Flushing ABSII Questions

[Smudgemo]

I'm thinking of flushing the brakes of the '96 ST1100 ABS I picked up last month, and have a couple of questions.

Is it as easy as any normal brake flush as long as you keep the reservoir from going empty?

What size bottle of fluid is appropriate? I flushed the clutch a few nights ago and still have half a bottle left over. No sense in buying too much.

The seller indicated the rear pads would need replacement fairly soon. I have not checked them yet, but also don't know that I can get a set of pads on short notice. If I want to replace them next week, will the system most likely be too full and need a bit drained?

I wouldn't normally be quite so hot to get something like this done on short notice, but the fires around here aren't out yet, so it looks like we'll have a very warm and potentially smokey holiday weekend. Figured I'd hide out in the garage and change the oil and brake fluid in my '76 CB, and at least flush the brakes of the ST.

I appreciate any feedback. A trip through the manual and past threads didn't seem to offer this sort of answer.

 

[Slydynbye]

Is that a big bottle or a little bottle that is half full? When you put in the Pads the Reservoir level will rise.
Make sure you get OEM rear pads. If you get non OEM they are much thinner and wear out faster.

Bleeding the brakes on all ST1100 ABS-II (1996-2002). This order should be followed

Left front caliper upper bleed valve, using the front brake lever.

Right front caliper upper bleed valve, using the front brake lever

Left front caliper lower bleed valve, using the rear brake pedal.

Right front caliper lower bleed valve, using the rear brake pedal.

Rear caliper front bleed valve, using the rear brake pedal.

Rear caliper rear bleed valve, using the rear brake pedal

Tip: Periodically tap the brake caliper you're bleeding with something like the plastic handle of a screwdriver.

This will shake loose any of the small air bubbles which may be adhering to the caliper internals.

 

[Smudgemo]

Right, I found the sequence and it looks pretty straight-forward. Which gives me pause, is all. The brakes work very well, so I think all I need to do is not empty the master by accident.

It's a 12oz bottle that I opened Monday night, and it has been capped since the clutch bleed. Maybe a little less than half left over. I can always run down and get more if needed, but I just wanted to shoot for the right amount.

 

[Skin]

Has anyone ever used suctioning to flush/bleed brakes or clutch on a ABS?
I have a manual vacuum gauge/tool that I “think” I can pull the new fluid through the system!?
Yes it has a inline deposit bottle before the gauge.
(Without buying speed bleeders)
Has anyone ever tried this?
Or do the valves in the system even allow this to happen?
Hopefully my question is clearer than my brake fluid

 

[SMSW]

I have used a vacuum pump to bleed my 1300's brakes. It is one of those units used by air conditioning guys. I attached a bleeder to the hose to admit air and lessen the vacuum and the hose goes to a homemade catch bottle. Catch bottle's second hose goes the the various bleed nipples on the bike. It has worked fine for me and is quick and clean to use.

 

[Skin]

I have used a vacuum pump to bleed my 1300's brakes. It is one of those units used by air conditioning guys. I attached a bleeder to the hose to admit air and lessen the vacuum and the hose goes to a homemade catch bottle. Catch bottle's second hose goes the the various bleed nipples on the bike. It has worked fine for me and is quick and clean to use.

Hey thanks SMSW, a smigit more clarity please...
You did this one bleeder screw at a time?
Did you do the same with the clutch?

 

[SMSW]

Hey thanks SMSW, a smigit more clarity please...
You did this one bleeder screw at a time?
Did you do the same with the clutch?

Exactly. Empty the reservoir. Fill with new juice. Go to the bleeder nipple and loosen it. Suck the fluid through the caliper/proport valve, etc. When there is maybe 1/4" of fluid left in the reservoir, refill and suck this through. Depending on how old or dirty the old brake fluid was, you might repeat with a third reservoir full. Then move on to the next nipple. You MUST follow the procedure or you will not flush the entire system.

Yes, I do the same for the clutch, though that is much simpler than the brakes.

I do my brakes either every two years or every year (depends on how much work I'm doing on the bike that winter). My old bled fluid has always been clear - slightly discolored, but clean and no dirt in it.

 

[Smudgemo]

Now that I've done both, I think in a year or two when I do it again, I'll get the 12oz bottle and then maybe a smaller bottle for just in case. I'm not positive 12 will do both clutch and abs brakes, but I think it will if the fluid you're replacing isn't super-old and you empty the reservoir of old before adding new. I got a motionpro bleeder valve which was super-helpful if you're solo since you can't see the front left very well when working the brake. Both flushes were actually very easy and it included replacing the rear pads before the flush.

 

[Skin]

In using the vacuum I found that around the base of the bleeding valve it’s drawing air and giving me a false indication of air.... I don’t/didn’t have any issue with air, just a flush!
I used vaseline around the base of the valve, but not a fan using Vaseline around brakes.
Any one else have that issue?
Or better yet a solution?

 

[Tdinova]

One way bleeder is what u use, never had a problem..

 

[SMSW]

In using the vacuum I found that around the base of the bleeding valve it’s drawing air and giving me a false indication of air.... I don’t/didn’t have any issue with air, just a flush!

Exactly, the bubbles are being sucked in around the nipple, but it is not a problem. With my mock-up of a vacuum bleeder it sucks the air right through the vinyl tubing and I've never had air in the caliper afterward. Been using this setup for as long as I've owned the ST and always had hard brakes with no spongy feel.

I always close the nipple in the middle of emptying the reservoir - so the air is pulled thru the hose and not allowed to pool in the nipple.

 

[JJames]

Is that a big bottle or a little bottle that is half full? When you put in the Pads the Reservoir level will rise.
Make sure you get OEM rear pads. If you get non OEM they are much thinner and wear out faster.

Bleeding the brakes on all ST1100 ABS-II (1996-2002). This order should be followed

Left front caliper upper bleed valve, using the front brake lever.

Right front caliper upper bleed valve, using the front brake lever

Left front caliper lower bleed valve, using the rear brake pedal.

Right front caliper lower bleed valve, using the rear brake pedal.

Rear caliper front bleed valve, using the rear brake pedal.

Rear caliper rear bleed valve, using the rear brake pedal

Tip: Periodically tap the brake caliper you're bleeding with something like the plastic handle of a screwdriver.

This will shake loose any of the small air bubbles which may be adhering to the caliper internals.

One thing missing here ? How to bleed the circuit from SMC to rear caliper ? Or am I missing something ?

 

[Slydynbye]

One thing missing here ? How to bleed the circuit from SMC to rear caliper ? Or am I missing something ?

Good point, Honda doesn't address it but, it makes you wonder how to clear that circuit.

 

[JJames]

Hand pump the front caliper/smc might work , or vacuum from the rear caliper ??

 

[jfheath]

The plumbing on the ABS 2 models equipped with linked brakes is very much the same as the ST1300 models. I've added a link at the bottom to a detailed illustrated document about this. Much of it is relevant to the ST1100 A

The biggest difference is that the Secondary Master Cylinder is vertically mounted, with the pushrod and rubber boot facing downwards - which helps to keep water ingress to a minimum. Just as it does for the rear master cylinder. There is no bleed valve at the Proportional Control Valve that I can recall, so the system is bled from the brake pedal to the rear caliper.

For the ST1100:

It is important to follow the correct sequence so that air from the line to the front centre pistons is cleared. The same line feeds the SMC.

When pumping the brake pedal, fluid flows through the SMC from the input port to the output port - the primary seal inside the master cylinder yields easily to pressure from behind, just as it does in any master cylinder, and the fluid continues through to the rear outer pistons. The output port of the SMC is at the top, so air bubbles are easily expelled.

The plumbing from the rear reservoir to the rear outer pistons is long. it goes forward to the headstock, down to the front calipers, to the SMC, back up the fork legs to the headstock and back to the rear caliper. There are plenty of places for trapped air to hide. Having a vacuum pump on the rear outer piston - rearmost bleed valve - is useful for maintaing a steady flow while going round the joints and hoses flexing and tapping to help dislodge air bubbles. Then the use a non return bleed valve without a vacuum pump to finish off.

When the rearmost bleed valve on the rear caliper open, and pumping the pedal or applying a vacuum, fluid flows through the SMC from the input port to the output port - the primary seal inside the master cylinder yields easily to pressure from behind, just as it does in any master cylinder, and the fluid continues through to the rear outer pistons. The output port of the SMC is at the top, so air bubbles are easily expelled.

However, it is always worth exercising the SMC plunger while the rearmost bleed valve on the rear caliper is open, to give the piston the full range if its movement.

The only issue that I have come across with the operation of the SMC is with the 3 pivot mechanism that links the fork leg, the SMC itself and the caliper bracket. Hidden behind the plastic shroud, it is easy to forget that it is there and the 2 metal plates can rust, and the needle roller bearings can become dry. It is worth taking this mechanism apart and checking that it moves freely.

The article I wrote for the ST1300 on getting rid of the air from the system has some relevance and may be worth a read. I didn't have my ST1100 ABS/CBS/TCS when I wrote it, but I checked afterwards from memory, notes, old photos and the 1100 manual - the plumbing and relative position of the various components on the ST1100 is the same. The ST1300 has an SMC which is an integral part of the front left caliper bracket, and it has a bleed valve up high near to the proportional control valve. Parts of the article may be helpful. I'll post a link in a minute. Download the pdf in post #1.

Link here

 

[JJames]

Thanks ! I'm going to have to read it twice . Doing the the brakes next week.