83 Brakes

[Re-Vision]

Finally getting around to working on my bikes again and I have three sets of brakes that appear to have problems, one that has a brake lever that wont pull in and two that have no pressure build-up at all. As I know less than nothing about hydraulic brakes, what is the first thing needed to make them usable again? I'll admit to not searching the archives as I'm looking for general guidelines to restoring the front brakes.  I intend to fix up two sets and sell one.     BDC

[Rikugun]

It depends to some degree on how thorough you want to be, how much money you want to spend and the condition of the parts available. I don't know the history of the components involved but would suggest disassembly of all the master cylinders and calipers to find which ones are in the best shape. You may be able to get away with reusing everything after a good cleaning. Worse case scenario maybe none of the pistons or caliper and MC bores can be salvaged. Hopefully with 3 sets to choose from that won't be the case but you won't know until you inspect all the parts.

You want to be carefull what chemicals are used to clean the parts as some will alter the rubber bits. Some service manuals suggest only using the recommended brake fluid for cleaning purposes. Assuming all the parts are mechanically sound, it may be easier to just source rebuild kits for the MC and calipers. Also, old hoses won't necessarily keep the brakes from working but new $tainless $teel hoses will perform better.

Can I assume your recent procedure has you feeling better resulting in renewed interest in working on your bike?  :D

[Re-Vision]

I've got one M/C apart, one I'll likely have to drill the cover screws out of and one still on a bike. One set of calipers with near perfect pads on one side and just about worn-out on the other. Looks like I'm going to have to spend some money if I go the stainless route and new kits. Yeah I'm feeling a lot better after I got the stents, I thought I was a pretty good Doctor until I realized I had a fool for a patient. How do you know when to install kits on the M/C calipers?      BDC

[RedBaron]

"How do you know when to install kits on the M/C calipers?"

Same reason you know when to rebuild a car caliper or master cylinder...braking is weak and the pedal or the lever in this case compresses too far before braking or must be pumped or the brakes work and you are losing fluid. You even might see fluid on the brake caliper. Then it is time to rebuild them with new seals, sand the inside cylinder lightly to get a smooth surface and check the piston for wear or scratches or  high points and low points and then replace it if so or replace it no matter what because you think you and the bike are worth the cost!

[Re-Vision]

Red, I know when to have the brakes fixed on a car I drive everyday. These bikes have been sitting for years and I have never ridden them. Also I've never fixed brakes myself.
BDC

[fret not]

BDC, I think the MC that the lever doesn't pull in has a stuck piston and needs a rebuild kit (just guessing as I haven't seen it).  Carefully check the bore for pitting and or scratches when you get it apart.  If pitted or scratched probably better to replace it.    The ones that don't build pressure may be out of fluid in the MC or significant air in the line.

These systems are about as simple as on a car, plus you can get to all the parts, and there are less calipers to bleed.

You can get "speed bleeders" on eBay to help bleed the system.  They replace the little bleeder nipples that look like a Zurk fitting.  I haven't tried them but the concept sounds good.  Also you can get a vacuum system from Harbor Fright to suck brake fluid down into the caliper(s) from the Master cylinder.  Gotta keep the MC filled with brake fluid or you will suck air into the line and have to start over.

With the standard original bleeders you will need an assistant to either pump and hold the master cylinder while you let off built up pressure and close the bleeder, or trade places.  With the stock equipment it is a 2 person job, with speed bleeders or the vacuum tool it can be a one person job.

Use only NEW BRAKE FLUID.  The stuff is hygroscopic and absorbs moisture from the atmosphere, which if you get enough can boil in the caliper under hard use, or more likely over time it will corrode the interior surfaces of the brake system.  But you already knew this.

[Jimustanguitar]

one that has a brake lever that wont pull in and two that have no pressure build-up at all.

The seized one definitely needs to be overhauled, but the other ones could just need to be bled. Air in the system will compress before you get pressure on the lever. If you're unaware of the condition of these units, bleeding them is an easy way to test them.

As far as speed bleeders go, it's just a normal bleeder with a check ball inside. If you have a catch can for the old brake fluid with an anti-siphon setup, you can just plug the air vent with your finger when you release the lever. That's what I've always done.

One other note, if you buy new bleeders. The hex head on them is 8mm, but bleeders are measured by their thread size. Don't get the 8mm ones, ours are smaller (6 or 7, I'll measure when I get home).

[motoracer8]

 Master cylinder rebuild kits are still available from Yamaha, $50, so is a complete master cylinder, $400

[fret not]

DANG!  Thats spendy.  At least they are available if you can't make the stuff you have work.  I mean the kit, if the rest of the MC needed replacement I would adapt something a bit newer. 

[Rikugun]

You can spend less if you poke around the interwebs a bit...

darkhorse (K&L) $29  http://www.darkhorsemotorcycleparts.com/front-brake-master-cylinder-rebuild-kit-for-yamaha-xv250-xs400-xv500-xj550-xz550-xvz1200/

K&L made in Japan $30 from E-Pay http://www.ebay.com/itm/Mastercylinder-Rebuild-Kit-XS400-XJ550-XZ-XT600-32-1089-/230890241550?pt=Motorcycles_Parts_Accessories&hash=item35c2217e0e&vxp=mtr

motorcyclecarbs.com  $42 http://www.motorcyclecarbs.com/MASTER_CYLINDER_KIT_YAMAHA_F_P6058C291.cfm

peak moto $16 (out of stock)  :(  http://store03.prostores.com/servlet/peakmoto/Detail?no=2223

[pullshocks]

Screw the rebuild, get one of these http://www.galferusa.com/accossato/

[RedBaron]

Red, I know when to have the brakes fixed on a car I drive everyday. These bikes have been sitting for years and I have never ridden them. Also I've never fixed brakes myself.
BDC

You're welcome.
Please do not "ride them" to determine if they need a rebuild. Just assume they need a rebuild if they have been "sitting for years".

[jasonm.]

the reason brake hydraulics go bad. Is as stated before the fluid is hydroscopic. It absorbs water. The system is not perfectly sealed. The water in fluid settles to the bottom aka calipers...and they corrode...seize. If the system is extremely water soaked...the master can also get stuck on its own. This is an aluminum environment with water....ever seen a motorcycle left outside for a long time and viewed the corrosion on the engine cases...That's what happens... :P

[PwrManDan]

Here is a good example of a system that was soaked after sitting outside for a very long time.