How to repair a brake reservoir?

[Scorch]

The sight glass on a Suzuki brake resevoir, the 1985 and up style.

Anyone know a good way to replace the sight glass?

[Suzsmokeyallan]

Its actually not glass but a type of clear plastic. On some other cylinders, I removed the retainer/surround from the body and then had some glass cut to size and used plastic steel to form a neat seal around it.
Its one way to repair the problem and I'm sure there are others, it depends on how good you are with working on such things.

[Scorch]

Plastic steel?

Brilliant! Does it hold reliably? I will give that a try, thanks.

Edit: Aha! http://cgi.ebay.com/ebaymotors/madura-G ... 53e401654f" onclick="window.open(this.href);return false;

[Suzsmokeyallan]

Devcon 'Plastic steel' has worked well on the application of the sight glass installation and it was still holding last time I saw it. Thats been almost a year and a half now.
Its good you found that little glass on ebay Neal, I might just buy one to check it out closely.

[Scorch]

Ok, I received a couple of the sight glass crystals today from New River Cycle Salvage. Cleaned the master cylinder and used clear Permatex RTV to hold it. Will test it for leaks tomorrow and take a pic. Looks great so far.

[Suzsmokeyallan]

I'll be surprised if the RTV will take the brake fluid on it without peeling, keep me posted.

[Scorch]

RTV is what they list as the adhesive in their kits.

Before

repairbefore1.jpg

After

repairafter2.jpg

I'm in business better than ever, and only cost $12.

[Scorch]

So, let me ask; if I use Brake Cleaner spray inside the clutch master cylinder, will that have a bad effect on the seals? I cannot get this thing to build up any pressure.

[Suzsmokeyallan]

Do you have a hand held vacuum like a Mighty Vac, if not a large syringe with a piece of hose can work in a pinch. Put some grease onto the bleeder threads to create a seal when you loosen it and apply the vacuum while squeezing the lever.
Many times on a rebuild a master cylinder can go into a mode of non action where the fluid just cycles back and forth but it never pushes the fluid forwards.
Did you rebuild the unit or was it working before?

[diamondj]

Sometimes you get an air bubble trapped at the banjo joint at the master cylinder and it doesn't want to move. You can try:

1. Unbolt the MC from the handle bar and tilt it a bit while bleeding it.

2. Go through a typical bleed cycle and then use a zip tie to strap the lever to the handle bar overnight. Then bleed the brakes again in the morning. I've used this a couple of times with success on my Suzukis.

3. Invest in a Mighty Vac bleeder to make sure you get all the air out. I had to do this when I upgraded some of my bikes to Brembo MC's. They are a real pita to bleed correctly.

Jim

[Scorch]

So, you think the brake cleaner did not affect the master cylinder internals?

Many years ago, I rebuilt a mc and used good ol' gasoline to clean the parts. It would not build any pressure and I learned that gas was not a good idea for brake parts. I had to rebuild it a second time to get it to work.

I did not rebuild this unit, it was working ok before I pulled the it down to replace the sight glass. Now, let me qualify that: I have only ridden the bike 20 miles, and for the last 5, the clutch was either 1. low on fluid or 2. something was wrong, because it was hard to shift gears and the system was not disengaging the clutch. When I got home, I opened the mc and saw it was out of brake fluid. Then, as the story goes, the sight glass crumbled, etc.

I tried using my brake vac pump, pulled about 5 ounces of brake fluid through it, not a hint of pressure on the handle. I even disconnected it at the mc banjo bolt and "bench bled" the mc. Still, no buenos.

I ordered a piston/cup assembly from Bike Bandit. I guess I will wait till it comes in and try rebuilding the mc. I sure want to ride this bike I bought 3 weeks ago

[Suzsmokeyallan]

Its possible the cup has freaked out from the cleaner and now allows fluid to bypass it, you have to be very careful what chemicals you use to clean the cups and other rubber parts. They can get very soft or curl up under pressure after a chemical has been in contact with them.
If the system has crud in it to a point where the fluid looks like mud or you are not sure of its history you need to overhaul it for your own safety and peace of mind.

[Scorch]

Yes, you're right. Rebuilt the Clutch master cylinder, there was a lot of "mud" in the piston area. Successfully bled the air out (note to others: be sure to turn the handlebars so the master cylinder is higher than the banjo bolt).

I could tell the rear brakes were worn down by the feel, so I pulled the caliper and replaced the pads (and they were right at the limit, a little metal was showing). Now, after pressing the new pads apart with a large flat screwdriver so I could fit the caliper back over the disc, the pedal does not get any pressure. I bled and bled, with the vacuum pump and without, no luck. The reservoir never ran empty, so why did the brakes stop working? There was plenty of pressure before I changed the pads. Help!

[Suzsmokeyallan]

Neal,,, that cylinder has gone out on you with more mud or crap. You have pushed the crap from the caliper back into the cylinder and now it wont build pressure due to a failed cup or stuff trapped around the cup allowing the fluid to 'cycle' and not move forwards.
You need to pull that master cylinder down for inspection, just remember any system thats been neglected is ripe for failure especially after you disturb it.
If you have no service history on an aged bike, and it looks like its never been attended to, chances are it needs an overhaul on the parts/section you are working on.
You are lucky, years ago when DOT3 was the only fluid available, a neglected brake cylinder usually meant the bore was pitted and a rebuild kit was not the fix.

Just so you know, NEVER push the pistons on a suspect condition caliper in unless you have the brake hose off or the bleeders open and a tube attached.
The crud around the pistons will go right back up the lines and into the master cylinder and wreck its function as you have now found out.

[Scorch]

I agree, will rebuild the rear one as well.

I am still using DOT3, should I change to DOT4?