rear brake master cylinder overhaul

[mbrood]

The manual says to basically drain the reservoir, break the lines (make a big mess) and then

pull the unit out. Does somebody have some "person info and maybe a few tricks"? My master "seems" fine but I've never had her open, the reservoir looks like junk (salt corrosion) and I just happened to come across a rebuild kit. It might have to be a winter project but I'm sure it's better to get the thing out and cleaned rather than wait until it "requires" it.

 

The fluid has been flushed and still looks great but so did the clutch until I purged the line with air pressure and quite a bit of crystaline crud flew out.

 

Thanks,

Mike

[skydoc_17]

Hey Mike,

Where to start! I placed my bike on the center stand, I placed a shallow pan about 18"x 18" under the general area of the master cyl. remove false tank cover, seat and right side side cover. I removed the frame brace that runs parallel to the seat that blocks the removal of the Master Res. I drained the Res. My hose that runs from the Res. to the master was shot so I cut the line off, below the res. and above the master cyl. with side cutters. there are two bolts that hold the res. to the frame, remove these. there are two wires that plug into the res. and run to the harness that goes to the dash, unplug these two wires. You will have to rotate the res. to get it to come out of the frame, it is very tight in there, don't give up, it will suddenly fall out of the frame when rotated properly. next, unbolt the master from the frame, I used a cresent wrench on the master to break the brake lines loose. There will be two of them. The brake lines are on the back and side of the master. You will need a GOOD pair of inturnal snap ring pliers to remove the snap ring from the end of the master. I bought a pair of snap ring pliars from Sears, with interchangable anvils, you will also need them if you ever do the front brake or clutch masters, I paid around $26.00 and they were worth every penny! Remove the guts from the master, I laid everything in the order it came out, clean the master and res. with brake cleaner in the aerosol can, install the new kit, Now you have two options, you can buy the Yamaha Res. to Master brake hose ($30.00) or do what I did, go to Tractor Supply and buy a foot of Chemical resistant tubing ($1.35) and cut to the right length. Put one end of the hose on the master with a hose clamp, put it back in the frame, reconnect the brake lines,as you rebolt it to the frame, Make sure you put the rod into the boot that goes to the brake pedal as you rebolt it. Now, wiggle the res. with the top on securely, back into the frame and reconnect the sensor wires, install the top of the hose with a hose clamp and bolt the res. to the frame. Fill the res. and bleed, and bleed and bleed the brakes until you get all the air out. I have some really good pics of this area of my bike in my photo gallery under "VR to R1 Brake Swap". Go to my profile, and on the right side of that page, you will see my photo gallery, click the photo that says VR to R1 brake swap 1" and there is a few pics of the right side of my bike cleared for the master removal. If you have any other questions, drop me a line and I will walk you thru it.

Brake Safe,

Earl

[Condor]

It is messy pulling the master and reserve out of there Mike. Just make sure that you rinse off all that DOT 3 that gets on the painted areas, or they won't be painted very long. A water flush works good. I rebuilt my master, but never did pull out the reserve. I probably should have because the baffle/gasket ended up pushing down on the low fluid sensor and gave false readings until I got in there with a piece of coat hanger and got some of the pleats compressed out of the way. Not perfect, but it did git rid of the red warning light. The master rebuild isn't that big of a deal. Pretty straight forward. The only thing you want to make sure of is that the expansion hole under the plastic 'L' fitting is clear. If you remove the fitting screws it will come off. It's a little stubborn due to the 'O' ring seal. At the bottom of the hole there are 2 holes. One looks like it's a false hole, but at the bottom of the false there's a very small orifice that allows heated expanded fluid back into the reserve. If that hole isn't clear the brakes will lock up on you. Other than that, and it being a PITA bleeding the system, you should be good to go.

[mbrood]

Thanks, I could see it was going to be messy and tight but you guys also gave some good tips. I think I'll tear into it and be done with it. My dad always first sprayed soapy water on the painted surfaces so there was less chance of damage.

[Gearhead]

My dad always first sprayed soapy water on the painted surfaces so there was less chance of damage.

 

Does that work? That tip alone could make my day!

 

Jeremy

[mbrood]

He said the soad (liquid dish soap) was a great "wetting" agent so it tended to stick rather than just bead and run off... and it was easy to get off later... yep, just use a hose.