Reverse brake bleeding

I had a problem with my brakes this week (almost starting on fire!!) and so I decided to tear them all down. I drained everything and pulled the pads. The oring and seal were exteremely dirty!! The pads are shot from almost starting on fire! Sooooo.....I am wanting to clean everything out and after I did, I tried to bleed the brake with the pull in brake lever/twist bleeder screw method and I am getting nowhere....do I need to do a reverse bleed??? I have read when there is absolutely no fluid in there you need to do that(??) Am I right? BTW, it is an '82 650. Thanks!

 

Reverse bleeding is really no fun.

Your problem is your master cylinder is air locked. Disconnect the banjo bolt from the master cylinder. Put a finger over the master cylinder outlet. Wrap everything in lots of paper towels and protect the painted surfaces of the motorcycle. Pump the master cylinder up until fluid spurts out past your finger (the reason for all the towels!).

After you put it back together and bleed the calipers you're likely to discover another problem. That rising banjo bolt out of the master cylinder traps a bit of air. Put the motorcycle on the side stand and turn the wheel all the way left to get the master cylinder leveled out. Now just jiggle the lever a bit - should see bubbles pop up from the bypass hole in the bottom of the reservoir.

On my Maxim I had to leave it sit overnight in the hard left position to let all the air work its way to the top and jiggle the lever again.

 

Vacuum Bleeder FTW!

 

I made my own bottle because I already had a vacuum pump. BUT, whether you purchase or build one...use the vacuum method.

I have worked brakes for years and the vacuum pump is the best way to bleed brakes properly, quickly, and by yourself!!

 

Guess I am going to buy one. When I have my son help me, and I unscrew the bleeder, it sucks fluid right back up....gotta get that bleeder/pump.

 

chacal sells one pretty cheap

 

kcoop, did you start your ride without disengaging the emergency brake??? What caused the near brake pad fire?

 

The vacuum pump works great, especially to fill an empty or partially empty system. It does seem to pull fluid right past a trapped air bubble or two depending on where they're trapped, though. It will also pull air back in around your bleed screw threads and make you think you've still got air in the system. Teflon tape (on the threads only don't block the holes) helps but doesn't fully eliminate this.
I find a combination of the two to be the most effective: Use the vacuum pump to get the system filled and get a good preliminary bleed; then use the old-fashioned method to be sure all the bubbles are truly out.

I also re-bleed after a couple hundred miles; the heat cycles will boil out any micro-bubbles into a few big ones.

 

I'll take your advise and give the brakes a re-bleed when I get back from Portland. It'll be interesting to see how much, if any, air is still in there.

 

I just re-bled mine after about 240 miles. I got one big bubble and two little ones.

 

Release emergency brake??? Guess I didnt know I had one?! Am I that dumb?? I know that the pads are really scoured(sp?) up. The rotor doesn't look too good either. I thought about asking a shop if they could turn it....I read different opinions about the subject....thoughts??

 

ok, here are some pics of the caliper after this ordeal. Looks like I need a rebuild???? What do you think?

 

Think I would get ahold of Len and order rebuild kit.

MN

 

kcoop, sorry. I was giving you a hard time about the emergency brake. It used to be common on cars of yesteryear to leave the emergency brake on and drive down the road. Doesn't take too long for the smoke to start pouring out of the rear brakes. Glazes the heck out of the rear brake shoes!

This is before they put warning lights for emergency brakes on the dash.

It does indeed look like it's time for a rebuild.

Loren

 

Kcoop99
I agree with the other guys...the brakes now need a rebuild. The root cause has not been uncovered. Now, seeing the caliper's there is more evidence of dirt fouling. Cleaning the calipers was not enough for my Seca 750. The calipers continued to lock up after sitting for a week.

There is a micro-fine port in the master cyllinder that allows the fluid/calipers to rebound. That port was clogged and causing all the problems.
Suggestions to clean: one strand from an 18 gauge wire. Bigfitz suggested one strand from a brass wire brush (more ridgid).

BTW, don't feel bad about the emergency brake...I had two bikes with front e-brakes built in the 70's!!!!

I looked at pricing for the seals, Len at XJ forum is the best by far.
Greg

 

Thanks guys! I can take a joke! No worries! Hell, I never know sometimes! I will get ahold of Len for the kit. Of course, just as I had it ALL ready to go....so I thought.

 

I bought that pump yesterday from Harbor Freight for 19.99....AWESOME! I used it with the caliper off to pull fluid in then I pumped the brake and pushed the piston out. I am going to clean EVERYTHING including seeing if the tiny hole in MC is clogged. I have looked at rebuilt kits and it seems they are just an oversived o-ring for close to 20 bucks....am I right here? The ring inside the caliper (by piston) looks good. I know in my pics the boot is messed up but do I need a 'kit'? Thanks!

 

Another thing....are these pads still useable? The have plenty of life (thickness) to them.....thoughts???

 

I would definately throw those ones away. Top one looks kinda glazed.


grz Thijs

 

Do yourself a favor. Clean it up real good, install a NEW rebuild kit, and replace those old, glazed pads. Your bike will love you for it, and so will your family.

Brakes are no place to scrimp. If you can't afford to do it right, don't ride until you can.