2 weeks ago, a low but quite loud hum that varied with road speed not engine revs.

Diagnosed as tyre noise and wheel bearing noise (nearside). Two new fronts and a bearing, not cheap but effective.
 

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Discussion Starter #12
Interesting, I had a noise like this 2 weeks ago, a low but quite loud hum that varied with road speed not engine revs.

Diagnosed as tyre noise and wheel bearing noise (nearside). Two new fronts and a bearing, not cheap but effective.
How many miles on your tyres/bearings before the replacement?
 

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How many miles on your tyres/bearings before the replacement?
Indy says the bearing was original and the car has done 133k miles so I think that's pretty good. The offside bearing is still good (checked with stethascope). Tyres had done 28K miles and were worn out.

He maintains that nearside bearings invariably wear out before offside due to more load being applied (overtaking/roundabouts etc) per mile of travel.
 

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Discussion Starter #14
Update: Well, I confirmed it's not the wheel bearings, not that I really doubted my indy, but I had to rule out the wheel bearings. So I removed my OE front wheels and mounted up my spare pair of OE rears (which have been sitting in my garage shod with the same kind of tires - F1 GS-D3s but in 275mm size, worn about 50% also, more or less), and voila. No more noise. (Good thing I kept my second pair of OE rear wheels/tires, and didn't sell them!)

So the problem has to be in the tires/wheels, as that's the only thing I changed and the noise went away. The OE-sized front wheels do not look bent and I don't recall hitting anything that would put such forces on them to bend anything. The tires look like they are worn evenly about 1/2 way through the tread or less, and there are no visible signs of any damage. I have sent a message to the TireRack to see what if anything can be done. I do recall some people saying GS-D3s get really noisy when they are highly worn, but I would expect that kind of noise to be more constant. What I hear is a rumbling and periodic "thumping" or noisy bearing-like sound (with the OE front wheels and stock size 245mm GS-D3s).
 

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Update: Well, I confirmed it's not the wheel bearings, not that I really doubted my indy, but I had to rule out the wheel bearings. So I removed my OE front wheels and mounted up my spare pair of OE rears (which have been sitting in my garage shod with the same kind of tires - F1 GS-D3s but in 275mm size, worn about 50% also, more or less), and voila. No more noise. (Good thing I kept my second pair of OE rear wheels/tires, and didn't sell them!)

So the problem has to be in the tires/wheels, as that's the only thing I changed and the noise went away. The OE-sized front wheels do not look bent and I don't recall hitting anything that would put such forces on them to bend anything. The tires look like they are worn evenly about 1/2 way through the tread or less, and there are no visible signs of any damage. I have sent a message to the TireRack to see what if anything can be done. I do recall some people saying GS-D3s get really noisy when they are highly worn, but I would expect that kind of noise to be more constant. What I hear is a rumbling and periodic "thumping" or noisy bearing-like sound (with the OE front wheels and stock size 245mm GS-D3s).
Forgot to mention that although diagnosed as tyre and bearing noise, the tyres were replaced immediately as they were worn out and the bearing was replaced two days later. Thing is, the rumbling noise was 95% cured by tyre replacement and the bearing noise was only really noticeable when steering into a bend.
 

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What I hear is a rumbling and periodic "thumping" or noisy bearing-like sound (with the OE front wheels and stock size 245mm GS-D3s).
See if you can isolate it to one specific front tire. If both of them seem to be contributing to the tire noise, then it's possible that this is just typical "tire roar" making itself known as they wear. On the other hand, if one tire is much louder than the other, it might have a tread-belt separation issue evolving. You're comment about the "thumping" noise is what would worry me about that possibility. If the noise is periodic in nature in a pronounced way, it probably isn't typical wear-induced noise.

Chuck
 

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... if one tire is much louder than the other, it might have a tread-belt separation issue evolving. You're comment about the "thumping" noise is what would worry me about that possibility. ...
+1
 

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Discussion Starter #18
You're comment about the "thumping" noise is what would worry me about that possibility. If the noise is periodic in nature in a pronounced way, it probably isn't typical wear-induced noise.
Because the noise went away with the wheel/tire change, that's what I suspect, too. I don't have time to isolate it as between left and right side until this weekend. (Right now I'm running on 4x275s with OEM rear wheels all around. Man, I forgot how much grip those 275s have up front! If it weren't for the marginal clearance issues I have, I would be keeping them on there!)

Guess I'll swap one side first, drive it, then swap the other. Maybe I'll get lucky and find out it's only one of the two that has the thump issue. But according to TireRack, the mfr defect coverage expires after 2/32" wear, and I'm probably below that so I'm probably on my own for replacements. I suppose I could just buy another tire, but don't like having one brand new and the others half worn. So that means at least two. And I'm not so sure I like how noisy these got when worn 1/3 to 1/2 way down (though my "spare" pair of OEM rears w/275s I've got on the car right now are easily more worn than these OEM fronts w/245s, and they're quiet!). Maybe I should go to the Eagle Asymmetrical F1s but I'm not wild about different tires front/rear, either, though maybe the Asyms are close enough in characteristics that it won't matter much. Perhaps I should just leave the OEM rears with 275s up front, wait until they wear out and then replace them with 265s and continue to run the OEM rear wheels, and forget about replacing the defective 245s on the OEM front wheels. If it weren't for the possible belt separation safety issue, I'd probably just live with the noise or have the tread shaved/trued on the OEM fronts as a way to help reduce noise (on directional tires, it's my understanding they get noisy if the tread is a bit unevenly worn, so truing them could help make them quieter).

Some questions. How does a tire store examine the tires for belt separation? Do they just spin them on a balancer or do they need them on the car to see if the circumference is bumpy instead of round? Do they put them on a machine? Is it possible just to take them to a shop while they are still off the car and test them on a machine rather than have to put the wheels back on the car again? It certainly would be more convenient to just haul them to the store while they're still off the car.
 
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