front calliper r1100rt

[Dingo55]

Hi all

Appreciate any help

Replacing front pads

Working pistons back and forth to make room for new pads

Got them to the point where I could push them by hand but not able to get them flush all at the same time

Now have three flush , one extended but now no movement at all 

Removed brake line 

Still no movement

Help

Cheers

Mark 

 

[Jim Moore]

What are you using to separate the pads? I jam a flat-head screwdriver between them and twist it. Sometimes I have to open the bleed valve, but I've never had one not move.

[Dingo55]

Thanks Jim

A couple of months back when installing new tyres I noticed the front left inner pad had substantial more  wear than the other three which I thought at the time was a bit odd

Checked again today and time to replace pads 

Other three pads still 80% good

One pad shot

Not sure what would cause that uneven wear

Just proceeded with normal procedure ie different widths of timber working pistons back and forth

Seemed to be going as per normal but then one piston became unmoveable

Removed the brake line 

Replaced line but didn't tighten

Lunch (frustration) break

Pistons moving ok

Installed new pads

Started bleeding process

Burst in lower left hose

I guess brake fluid will seep out overnight so expecting to need to do full bleed when new hoses available 

Appreciate any advice 

Cheers 

Mark

[Hosstage]

After repair and a ride to break in the pads, let the bike cool, then take a short ride without using the front brake. Carefully touch the rotor to check for heat. If it is abnormally hot, your caliper is sticking and needs service or replacement.

You may even be able to tell after pad replacement and bleed by spinning the wheel and checking for brake drag. It may not stick then, but a heat cycle as mentioned may cause the issue to return.

It's rare that I've seen one stick, especially as long as yours has been, and then magically start working properly, but it's possible.

[Jim Moore]

If those hoses were original you needed to replace them anyway. Galfers and Spieglers both make steel-braided lines for that bike. l normally buy them from Tom Cutter at the Rubber Chicken Racing Garage. 

[Skywagon]

It’s likely sticking vs rotor warp. Clean the pistons to the point you  can move them easily with your fingers. If you are having to force them then that is a good sign of dirty pistons. 
 

Then do what Hosstage said.

 

I think Boxflyer posted a while back how to service them

[The Fabricator]

If the pistons don't move the same, then it could be assumed there is dirt/corrosion causing a piston to stick/drag.

One pad worn down and the other 3 still 80% indicates the worn pad's pistons are stuck, not retracting, causing the excessive wear due to the pad constantly being forced against the rotor.

It is to be expected all 8 pistons movement  will not be the same.  It is common.

Remove the pistons, clean the bore.  This means dismantling the caliper.

The seals will not leak, if you don't damage them.

Do not clean the seals with anything not compatible with the rubber.  If they swell from a chemical cause, the brake will be mushy.

The only time I replaced the front pads on my 2000 r1150gs, I removed the seals  for cleaning.

Apparently they didn't like being removed and the feel was very mushy.  I didn't use ANYTHING for cleaning other than a rag.

The pistons and piston bores cleaned lightly with  fine scotch brite.  Rag and water wipe down.

I ended up deleting the dust seals, and the lever feel is solid with a small lever movement to initiate braking. There are plenty of calipers built with out dust seals.  I am not denying the value of dust seals.  Oil seals only is adequate.

5k miles ago. Performing well ever since.

The seals pull the pistons back after the brake is released.  

It's a small difference from too much 'pull  back' and  'just enough'. Too much retraction means mushy brake due to a lot of the lever movement used  to move the pistons to take up the 'pull back' distance.

Take the cover off the reservoir when pushing the pistons back.  Be aware that  brake fluid WILL SQUIRT OUT of an open reservoir.  Brake fluid will damage paint.   Clean off with water and rag.  Cover the open reservoir with a rag.  

[9Mary7]

Since the left brake line burst and the stuck piston was also on the left caliper, I would check for foreign matter (brake line rubber) blocking an internal port. As Tom TF said, 

10 minutes ago, The Fabricator said:

Remove the pistons, clean the bore.  This means dismantling the caliper.

 

[Dingo55]

Morning all 

Thanks for your replies

Much appreciated

Pistons didn't seem overly dirty

Bit tough to get some initial movement (as usual) but could move them with fingers eventually

If there is brake line gunk in the calliper passages how easy is that to remove?

Thinking to get new brake line made locally (supply issues are crazy)

Is it an option to take the metal section of brake line that goes over the front fender out and have brake hose from the R/H side T block

over to the L/H calliper direct?

Thanks again

Cheers 

Mark

 

[Lowndes]

Dingo,

 

To thoroughly clean the insides of the calipers I had to disassemble mine.  There are passages (drilled holes) that cannot be reached without disassembly.  The calipers are very simple and easy to reassemble with one reservation.  Only disassemble one caliper at a time and then disassemble and clean only one half at a time.  This is the easy way to keep all the parts in order.  Be very careful with the two rubber "piston rings" in the cylinder walls as the inner and outer rings are different AND DIRECTIONAL.  I could not find any torque values for the caliper halves bolts so I used values of similar size bolts into aluminum.

 

If you look closely at the passages (galeries) drilled in the caliper halves you will notice that the cylinders are on dead-ends and therefore do not get flushed when bleeding the brakes.  They are also at the very bottom of the hydraulic system which means bits and pieces of decomposing OEM brake lines will settle in there and cannot be flushed out.

 

These are pics of the calipers on my '99 R1100S.  Notice the black junk (decomposing brake lines) in several of the pics.  It had locked up the front wheel which is why I had to disassemble them.  I installed Spiegler lines everywhere including the clutch during reassembly.

 

My pics:  https://photos.app.goo.gl/kN8PyDxEirl9iVS02

 

"Is it an option to take the metal section of brake line that goes over the front fender out and have brake hose from the R/H side T block

over to the L/H calliper direct?"

 

Yes, there are several options for the front brakes.  I used a double drop from the steering head connection, one line directly to each caliper.  This required a longer banjo bolt for the double banjo there.  See my pics and below diagram, second from left.  Your idea looks like the third from the left.

 

https://spieglerusa.com/brakes/brake-lines-accessories-tools/cycle-brake-line-kits.html

 

[Dingo55]

thanks Lowndes

Appreciate your reply and the time taken to send pics

Ended up taking callipers to a motorbike mechanic

He found nothing internally

He in fact said he had never seen callipers in such good nick given the age etc

He showed me some horror pics of others he's worked on

Getting some braided lines made locally so hope to be back riding soon

Thanks again

Cheers

Mark