quality of brake discs...does it matter?

Ramanujan

Hi,
I've had my first set of disk brakes for a few months now (Avid BB7's)
At first I had some cheap 160mm shimano disks and the stopping power was hardly any better than caliper brakes (I use them exclusively on the road). I was so disappointed with them that I got a pair of 180mm disks (again cheap-ish Shimano ones) and they are a hell of a lot better and stopping power is great. However no matter what i do I can't get them to stop squealing (yes, I've tried everything).
I was wondering what the advantages are of better quality disks? If I paid for better quality disks would I get better stopping power and quieter braking?

thx!

guandax

In my experience squeaky brakes have always been down to contaminated rotors or pads. I now always remove my wheels or cover the rotors with Tesco bags when using aerosol/spray oil. There are a few good articles worth reading in Tech FAQ section such as http://www.bikeradar.com/forums/viewtopic.php?f=40073&t=12674934 and http://www.bikeradar.com/forums/viewtopic.php?f=40073&t=12666026

Good luck.

Al

cooldad

Simple answer - no.

Chunkers1980

Not really to actual power, but holes ect can effect them as well as heat disputation

cooldad

But Shimano are good quality, and have plenty of metal - unlike some expensive blingy lacy things.

thelonegroover

I had a bike with Avid BB7's, they didn't squeal at all, however, another bike with Avid Elixir 5's did. No matter what I did I couldn't stop them squealing. I think my current Shimano Deore brakes are much better.

The Rookie

The avid CPS washer system reduces the mounting stiffness and makes them more prone to squealing, my old Juicy's used to howl like a Banshee when I had my lightweight alligator disc, swapping to a stiffer disc stopped it, when I went to a shimano IS mount caliper (so much stiffer mounting) I can fit the alligator and it makes no noise.

I do not believe (nor has anyone been abled to explain why it does in a way that then stood up to interogation) that contamination makes a disc brake squeal, a squeal is something resonating at it's natural frequancy, sintered pads are worse than organic (organic having more hysterisys and act like a damper).

Squealing can be made worse by badly aligned calipers or pads not worn 'square'. Avid BB7's usually give excellent performance when adjusted correctly, as good as most Hydro's.

levolon

here you go , save me arguing

http://www.pinkbike.com/news/Tech-Tuesd ... -2011.html

cooldad

Not often I agree with cyd but...
My theory on brakes in general is that people fark around with them too much. Give them a rinse with a hose now and then, change pads as required, otherwise just leave them alone.
My current ones on my main bike are 5 years old, never needed anything other than new pads.
Couple of Shimano sets - replaced fluid after 5 or 6 years of hard use on one bike. Never touched the other.
Some 10+ yr old Hopes - one fluid change although not used much now.
Just leave them alone, they squeal sometimes - ride them, hose them, it goes away until it comes back and goes away again. Etc.

thelonegroover

I'm not quite sure you are correct. I notice the frequency of the squeal stays the same but it's the volume that changes as speed changes. Disks squeal because the relevant frequency has been reached, the squeal gets louder because the amplitude increases not the speed. You could try installing some thin gasket type material between the disk and the wheel. Or install slightly thicker or thinner disks.

The Rookie

Sound frequency is unrelated to speed as it's something reaching it's resonant (not relevant!) frequancy.....

Giraffoto

Didn't we have this conversation some time ago, and in the same circumstances (guy asks a question, gets it answered straight away, thread turns into a long running debate over what makes disks squeal)?

Relevant stuff:

Ramanujan wrote:

If I paid for better quality disks would I get better stopping power and quieter braking?

cooldad wrote:

Simple answer - no.

and . . .

cooldad wrote:

My theory on brakes in general is that people fark around with them too much.

thelonegroover

Some members like to expand and elucidate sometimes. Agreed, the simple answer may well be ‘no’ however some things aren’t quite as black/white or yes/no.

The Rookie

lon 456 wrote:

here you go , save me arguing

http://www.pinkbike.com/news/Tech-Tuesd ... -2011.html

So it says contamination with no explanation how....like I said, doesn't stand up to interrogation.

And I did all it said, no difference with the Juicy's, and I once worked on a car where you could get the brakes to howl like you wouldn't believe, small mass added by the brake supplier (Brembo) to the pad and they were silent as church mouse.....it's all about resonances, because Avid aren't going to admit they will squeal by design are they?