Hydraulic Disc Brakes

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pickerd1
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Hydraulic Disc Brakes

Postby pickerd1 » 19 Oct 2015, 10:40am

I have disc brakes fitted to a few bikes now. Two have TRP HY RD fitted and one has Hayes mech disc fitted.
With both the TRP HY RD fitted bikes I experience a lot of 'judder' under heavy braking, with the mech disc equipped bike I don't experience this.
Prior to fitting the TRP HY RD brakes there was no judder.
All the bikes are designed for disc brakes.

I have tried the following to attempt to remedy the problem ...
1 - replacing the rotor in case it is warped or uneven.
2 - adjusting the wheel bearings in case they are loose
3 - adjusting the headset beatings - initially I tightened the top nut to 2Nm, but I tried going up to 4Nm
None of these things made any difference.

I suppose disc brakes put more force on headset bearings than rim brakes as they have more mechanical advantage as the braking point is further away from the bearing and they are more powerful?? Hydraulic discs are probably even more powerful?

Is this a common problem?

Are there any solutions?

rmurphy195
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Re: Hydraulic Disc Brakes

Postby rmurphy195 » 19 Oct 2015, 11:16am

Tried this? https://www.youtube.com/watch?v=1T2RLgQoyvs

Also consider swopping to sintered discs if you are using organic - my be shop did this to cure a similar problem on mine. But I'd look at careful alignment first.
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""You know you're getting old when it's easier to ride a bike than to get on and off it" - quote from observant jogger !

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NATURAL ANKLING
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Re: Hydraulic Disc Brakes

Postby NATURAL ANKLING » 19 Oct 2015, 11:44am

Hi,
I am not conversant with hydraulic brakes on cycles at all and little experience with disc brakes on my bike which I have been riding for some months.
Though have worked extensively on cars and motorcycles for nearly forty years.
Never seen that problem on motor vehicles which I worked on myself.

Vibration is either lose or malaligned parts / warped /non manufacturer recommended parts :?:

In the video it suggests that the parts be faced with fancy tools.
In my opinion this is to correct badly manufactured parts that should never be there, quality control needs to be investigated as these are brakes........

You need to look closely at alignment of pads / callipers first, then the disc which even new might be warped / integrity of mounting?

Quality control is necessary in ALL machined / made parts to ensure suitability and of course quality for end user.
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Brucey
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Re: Hydraulic Disc Brakes

Postby Brucey » 19 Oct 2015, 6:27pm

the #1 reasons for judder are contamination and disc thickness variation (new discs are never perfect...).

Discs can be really quite warped and not cause judder, but the slightest thickness variation will cause it. Often the two things go hand in hand because a warped disc soon wears on the high spots and then becomes uneven in thickness.

That the brakes judder with the HyRd brakes may indicate that they need bleeding out (even a tiny air bubble will work like a spring).

If you fit a disc to the front that has been run on the rear for a while, it ought to be worn so that it has a consistent thickness. This will reduce the chances of judder. Using more abrasive pads will help too.

Other things that can make a difference are

- fingerprints on the disc
- tiny splashes of lube or polish on the disc
- contamination in the solvent that you use to clean the disc
- contamination of the pads
- caliper alignment
- pad wear (tapered pads can do weird things in hydraulic systems)
- loose bolts

but I'm sure there are others too...

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

pickerd
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Re: Hydraulic Disc Brakes

Postby pickerd » 19 Oct 2015, 7:24pm

Discs are used and on installations that previously did not judder.
Similarly the calipers worked ok so probably not air in line.
I'll try cleaning and aligning.

pickerd
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Joined: 22 Mar 2015, 7:01pm

Re: Hydraulic Disc Brakes

Postby pickerd » 19 Oct 2015, 7:25pm

Can't be air in line on HY RD can it!!!!

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NATURAL ANKLING
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Re: Hydraulic Disc Brakes

Postby NATURAL ANKLING » 19 Oct 2015, 8:18pm

Hi,

http://singletrackworld.com/forum/topic ... ake-judder :?:

https://yacf.co.uk/forum/index.php?topic=72021.50

You are not alone it seems.

It would be interesting to look at pads and see how they have worn?
Did it do it from new pads?
If the pads are wearing at an angle this might tell you some thing like the whole mechanism is flexing under braking, which is not good.
I would start with looking at pads and work on to aligning them onto disc (sitting flat) if the pads are flat to start with?
If You Don't Try You Don't Do.....Don't Do You Don't Get...I'm Still Trying....Well Very..
You'll Find Me At The Top Of A Hill...............Somewhere...After Dark..

Brucey
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Re: Hydraulic Disc Brakes

Postby Brucey » 19 Oct 2015, 8:26pm

pickerd wrote:Can't be air in line on HY RD can it!!!!


I don't see why not; it is an 'open' system, just writ small. If there is air under the diaphragm, not enough fluid or w.h.y., it can surely misbehave just like any other hydraulic system.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

pickerd
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Re: Hydraulic Disc Brakes

Postby pickerd » 19 Oct 2015, 9:04pm

Sorry Brucey there may be air in the system I agree. I meant there are no hydraulic lines as such as they are mech cable actuated. ;)

pickerd
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Re: Hydraulic Disc Brakes

Postby pickerd » 19 Oct 2015, 9:07pm

It's strange also that the rear brakes don't suffer the same problem. Although maybe not as the rear is in a triangular frame and not on the end of a lever (fork). The same may be happening but it goes unnoticed.

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RickH
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Re: Hydraulic Disc Brakes

Postby RickH » 19 Oct 2015, 10:58pm

I find I often get a bit of "thrumming" on the front brake of the tandem when I put new pads in. It fades away fairly quickly & I've always put it down to the pads catching the spokes of the disc slightly (they do show signs of wear slightly inside where the circle of the disc is continuous). Whatever the cause, I find it disappears fairly rapidly with brake use.

Rick.

rmurphy195
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Location: South Birmingham

Re: Hydraulic Disc Brakes

Postby rmurphy195 » 20 Oct 2015, 12:27pm

The "bit of copperease on the back of the pads" solution looks interesting - It's what I have done for years on cars when replacing disc pads, to avoid odd noises!

It also reminded me of an email I received back from TRP when I asked about regular maintenance - this reads.

    "Thanks for your inquiry. You shouldn’t have to lube anything on the Spyre brake on a daily basis. As for a dab of Copper Ease on the backs of the pads, this would not hurt at all. Typically not needed but if you experience some squeal or rattling then that would be something that I could see helping"
Brompton, Condor Heritage, creaky joints and grey hair
""You know you're getting old when it's easier to ride a bike than to get on and off it" - quote from observant jogger !

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foxyrider
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Re: Hydraulic Disc Brakes

Postby foxyrider » 20 Oct 2015, 12:29pm

i get it with my HyRd's - between myself and our mechanics we've narrowed it down to sintered pads. sintered pads i get popping, organic i don't - least nowhere near as bad. We've had the same on brand new bikes and replacing the sintered pads has always significantly decreased the popping. i don't get it all the time just under heavy braking! :D
Convention? what's that then?
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pickerd
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Re: Hydraulic Disc Brakes

Postby pickerd » 20 Oct 2015, 1:20pm

Ok I have loads of good ideas to go at now.
Can anyone recommend some organic pads suitable for the HY RDs?

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NATURAL ANKLING
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Re: Hydraulic Disc Brakes

Postby NATURAL ANKLING » 20 Oct 2015, 2:23pm

Hi,
Along with the other suggestions , as said up thread "Contamination" pad / disc is worth looking at.
If You Don't Try You Don't Do.....Don't Do You Don't Get...I'm Still Trying....Well Very..
You'll Find Me At The Top Of A Hill...............Somewhere...After Dark..