Author Topic: ST1300 Rear Brake Pads Replaced Issues Tips and Fixes  (Read 1204 times)

Offline Itdepends

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ST1300 Rear Brake Pads Replaced Issues Tips and Fixes
« on: March 26, 2017, 02:18:52 PM »
I'm not a big one for pictures- so I'm afraid this will be a wall of text- however I thought I'd share some experience in fitting (for the first time) new brake pads to the rear caliper of my ST1300.

After taking front and rear wheels in to have new tyres fitted I decided to replace the rear brake pads. The reason I wanted to change them was that I was fitting Michelin Pilot 4's which I've heard last really well on the ST's and wanted to make sure that the pads didn't wear out before the tyres- perhaps I'm being a bit optimistic but we'll see.

The new pads to be fitted are EBC HH- they spec the same pads for both the front and rear of the bike. Having recently performed a complete brake fluid change and bleed the task at hand was to be just the pads.

A couple of days after fitting I had the chance to take the bike out for a test ride and found that braking performance was poor, the rear brake appeared to be dragging and the caliper had gotten sizzling hot after only 3-4km of riding. Inspecting the caliper I found the center and rearward piston were working but the forward most piston had not moved from the fully retracted position. I tried increasing the pressure on the front and rear brake pedals but it still refused to move. Putting the bike up on the center stand and manually activating the secondary master cylinder (on the front wheel) was also not successful. After removing the rear wheel and caliper I found the pad had actually bent and cracked the friction material. This probably occurred as I was trying to apply extra pressure the pad "cocked" at an angle in the caliper and bent under the pressure from the center or rear most piston.

Ok- that's the problem- here's the cause and the solution. When changing brake pads you need to (obviously) push the pistons in to allow room for the new, thicker pads. I had pre cleaned the pistons prior to this procedure but made a mistake when pushing the pistons in. I'm used to changing pads where the pistons push in until they are flush with the surface of the caliper assembly- the ST1300's don't retract until flush- and while trying to get them flush I had either seized the forward most piston in the caliper or (more likely) I had pushed the piston in far enough to seal against the brake fluid inlet port.

I can't prove this without dismantling the caliper- but I strongly suspect that the brake fluid inlet port for the forward most pot comes in from the side (instead of the back). The rear caliper has a brake line to the center pot (top) which activates from the front brake lever and a second line to the back of the rear pot which activates from the rear brake lever. The rear brake lever also operates the front pot- which means there's a fluid connection from the rear to the front pot. I think I pushed the piston back far enough to seal against that inlet port on the front most pot- and that the inlet butted up against the side of the piston- which means that regardless of how much pressure I applied it wasn't able to get behind the piston to push it out.

The fix was relatively simple- using an old pair of circlip pliers to gently grip and rotate the frozen piston and pull it out slightly. Once it was out a little I was able to push in the rearward piston by hand and observe the forward piston move further out- problem solved. New pads, reassembled and a test ride later- all good.

Another couple of things that I noticed which can be a trap.

The spring/slider that holds the opposite end of the pads to the slider rod is not symmetrical. It falls out easily and can be put in upside down. There's a little tab that pokes up on each end of the slider (or pokes down if you've put it in upside down). Make sure it points up- it stops the pad at that end from falling out if it's loose/pushed outboard too far.

The spring/anti rattle bracket that goes above the pads is also not symmetrical. There are a couple of tabs that poke down from the top. These tabs should be on the inboard (wheel) side of the caliper assembly. They help to hold the inboard pad in place- this pad stays in place within the caliper as it wears and the caliper assembly (including pad) moves in towards the brake disk. The outboard pad is the one that moves in towards the brake disc as it wears (while the caliper body on the outboard side stays in place). If the bracket is installed in reverse then as the outboard pad wears it will push against and bend these tabs- this will result in the rear brake binding/dragging.

Anyway- food for thought- even though I made a mistake- it's an easy one to do- and I strongly suggest you do the pads yourself to be sure it's done right (after learning from others experience - or- if you get a shop to do it- test ride and check after the work is complete. A simple mistake like this could have resulted in needing a replacement rotor if not picked up in time.

Cheers,

Daniel
 

Offline Brock

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Re: ST1300 Rear Brake Pads Replaced Issues Tips and Fixes
« Reply #1 on: March 26, 2017, 03:17:22 PM »
Good writeup.

The pistons will actually go flush, but you need to be carefull that it doesnt go slightly crooked and jam as you found out.
Brock
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Offline alans1100

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Re: ST1300 Rear Brake Pads Replaced Issues Tips and Fixes
« Reply #2 on: March 26, 2017, 06:20:51 PM »
You have a slight misunderstanding of how your system works.

The foot pedal directly operates the centre pot in all three callipers.

The hand brake only operates the outer two pots on the front callipers.

Any braking (foot or hand) causes the left front calliper to activate the secondary master cylinder which in turn via a Pressure Control Valve the out two rear pots. Unless the bike is moving the front brake lever has no effect on the rear. 

When I replace my pads I usually just slide the old ones out - push the pistons back in and slide the new ones back in making sure they locate properly but next pad change will include overhauling callipers and master cylinder seals since they haven't been touched in 200,000 km.

How I do it on the 1100A

Front http://ozstoc.com/index.php?topic=11604.msg1212622#msg1212622

Rear  http://ozstoc.com/index.php?topic=11602.msg1212587#msg1212587





« Last Edit: March 26, 2017, 06:33:49 PM by alans1100 »
1999 :bl11  2004 :13Candy

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Offline Itdepends

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Re: ST1300 Rear Brake Pads Replaced Issues Tips and Fixes
« Reply #3 on: March 27, 2017, 10:05:18 PM »
Thanks for the clarification Alan- I've had another look at the linked braking system and you're absolutely right- the wiki link below is a good (colour) layout.

http://stwiki.notonthe.net/twiki/bin/view/ST13/LinkedBrakingSystem
 

Offline alans1100

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Re: ST1300 Rear Brake Pads Replaced Issues Tips and Fixes
« Reply #4 on: March 27, 2017, 10:56:26 PM »
The 1100 manual goes a little further in that the delay valve mentioned in your link allows full braking on the rear before full braking is applied to the front.

1999 :bl11  2004 :13Candy

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Offline mr2u

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Re: ST1300 Rear Brake Pads Replaced Issues Tips and Fixes
« Reply #5 on: September 20, 2017, 01:12:27 AM »
Thanks Alans1100
I was just about to ask the question about my front lever not stopping my back tyre, now i know why, the bike has to be moving.
I kind of thought that this was the case but now i know, again Thanks.

Mr2u    :blk13
They say money cant buy happiness, but i say it can get you a damn good bike!