I have a 2005 Honda CRV (RD7), with 190k km on the clock. Over the last 10000km or so, there's been a slight hum coming (I'm pretty sure) from the rear, and sloooowly getting worse.
The specifics of the noise:
- It starts getting noticeable around 60km/h
- It peaks in volume around 70km/h
- It seems to get slightly attenuated from around 80km/h onwards
- It is worse when I have load in the rear (1-2 passengers)
- It's a really loud hum, filling the cabin, but with no specific rhythm to it
- I can't say for sure that it gets worse or better in turns
Some background:
- About 20k km ago, I put a new set of Pirelli P7s on the rear. At the time, I wasn't aware that my rear suspension was in need of some work, and the tires accordingly feathered.
- I replaced the rear shocks about 7000km ago, but the damage to the tires had already been done.
- I have checked all the other recommended sources of noise, including flushing both the transmission and rear diff - this does not seem to have materially improved the noise.
- I've had the car for almost 3 years, and do an equal mix of city and highway driving.
- I'm in Brisbane, so salty air could be a concern. To the best of my knowledge though, the car has never done any beach driving.
- Also to the best of my knowledge, the car has never done any serious towing (or carried big loads), or gone proper offroading.
In summary, I can't for sure pinpoint the noise source to bearings (usual tests like spinning, tugging, cornering have inconclusive results). I also can't get any consistent idea of how long a set of bearings on the CRV should last. The tires are definitely feathered (probably about 1-2mm ridges), but I have no idea how much noise they would contribute with all else being equal.
Based on a LOT of other posts on the net, service center and mechanic opinions on this particular issue isn't always accurate, and unfortunately I don't have the money ($500/bearing installed, $150-200/tire) to throw at the problem and hope for the best.
Any advice would be greatly appreciated!
PS - I am probably skilled enough to install the bearings myself, but they're still $150 a side, and apparently on this particular model there's an issue with getting ABS sensors out of the hub without breaking them, which will add another $50-100 per side potentially.
UPDATE
Ok, I've rotated the tires front to back, and also tested with the spare in the place of the heavily feathered tires in the back. I found:
- There is a slight reduction in overall noise, but it is not completely gone. Whether this is because there might still be a different problem, or whether it is because the feathered tires are now generating noise at the front, but resonating through the cabin, I don't know.
- With the slightly reduced noise, I tried the swerving slowly at about 60km/h trick. The noise seems to dissipate slightly when I veer right, and stays about the same when I veer left. For reference, this is a right-hand drive vehicle.
- The pitch changes slightly between about 60 and 80km/h, after which it drops in volume to about 100km/h, making it difficult to detect.
- At 100km/h, it becomes 'rhythmic' - basically coming and going at probably 1Hz or so.
UPDATE 2
Just did some more reading on tire wear patterns. It seems that the guys at the shop describing the issue to me, had their terminology wrong. What I have, is heel/toe wear, NOT feathering. It is also not related to my (previously) worn suspension, since that would likely cause diagonal wear.
Would this cause road noise as well?