ABS 1998 st1100 has me beaten, advice and suggestions needed

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Hi all

I have an st1100 98 abs aw bike. the problem is that the back brake was constantly rubbing So. I have done the following

1.front calipers thoroughly cleaned
2.rear caliper COMPLETELY stripped all seals replaced all pistons polished reassembled put back on with new pads, all honda seals and pads
3. rear disc replaced with new disk and bolts, both honda, old disk warped
4. brakes bled in correct sequence and flushed through with approx 250ml of brake fluid. there is no air in there!!


Test ride, 3 miles down the road using the front and rear brakes and the back disc is red hot and the bike is pulling like I am resting my foot on the rear brake pedal ie back brake moderately hard on. I stop for ten minutes let it cool down force the rear pistons open so pads are not rubbing at the rear ride home on the front brake only.

only other symptom is the rear pedal before the ride was soft with alot of travel but if pumped did go hard as I would expect it to ie has resistance. the abs light is on and tcs light is on too not sure if this helps

any advice plaese as I am completely stumped and it is now costing alot of money chasing the fault

Rob
 
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OP
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So some more investigation reveals that the secondary master cylinder can cause these symptoms, I have changed it for a spare i has and will test ride later and report back. in the mean time i am going to order a rebuild kit But does anyone know if the smc rebuild kit is the same as the master clutch rebuild kit ?

Thanks

Rob
 
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I've recently rebuilt my clutch(32-1081) & front brake(32-1079) MC using K&L kit, did not perform the rear MC(32-1080) yet but I see they have different part numbers for clutch, front & rear MC kit.
So I don't think they're the same kit, maybe someone will chime in later to confirm.

Ray
 

Slydynbye

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Are you sure the disk you changed is correct? I know I had trouble trying to use Wheels and disks from "ABS ST1100s"
 
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Did you clean, lube or replace pad hanger pins?... Another thing to check is the pivot mounts on the left fork for the caliper/smc. The mounts have needle bearing inside... the needles need to be well lubed with water proof grease and the bushing should be cleaned. The shoulder of the mounting bolts and the head of the allen bolts for that side are also pivot surfaces also and should be lubed. If the mounts are not pivoting properly, they can cause the smc to hang up...
 
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This is what the manual says about diagnosing the problem...

Pre-start self-diagnosis procedure (everyday check-up)
1. Turn the ignition switch ON
2. Be sure that the ABS indicator lights 1 and 2 come ON.
3. Start the engine.
4. Ride the motorcycle and raise the vehicle speed to approximately 6 m/h (pre-start self-diagnosis completes).
5. The ABS is normal if both the ABS indicator lights 1 and 2 go off.

Retrieval of codes:
1. Turn the ignition switch OFF.
2. Turn the ignition switch ON while pressing the ABS/TCS indicator light switch. The ABS indicator light 1 and 2 should come ON.
3. Hold the ABS/TCS indicator light switch pressed (for approximately 5 seconds). The ABS indicator light 1 and 2 should go OFF.
4. Release the ABS/TCS indicator light switch immediately (within 1 second) after the ABS indicator light go OFF. Output of the problem code starts and the ABS indicator light 1 blinks. (The ABS indicator light 2 is OFF this time.)
Clearing:
5. Press the ABS/TCS indicator light switch during output of the problem code (while the ABS indicator light is blinking). > The Problem code is cleared and the ABS indicator light 1 and 2 comes ON and stay ON.
 
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Thanks for the code diagnosis I will check it later today, im okay running without abs or tcs anyway but it would be nice to get it fixed.

I rechecked everything and have been on it for a few hundred miles and the only problem now is the rear brake is again non existent. I have re bled in correct sequence but to no avail. Does anyone know what might be causing the rear brake to be like a sponge??
just to recap I have completely rebuilt the rear caliper including pressure seals dust seals brake pads and new disc
the front have ben overhauled and cleaned
the smc on left fork was changed for a spare I had, this seemed to stop the rear dragging
the system has now had over 1/2 litre flushed through in several bleds

the rear brake is still non existent, Argh
 

Don-STOC237

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When you say "the rear brake is non-existent" do you mean during the ride, or while testing when stopped? When I had my 98abs, the pedal always felt very soft with the engine off but firmed up when riding. I think it has something to do with the abs system.
 

wjbertrand

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You don't mention the rear master cylinder. If the pressure relief or return port in the master cylinder is plugged, brake pressure will not be released after using the pedal. The port is very small and easily blocked. Happened to me on a different bike (Honda VF750F Interceptor) and I solved it rebuilding the rear master cylinder and cleaing out that return port with some fine wire.
 
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okay update time

thanks for all info. smc has been changed in addition to the full rebuild at rear including pads and discs and overhaul at the front, the brakes are no longer dragging, the last issue to sort with the brakes is that there is effectively no back brake

when the bike is on its stand running or not if you pump the rear barke pedal several times it does give resistance, when riding the bike same again but the pedal bneeds pumping 6-10 times before it does anything. the front brake work as I would expect a 17year bike to work. its just the bake brake now that I cant get working. not sure there is anything else I can add in terms of the symptoms. it feels like its full of air.

the only thing I have not been near is the rear brake master cylinder? as noted by WJBertrand, would this cause the rear brake to be V weak?

Just to compound my love of this newly acquired bike that so far has needed head bearings and bottom yoke replacement, wheel bearings replacement front and rear, all fluids changed, rechrome and completed strip and rebuild of the forks including new bush guides and seals, and the rebuild of the brakes at the rear ( ongoing Issues) and overhaul of brakes at the front It has developed a fueling problem on test rides but Ill start a new thrad for that~!!!!!

I thought these bikes were built for mileage!!!!! moan over any further advice on rear brake would be appreciated
 
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Sounds like you either have a large air bubble in the rear brake system, or maybe the rear master cylinder needs an overhaul. I'm voting for air... try forcing fluid in reverse to the master cylinder. If that doesn't work, remove the caliper anti-pivot bolt and rotate the caliper on the axle a little to try and dislodge the air pocket.
 
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update:

I have purchased a hand pump, this should make things easier.

so just to check I haven't misunderstood its a likely hood of air, that bit I get.
Its location could be at the smc as the rear brake pedal will not actively pump fluid to that point unless the bike is moving? so does that mean I need to physically release and exercise the smc while pumping fluid through to dislodge potential air from there?
does pumping the rear brake pedal with either rear nipple open or either front lower nipples not pass air by the smc when stationary? ( in the correct order of course)

I will release the rear calliper and spin it to try to eliminate potential air from there.

Sorry to be a pain all info is greatfully received. as a side I assume I just connect the hand pump to the nipple and pump with no need to do any manual input at the foot brake or lever???? I ve always bled brakes manually, hang over from when I used to fix my cars 25 years ago and could not afford mechanics or fancy equipment. 25 years later I still cant afford mechanics but I now have a hand brake bleed pump lol.
 
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Be very careful when using the vacuum pump... keep a close watch on the fluid level in the reservoir... you don't want to suck more air in!
 
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Update

I was careful, I used the pump to suck through another 1/2 litre of fluid. this is getting expensive.

I tied the front brake with a cable tie over night and weighted the foot pedal over night. I have good front brakes but still bugger all on the rear. I agree it does appear that I have air in the system but have no idea of where and how to get it out. it is only affecting the rear and the system has been bled manually several times and once using a vacuum pump. there is no fluid loss either. it has to be air but with the amount of fluid I have pushed through the system I cant understand where it could be hiding??? is there something else on the operation of the rear foot brake that gives the impression of air ie push all the way down for minimal braking. because given the litres of flyuid ive put through its not reasonable to still have air there. and no matter how much fluid it doesn't get any better. if I pump the rear 7-10 times it does firm up if that gives any clues.

the bike is in constant use daily and although im fast developing a slow speed filtering technique using the front brake its counter tuitive and need to get the rear properlysorted if there are any more ideas out there?
 

Slydynbye

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I haven't seen any mention of the SPECIFIC bleeding procedure for the ABS/TCS. Do you have a manual that you are following?
There is a sequence that needs to be followed.
 
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