Rear brake not functioning

[Rolland]

This is the ongoing project in bringing back to life my 2001 R1100RS I have solved the fuel problems and got it running now but need to work on the next problem. 

The rear brake does not work, I do have front brakes just no rear, the rear reservoir is empty altho no signs of leaking. the brake lever works up and down but does not have any effect on the system. It has ABS system. This bike did sit for a couple of years 

I read the other post on bleeding the system on a later model and wondered if the system is the same on my model. 

I have a Haynes manual ordered and a friend said he has a pressure bleeder will those work on  this system or am I going to have to bite the bullet and take it to the dealer. Normally I can fix most problems but the abs system is new to me. 

[Jim Moore]

You may have been reading about the servo brakes on the later models. Your bike has ABS, but it's not particularly complicated. You can fill the reservoir and bleed just like old fashioned brakes. Only difference being you need to take the tank off and bleed at the ABS module also.

 

that being said, I don't like the empty reservoir. It's empty for a reason. You may have an additional problem there, but I'd def try filling and bleeding first.

[dirtrider]

9 hours ago, Rolland said:

This is the ongoing project in bringing back to life my 2001 R1100RS I have solved the fuel problems and got it running now but need to work on the next problem. 

The rear brake does not work, I do have front brakes just no rear, the rear reservoir is empty altho no signs of leaking. the brake lever works up and down but does not have any effect on the system. It has ABS system. This bike did sit for a couple of years 

I read the other post on bleeding the system on a later model and wondered if the system is the same on my model. 

I have a Haynes manual ordered and a friend said he has a pressure bleeder will those work on  this system or am I going to have to bite the bullet and take it to the dealer. Normally I can fix most problems but the abs system is new to me. 

Morning Rooland

 

If your 2001 1100RS still has an ABS system then it is the ABS II system. 

 

Those bleed pretty well just like non ABS systems (straight through) except there are also bleeder screws on the ABS hydro unit that also needs to be bled as air can accumulate in the hydro unit above the displacement pistons.  

 

You can use a pressure bleeder but have to be careful to not over-pressurize the system & it is difficult to seal a pressure bleeder to the motorcycle master cylinder reservoir. 

 

You have to be very careful when using pressure bleeders to not blow brake fluid on the paint or dash as brake fluid will ruin both. 

 

One important thing a lot of new BMW owners miss is there is a rubber bladder type seal just under the rear brake reservoir cap. That rubber bladder needs to be removed before checking or adding fluid (do not put new fluid on top of that bladder). 

 

If you are ultra careful with that pressure bleeder, & can find a solid way to connect it to the caliper bleed screw, & don't over back-fill the rear reservoir then you can bleed from the bottom up (from caliper bleed screw to the master cylinder). This is the way the factory does it. 

 

Power bleeders are good but can also increase the risk of mistakes so using a power bleeder is probably not the best thing for a first time brake service. 

 

One thing to keep in mind on older motorcycles (especially ones that have not been ridden in a long time) is there is probably a gunk ring in the last part of the master cylinder piston travel. Seeing as you currently have no rear brake probably means that you have already stroked the rear brake pedal full travel. Pushing the master cylinder piston into & past that gunk ring can ruin the piston seal & cause future leaking or brake pressure bleed down. 

 

I usually just use a hose & bleed bottle on the open caliper bleed screw with the end of the hose exiting "below" fluid level in the bleed bottle. That allows quick continuous brake pedal stroking without closing the bleed screw after each pump-up (no need to close bleed screw after each pedal pump up).

 

The fast pedal pumping with no stopping to close bleed screw allows an empty system to fill & bleed out quickly. The pump & hold method makes it difficult to get the air out of a completely dry system. 

 

You should be able to get a somewhat firm rear brake without bleeding at the ABS hydro unit but there will still be air trapped in the hydro unit that should be bled out. But you should be able to get enough rear brake without hydro unit bleeding to check for leaks (that rear brake fluid went somewhere!) & sort of test the rear brake system for function & leaking. 

 

It isn't rocket science or anything special but do be very careful with the brake fluid as it as a great paint remover & plastic etcher.  

 

 

[Lowndes]

Rolland,

 

If it has not been done already, you need to replace the OEM brake lines on that bike.  You would want to do the replacement before the bleeding process or it would just have to be done again. 

 

If they are the black rubber lines, maybe 1/2 inch diameter, those are the OEM brake lines between the master cylinders and slave (brake) cylinders. This is a well known problem.  The brake fluid will slowly attack the rubber lining and cause your brakes to fail, possibly squirting that brake fluid on you and the bike if you don't have other things to worry about right then.  They seem to last about 15 years on average.

 

There will also be small, steel tubes to and from the ABS module under the tank that Dirtrider referred to above that make up part of the hydraulic system.  They are OK unless rusted or kinked.

 

Galfer and Speigler make kits for replacing these OEM lines on these bikes.  These brake lines are often referred to as "braided stainless (steel)" or just "braided" brake lines.  They are actually three layers, innermost is the PTFE tube for the brake fluid, outside that is the braided stainless steel wire mesh reinforcement for the tube, and covering everything is the clear (or colored) plastic coating that protects the other bike parts that may come in contact with the brake lines.  

 

These kits are usually made up per the order.  It may take a week or two to get the kit.  You can get a variety of colors in the lines and fittings.  If you have or may get a set of "bar backs", you can request a few extra inches of brake line for the front brakes from the handle bar master cyl to the ABS steel line connection.  If the offset isn't too large, the original length hose will work with careful routing of the new line.

 

https://www.galferusa.com/

 

https://spieglerusa.com/

[Rolland]

Ok thanks for the information and direction I am going to have to dig into the system and see what has happened I suspect from what has been posted that there must be a stuck piston some where not letting the rear brake get fluid to it. 

 

[szurszewski]

1 hour ago, Rolland said:

Ok thanks for the information and direction I am going to have to dig into the system and see what has happened I suspect from what has been posted that there must be a stuck piston some where not letting the rear brake get fluid to it. 

 

 

 

Have you tried filling the reservoir? If you don't have fluid, nothing is going to do anything...

[Rolland]

yep filled the reservoir just can't get the fluid to the  brake cylinder. it routs the fluid from the master cylinder to the abs block under the tank then in to the brake cylinder so I am assuming the blockage or whatever is  in the block 

[dirtrider]

5 minutes ago, Rolland said:

yep filled the reservoir just can't get the fluid to the  brake cylinder. it routs the fluid from the master cylinder to the abs block under the tank then in to the brake cylinder so I am assuming the blockage or whatever is  in the block 

Evening Rooland

 

Probably not a blockage, because of the amount of air remaining in the system you are most likely just compressing that air but due to the limited master cylinder stroke it can't compress it enough to push it through. 

 

First, make sure that the rear bleed screw is not plugged, then put a hose on the open bleed screw, then place that hose down in a jar or bottle to almost the bottom, then put enough brake fluid in that jar or bottle to cover the bottom of the hose.   

 

Then stroke the rear brake pedal about 3/4" to 1" (no more), do this a few times to pre-bench-bleed the rear master cylinder.

 

Now pump the heck out of the brake pedal (many times real fast), that usually pushes the fluid in far enough to push the air out.