Brakes

Message

D-Rider · #1 Post by **D-Rider** » Wed Sep 08, 2010 11:38 pm

At the weekend I had a quick fettle on the brakes.

I did the bobbin cleaning on the front discs as I'd not got round to it this year - so that's now out of the way.

For some time I'd been thinking that I really must bleed the rear brake again as it wasn't doing much and was quite spongey .... but, hey, it's an Aprilia rear brake and with the stonking engine braking available, it had never risen to the top of the priority list - especially as it was good enough to pass an MOT.

Anyway I eventually got round to taking a look.
First thing I did was take the rear calliper off to clean it up .... and immediatelly noticed one pad was virtually untouched while the other has very little meat left on it.
The cause was quickly spotted - the thick pad was jammed solid by crud.
Well I freed it up, cleaned it and the calliper, reassembled with copper grease (where you are supposed to put copper grease) and job's a goodun.

Unsurprisingly, this has sorted out the lack of braking power and the spongeyness - having a pair of pads squeezing a disc is so much more effective than a single pad pressing on one side.

Now it has made me wonder. On the forums there have been a few people that have repeatedly tried to bleed their rear brake without success and just can't get it right.
..... well, maybe for some of them, the hydraulics are fine and they just have a stuck pad - giving exactly the same feeling through the pedal.

rick · #2 Post by **rick** » Thu Sep 09, 2010 6:54 am

You may be right!

I have to do the bobbins on mine... none of them move freely (all the tabs are still down) and I do get the pulsing effect at times.

Regarding rear brake, mine is bloody fantastic and the pads are evenly worn on both sides... makes me wonder whether I should bother upgrading to a braided hose at the rear

Aladinsaneuk · #3 Post by **Aladinsaneuk** » Thu Sep 09, 2010 7:42 am

for the rear brake - if it is not broken, do not fix it.....

Dalemac · #4 Post by **Dalemac** » Sat Sep 11, 2010 10:51 pm

My rear brake has been awesome since i cleaned the caliper and put new liquid in the lines! only problem is that when i use it, it binds on for a few minutes, making it impossible to move around.

should figure out whats causing that i guess....

Aladinsaneuk · #5 Post by **Aladinsaneuk** » Sat Sep 11, 2010 11:05 pm

sticking pad?

Dalemac · #6 Post by **Dalemac** » Sat Sep 11, 2010 11:08 pm

the pads dont appear to be sticking, if i leave the bike alone for 5 minutes and come back, its loosened up and off i go. Seems to be related to heat/friction if that makes sense...

D-Rider · #7 Post by **D-Rider** » Sat Sep 11, 2010 11:27 pm

Dalemac wrote:My rear brake has been awesome since i cleaned the caliper and put new liquid in the lines! only problem is that when i use it, it binds on for a few minutes, making it impossible to move around.

should figure out whats causing that i guess....

Aladinsaneuk wrote:sticking pad?

No - this is a known problem and has resulted in some fairly scary rear end lock ups.

The problem is an over-filled reservoir - some numpty-mechanics put too much fluid in and when it warms up and expands a bit it applies the brake.

Get some fluid out of there and I expect it will all be nice again.

Dalemac · #8 Post by **Dalemac** » Sat Sep 11, 2010 11:37 pm

possible, i will extract some fluid tomorrow and report back....thanks for the tip!

D-Rider · #9 Post by **D-Rider** » Sat Sep 11, 2010 11:49 pm

Dalemac wrote:possible, i will extract some fluid tomorrow and report back....thanks for the tip!

No worries

davebms · #10 Post by **davebms** » Sun Sep 12, 2010 10:25 am

another poss cause of the problem is no free play in the actuating rod
so when the piston is back it will not clear the recuperation hole so fluid cannot get back to the reservoir ... normally only happens when peeps adjust the pedal position

paddyz1 · #11 Post by **paddyz1** » Sun Sep 12, 2010 7:57 pm

I had to bleed the rear brake recently and it would not get all the air out while the calliper was in situ. The only way to get full pressure was to remove the calliper and bleed the air out by rotating the calliper to get all the air up to the bleed nipple. An extra 5 minutes work and it is working fine now.

davebms · #12 Post by **davebms** » Sun Sep 12, 2010 8:54 pm

paddyz1 wrote:I had to bleed the rear brake recently and it would not get all the air out while the calliper was in situ. The only way to get full pressure was to remove the calliper and bleed the air out by rotating the calliper to get all the air up to the bleed nipple. An extra 5 minutes work and it is working fine now.

yes thats probably the only way to do it . i think that technical the rear is up-side down ,the norm is fluid in at the bottom air out the top . lots of odd attributes to the falco ,still the most enjoyable ride I've had in years !! as luck would have it the front end comes down with throttle roll of as i cannot reach the rear brake at all

back_marker · #13 Post by **back_marker** » Sun Sep 12, 2010 9:13 pm

I quite like my rear brake as it is - gives just enough bite to allow you to scrub off some speed mid corner but it is virtually impossible to lock up the back wheel

Dalemac · #14 Post by **Dalemac** » Fri Mar 25, 2011 8:02 pm

I never really got round to fixing this issue - knida bad as i have done quite a few miles since then!

If i use the rear brake - it binds the wheel, makes it very difficult to turn and manouver.

brake fluid level is fine, everything seems to be working mechanically.

another poss cause of the problem is no free play in the actuating rod
so when the piston is back it will not clear the recuperation hole so fluid cannot get back to the reservoir ... normally only happens when peeps adjust the pedal position

Could someone explain this a little more?

Dale

Falconihlist · #15 Post by **Falconihlist** » Fri Mar 25, 2011 9:09 pm

I stripped my rear brake a few weeks ago when fitting a HEL line, and noticed that the pad retaining pins had developed grooves in them where the pads rub against them. Swapped them out with some new ones, and after bleeding the caliper properly, haven't had any troubles since. Only changed the line as it came with the set for the front. Did remove the pistons and gave everything a good clean, small bit of dirt in there was causing one of the pistons to bind slightly as well.