My Micra failed its MOT on an ineffective rear left brake + handbrake. I already had all the brake service bits so this weekend I did the following:
Replaced rear wheel cylinders (they were leaking hence the inoperative brake!) with new ones
Replaced both sets of rear shoes
Cleaned the rear drums (there was no noticeable lip or groove, so no need to replace them)
Was going to change the front brake pads but the ones on the car have around 8mm of pad left on them so figured I'd leave them on (even though they were a bit manky).
Changed the front discs (standard non vented ones).
Adjusted the brake drums so that they grab on single handbrake click (so possibly a smidge too tight).
Bled the rears + topped fluid up.
Now I seem to have a problem!
I can hear a definite scrapy-ish sound eminating, directly related to wheel speed. It's not constant, but rather a 'hhwoo-hwooo' type of sound, which sounds similar to when you rotate a front wheel and the sound the pads make on the disc.
I cannot seem for the life of me to figure out what it is since… it seems to appear only when coasting!!
The noise only comes when the car is rolling at speed and you put it in neutral (or clutch in) and let it roll. If the car is accelerating or slowing down the noise goes away!
I'm completely stumped. By the fact that it only makes the noise when coasting and not when accelerating, I am inclined to believe that it's the fronts that are making it.
Please note that the brakes work flawlessly. There is no vibration, the pedal is not spongy, there is no squeaking. The car pulls up in a straight line when braking. Brakes work well when hot as well as when cold. There is also absolutely no vibration when driving the car at any speed (well, haven't tried it over about 75mph), suggesting it is something to do with the brakes rather than the roadwheel.
I'm at a loss as to what it could be..
- Loose wheel? First thought due to the nature of the sound, but nope, all wheel nuts tight as a badger's ****. Plus I have the unfortunate experience of knowing what a loose wheel sounds and feels like.
- Sticky caliper piston? Would've expected it to make that noise all the time, not just when coasting. Also looking at the old brake discs, it did not appear that there was any lip at all, and most certainly not only on one side. Also the car doesn't pull to one side!
- Warped brake disc? Ditto as per sticky caliper + would feel some vibration when braking
- Brake fluid over filled (it's almost to the top of the reservoir)? Why when coasting only though?
- Loose caliper bolts? Tightened them as per manual, but would this have such an effect? Again though..why only when coasting?
- Rear drums overadjusted? Plus I have no idea why they'd only make a noise when coasting and not when accelerating.
I'd check the last 4 points, but my dilemma is that I'm at work until it's dark and my car is parked on the street, so dismantling any drum brakes etc. won't be very easy/pleasant, so was hoping that somebody here could narrow it down.
After another drive it seems the noise is coming mostly from the front right wheel... as said previously, brakes work flawlessly. It also seems to make a kwoo-kwoo sound per each revolution of the wheel, but not evenly spaced within the revolution (suggesting it's something to do with the wheel or rotor).
I'm inclined to believe that it might be pad contamination or something to do with a sticky caliper, but would've expected some noticeable impact on performance!
My MOT retest is on Friday, and even though I don't think any of this would have any effect on my braking efficiency (since they work very well), i'd like to get it sorted ASAP.
Thanks everyone
Replaced rear wheel cylinders (they were leaking hence the inoperative brake!) with new ones
Replaced both sets of rear shoes
Cleaned the rear drums (there was no noticeable lip or groove, so no need to replace them)
Was going to change the front brake pads but the ones on the car have around 8mm of pad left on them so figured I'd leave them on (even though they were a bit manky).
Changed the front discs (standard non vented ones).
Adjusted the brake drums so that they grab on single handbrake click (so possibly a smidge too tight).
Bled the rears + topped fluid up.
Now I seem to have a problem!
I can hear a definite scrapy-ish sound eminating, directly related to wheel speed. It's not constant, but rather a 'hhwoo-hwooo' type of sound, which sounds similar to when you rotate a front wheel and the sound the pads make on the disc.
I cannot seem for the life of me to figure out what it is since… it seems to appear only when coasting!!
The noise only comes when the car is rolling at speed and you put it in neutral (or clutch in) and let it roll. If the car is accelerating or slowing down the noise goes away!
I'm completely stumped. By the fact that it only makes the noise when coasting and not when accelerating, I am inclined to believe that it's the fronts that are making it.
Please note that the brakes work flawlessly. There is no vibration, the pedal is not spongy, there is no squeaking. The car pulls up in a straight line when braking. Brakes work well when hot as well as when cold. There is also absolutely no vibration when driving the car at any speed (well, haven't tried it over about 75mph), suggesting it is something to do with the brakes rather than the roadwheel.
I'm at a loss as to what it could be..
- Loose wheel? First thought due to the nature of the sound, but nope, all wheel nuts tight as a badger's ****. Plus I have the unfortunate experience of knowing what a loose wheel sounds and feels like.
- Sticky caliper piston? Would've expected it to make that noise all the time, not just when coasting. Also looking at the old brake discs, it did not appear that there was any lip at all, and most certainly not only on one side. Also the car doesn't pull to one side!
- Warped brake disc? Ditto as per sticky caliper + would feel some vibration when braking
- Brake fluid over filled (it's almost to the top of the reservoir)? Why when coasting only though?
- Loose caliper bolts? Tightened them as per manual, but would this have such an effect? Again though..why only when coasting?
- Rear drums overadjusted? Plus I have no idea why they'd only make a noise when coasting and not when accelerating.
I'd check the last 4 points, but my dilemma is that I'm at work until it's dark and my car is parked on the street, so dismantling any drum brakes etc. won't be very easy/pleasant, so was hoping that somebody here could narrow it down.
After another drive it seems the noise is coming mostly from the front right wheel... as said previously, brakes work flawlessly. It also seems to make a kwoo-kwoo sound per each revolution of the wheel, but not evenly spaced within the revolution (suggesting it's something to do with the wheel or rotor).
I'm inclined to believe that it might be pad contamination or something to do with a sticky caliper, but would've expected some noticeable impact on performance!
My MOT retest is on Friday, and even though I don't think any of this would have any effect on my braking efficiency (since they work very well), i'd like to get it sorted ASAP.
Thanks everyone
