Brake or Transaxle noise at low speed?

[bmillerbiop]

I have a 2004 Prius with high-mileage (125,000) and have been noticing several odd noises at low speed. (My dealer doesn't provide much insight w/o an expensive diagnostic) (FYI - the transaxle fluid was full and not overly burned at 120K, dealer says brakes are good, and CV joint boots are not broken).

1) Since about 60K miles, a scraping/chuffing sound like a dry bearing that occurs below about 15 mph, sometimes only on turns, sometimes when traveling straight, sometimes is silent. (disk pad contamination?)

2) When coming to a stop while turning, below 5mph, there is a regular ticking noise kind of like bad CV joints, but it only occurs when brakes are applied. (regenerative braking system?)

3) At very low speed (e.g. even when I push the car in neutral), there is an occasional whirring sound, like a small gear-driven armature that sounds like it's in the hub and directly correlates with the speed of the wheel. (antilock braking sensor?)

The corker is that all of these are intermittent, so it's hard just to drive up and show a mechanic. Nothing is smoking and screeching, but I do a lot of long-distance driving and would hate to be out in the boonies and have something lock up and blow at 70 MPH.

Anyone have some insight?

Thanks in advance,
Bill M.

[Bill Lumbergh]

You may have some noise from the brake pads rubbing across the rotor, even without the brakes actually applied. periodically we'd see this on Hondas at the dealership where I worked. We'd simply pull the pads, put a liberal dose of anti-seize on the backings and slap it back together.

I think as time goes on the pads tend to loosen up in the mounts. Still on your first set?

I've also seen new pads, straight from the dealer, that made horrible noise when they got warmed up. If a close inspection of the front brakes reveals nothing, I wouldn't sweat it. You've got pretty high mileage!

[bmillerbiop]

Thanks! Yeah they're still the original pads at 125K - amazing! (My Acura Legend used to go through 'em every 20-25K miles.

Any thoughts on the other noises?

[galaxee]

if you can hang on till tonight i'm sure DH will be interested to read and contribute his opinion, if he's not too tired.

[galaxee]

<div class='quotetop'>QUOTE(bmiller @ Apr 24 2007, 04:38 PM) [snapback]429259[/snapback]</div>

I have a 2004 Prius with high-mileage (125,000) and have been noticing several odd noises at low speed. (My dealer doesn't provide much insight w/o an expensive diagnostic) (FYI - the transaxle fluid was full and not overly burned at 120K, dealer says brakes are good, and CV joint boots are not broken).

1) Since about 60K miles, a scraping/chuffing sound like a dry bearing that occurs below about 15 mph, sometimes only on turns, sometimes when traveling straight, sometimes is silent. (disk pad contamination?)

2) When coming to a stop while turning, below 5mph, there is a regular ticking noise kind of like bad CV joints, but it only occurs when brakes are applied. (regenerative braking system?)

3) At very low speed (e.g. even when I push the car in neutral), there is an occasional whirring sound, like a small gear-driven armature that sounds like it's in the hub and directly correlates with the speed of the wheel. (antilock braking sensor?)

The corker is that all of these are intermittent, so it's hard just to drive up and show a mechanic. Nothing is smoking and screeching, but I do a lot of long-distance driving and would hate to be out in the boonies and have something lock up and blow at 70 MPH.

Anyone have some insight?

Thanks in advance,
Bill M.
[/b]

have you had the backing plates for the front brakes checked? wheel bearings? check the backing plates by lifting the front end and spinning each front wheel. you'll hear a scraping sound. you can check out the wheel bearings by driving down the road, and pulling the steering wheel left to right. you should hear the noise stand out more in this situation. just don't get pulled over for erratic driving!

[qbee42]

Regen braking is not a factor at low speeds, so it's not that. As for hearing a noise when pushing in neutral, remember that the Prius never disengages the transmission from the drive train; there is no real neutral in the conventional sense. You are still spinning MG1 and MG2. I would look at the brakes and bearings.

Tom