Sticking brake

[marcusfordus]

Whilst making an emergency braking manouvere today, after Mr Transit van driver pulled out into my lane, something was not quite right with the brakes.1/4 mile after the nads meets tank situation I parked up and left the bike for a few hours, non the wiser. Now the 22 miles back home were a different kettle of fish, within 2 miles the rear brake developed a squeel, so I stopped had a look and nothing seemed out of place, resumed the journey home taking it steady following the local A road traffic without heavy braking.
When I got home I found the rear disc a very nice shade of blue, so a strip down was called for, of the rear brakes. The Pads are now the new HH purple specials and have about 4mm left per side of their copperness. The pistons are as clean as clean can be and they slide out fine and can be pushed in with force, by hand, the caliper sliders are fully moving. So what the f**k went wrong !
It seems the minimum I need to fix would be a new disc and pads, but could it happen again :cry:

Whilst in the stripdown mode I cleaned everything on the rear end and repainted the rear wheel. Question no.2 is how much of a bobble should there be on the cush drive rubbers, the inner edges have about 5mm on each section but the outers have 2mm angled through wear, bobbles. When do these get replaced, as I had no slopiness on the rear drive take-up ?

 

[R2B2]

If you're sure the rear caliper pistons and slider are free then you need to look if anything has stickied up at the front end. Sounds like the secondary master cylinder could have stuck when it entered the new territory associated with an e-stop. Also check the left front caliper swivel fixing (the lower bolt) to make sure that is free.

Either of these sticking would cause the prob you had, as it would hold some pressure on the rear brake.

PM me if you want me to be a bit more specific.

 

[Hornblower]

I think R2B2 is on the right track and it is to do with the left front caliper, but it could be the pistons or caliper slider sticking as well as the swivel pin . :beer:

 

[R2B2]

I thought of that Andy but he would have a heat damaged disc on the front left then as well..........

 

[gypsy]

Not sure but Titan had a similar prob on his and it turned out to be the pin on the rear caliper being less than smooth so it wasnt letting the pads return properly :dunno:

 

[marcusfordus]

Brakes

It looks like the replacement project I was planning is now coming sooner than later,I was going to swap the hoses anyway, but it now looks like a discs and pads job as well.
Was I right in thinking the carbed Bird used different pistons/pressure on the linked brakes to the injection ?
After 41,000 miles and I had noticed it was a bit lacking on the braking front of recent.

It's bank holiday Monday and the bike is in bits:xm

 

[gypsy]

if ya want another pair of eyes to have a look i'm out and about this morning and youre just up the road from me i think?

 

[marcusfordus]

Rain oh Rain

I wouldn't want anyone coming out in this rain, here at J28 M1.
Good news is, with being on the PC instead of out on the bike, I have sourced one set of 2nd hand goodrige hoses and one brand new rear disc .

 

[gypsy]

what rain :dunno:
just been to Sutton / Matlock lovely day
Suns out 2 stops down the 38 from you

 

[marcusfordus]

Brakes pricing

Been looking for the replacements today, after getting the other bits on ebay, what I have come up with is, EBC prolite front discs, three sets of HH pads and delivery for ?325.80. Is this a good deal ???

 

[Stevebrooke]

I wouldn't want anyone coming out in this rain, here at J28 M1.
Good news is, with being on the PC instead of out on the bike, I have sourced one set of 2nd hand goodrige hoses QUOTE]

It was you that one them on eBay was it?

Good move. I'm sure they'll do the trick.

 

[marcusfordus]

ebay bits

I did get the hoses and a new rear disc over the holiday weekend.

 

[marcusfordus]

The update

Brand new Goodridge hoses fitted last night, bled the damned things tonight. I have gone through a litre of fresh brake fluid already. Would I be wise and try bleeding them again after a short rideout, as there might be a few trapped tiny bubbles that will work their way to the outer points of the system ????.
Much firmer on the lever's now. I am just waiting on new cush drive rubbers and the back end can go together and then the new Pro-lite discs get fitted at the front. Lets hope ?470 was well spent.

 

[marcusfordus]

Oh bugger

Well after the full strip down and rebuild, things were looking good. After 12 miles I pulled in a petrol station, to be met by that dreaded rear brake squeel again.
So what is the cause, all the calipers had every last bit of brake residue removed, the sliders were re greased, front pivot and linkage greased, pads pins polished and greased. At a loss :xm where to look next.

Could the rear caliper have a piston that sticks, bearing in mind it is now on a new disc and pad set, so they are pushed all the way home, could the PCV be up the swanny ?????????

 

[R2B2]

Odd!

I know I already said it, and I noticed you said the front pivot was greased, but did you check that the secondary master cylinder is returning ok?

Failing that, is it poss that the rear caliper is somehow out of alignment?

 

[marcusfordus]

Rear caliper

Whipped it off tonight and found the front piston on the rear caliper out about 2mm more than the other two. This is causing the pads to drag on their front edge.
I thought the secondary m/cylinder operated both outer rear pistons through the PCV, if this was playing up, wouldn't both pistons be stuck out, or is it just because it is first on the fluid line in the caliper ????

 

[Stevebrooke]

Whipped it off tonight and found the front piston on the rear caliper out about 2mm more than the other two. This is causing the pads to drag on their front edge.
I thought the secondary m/cylinder operated both outer rear pistons through the PCV, if this was playing up, wouldn't both pistons be stuck out, or is it just because it is first on the fluid line in the caliper ????

I had a similar problem on mine which has just been sorted by my local Honda dealer. Everyone who looked at it thought it must be something to do with fluid/bleeding.

It was actually a seized slider. It sounds like yours could do with cleaning up.

 

[marcusfordus]

Slider

Which one was the offending item ?

 

[R2B2]

.
I thought the secondary m/cylinder operated both outer rear pistons through the PCV,

Yeah, that's right.

Both the outer pistons on the rear caliper share the same chamber, so hyd pressure should be the same on both and there should not be one piston dominant over the other. They are both subject to the same hyd pressure, no matter which one is closer to the brake pipe entry point.

I do feel that something is not coming off rather than something not going on, if you see what I mean.

Is there any way you can do this test........

1) Ride the bike to, say 50 or 60 mph.

2) brake quite hard with the front brake ONLY, to a dead stop. Let go of the front lever.

3) without touching anything else put the bike on the centre stand.

4) rotate the back wheel by hand.

If there is any drag on the back wheel then one of these apply:

One of the rear caliper outer pistons is sticking on,

OR,

the sec master cyl is sticking in the compressed position (but then both outer pistons should be activated).

OR,

the rear caliper slider is sticking.

If none of these conditions occur, do the same test again but brake with the rear brake ONLY. If the rear wheel is dragging now, it's fair to say that the middle rear piston is sticking.

This test should at least identify which end of the bike the problem is coming from. Find this, and then we can look closer at the cause.

(Without trying to confuse matters, - there is the remote possibility that the rear master cyl is sticking. If this was the case, then to eliminate this possibility, when doing the second test above, do this: If the rear wheel has drag, without moving the bike, have somebody lean heavily on the rear of the bike so as to raise the front wheel by pivoting the bike on the centre stand. Now rotate the front wheel by hand. If the rear master cyl was sticking, then there will be some drag on the front wheel [via the center piston on the front calipers]). An unlikely scenario, but you never know!

Call me if you want to discuss.

07767 835829

 

[marcusfordus]

It's a slider

The front rear caliper slider is the problem, watched it stick when it was all put back and cleaned again, not sure if it is cured yet, as it is well pi**ing it down and can't be bothered to go out yet, I shall get out later to give it a test.
Thanks for all the pointers from everyone, saves loads of time when people have had just the same thing happen to them :bow:

Took it out and everything as smooth as could be for 6 miles, using the brakes as you would in everyday riding. I thought I would try the old emergency brake thing again on an empty road, you guessed, the dreaded squeek was back as the front leading edge of the pads was stuck on again.:xm