Disc brake squeal/vibration

[Eric_aus_Chemnitz]

Ok, I’ll try:

So, I tinkered a bit

Material: stainless steel tube 8mm in diameter (0.3"), from the hardware store for 12,99€ per meter.

Weight: approx. 50g (inkl bolt)

For the 29" Unicycle I needed 27cm (10.6") of Tube

I haven’t driven it yet (had to work) but will try tomorrow.

If somebody wants to copy this, just do it. If unicycle.com (nimbus) is interested in this, I would find it only fair if they would involve me too.

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construction:

I flattened the ends of the tube with a bench vise and then took a sledge hammer so that the ends get absolutely flat.
After this I rounded the edges with a file. The both ends stand 90° to each other, the upper end, that will be attached to thesocket of the rim brake, is bent a little bit to the side, so that it can be attached planar to the socket.
On the side for the d’brake I drilled a 6mm hole into the flat end and on the other side a 5mm hole for mounting onto the rim brake socket and a 4mm hole with M5 thread for the brake hose clip. The thread cutting into stainless steel with a normal (discounter) threader was a bit tricky but worked with much oil and patience. Probably this hole can also be left out when only the upper brake hose clip is used.

To avoid the caliper from bein inclined on the d’brake you have to use a shim on the other screw that is as thick as the flattened tube. I already had shims on them and so I just replaced the one shim by the flattened tube. If you don’t have any shims there yet, you have to try if you need to bring the crank about 1 to 2mm more to the outside with a spacer.

Have fun copying it (if you like it) and I hope that it holds.

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Works as designed

Today I raced dowh the hill and am totally excited. A threateningly vibrating and loud brake became an absolutely quiet one with fantastic braking force.

I’ll upgrade my 24er as well, despite I have no problems with it untill yet.

[LanceB]

That’s great, thanks a lot, Eric.

[jtrops]

That’s a really cool device. I was thinking about a disc brake based on what I know from bikes, and I forgot about the Dbrake. I’m sure that is the reason the vibrations are so bad on the uni It probably just hums on that boom mount. The brace up to the maggie mount is a great solution.

[kahunacohen]

I have had the Oracle 36 for a year and a half. When applying the brakes on a downhill the whole uni resonates. I was told by Josh from UDC that it just needed breaking in, but it still does it after a year and a half.

[Nurse_Ben]

Some brake rotor/pad combo’s are really loud.

Yup, and some need more work than others, it can be a variety of issues from pad design to rotor design, even harmonics.

After having tried all the easy fixes, now it’s time to try changing one thing at a time, in the order of least cost:

Pads
Rotor
Caliper

Organic pads do seem to help, but semi-metallic work the best when hot, so if you’re having glazing you might want to see if there is an all metal pad.

My favorite cheap rotor is the Avid that comes stock with BB7 brakes.
My favorite expensive rotor is the Hope Floater

In terms of calipers, the one you have is the cheapest you can get, I gave mine away for the same reasons you are describing. A good Shimano caliper like the M575 or similar is all you need.

[pierrox]

@kahunacohen

I was told by Josh from UDC that it just needed breaking in, but it still does it after a year and a half.

Yes it does a bit, but for sure the little D part holding the brake must have problem resisting the forces it takes when you brake. The reinforcement part seems to be the right answer.

[Moslki]

@Nurse Ben

Yup, and some need more work than others, it can be a variety of issues from pad design to rotor design, even harmonics.

After having tried all the easy fixes, now it’s time to try changing one thing at a time, in the order of least cost:

Pads
Rotor
Caliper

Organic pads do seem to help, but semi-metallic work the best when hot, so if you’re having glazing you might want to see if there is an all metal pad.

My favorite cheap rotor is the Avid that comes stock with BB7 brakes.
My favorite expensive rotor is the Hope Floater

In terms of calipers, the one you have is the cheapest you can get, I gave mine away for the same reasons you are describing. A good Shimano caliper like the M575 or similar is all you need.

Thanks a million for your advice Nurse Ben. It helps a lot. Makes sense to follow these steps in that order untill I get a happy combo. When I was trawling the forum for a solution to this problem I’ve noticed you have tried many brakes in the past so I know how valuable is your advice on this matter

[entropy]

@Eric aus Chemnitz

to eliminate vibration of the d’brake, you could try Hugos solution. With this setup he successfully eliminated any noise and vibration.

Also note this solution if you don’t have a KH frame.

I gave Hugo’s method a try. It works pretty well - still some high pitched squeaking, but most of the vibration is gone. Made a previously unusable brake (due to vibration) useful again. Worth doing for sure.

[Moslki]

Hi there

I forgot to update my brake/pad situation (have been away from the forum for a few months!). For all of you that were also having problems with the same brake/pad combo as mine: as advised on this forum I kept the original calliper and rotor but changed the braking pad (Clarks Organic Disc Brake Pad for Tektro Volans/Auriga Twin/Auriga Sub/Auriga E-Sub Bikes).

Glad to say that the brake has been working fine since I fitted this organic pad quite a few months ago. I might get the odd hum here and there but, thankfully, no vibrations. Very smooth breaking. So I’m really happy with it. It works way much better than the original pad that came with the Oracle 36 unicycle (the tektro) and the other pad I tried afterwards (jagwire). Another plus: the clarks Organic pad is way cheaper than the Tektro or the jagwire.

Where I live is very hilly and as far as I can tell this pad works well (no problems with breaking in very steep hills).

Hope this helps to someone and thanks again to all of you that helped me along the way