R1100RT brake bleeding question

[Asymmetrical]

I just finished a brake fluid flush using a vacuum brake bleeder on my '97 R11rt. All is fine with the rear brake, but the front is now mushy.

 

Unfortunately, I vacuumed out a bit too much from the front master cylinder reservoir so that the fluid got just slightly below the feed hole to the master cylinder itself.

 

So I've loosened the banjo bolt and using the brake lever expressed some fluid from that point, which was weeping out with no sign of air, so I think that's okay. I've also re-bled the front brakes both sides a couple more times without solving the problem.

 

When I apply the vacuum hose to the bleed nipple and loosen the bleed nut, it seems air is coming from the threads of the bleed nut, but no air seems to be coming from the caliper itself though it's hard to tell with the air weeping in from around the nut.

 

At this point, I'm not sure what to do next, but the front brake lever isn't hard like I remember it and seems a bit spongy. Any thoughts about what to do next?

[Michaelr11]

Try using a Speed Bleeder valve. Put the vacuum away, pump the lever GENTLY by hand. This will push any air bubble down to the caliper and out the bleeder. If you don't pump gently a squirt of brake fluid will spout over the reservoir and onto the dash or onto the tank. The speed bleeders do work - my lever is very firm. Watch the level in the reservoir - keep adding fluid.

 

You may have introduced a lot of bubbles into the system. Another option which you might try first is to tie down the brake lever and leave the system pressurized over night. This should force any air up the line into the reservoir. If you try this first, then bleed it with speed bleeders after.

 

[dirtrider]

Afternoon Asymmetrical

 

Well you probably pulled some air down into the ABS controller. More than likely you are now going to have to remove the gas tank and bleed the at the ABS unit.

 

Maybe first try turning the handlebars fully left and right while pumping the brake lever (cover on). Do this before removing the tank.

 

Once you get air trapped in the system in the high spots it is very difficult to dislodge as the fluid will just freely follow under the air without pulling the air along with it.

 

Maybe try riding the bike and getting it into a low speed ABS event as that can sometimes move the air out of the high spots.

 

[Asymmetrical]

D.R. - the bad news is that I have a full gas tank, so I suppose I'll have to see if I can siphon the contents or drain off what's in there before removing it and getting at the ABS controller. I suppose the good news is that I can replace the fuel filter while I'm at it and flush the controller too.

 

Michael - I don't have speed bleeders handy so, I can't try that suggestion right now. However, I will tie down the brake lever to see if any air bubbles that remain in the calipers work their way north tonight - though if this worked it would be so easy that it would rate as the easiest fix I'd ever experienced.

 

On the other hand, if the problem is in the ABS controller, I suspect tying the lever back won't do much. Thanks to you both for the suggestions.

[AndyS]

On the other hand, if the problem is in the ABS controller, I suspect tying the lever back won't do much. Thanks to you both for the suggestions.

You have nothing to lose by tying the lever back.

Then try a re bleed or two! You would do well to try and bleed out the ABS unit too.

 

[BrianM]

You should be able to get all the air out of the system without bleeding the ABS unit.

 

I changed the front brake lines and never bled the ABS.

 

When I bleed, I fill the reservoir, put a piece of clear tubing over the bleeder (I have one of these - http://www.lislecorp.com/divisions/products/?product=66&division=1&category=1), make sure the tubing goes up and then down to create a place for the bubble to move up out of the caliper. Put some pressure on the lever. Open the bleeder. Pump the lever until the reservoir is low, but not low enough to expose any of the holes at the bottom of the reservoir. On last pump hold lever and tighten the bleeder. You do not have to close the bleeder after each pump of the lever. No need for a vacuum bleeder or speed bleeders.

[Asymmetrical]

Andy - I agree - I tied the lever back last night with no success in eliminating the air by this morning. So it looks like I'll be removing the fuel tank to get at the ABS controller for a bleed.

 

Instead of draining a nearly full tank is there a way to simply plug the fuel line while removing the tank? Or is the connection to the tank in an inaccessible place making this impossible?

 

Brian - thanks for the suggestion, but I've already got a vacuum bleeder kit with all these parts, so I'm well fixed for hoses, cups, etc.. My error was in not paying close enough attention when I was at the caliper bleeding off old fluid. I let the master cylinder fluid level in the reservoir drop below the bottom and vacuumed some air into the system.

[AndyS]

That's where the quick disconnects on the 1150 are a real bonus.

However it is not all loss. If you clamp the rubber hose from the fuel tank (well before it joins the plastic pipe of the fuel manifold). Remove the cable clamp, slide off the hose and then in the free end of the rubber hose, push a metal dowel of some sort up the end of the rubber hose to block it off.

Repeat with the other hose.

 

Personally, I would get a length of clean garden hose and siphon the tank dry, that way you can make sure you have got rid of any cr*p in the bottom of the tank (make sure you siphon out both sides though).

[eddd]

Prior to installing quick disconnects, I used a drift to plug the lines. But your problem will be the weight of the tank when full. It is ackward to lift. I'd suggest you drain the tank first.

 

You'll need a container(s) to hold the fuel and a large funnel or piece of hose to slide over your tank's hose. You will likely have some small spillage so take the appropriate safe guards.

[aterry1067]

FWIW, I bled my ABS unit with a vacuum pump, with the tank still on the bike, although I only had about 1/4 tank of gas. It's a PITA to get to, but it CAN be done. I slid the tank back, and lifted the tail of the tank a few inches to get access. I then supported the tank with an empty 20oz soda bottle I think (whatever happened to be handy), stuffed up into the cavity under the tank.

 

With a vacuum pump, you will see air bubbles from the sides of the bleed valve, even when there is no air in the system. The pump is pulling air from around the valve itself. This can be seen by completely closing off the valve and, with fluid still in the hose, give a quick pump or two. The main thing is to make sure you get fluid from the reservoir to your bleed point while maintaining constant negative pressure on the line, thus completely flushing the line. As you know (especially now), keep an eye on your reservoir level. You aren't the only one. I've sucked more than one reservoir dry myself.

[Bob in WV]

This sounds like my problem after replacing the left fork seal. I had to disconnect the brake line to get the slider off and lost all of the fluid. After reassembly and bleeding the brake was still mushy. Took one full pump to get brakes to hold. After a few days and several hundred miles all is well. The air goes away, at least it did for me. I too used a vacuum bleeder.

Bob

[AndyS]

Hi Bob, welcome to the group, Where are you from? I had a quick look in the profile and couldn't see.

Just for info though, you can do that seal work woth the lower fork leg in situ and save a lot of hassle...just sayin'.

Anyhow it's good to have you around.

Andy

[Asymmetrical]

After sitting for a couple of days, the front brake seems to have firmed up a bit and its travel is less. The lever now has approximately 1.5" of travel from 'at rest' to completely firm. (With the brake thumbwheel at #1 position.)

 

To be honest, I don't recall if that is any worse or better than it's ever been. But by comparison, the rear pedal has almost no play before it comes up hard. It's worth noting that the geometry of the rear pedal actuation is probably different than the front, so perhaps this is not be a good comparison to make.

 

At this point I'm not sure whether the front brakes still have some air or not. Should I be getting less than 1.5" of lever travel before it comes up hard?

[dirtrider]

Morning Asymmetrical

 

No way to know for sure how much lever free play you SHOULD HAVE. A lot of reasons for that to vary slightly as the bike gets older.

 

The rear is only a single caliper with a single piston caliper so that would normally be a bit shorter stroke to firm.

 

On the front-- it should be the same as it was before the bleeding process. ALWAYS take note of the lever travel to firm lever before doing any brake work so you know if you introduced any air during the maintenance process.

 

As long as you can’t easily pull the lever clear to the grip it doesn’t have much air in it.

 

The front will have a bit more lever travel as it has to apply 2 calipers with 4 floating pistons each. A lot depends of the relaxed piston retraction due to seal stiffness, and corrosion, and brake pad seating position.

 

If you have enough lever firmness to ride it safely then just ride the bike. Most air that isn’t trapped in the lower areas like behind the caliper pistons will eventually work it’s way up and out (air likes to raise on the fluid as the fluid likes to travel downwards due to gravity).

 

While riding, maybe try to get it into a front wheel into a low speed ABS event as that will deep cycle the ABS controller pistons and help purge the air out of the top of the controller area.

 

 

 

[Asymmetrical]

D.R. -- That's very helpful. Unfortunately, it's too late for me to now take note of lever travel before I bleed (next time!). The good news is that since the lever's full hard position is more than 2" away from the grip, I don't think there's much risk in following your other advice to give the ABS a workout to see if that purges some air.

 

Many thanks to you and all the rest for sharing their expertise.

[Bob in WV]

I have a small farm in Jackson County West Virginia and am new to this board. Registered with ADVRiders also. When I replaced the seal on my left fork I just removed the front wheel and dropped the fork slider. I did update my profile.