Rear Brake Pads Replacement Trophy 900

What you are trying to do is to get the new pads to settle into there correct operating position. One or two pushes on the rear brake pedal should be all that is necessary. Sounds to me like maybe the first piston you pushed home has blocked in place. Have you checked to ensure there is sufficient brake fluid in the rear brake master cylinder reservoir?

 

Hi Drob, just got back in.

What I suggest you do - assuming you have the time and the motivation - is to take various pictures as you remove the calliper from the bike and the brake pads from the calliper and I'm sure we'll be able to work something out.

Is now a good time to suggest buying a Haynes or Triumph workshop manual?

 

a collar of crud can form around the part of the piston that gets exposed, if you can remove pads and take the calliper off , try and get the piston out as far as you can you might see, in the gap in caliper where pads go some crud around the piston, try cleaning that off as well. if you haven't already that is. The other thing is an air bubble in the system, GL

 

Hi Drob you are obviously getting there.

Re the reservoir - you found it under the seat and it has fluid in it so that's OK.

Re what's in your pics - I would never put copper grease around the pistons. Once they have been thoroughly cleaned the brake fluid will lube them.

In pic 5 I would say that piston needs cleaning some more and if the other is in the same condition there is still work to be done. The piston looks like it needs a little more aggressive attention with perhaps either fine emery paper or wire wool. They need to be properly clean to work properly.

Brake fluid - is it clean and clear? If it looks black it will not work so well. Also if the brakes need bleeding they will not pull up the bike that well.

General points - on your bike I believe you have a double disc set-up up front? That's where 80% of the bike's braking occurs, so just make sure you are using mainly the front brake to shake off speed, not the back one.

 

Looking at your picture 5 drobe is that dirt/crud around the piston base of rubber ? because if it is rubber it will mean it is the dust seal disintergrating which will lock the piston up, I had that and could not remove the pistons at all and had to buy another calliper,
I would remove the pistons and clean them up with metal polish not emery paper that will scratch them and may cause a leak (sorry biglad) and re seal both then refit with rubber grease and bleed the system with the pistons held back or in.
the back brakes do suffer from dirt on the pistons and require cleaning from time to time and using rubber grease not only helps the piston to slide but makes it easy to keep clean as the dirt sticks to the grease and can be wiped off but do not use to much of it, you do not want it getting on the pads

 

You only need to put a very thin sliver on the backs of the pad plates and only where the pistons touch the pads.

Also, can't remember if I said anything about about the 2 pins that hold the pads in place? These need to be really clean so the pads will move on them easily.

Make sure you have enough brake fluid DOT4 in stock - a minimum of one new 250ml can.

Dave

 

if biglad will forgive me for butting on the thread,
you should not see any rubber exposed as you have, you will need to re seal the pistons,
bleeding the brakes is easy, once you have re sealed the calliper and fitted it with the new pads back on the bike,
suck out the old dark fluid from the reservoir and refill with new fluid dot 4 as biglad said, now slide a bit clear plastic tube on the bleed nipple on the caliper, find a small ish jar and put the tube in it with a small amount of fluid so the tube is in the fluid, now loosen the bleed nipple half a turn or so and opperate the brake leaver and pump fluid through the system making sure the reservoir does not get empty, keep doing this until you get clear fluid through the tube without any air bubbles, then tighten the bleed nipple, pump the brake lever until the pads have hit the disk and top up the reservoir to the correct level, thats it.
Keith

 

Sorry Keith But I have to disagree with you on the visibility of the rubber seals in the callipers. It is perfectly normal to see the dust seal (which is what we are seeing in the pics). However the rubber seal that really counts (the one that control the hydraulic pressure and action) is much deeper within the calliper and is always unseen unless the piston is removed.

 

Oh I agree with you re the one that counts biglad, but if the dust seal swells it can lock up the piston, I have a calliper in the garage to prove it and it is also a problem with salt on Honda's, we might be talking about differant callipers on my 1992 trophy and the speed triple I can not see the dust seal well only a very small flat edge when the pistons are in and no way should the dust seal expand up between the piston and the calliper as shown in drob's number five picture.
Keith

 

That sounds good brob, but it seems you still have some air in there, re bleed the system and make sure you only have clear fluid comming out with no bubbles and hold the brake pedal down to the end of its travel on the last stroke while you do the bleed nipple up.
Keith

 

That's OK then just make sure there is no air in there. Keith