Total brake overhaul for ST1100AN

Joined
May 26, 2009
Messages
58
Location
Helsinki, Finland
Bike
ST1100AN
I have an ST1100AN and my gf bought an ST1100AP couple of months ago. So, there are two ST1100 ABS I's on my hands and both with brake problems. I'm going to repair both systems and I will update this thread always when I have something new to tell. Good tips are also welcome.



Problem list/symptoms:

ST1100AN

-ABS/TCS is not working, ABS 2 and TCS warning lights are blinking and TCS-off light is on. After pressing ABS reset button TCS light goes off but ABS 2 light continues to blink. I can't get a proper fault code from the system. Last codes I saw was 1 blink, "Crank angle sensor" and 8 blinks, rear pulse sensor(?).
-Front brake disc is twisted
-Left front caliper is stuck


Edit: There's also very rough running, increased fuel consumption and engine is running very cold. And leaking exhaust. But main thing is the brake system.

ST1100AP
-ABS is not working, I can't get proper fault code either. After reset the ABS 2 light stays on or blinks.
-Brake hoses are most likely original so brakes feel like an old rubber band.


Edit: ABS 1 light is dim in AP.
 
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British Columbia
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2021 RE Meteor 350
Can't help with ABS problems - never owned one - however, engine running cold has one reason only - stuck open thermostat. Before you assume that though, if you are not familiar with how the temp gauge normally reads, the needle will stay far to the left, maybe 1/5 of the way up, under normal speeds. Sitting in traffic will see the needle rise to just at, or slightly after the 12 o'clock position, before the fan cuts in.
 
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STonewall
Joined
May 26, 2009
Messages
58
Location
Helsinki, Finland
Bike
ST1100AN
Too much fluid pressure in the system? That is possible as well... How should I clear that? Bleeding fluid from system via bleed nipples?
 
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STonewall
Joined
May 26, 2009
Messages
58
Location
Helsinki, Finland
Bike
ST1100AN
Short answer - yes and/or from the fluid reservoir.

I'm not sure that I understand this - but let me describe what happened with mine.

Fitting new brake pads. Cleaned pistons, pushed them back all the way in, fitted pads. All round.
Later, turned on the ignition. A click (fuse blowing) followed by silence - no customary whirr of the modulators.
ABS lights indicating a fault - cant remember which bulb.

Checked fuses. Modulator fuse had gone. Thought about what I had done. Now I don't do the 4K, 8K, 12K service schedule. I keep records of what I have done, when and at what mileage - all on a database. You can find it on this forum somewhere - I'll find it and put a link in later. So I had flushed out and replaced the fluid when it was getting dirty and coming up to about 18 months, but the pads were only half worn, so they weren't changed. So when I pushed in the pistons all the way, there was too much fluid in the system.

I took the cap off the rear reservoir, and fluid spilled out all over the place. I realised what had happened and removed enough fluid to take it down to the line (I think I spooned it out !). Did the same with the front. Sealed it all up, replaced the fuse, turned on the ignition and all was well.

I reckon that there was too much fluid pressure on the modulators for them to turn. The fuse blew.

That was my explanation to myself. It may be complete rubbish but I don't have a better one.

[edit]
Link to the service database that I created.
The Microsoft Access version is at post #1.
There is a clunky (but useable) version for Open Office at post #20
[/edit]
That could have happened with the AP. I'll check the fluids and fuses first next weekend and then I'll report more.
 
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STonewall
Joined
May 26, 2009
Messages
58
Location
Helsinki, Finland
Bike
ST1100AN
Project is advancing: I changed brake fluids from both bikes and I found out that both have rear pulse sensor down. I replaced AP's sensor with working one and its ABS-TCS system started to work. I tried that same sensor to AN and it burned the pump fuse. System cleared itself and fault code number 1 became visible. "Crank angle sensor" is broken from front modulator.
 
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STonewall
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May 26, 2009
Messages
58
Location
Helsinki, Finland
Bike
ST1100AN
I finished cylinder head repair for AN and now back to the brakes:

ST1100AP

-New braided steel brake hoses
-Fixed ABS 1 light
=>Bike is working properly

ST1100AN

-Used but good front discs
-Braided steel brake hoses
-Overhauled modulators
-Overhauled brake calipers and master cylinders
-New rear pulse sensor
-New battery
-Alternator check
-Cylinder head repair

=> all two ABS and one TCS warning light were either constantly on or everything was flashing. I checked the fuse box and ABS main fuse had poor contact. After fixing the fuse box lights just stay on.

=>> that thing doesn't work. Any ideas?
 
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STonewall
Joined
May 26, 2009
Messages
58
Location
Helsinki, Finland
Bike
ST1100AN
I mean that the ABS lights and TCS light stays on when the bike moves, also. System should arm itself in 10 km/h and this system doesn't arm itself in 0-120 km/h and the brakes do lock. Situation is better now because system was completely silent before modulator overhaul and now both modulator whirr when ignition is turned on or system is checked.

Now, I'm thinking... When the system gave me code 1 it armed and checked itself. I used other bikes rear pulse sensor for testing. After that the modulators were overhauled and I bought new rear pulse sensor which is now installed. And yes, gap between pulse ring and sensor is right and the sensor is not damaged meachanically, no scratches etc. But the system doesn't arm itself. AND TCS is also dead. Looks like you're right about systems disability to gauge wheel rotation speeds. And that means faulty rear sensor or faulty rear sensor wiring because system did arm with another sensor...

I'll try a sensor from AP as soon as possible and after measuring the resistances in system wiring.

BTW, your link to system fault codes is good but there are differences between our systems. These two bikes are built with ABS 1 ('92-´95) and is your AY younger one, from 200- something? Most differences are in hardware but fault codes are slightly different also. Code 1, one blink, is hydraulic fault in front system in ABS 1 and crank angle sensor in ABS 2 if I remember this correctly.

I'll collect similar data pack of ABS 1 system when this project is done :)
 
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STonewall
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May 26, 2009
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58
Location
Helsinki, Finland
Bike
ST1100AN
There are three wires in both sensors. Voltage between blue and green should vary in 0.5-4 V range when wheel is turning and black wire has continuous 10-12 V voltage. I measured the rear wheel sensor today and it was ok. So next measuring will include front sensor and as much wires I can reach.
 
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STonewall
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May 26, 2009
Messages
58
Location
Helsinki, Finland
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ST1100AN
Front sensor: black, continuous ten-point-something volts, between blue and green CONTINUOUS 4.070V which ISN'T VARYING when the wheel is spinning! Air gap was 0.8 mm and sensor looks good...

...and so does the pulser ring. Is there any chance that the ring isn't magnetic anymore? One bolt is missing from that ring.
 
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STonewall
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May 26, 2009
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Location
Helsinki, Finland
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ST1100AN
Thanks,

Now the system tried to arm itself, after that fuse fixing, and I got fault code 5. It is faulty front sensor in both ABS 1 and 2.
 
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STonewall
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May 26, 2009
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58
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Helsinki, Finland
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ST1100AN
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STonewall
Joined
May 26, 2009
Messages
58
Location
Helsinki, Finland
Bike
ST1100AN
And now I'm facing a new funny situation: Front modulator pump is buzzing about 50% of the time, especially when I accelerate or slow down and even without braking. I can feel slight vibration in brake handle when I slow down and the pump motor, I guess, is working. But lights doesn't came on and the system doesn't show any problem code.
 
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Hello, I'm also having a issue with brake on my ST1100 (rear only). Caliper pistons not releasing pressure back after brake pedal depressed. I removed rear caliper and can depress center piston ok but the outside ones won't depress together, I can press 1 side down (that makes other side go out) same reversing try....any direction help would be great. Thx
 
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STonewall
Joined
May 26, 2009
Messages
58
Location
Helsinki, Finland
Bike
ST1100AN
Hello, I'm also having a issue with brake on my ST1100 (rear only). Caliper pistons not releasing pressure back after brake pedal depressed. I removed rear caliper and can depress center piston ok but the outside ones won't depress together, I can press 1 side down (that makes other side go out) same reversing try....any direction help would be great. Thx
I guess that you need to do caliper overhaul. Take the pistons out, poliwh them, hone the cylinders with fine (#1000) grade sandpaper and replace the seals and fluids. But note that I'm writing about ABS 1 system which is different than your ABS 2 system. I guess your bike is post-'95 because you wrote about three pistons.
 
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STonewall
Joined
May 26, 2009
Messages
58
Location
Helsinki, Finland
Bike
ST1100AN
And now more "advance", system died and it gave me fault code 5, front sensir fault. Which I just changed. Investigations will continue later, I'm riding in Germany now.
 
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STonewall
Joined
May 26, 2009
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58
Location
Helsinki, Finland
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ST1100AN
vanne1.jpgvanne2.jpg I guess I found the fault... Wire has touched the wheel and that had caused interference to the system. Strange thing is that modulators have buzzed always when when riding, not only when braking.
 
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West Michigan
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'98 ST1100
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8470
https://www.maximintegrated.com/en/app-notes/index.mvp/id/1076]I just read this thread and realize that I am missing a lot of fun by not having an ABS equipped bike to work on.

Just thought I'd explain how I believe the "pulse" signal is produced. The pulser ring isn't magnetic and the sensor isn't a Hall effect sensor.

The sensor must be a variable reluctance sensor. There is either a magnet inside the sensor or a coil inside the sensor that a current flows through creating a magnetic field. Also a sensor coil. As the pulser ring rotates, there is alternating air and then metal passing through the magnetic field. A stronger magnetic field is created when the metal is present, because of the change in reluctance. Reluctance is analogous to Resistance in an electrical circuit. As the reluctance changes, the strength of the field changes and this produces/generates a change in the voltage across the sensor coil. The output voltage of the sensor is actually the voltage across the sensor coil.

Also see : https://en.wikipedia.org/wiki/Variable_reluctance_sensor
https://www.maximintegrated.com/en/app-notes/index.mvp/id/1076
 
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