80 xs11 special - lots of front brake questions

[nezzer]

I am in the process of doing some much needed maintenance to my 1980 xs1100 special.

Last season I noticed my front brakes seemed different, like I had to really squeeze down on the lever in order to get the brakes to activate, although once they activated they seemd fine. Also sometimes the brakes would lose almost all force, they did very little braking even if I really cranked down on the lever. Not much later they would return to normal.

I figured it was air in the lines and since it was close to the end of riding season I didnt investigate any further. Now I am looking very closely at my brakes and have a number of questions.

1. The calipers are held on by a single bolt. I read these things are supposed to swivel, I presume with the bolt as the axis of rotation. How easy should it be for the calipers to swivel? With the proper torque on the bolt, my calipers dont seem to swivel at all.

2. Perhaps on a related note, my manual says there should be an o-ring on the top of the caliper (part 12-24). I dont see these o-rings on my calipers. What are they there for?

3. My front wheel spins freely when my calipers are off. Once I loosely attach my caliper it is a real tight fit getting my pads in to postion. Once the caliper is secured with the pads in position, the wheel barely spins at all. It turns maybe 1/8 rotation when it would turn 4 or 5 rotations with no calipers attached. Just as I write this out it occures to me I should try taking a C-clamp to the piston to get it to compress. I will give tat shot this weekend.

4. Were slotted rotors factory equipment on the 80 special? Mine are not slotted by my manual keeps showing pictures with slotted rotors.

5. Last question, I drained my front brake master cylinder and lines of brake fluid. I then filled the master cylinder back up. I am trying to bleed the brakes but have not had any luck. I have followed what others have suggested, attaching a tube to the bleeder valve and keeping the end of the tube submerged in brake fluid. When I pump the brake lever no fluid comes out at the bleeder valve. Actually the opposite occurs, a vacuum is created that sucks fluid up the tube towards the bleeder valve. No matter how much I pump the brake the vacuum level seems to stay constant, never actually sucking fluid into the bleeder valve but also never pushing fluid down from the MC out the bleeder valve. During this time I have turned the banjo bolt on the other caliper such that no fluid should be entering it. I did this just to help eliminate some of the parts as possible sources of the problem. Any thoughts?

I know this is a lot of material for one post but I just plain have lots of questions. Thanks for any help you can offer.

[HobbyMan]

start by cleaning you spooge hole if you haven't already done it. There should be a tech tip explains it. If it is clean, completely disassemble you brake system and clean it. Pull the pistons and mc plunger out. Clean it with some sort of solvent and flush it with brake fluid. Blow out your lines with an air compressor. When you first put fluid in it, it may take a while to "prime" it. Just keep bleeding it. Usually when there is a vacuum created, that means that the plunger assembly in the MC is full of crud.

[Ken Talbot]

I would suggest taking the entire system off the bike so you can clean it thoroughly. It sounds like you've got spooged-up calipers, the pressure release orifice in master cylinder is plugged, the caliper pivots are gummed up, etc, etc. You will find it a lot easier to work on on a bench with good lighting.

[Boothman]

Can't say any more than what Ken already has. Take it apart and clean the livin' daylights out of the system. Bench bleed everything twice and reassemble.

Not sure what condition your brake lines are in, but inspect closely too and if cleaning is not the answer, consider having new lines fabricated. I have found my local Harley rebuilder to be a good machine shop. Those oil leakers need a lot of fabrication!!

[fredintoon]

Weird but it works

Hi Nezzer,
the Special's front brakes are totally strange swivelly things copied off a Beemer but they work OK if (like all the other posts tell you) they are cleaned out & bled properly. Have you noticed that the pads are tapered? Don't worry, they are supposed to be. If yours ain't the pads are worn out. You don't see the calipers swivelling as you apply the brakes because they only turn on their posts to take up pad wear. My XS11SG does have o-rings atop the swivel posts and all three of the brake disks are slotted. '80 was the first year for slotted disks so either a PO swapped in plain ones or yours is a late '79 not registered until '80.
Fred Hill, S'toon.

[pggg]

Nez, get a syringe, fill it with brake fluid, pump it thru the master cylinder and into the brake lines, bleed the air out the calipers when the pressure builds. Won't take long.

[nezzer]

5 great replies within 6 hours of posting; that is pretty good forum activity for a 27 year old bike!

I will take apart and clean the entire front brake system. Hopefully it does not end up being more than a 5 beer job b/c I am anxious to ride it, but better safe than sorry.

[TADracer]

Nezzer,
One more thing (Ok, two.....maybe three).
1. Check the caliper bolt for straightness. Sometimes they will bend ever so slightly. If it is bent, replace it. Readily available at any hardware store for a buck or so.
2. Torque the caliper bolt to 18 Ft. Pounds then put the locking nut on top. 18 Ft. Pounds ain't much so dont overtighten.
3. Take a C clamp and run your caliper pistons in a bit. Only a few thousandths makes it so much easier to get the caliper and pads back on the disk.

[mro]

Brake woes

Read thru post...

surprised no one mentioned easiest way to get the MC primed is to disconnect hose fitting, fill MC, stick a finger over hose hole and pump handle. Finger will let fluid out and keep air from getting in. Sometimes need to lightly tap MC to get all the air out of it.

Priming the MC by itself makes it much easier to bleed the rest of the system. Also sounds like you may want to remove and check the caliper pistons for corrosion. Can make them stick. This also makes it easy to clean caliper.


mro

[Boothman]

MRO is right on track and thinking like an XS. I did not want to suggest you spent money replacing lines when that is not your issues.

Sometimes I forget that those who review these posts may not be experienced mechanics and i apologize. I do not intend to sound like a dic*.

What has been printed here is the best advice and you should be OK.

[mro]

drawing the line

Might as well say something about lines too

stock type brake lines when replaced with the ss lines make a big time stopping difference.

Have stock type on a couple XSes and SS on the hot rod.
Less effort and can lock up front wheel on the hot rod.

Believe manual recommends replacing em after four years even if no problems.


mro

[pggg]

Hey Booth, replacing the lines is the best option for a start on 1/4 century old brakes, mro a 50c syringe does the trick in a couple minutes, all hoses bolted, presumably those Mit-Vac gadgets are the same thing?

[John]

Mighty Vac

The Mighty Vac works just the opposite way. It sucks the fluid down from the master to the caliper. I prefer the reverse bleed method, from the bottom up.

[cajun31]

What about the rear brakes

I would strongly suggest that if you find the front brakes to be full of crud that you do the same clean on the rear. It won't take that much more effort and you will feel a lot safer. It is no fun having either the fron or rear brakes lock up or drag. Who knows your gas mileage might get better.