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Road/hub bearing/gear noise at about 35-40 mph

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by speedy7, Apr 20, 2014.

  1. speedy7

    speedy7 Junior Member

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    2005 with 106K miles, newish Michelin Defender XT tires

    I had both front hub bearings go out on me recently and replaced them with a Moog and a Timken unit (2 weeks apart). After replacement, I still notice what sounds like dry bearing or gear noise at 35-38mph, starting at about 25. There could also be tire noise mixed in. I don't drive this car normally, so it's hard for me to figure if this is normal noise for this car. I know the tires and low sound deadening on a Prius makes it much noisier than other cars, but even so, I just want to make sure there is no well known issue with other components. When the car gets up to highway speeds, that noise is masked by regular road and engine noise and the overall noise level is about what you would expect for a car like this. The noise at low speed remains the same whether in straight line or in a turn, or with the engine in neutral.

    Any feedback on this low speed noise is welcomed....
     
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Check the transaxle ATF fluid level, and better yet, replace the ATF if this had not been done over the last 60K miles.
     
  3. speedy7

    speedy7 Junior Member

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    That was my next thought, based on some further reading. It has not been replaced as I don't think I saw it on the maintenance schedule yet. Though, if it's making this noise, it's probably a bit late..... :(
     
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Yes - well if you see lots of metal shavings on the drain plug magnet and nasty-looking drained ATF then you'll know there is something wrong with the transaxle bearings, but as long as it continues to function it would be reasonable to live with the situation as-is - since the problem is only apparent at lower speeds.
     
  5. speedy7

    speedy7 Junior Member

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    Well, I did a quick check at the fill plug and there is plenty of ATF and it doesn't smell burnt or anything. It is a bit dark, but I suppose that's to be expected after 100k miles. I will change it regardless and will get to check the drain plug magnet at that time.

    I have to say I'm a bit disappointed in a Toyota needing both front hubs and having a noisy transaxle at just 100k miles.
     
  6. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Yes - well if you have not owned that car for too long, then who knows how it was driven previously. Maybe the prior owner thought the Prius was a Jeep and repeatedly drove through water deep enough to submerge the bearings. If so, that would not encourage a long service life.
     
  7. speedy7

    speedy7 Junior Member

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    I've owned it since new and it hasn't been abused...

    I hear that all these newer cars now use ball bearings instead of roller bearings, and while it reduces resistance a little bit, it also wears down faster due to less surface area in contact. That, coupled with the difficulty in removing the hub from the steering knuckle makes for higher costs and hassles for owners...
     
  8. Patrick Wong

    Patrick Wong DIY Enthusiast

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    So, did you actually remove each steering knuckle and press the bearing out? I guess so, since you mentioned you used Moog and Timken bearings.
     
  9. speedy7

    speedy7 Junior Member

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    Yes, there is no way of removing the hub without removing the whole knuckle, which is relatively easy. The steering knuckle looks like aluminium and the hub is steel, and the different metals seem to have a reaction that almost fuses the two together. Toyota coated the surfaces with something, but it didn't help. I had a 6 ton press, but couldn't press it out and actually bent my press in the process. In the end, it took a sledgehammer to separate the two.
     
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  10. Patrick Wong

    Patrick Wong DIY Enthusiast

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  11. speedy7

    speedy7 Junior Member

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    Huh, I wonder if that was a result of the difficulty the service folks had in getting the hub off. The factory manual has a procedure for replacing the hub, and the part is available from Toyota, so it is designed to be replaced separately from the knuckle. I think if I had a beefier press, it would have been easier. This method of attaching the hubs to the steering knuckle is pretty common on many cars, but it was the dissimilar metal reaction that caused all the problems. I've changed out similar hubs like this on cast iron knuckles without any problems.

    The sledgehammer is not my preferred method, but by making a hardwood cradle for the knuckle, and using a load spreading brace to hammer on the hub, nothing was damaged. The first one took most of the weekend to figure out how to separate, the 2nd one took 4 hours start to finish for the whole job....
     
  12. KhaPhoRa

    KhaPhoRa Member

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    I used a similar setup with two blocks with wood over it.. 8lb sledge using the axle nut socket as a punch and they popped out.


    the Seahawks training facility ?
     
  13. Patrick Wong

    Patrick Wong DIY Enthusiast

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    You are correct. I bought the front hub/bearing in 2009 (part number 43510-47011) for $67.69 (MSRP of $89.07); but did not need to use that part. I see that the pricing is now double: $134.97, MSRP of $179.96 at AutoNation Toyota Gulf Freeway (Houston):
    2004 Toyota Prius Parts - AutoNation Toyota Gulf Freeway Parts


    Do you recall the pricing you paid for the two hub/bearings that you installed?

    Can your hydraulic press still be used after being bent; or was it damaged to the point where you no longer can use it?
     
  14. speedy7

    speedy7 Junior Member

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    I paid $149 for the first Moog part from a local AdvancedAuto since I was in a hurry. The Timken part came from RockAuto for $119 shipped. So THAT'S what the old ToyotaWorld site is now called!

    The press was a cheap 6 ton one from Harbor Freight that I paid $50 for, but unfortunately it was not beefy enough. I plan on straightening it as it is still useful for less heavy duty jobs. The 20 ton press would probably do the job, but is much bigger and takes up more room.
     
  15. speedy7

    speedy7 Junior Member

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    So I replaced the trans-axle fluid with Toyota WS ATF today. The old fluid was dark, but didn't smell burnt. The drain plug magnet has some super fine black carbon like material on it, that's it. So it doesn't look like my trans-axle is falling apart, but the fluid change resulted in no change in the noise. At this point, it looks like these are my possible causes:

    1) Bad new hubs? Unlikely as they seem to spin smoothly and quietly after I put them on
    2) Tires? I swapped the front and back tires with no difference in the noise. There is no noise coming from the back.
    3) CV/drive shafts? It's possible, though the boots are not torn and there is no clicking noise on turns or anything. Is there any history of these CV shafts going?
    4) Trans-axle wear? Could it be after 100k miles, this is what the trans-axle sounds like? Could the CVT transmission be more susceptible to these types of noises as it wears? This is my first car with a CVT transmission and I have no idea how well they wear or what noises they make when they do.

    I've gravitating towards #4 and fear that I may have to put up with it. Maybe I am too sensitive. The wife, who drives it daily thinks it's been like this for a long time and is normal, but then she never heard the wheel bearings falling apart either! :)
     
  16. Patrick Wong

    Patrick Wong DIY Enthusiast

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    If your wife doesn't have a problem with the noise and it doesn't get worse, then it sounds reasonable to live with the situation as-is. I don't think the CV joints would cause the noise.
     
  17. KhaPhoRa

    KhaPhoRa Member

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    the Seahawks training facility ?
     
  18. speedy7

    speedy7 Junior Member

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    After 2 years and about 35K miles, I have an update on the noise. It was the Moog hub! I found this out because that hub started making a racket recently (after only 35k miles) and I swapped it out for a Timken unit. Now, it is like when it was new, with no excessive noise. That Moog hub must have been a POS and was making bearing noise even when it was new!
     
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  19. ILuvMyPriusToo

    ILuvMyPriusToo Senior Member

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    Glad you tracked it down. Yes, bearings seem to be a problem - I had to have my front right replaced after only about 65K. Terrible Engineering/QC.
     
  20. Lucifer

    Lucifer Senior Member

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    Was reading the post and suspected one of the new hubs was at fault, going by the sound and the mph, both my gen 2+3 needed front bearings at 40,000, sucks but what you make on the popcorn you lose on the peanuts.