Disc brakes & vibrations

[Rohloff_Brompton_Rider]

P
Perv! :-)

I've just got this....doh!!

 

[SatNavSaysStraightOn]

Explains the flushed look perhaps! Took me hours to get all the mud off everything. The kids pointed out I had panda eyes! Great fun though.

and there was me thinking it was the 700m of climbing that caused it!
still trying to get the mud off everything. finally got as far as my bike today...and found a bike under all that mud. how it was still functioning is beyond me. i pulled so much grass out of the pulley wheels on both bikes not to mention additional grass & debris from the middle sprocket - it was that well padded I am amazed my chain stayed on the bike - quite impressed with the bike for £225!
just need to deal with 1 scratch on the front forks (to bare metal) & some nasty cable rub that have both happened as a result of the weekend! thanks for the fun, we really enjoyed it.

 

[Night Train]

The uneven wear will be down to caliper poistioning. It's a simple fix though with Deores. Stand the bike upright and slacken the caliper mounting bolts so that the caliper moves sideways easily, then simply apply the brake. Get Stuart to hold the brake on, and do up the caliper bolts to finger tight, then a quarter turn alternating between the two screws until the bolt is nipped up firm but not massively torqued. Release the lever and check the wheel spins freely without binding at any point on the rotor. Job done.

Hmmmm, [considers designing a cam type device that can move the caliper sideways at the flick of a lever.... Could be a best seller.]

 

[Cubist]

Hmmmm, [considers designing a cam type device that can move the caliper sideways at the flick of a lever.... Could be a best seller.]

It might. You may even be able to sell the patent. Judging from the ladies' reactions on here you may get more from Ann Summers than Shimano though. I was going to type that keeping the calipers centralised was a pain in the arse, but that'll introduce a whole new dynamic into the thread.

Avid go for the win with a little stack of dished washers, which manage to introduce slop into the mix. Hope used to used a whole bagful of shims which were a royal pain to use. I like the unsubtle Shimano slotted bolt hole approach. Whichever way it works, it helps to centre the caliper on the rotor before doing it up, and then, periodically, re centring it whenever it starts to skim the disc.

 

[rusty bearing]

It's also possible that vibration of that intensity is as a result of a stuck piston which will in turn badly deflect the rotor and produces pad wear like the photo. Unfortunately you can't do a caliper rebuild on Shimano brakes, they don't do parts so it's a new caliper.
To check remove caliper from bike ,take pads out and gently pressing the lever a little put your finger against each piston.

 

[Pumpkin the robot]

On car and motorcycle brakes, vibration is normally a warped disc.

 

[rusty bearing]

True I've experienced that myself on an old wreck I once bought.
The reason I mention the stuck piston is we had one through the workshop recently with that very symptom described (Hope mono mini) and yes, the outer piston had seized solid. Rebuilt with new seal and no vibration at all despite having a slightly out of true rotor.

 

[SatNavSaysStraightOn]

The bike itself has been very well looked after by its previous CC owner and is in alround excellent condition. It is not a warped brake disc, but I did notice that the pistons (assuming that is what I was looking at) seems a touch 'odd' for want of a better explanation. I was not entirely convinced that the outer one (?) was functioning. When I put the pads back into the slot, they did not line up with the slot in the (insert name of other bit I can not remember what it is called - 2nd coffee needed). I had to ease one of the black round things (assuming that is the piston) - the inner one, back over to allow the pads to line up with the slot in above nameless thingy... yep 2nd coffee clearly needed. the outer one of these was not really visible to be honest. Can't tell you what the fronts looked like because the pads went back in without any issues and allowed the wheel to go back on immediately. With the rear, I had a touch of a fight getting the wheel back on, until I 'had words with' that black round thingy and eased it back over. It could just be an adjustment issue and once my OH gets home tonight and I have swatted up on the workings of hydraulic disc brakes I can have a better look at life tomorrow and no doubt ask a whole load more questions with thingies, black round discs and completely incorrect terminology and you can all tell me I need another coffee....

 

[Rohloff_Brompton_Rider]

Quick question

I've got a 2nd hand mtb (via a cc member & the for sale forum) which has disc brakes and recently the rear brake has started to make some noises that are not dirt related. The front brake behaves normally and this is not something I have had with my old mtbs with disc brakes.

It's not the noise that concerns me, more the vibrations coming up through the seat which without putting too finer a point on it out do any vibrator I have every had.

Is there are problem or can I just go on 'enjoying' them?

I've only just noticed the vibrator part of your original post.....some of the other comments make sense now.....doh!

 

[Rohloff_Brompton_Rider]

Have look on YouTube for videos about servicing hydro brakes. It's really easy and usually sandpaper sorts most problems out.

 

[SatNavSaysStraightOn]

I've only just noticed the vibrator part of your original post.....some of the other comments make sense now.....doh!

too much tramadol! how are things?

 

[Rohloff_Brompton_Rider]

Not had any since last night and feel sharp as a tack thanks. Gunna try to manage the pain with paracetamol.

 

[SatNavSaysStraightOn]

Have look on YouTube for videos about servicing hydro brakes. It's really easy and usually sandpaper sorts most problems out.

not sure this one is a sandpaper problem... shall have to dig... but also keeping an eye on the weather (tis snowing lightly here) and meant to be going to see a hole in a canal later on this afternoon...

 

[Rohloff_Brompton_Rider]

I'll bet a shilling, that the pistons have crystallised fluid on them, sandpaper sorts this out and allows the pistons tp go back and forth.

 

[Rohloff_Brompton_Rider]

Servicing motorbike brakes videos are usually better than mtb videos.