HOW TO: Rebuild Your Master Cylinder

This is going to be a real quick how-to on rebuilding a master cylinder. The cylinder we'll be working on comes off an 1982 XJ650. Yours may be different.

About two weeks ago, I was getting ready to go for a rather long ride. While doing my pre-ride inspection (you do those, right?) I noticed my brake fluid level was a bit low in the window. No problem, I thought. I grabbed my #2 Phillips screwdriver and removed the first screw from the master cylinder lid. It's when I went to remove the second screw that I ran into trouble. I slipped the screwdriver into the cross and gave it a slight counterclockwise twist. The head of the screw literally came right off. Every part of me screamed obscenities all at once. I was none too happy and a little concerned my "long ride" was officially over before I had even left the driveway.

I pondered my predicament and came up with this as a quick fix.



I filled the master cylinder with fluid and clamped it down with both the remaining screw and a radiator hose clamp. It worked fine; didn't leak once in the last two weeks of use. I knew, however, that this was not a permanent fix so I placed an order with chacal for new screws, a reservoir gasket, sight glass and adhesive, and a rebuild kit.



Luckily I had another rebuildable master cylinder I had picked up at a garage sale last summer. I asked one of my customers to clean it up a bit with his sand blaster. Here's our rebuild candidate:



Not the best paint on the outside, but the inside cleaned up real nice. Anyone have a suggestion on what kind of paint to use that brake fluid won't melt?

Okay, I think we're ready to get this thing torn down, cleaned up, and put back together.

Here are the steps:
1. Remove the rubber dust boot from the rear of the master cylinder bore.



It fits into a grove in the cylinder piston. Our kit contains another, so don't be afraid the give it a good hank to remove it. It fits snuggly into the bore above the retaining E-clip.
2. Remove the E-clip using a pair of snap ring pliers.



You may need to use a pick or some other pointed tool to remove corrosion to get at the E-clip.
3. Push the cylinder contents out of the bore by placing a screwdriver into the bore via the threaded hole where the brake hose screws in.
4. Take your time and do a thorough job of cleaning the bore, the groove where the E-clip goes and the two small orifices that connect the reservoir to the cylinder bore.





5. Install the rubber cup onto the piston. The cup's taper should be tapered toward the rear of the cylinder.
6. Install the rubber cup onto the end of the tapered spring. The nub sticking out of it's center will fit into the hole in the end of the spring.



7. Slide the spring with the rubber cup into the bore followed by the piston. Use a little brake fluid (DOT 3) to lube the cups.
8. Depress the piston and install the E-clip.



9. Install the rubber dust boot, making sure it is seated firmly against the E-clip.
10. Using a small amount of sealant, lay a bead in the grove of the sight window seat.
11. Carefully set the sight window into the recess and apply pressure to bed the window into the sealant. Allow it to cure before filling with brake fluid.



That's about it. Your master cylinder is pretty much done. Reinstall it on your bike, fill it, cap it with a new reservoir gasket and screws, and, after bleeding your system, you're good to go.

 

Very nice, you didn't show us the removal of the broken screw, though.

 

That's cuz it's still in there... just not in this one. I'm sending that one to my machine shop to be fixed.

 

O.K. it was a doner M/C.
Regards paint, havn't found any, I just pollished mine, less ag'

 

Yeah...paint. Duplicolor "brake and caliper" paint doesn't hold up AT ALL; their engine enamel does a bit better; PJ1's black epoxy frame paint...sorta. It doesn't immediately dissolve and come right off, but brake fluid still "attacks" it. I'm going to do an experiment with baking it in a low-temp oven to ensure it's fully cured and try it again. (I'm experimenting using a fluid reservoir cap that was so corroded away on the underside as to need replacing.)

Polished looks fantastic, Wiz; but there are some bikes that need it to be black.

*EDIT* Nice write up too Don, thanks.

 

Don fantastic write up as we have come to expect from you. Thanks!

 

gun kote
NOTHING but sandblasting takes this stuff off

 

I was just thinking either gun kote or Por-15. I've got Por-15 at work. I may try that. It world probably work for repainting the levers, too.

 

Is that gun kote generally available in local stores? I am looking in redo-ing my MC within the next week or so (am going to do the same, rebuild a spare I have). I was thinking about just polishing it, however my MC is a Seca dual disk which is jammed behind/under the headlight. So I think a black finish would be best just to 'hide' it. So I am interested in anything for painting it ;-)

Great write up!

 

I'm not sure where you'd find gun kote.. Here's an online source. If they have a contacts page, you could call them to see if they had a local distributor you could go to.

On a side note, I forgot to give instruction on removing the sight window. I know there are two kinds out there. I'll see if I can get a picture and put together something later on.

 

i'am pretty sure brownells is online only, they are the only place that has gun kote in spray cans also
you can get 16oz cans from the mfg. to use in a air brush that will last the rest of your life, 2oz does all the covers on a engine

 

Being that I am lazy, i'd go for the aerosol so I don't have to go buy a airbrush ;-)

Any other recommendations for paint? if I had a sprayer i'd just get some black powder coat and coat it and bake it in a toaster oven.

 

Ouch, I just went to that link. Pricey. Averages 30$ a spray can

 

Quote: "On a side note, I forgot to give instruction on removing the sight window. I know there are two kinds out there. I'll see if I can get a picture and put together something later on."

Anybody got anything about this? I'm putting a shopping list together for chacal and wanted to ask him or anybody for that matter, how do you know which type of sight window to get?? I feel like mine is glued in but don't wanna waste $ on the wrong sight window.

ps. not sure if I quoted this the right way but you get the point

 

Now if we can get something like this for a Seca MC, I'd be all set ;-)

 

Also:

If the "Guts" of the master Cylinder you are about to rebuild look as funky as the Guts in the Model used for this instructional; it would be a good idea to examine the MC Bore after it has been cleaned with Disc Brake Cleaning Fluid.

After cleaning, visually inspect the Bore.
Look for Build-up or Pitting.

The Build-up needs to be removed.
Heating it with a Pencil-Tip flame of a Butane Torch will soften it and allow it to be cleaned without scraping the Bore.

If the Bore is Pitted ... You'll have to "Hone" the Bore.
Roll a tight Cylinder of 800 Finishing Paper on a Wooden Dowel
Lube the Roll of Finishing Paper with WD-40
Stuff the Rolled-up Cylinder of 800 into the Bore so that the roll does not unwind when rotated.

Use a Variable Speed Drill and Rotate the Roll in and out ... at different speeds to refinish the Bore and (hopefully) eliminate the Pitting.

 

There two types of original sight windows that were used, and depending which type your original master was equipped with will determine which type of replacement glass window to order, since both the original and replacement windows differ in size depending on which style was originally used:

a) Sight window Type A was originally pressed into the cavity in the master cylinder body....there may have been some type of sealant used, but I'm not sure. This type of sight window is larger than the Type B below. This type of sight window can be a beast to remove from your original m/c, as you have to sometimes pick it out, piece by piece.

This Type A sight window is, to the best of our knowledge and experience, used in ALL versions of the large-bore master cylinders (dual-disc bikes) and only in SOME of the smaller-bore master cylinders used on single-disc bikes (including the 1100 front master cylinder, which is a small-bore m/c).

b) Sight window Type B was originally retained in the cavity in the master cylinder body via a "C"-shaped clip that is inside the reservoir....and once you remove this c-clip, the entire sight window can just be pushed out from inside the m/c. This type of window is relatively easy to remove, and uses a smaller window than the Type A window above.

This Type B sight window is, to the best of our knowledge and experience, used in MOST versions of the small-bore master cylinders (single-disc bikes, including the 1100 front m/c) and NEVER in the larger-bore master cylinders used on dual-disc bikes. This "clip-retained" style of sight window seems to have been an "earlier" design, and phased out over time, and replaced completely by the pressed-in style (Type A) window by the 1982 model year (which is when the larger-bore, dual-disc m/c's started being used on the XJ models).

 

Here's how chacal explained it to me:

I hope that helps. It got me into the right parts (I was a Style B).

 

Gamuru, thanks for relaying the message. I have the 81' 650 as well and suspect I have the style B kind as well.

Chacal, expect a list from me asap. Thanks for the descriptive comments on different sizes also!

 

Thanks, Rick, for the tips! All are excellent suggestions.

 

hey guys. I just followed this Howto and replaced my MS. got my parts form Chacal just like Gamuru. works greats, and was a pretty easy process!

 

Congrats on a job well done!

 

On my XJ550, which looks the same as yours, the "O-rings"/seals that go around the plunger "open up" in one direction, if you know what I mean. Do both point in the same direction or different direction? How are they oriented?

 

The Seals are positioned to Expand and apply Pressure:

I----≫≔≕≫----I The Open End placed toward the direction of travel when the Lever is pulled.

 

Gamuru- thanks, another great thread. so far my mc is in perfect shape, sans the sight glass but i'll save this for the day things change.

ron

 

Search the Forums about the Sight Glass.

You can get a Domed Wristwatch Crystal to replace the Sightglass that is a PERFECT Fit.

All you have to do is Epoxy it in place.

 

sweet, thanks Rick.

 

Great help

 

"The Old School Method"
Replacing Site Glasses with Watch Crystals
by: Rick Massey
All rights reserved.

I mixed some regular 5-Minute Epoxy. I used the narrow ends of toothpicks (many) to place the small amount of epoxy behind the crystal. [It was more like a "smear" than it was a bead.]

The outside sealing got done by placing a partial drop of epoxy at the edge. Tossing the toothpick that was used to apply the epoxy and using many other toothpicks (I had a half-dozen between my lips) to "drag along" the freshly mixed sealant taking advantage of its slow capillary action.

I used a bunch of soda cans and shot small amounts of UN-mixed epoxy on the concave bottom of the can. Then, when the epoxy you are working with just begins to "Pull" ... shitcan that mix and blend yourself one of the UN-mixed ones you have lined-up.

Once you have the sealing bead all around the new CRYSTAL ... take full advantage of it being crystal and shape the epoxy around the inside diameter of the window.

Use your little finger moistened with "Good Old-Fashioned Spit" (saliva) to make a nice looking finish ... like a glazer would do on a window.

Clean-up BOTH the Crystal AND the shape of the seal with lacquer thinner.
Use old, cotton, T-shirt cloth and moisten the cloth stretched tightly about your finger. Closer to "Damp" than "Moist"

The lacquer thinner will clean the glass off anywhere you might have goofed while simultaneously helping you apply a really fine-looking bevel on the epoxy around the glass.

If it isn't crystal or glass and you touch it with lacquer thinner; you'll be back to Square One, immediately.
- 30 -

 

rick, still got issues... rebuilt my mc. cant get a lever.... if i block off any part of the rubber hose i get lever instantly... is this turning out to be a caliper issue?

 

Certainly, smells like it.

Go "Old School"
Get a "One Man Bleeder"
Attach a "Union" and some TIGHT Rubber Windshield Washer Hose ( 2-1/2") on the Hose that slips on the Bleeder.
Yank the Bleeder.
Wrap with 3 Winds of Teflon Tape.
Puncture the Bleeder Hole if the Tape covered it.

Fill a Small Glass Jar 1/3 Up with Brake Fluid.
(Duct Tape the Jar to something that wont let the jar fall-over.

SUBMERGE the 1-Way Valve in the Jar and keep the 1-Way under Brake Fluid,
Attach the Hose to the Bleeder.
Open the Bleeder.
PUMP the Master, ... s-l-o-w-l-y.
Let the New Brake Fluid get pushed through the lines and OUT the 1-Way.

L@@K for Bubbles leaving the 1-way.
Once you have a SOLID Stream of NO AIR, ...
Close the Bleeder.

Pump 5 Times.
On 6 ...
Open the Bleeder.
Let the Fluid get PUSHED-OUT.
HOLD the Lever to the Handlebars when you do 6.
Close the Bleeder.

One of two 5 Pumps
With Bleed on 6 and Close the Bleeder...
should get all the AIR out of the System.

Dual Calipers?
Do the one furthest frpm the MC 1st.

 

Ill try it. Lol. Thanks. Only 1 caliper.. that's why I'm so flustered

 

Thanks for the How-To. Using it right now. I only wish mine looked half as good as your starting point. My dust boot on the piston disintegrated when I tried to pull it out. Had to dig the base out using a jackknife. And the e-clip is proving a bugger to get out - rusted and stuck. Of course I don't have pliers that will reach in there, soo..

 

If you have an old pair of Needle Nosed Pliers you can sacrifice, ... take them over to the Grinder with a cup of water and fabricate a Tool.

Remove a good deal of material.
fashion the JAWS with a DREMEL.

 

Thank you Rick! I was getting frustrated - every snap ring pliers I could find would not fit. So I fashioned my own - by hand mind you (no grinder). they were not as nice looking as yours, the first tips were too thin and broke. Second attempt success!

Good thing I love this bike, or I think I would have set fire to it a couple times....

 

Lol.... I wouldn't trade mine for a million dollard but sometimes I still want to set her on fire. Rick is a top notch guy. Great post and great ideas rick

 

The Circlips that come with the Rebuild Kit are even MORE difficult to remove.

The Clip is "Wider" ... and there are three "Humps" triangulated around the Inside Diameter to act as GUIDES for the Shaft Section of the Plunger.

You need to compress the NEW C-Clip until the ends touch and lift it out along the Plunger Shaft as the CUP-Return Spring shoves the whole guts out of the Cylinder.

 

Brake fluid is a great hydraulic oil but a poor rubber preservative.

There is a lubricant/preservative specifically designed for assembly of rubber seals on brake parts. Red sticky goop called Castrol Rubber Grease made from a castor oil base.

Coat seals and cylinder bore lightly upon assembly and they not only go together easier they will also last much longer.

Some of the caliper and master rebuild kits include a small sachet but if not it is readily available on ebay.

 

If that envelope you get along with Brake Parts contains "Sticky Stuff" ... It's not likely a SEAL Lubricant.
Those little Packages are more likely to contain an adhesive intended to keep the Brake Pad and Caliper Piston held-together.

"Anti-rattle" ... "Anti-squeal" Compound.

Nearly every Service Manual with a comprehensive Brake Overhaul and Maintenance Section provides the same instructions when Installing Master Cylinder, Brake Cylinder Seals and Caliper Seals.

"Use ONLY Fresh Brake Fluid from an Unopened Container"

 

The red sticky stuff in the sachet is certainly no adhesive, it wouldn't hold a fly to the ceiling. It is there to assist with the assembly, preserve the seals and to generally improve the smooth performance of the mechanism. It is exactly the same look, feel, consistency and smell as the stuff in a tub of Castrol Rubber Grease I have in the garage. (Been using it on 4WD brakes for years)

Here's the spec for the branded tub I have:

http://msdspds.castrol.com/bpglis/Fusio ... Grease.pdf

It is particularly suited for situations where you want to assemble a caliper or master that won't be used for a while. That's why brake master cylinder re-sleeve shops use it liberally on cylinders they re-sleeve and put on the shelf.

The product was originally developed by Castrol in the UK for Girling. Perhaps it isn't popular in the US, but that's what's in the sachets that came from Len.

 

Does anybody by chance have the pictures from the original post?

 

Not sure why pics are missing . . . These are NOT the pictures you quest for, but perhaps this will help you?
http://www.xjbikes.com/forums/index...to-rebuild-your-caliper-and-m-c-w-pics.41403/
Good luck

 

....anyone else not able to see the images? What a bummer.

Edit, nvm.

 

Could the images be reuploaded?

 

Why cant i see the pictures on the write up?
Thanks!

 

The original photos were hosted by another server. The account has either been suspended, or the photos removed by the owner.

 

I know this thread has been dead for 2.5 years, but I was also disappointed by the lack of pictures. This thread should do for anyone else who comes in here looking for info. First page is caliper rebuild, second is master cylinder.

 

Thanks for posting!