Bloody Hydraulic Disc Brakes

insaino86

Hi

I recently uprgraded my stock cable disc brakes with clarkes 2s hydraulic discs.

To start with how poor are the fixing screws, I have stripped 2 nr bolts on the calipers and 1 on the bleed resivoir, yes had to bleed the rear brake upon installation.

However I cannot set up either brake with out rubbing and yes tried the loosenint he bolts pressing the brakes and retightening them. The problem is there is not enough space between the pads you are talking 0.1 mm either side and with a tinyt flex in the rotor you cannot stop the rubbing, is there any way of widenign the pads, trying to prise them apart doesnt work ????

nicklouse

been out and bedded then in yet?

and the rotor should not flex. if it is you have not set the caliper up correctly.

estampida

so gentle with those bolts, its not a toy......

but pad separation:

There are 2 different parts to the brake system that hold fluid, the section (master cylinder) that operates the caliper has a seal from the reservoir.

To make the pistons in the caliper retract, place the pad separator that came with the brake into the caliper (brake shoes still in caliper) - as a note -pad separator looks like a small fat plastic credit card normally black or red

once separator is in caliper flick the brake lever (this activates the poppet valve within the master cylinder) and will let some brake fluid back into the reservoir.

Do this a few times and remove pad separator, and look at that they are retracted.....

calipers can be re-centred by hand / eye or using feeler gauges

and again its not a toy don't bend it

The Rookie

Disc brakes work as well as they do by having minal clearance allowing the best mechanical advantage between lever and caliper, the more they have to retract, the less advantage you can run - fix your defective discs don't blame your new disc setup.

Never stripped a bolt - don't be so ham fisted!

When aligning the caliper do so slowly as otherwise the caliper can twist under the bolt head, somehow I think that could be an issue for you.

insaino86

i think i may has mis lead you with rotors, I was refering in general, on how easy that they could bend and with the small clearance that it could be problematic. the rotors are brand new with the brakes and installed properly. The pads are the problem.

What do you mena by Flick ing the brake levers as a solution???

The Rookie

Well as 0.1mm clearance is not rubbing, forget about it, if they flex under load they'll spring back, it's how it's all MEANT TO WORK, why are the pads now a problem, if you have 01.mm clearance and the calipers are aligned and the discs are straight there can be no rubbing, however a little rubbing is 100% normal on discs, you'll hear it but it doesn't actually do anything.

Flicking as in just pull them and let go.

estampida

truing brake disk's is possible

just use a shifting spanner on the disk where the alignment is out and flex it gently

you can buy a tool to do this

http://superstar.tibolts.co.uk/product_ ... cts_id=571

but be gentle, its not a toy

jimothy78

insaino86 wrote:

However I cannot set up either brake with out rubbing and yes tried the loosenint he bolts pressing the brakes and retightening them. The problem is there is not enough space between the pads you are talking 0.1 mm either side and with a tinyt flex in the rotor you cannot stop the rubbing, is there any way of widenign the pads, trying to prise them apart doesnt work ????

the first time I installed disc brakes i had problems with rubbing because the paint on the IS tabs wasn't very even and hence the callipers didn't mount perfectly square to the discs. Removing the offending paint from the area made all the difference., so maybe check that everything's square?

When fixing the callipers into place, get set up so you have some daylight behind the callipers and look through between the pads/rotor. Adjust one mounting bolt at a time until the spacing is constant on both sides, from front and rear and top to bottom. Personally I tried the "squeeze the levers and then tighten" technique, but found that at best it gave a rough starting position, as tightening the bolts generally caused movement from that position - much better results adjusting by eye from here on.

estampida

insaino86 wrote:

i think i may has mis lead you with rotors, I was refering in general, on how easy that they could bend and with the small clearance that it could be problematic. the rotors are brand new with the brakes and installed properly. The pads are the problem.

What do you mena by Flick ing the brake levers as a solution???

fli cking the brake levers? - it activates the poppet valve in the master cylinder as described further up

insaino86

hi everyone.

I have now set up the calipers perfectly. it seems my problem is the rotor and that it isnt spinning true. I have tried 3 times to reinstall this. Is there a trick to this or are my new discs warped or could it be the wheel disc mounts??

Giraffoto

insaino86 wrote:

hi everyone.

I have now set up the calipers perfectly. it seems my problem is the rotor and that it isnt spinning true. I have tried 3 times to reinstall this. Is there a trick to this or are my new discs warped or could it be the wheel disc mounts??

It's easy to true a brake disk, just not a job for the ham fisted . . .

Tweak it gently with an adjustable spanner in the direction you want. Take it slowly, be gentle, check and recheck. Too little is always better than too much.

stubs

estampida wrote:

fli cking the brake levers? - it activates the poppet valve in the master cylinder as described further up

:? Poppet valve in the master cylinder. Never seen a poppet valve in a master cylinder on a MTB. I know some car ABS systems have poppet valves in them but a MTB ?