How I reset rear brake so it works plus effectively

[Wolfchen]

If its one weak point all XS bikes have its the single pot disc brake caliper.

I've read the new to XS650 Checklist post and a few others but these do not address a particular maintenance issue. How to get the rear disc brake common to all XS models to work as designed and more effectively. The information also applies to the XS650 front caliper assembly as well.

Assuming the caliper piston is not seized or pitted and the lip seal is intact we can proceed. It is also understood the pads are to be replaced for safety sake.

I first thoroughly clean all debris / paint and gunk from around the caliper housing, pads, steel slider clips and Y fork. A hand-held stainless steel pool cleaning brush is most effective in cleaning yet gentle enough to leave parts undamaged. Pad shims need to be rust free.

Afterward these parts must be polished in order that the brake pads are able to move fractionally left & right < ---- > on the steel slider clips freely (inside the Y fork) as the piston acts upon them. We can't expect the brake to function properly if parts cannot interact smoothly.

The caliper housing (portion containing the piston) needs to be able to seat completely vertical into the Y carrier e.g. the "fork". See the first pic.

Carefully remove all paint from beveled angles and gently polish the intersecting surfaces. The caliper needs to be able move fractionally fore & aft while seated; slightly - by only 1 or 2 degrees. Excess paint will hamper this slight movement.

Once the slider clips are brushed and polished they'll permit easier pad movement.
Make absolutely certain the caliper Y fork is equally centered over the disc. See the second pic to view the clips.

The steel caliper mounting bolt requires deep cleaning & mirror-like polishing so the caliper can slide < ----- > along its length freely. This is a key issue.

Carefully re-assemble the now VERY clean Y fork, caliper and install new pads. The caliper / pad assembly drops down over the disc. See pics.

Apply Ant-seize paste on the polished caliper mounting bolt along its entire 2" length.
Make certain the covered slider barrel is clean inside. The two parts locate the caliper onto its carrier; e.g. the Y fork. Use the factory recommended torque limit on all fasteners and apply Locktite or other thread glue.

Brake disc(s) should be free of defects; grooves, rust, galling or glaze.
If it cannot be cleaned with emery cloth & solvent / steel wool it should be re-surfaced. Most auto parts stores can cut rotors.

Make sure the master cylinder operates properly with new DOT fluid. Brake lines often need to be bled before the brake can be used effectively. Afterward the brake pedal or hand lever should feel firm and apply enough pressure to activate the brake so the bike comes to a complete & safe stop. Test the brake's action before riding off by pushing the bike and firmly applying the brake(s).

Defective or leaking master cylinders should be replaced or rebuilt.
This is a key safety issue.

With proper set-up and maintenance the stock XS disc brake system will do a good job of stopping these decades old machines. This comment doesn't apply to road racer machines of course.

In the repaint (blue taped) pic the rear brake disc is grooved.
Its headed for a brake lathe at the earliest opportunity.

Ride safe.
..........

 

[Capt_Zoom]

While rebuilding the brakes is great and all they are still a relatively weak brake. I upgraded my front to a 4 piston using pandemonium's kit along with a different brake and mount plate. But i'm still stuck with the craptacular xs650 rear disc brake.

Anybody know of a good rear brake caliper swap that doesn't break the bank?

 

[Wolfchen]

Sources for rear caliper:

All Yamaha > V-Max, SRX, RZ400

Rear caliper just sits "floating" on top of its disc. Would be a relatively painless operation to mock-up a carrier out of heavy cardboard. Use the 650's oem aluminum rear carrier for the bottom half of an adapter.
Transfer measurements, make a drawing, get a local fab or machine shop to craft your adapter piece.

Looks like a V-Max rear / four pot caliper could be easier to adapt / mount.

The rear brake handles only 30% of the load; its the front calipers that do most of the work.
Example: 100 bhp XS1100s / XJ11s do fine with same rear caliper as the XS650 disc setup.
..........

 

[yamaman]

weak brakes? you must be doing something wrong, mine will lift the rear wheel off the deck under hard braking. let us know how you go getting your disc machined at a car shop. if that fails for ya, there is a few fixes for that somewhere on this site! ☺

 

[littlebill31]

Old rubber lines will swell under pressure and cause a bad feel. Also the master cylinder piston can cause this.
Just changing the fluid is futile.
Here are some pics of a "good" front brake m/c:



It is a front m/c, but you get the idea of what can happen in the course of a few years.
This is why you also do not mix old and new fluid. Change it completely.
As you can see the old fluid has caused the internal piston to become, well, shitted up.
This particular m/c looked "ok" from the outside. Nicely painted as well, but once I pulled the piston from it, UGH. If you haven't rebuilt the m/c, front and rear, it can be bad news. The price of a rebuild kit is cheap insurance.
If the rubber seal (pic #2, old vs. new) on the m/c piston is bad it will cause the brakes to not work well. The other seal, at the end of the spring, needs to be addressed also (pic #3).
They will blow out when going to the grocery store, shooting fluid out at every frightened lever pull and making you realize how shitty a rear drum is.

 

[Ghetto]

New lines with some good pads and you shouldn't have any issues.

 

[Wolfchen]

OK OK its just a very basic guide sharing how to getting the Stock brake setup so it may work a tad better than slapping in new pads. Like others my machine was a pretty sad victim of severe PO neglect. Some of us do the basics and some of us have to go the extra mile with painted, ah vanity, calipers. Haven't gotten to stainless hoses and custom caliper set-up; yet.

If we must have chapter and verse on brake maintenance & upgrades we can write it all out ... and purchase / create a gonzo brake system with all the above included.

As for "weak" its a relative term for each model application and the bike's actual day-to-day usage given that these are 30+ yr. old bikes.
With proper maintenance oem 650, 750, 850, XS11 brakes = will work properly "most of the time."

"The rear brake handles only 30% of the load; its the front calipers that do most of the work.
Example: 100 bhp XS1100s / XJ11s do fine with same rear caliper as the XS650 disc setup."

Qualifier:
If we bump up the performance envelope oem XS calipers may not provide sufficient braking power for those who dance their bike on the racer's edge; diving into hard sweepers, repeatedly doing far more braking than most of us can conceive, or in my case; have the guts to perform. The guys running killer rad powered XS1100s make the switch to a hi-perf brake setup pretty quick. My XS11 was bone stock.
But I digress.

So here we go:
New custom stainless steel brake hoses - check
New Magura Master Cylinder - check
Custom adapted R-1 / GSX / brake rotors / calipers - check
Use only the best hi-perf brake pads - check
New DOT brake fluid / complete change - check

Now there's an ebay user, a machinist, who specializes in resurfacing & re-drilling bike rotors via exchange - he says he uses Blanchard Grinding. Pretty pricey, though less $$$ than a new rotor.

Was wondering why I'd seen a bike with strange patterns on the disc. Now I know why. So I stand humbly corrected on the cutting / resurfacing rule - "motorcycle disc alloy is of a different composition than used on autos" The end result could be a wavy, chatter-marked, useless rotor, er - paperweight.

AHRMA Source for resurfaced rotors
Resurfacing $55 including shipping Disc Drilling $100.00 and up. Disc thinning $85.00 Frame and swingarm strengthening, modification. Frame restoration Custom axles and Wheel spacers, custom control cables, See ad in AHRMA handbook. Tool Salvage & Motorcycle Works, 15709 Euclid Ave., Cleveland, Oh 44112 216.451.5500.

My rear disc is grooved - not bad but enuff for concern.

And, yes I do a complete brand new DOT fluid change every year, especially given the sorry appearance of my bike at first meeting.
Should have included all the fine points.

"I walked away from that crash...." Manfred

Summit's selection is not universal: they have rotors for Honda GL1500, later BMW w/ABS,
XVZ1300 Venture Royale.

 

[Wolfchen]

Super-cleaned mucked up rear rotor with emery cloth / scotchbrite pad last night. Brake action is much better.
Pulling some G's ...

Holy stoppies!
If the front brakes gets the same treatment gonna need a new seat and pants covered in velcro.

 

[Punkskalar]

I resurfaced my front rotor using a 90 Degree Die Grinder and a 3m ScotchBrite pad. Used a new 1 piece flex line, and a new master cylinder. I never even cleaned the inside of the caliper, just installed, bled the fluid, and I can almost do stoppies on the XS... If it wasn't for my narrow 21" front tire, I think it would do it

 

[jetero41]

Just throwing this out there......

Anti-seize on the caliper bolts ???
I work an Auto supply store and work mine and the families cars and I regularly see crapped up anti-seize applications ( ie. dirty and very STICKY ) .
IMHO, I always use a very good grade of caliper grease on the pins (slides) and bores.

 

[gggGary]

Yes properly maintained the stock brakes are a decent match to a stock XS650. I have several different custom brake setups but alas none have hit the street yet. In my mind it's all about the front. Even the single leading shoe rear drum brakes are just fine. As someone else said if the front is working well who needs a rear?\

Nice write up and thanks for your efforts Wolfgen. Always nice to get people thinking of brake overhauls as the layup season arrives in the northern parts of the globe.

 

[donald]

Just throwing this out there......

Anti-seize on the caliper bolts ???
I work an Auto supply store and work mine and the families cars and I regularly see crapped up anti-seize applications ( ie. dirty and very STICKY ) .
IMHO, I always use a very good grade of caliper grease on the pins (slides) and bores.

I was always told that anti-seize was for parts that do not move and that the proper grease is for parts that do move.I have also seen cases of anti-seize which is not a lubricant but more of a rust or corrosion resistant coating becoming very sticky.

 

[Wolfchen]

The paste is a high temp copper-based formula.

Ran the heck out it, zero problems, brake works like brand new.

I check on things weekly, compulsive that way ...
it'll never get the chance to be a problem.

 

[Cornish Pixie]

While rebuilding the brakes is great and all they are still a relatively weak brake. I upgraded my front to a 4 piston using pandemonium's kit along with a different brake and mount plate. But i'm still stuck with the craptacular xs650 rear disc brake.

Anybody know of a good rear brake caliper swap that doesn't break the bank?

Going the same type of route with mine, have got a Brembo Goldline caliper off of a Ducati 916 sitting in the garage to go on it and will be using a Ducati/Apprilia/Guzzi disc to suit.

How was the pandemonium kit to fit and are you running mags? in which case did you end up fitting the caliper on the RH side as their online instructions say will be neccessary?

 

[Darkdruid]

I had a Bandit master cylinder for my front brake on my last XS and that made a difference to the power i.e. it actually stopped the bike!