Brake refurb

So, my 35 yr old bike has 35 yr old brake lines. Already talked with Len. But, I want to take apart the caliper and master cylinder to verify a) it's rebuildable and b) actually needs a re-build (likely).
I took the caliper off and realize the piston isn't moving so well. So, I connected the lower brake line between the MC and caliper and thew some fluid in the reservoir. No matter how much I pump the handle, I get only air moving in the line. I know when I got the bike, I could actuate the front brake and it would hold the bike. What gives? Anything special I need to do to prime the master cylinder? I just need to drive that piston out of the caliper so I can service it.

 

There are a couple ways to get the piston out. Some recommend using an air compressor. I'm personally a bit cautious with that technique, as I worry about how fast the piston could fly out once it starts. Another idea people have had success with is using a grease gun. When I did mine, I just used the force from the brake fluid. However, it took quite a while to bleed the brakes until they started to really function again,even to the point that I almost gave up. But it will work once the air is out.

 

Grease gun! Works every time...no fail. All you need is a solid bolt to seal the banjo bolt hole, open the brake bleed nipple two or three turns, and insert the grease gun on the nipple and start pumping. The hydraulic action will smoothly and evenly apply pressure on the piston and it will slide right out! Just make certain you clean every speck of grease out of the caliper which should be part of your rebuild anyway.

 

Also, on a 35yr old bike....me personally, I would just go ahead and rebuild and replace everything....master seals, caliper seals, hoses, pads. Shouldn't cost more than $100-$150. It'll make a world of difference.
I just did a 550 Seca, was not hard at all.

 

+1 full brake system rebuild. Going is only fun if you can stop.

 

Tried pumping more fluid last night, but something about the MC isn't working properly, so tried air. Blocked off the banjo joint port w/ one of the mounting bolts. Couldn't get a great seal on the bleeder, but thought I might have about 90 PSI and nothing moved. I ended up throwing it in my vise and used vice grips on the edge of the piston (yea, not pleased about that, but that part will never need to go into the bore of the caliper). I can make it rotate in place, but it takes quite a bit of effort and I haven't figured out how to get it moving out. I'll try again later, but the gas tank is calling since carbs came back yesterday!

 

Grease Gun <<<<<<<<

If you have air use that, but put a rag between the piston and the caliper ears and ramp the pressure up by squeesing the air valve slowly.

 

I pinned 1 brake pad in so that the piston wouldn't "fire" out of the caliper, but nothing budged. On the phone with Dave this morning and he also said "grease gun", so I'll swing by my dads to pick his up tonight.

 

Steam baby steam

 

what about dropping it in boiling water to loosen it up?

 

Grease, and it will come out!!

 

Not even funny how well it works!

 

Got the caliper all cleaned up, just sanded, primed, painted the underside of my gas tank (the red's going to look nice if anybody cares to look!).
Now, I tried to get the master cylinder off to pull it apart. What's the trick to getting the brake switch out? I don't want to damage it.

 

There is a hole on the underside of the switchgear. Use a unbent paperclip in that hole to push the switch catch, so the switch can be removed.

 

Unclear on just where that clip goes. Nothing seems to jump out at me and I've seen a switch or two over the years.

 

That hole....right there in the top center of the pic......you can use just about anything blunt (I think I use 1/4" extension). Put pressure there and then grab the black plastic that houses the wires (just to the right of the hole) and gently pull....should come right out. Spray it with some contact cleaner.

 

It'll be one of those moments....once you see it!

 

right! It was completely obvious once I got it out!

 

That's the beauty in thes bikes. Pretty much everything is obvious. I'll say it again--- these XJ's were simple bikes built by simple people using simple tools but they had a GENIUS idea.

 

Next thing is getting the MC apart. I found 1 write-up where the photos are missing, but it may have enough for me to go on.

 

Attached is a write up I did for my Yamaha Venture....basically it is identical (parts may look slightly different) to your Seca. Obviously my write up is about clutch hydraulics and you won't have a clutch slave cylinder to contend with, but it should give you a pretty good starting off point. I highly recommend the Master Cylinder Snap Ring Pliers.....about $20 on line....just saves a ton of hassle, as my normal snap ring pliers were just a thin blonde hair too short!
http://www.venturerider.org/forum/showthread.php?116337-Clutch-Hydraulic-Rebuild-Tutorial

 

I finally got my MC apart and things look pretty good overall. I could probably use a decent brush to get in the corners, but the bore looks nice and smooth. Rebuild kits have shipped, so light at the end of the tunnel!
Yes, that tiny port is clear. I put a strand of wire through it easily.

 

The bore may be smooth, but the seals will need replaced.

 

Question about brake fluids. I bought some synthetic DOT 3/4 compatible fluid. I hear DOT 5 won't eat paint and isn't hygroscopic. Why couldn't I use DOT 5 on my bike when I'm replacing or re-building the entire system (i.e. no trace of old fluid in the system)? Is the type of rubber used in the seals the determining factor here?

 

You can use DOT 5, just don't mix.

 

Except that DOT5 pretty much sucks when used in systems not designed for it. Bye, bye seals (unless you use all-new the whole way through, including new lines).
Then there's the issue of DOT5 absorbing air. Better be absoultely sure that all the air bubbles are removed during bleeding, or you will have permanently spongy brakes.

Personally I think DOT5 is great for machines that spend most of thir lives sitting, but not so great for machines that are used regularly.

 

Cost seems to be the biggest reason not to use DOT 5. I don't see the benefit in spending the extra money.

 

So, I had my way with the MC cover and think it looks a ton better than before.
Next to it (or below it), the MC looks pretty horrible, but that "paint" on it seems rubbery and odd. I feel like I'd need to completely strip it before repainting. Not looking forward to that, given the variety of bumps and protrusions on it.

 

Firstly, I dearly hope that you did not "have your way" with the master cylinder cover, or any other part of the bike.

Secondly. the paint gets that way from repeated exposure to brake fluid. It softens, then never completely hardens again. Sort of like what happens when you "have your way" with a master cylinder cover.

Be safe; wear gloves.

 

[="k-moe, post: 529324, member: 11887"]

Firstly, I dearly hope that you did not "have your way" with the master cylinder cover, or any other part of the bike.....[/QUOTE]

Oh, COME on now---)

[="k-moe, post: 529324, member: 11887"]
Secondly.... It softens, then never completely hardens again. .....[/QUOTE]
Um, if he having his way, wouldn't it harden then never completely soften?

 

I'm only guessing as to the aftereffects of exposure to glycol based lubricants.

 

Microsquirt/ fuel injection

 

Well this thread took an unexpected turn.

 

Wow, The MC lid gasket seems to have enlarged and won't fit anymore. I did not see that coming! It cleaned up really well but seems to have grown. Guess that's one more order for Len before this bike hits the road!

 

Probably picked up moisture from the humidity. Put it in a small jar of uncooked rice for overnight and see if it draws the moisture back out. (don't cook or eat the rice afterward....)

 

I wondered about the moisture thing. I'll try that.

 

Look at Mr. Moneybags here!

 

I've done that with some diaphragms that expanded on a cb200t, too----they got Waaay too big after sitting open for a few weeks... I got them to shrink back to size, installed them, rode the bike for a year before another fellow bought it

 

Bleeding is not going well. I got new parts from Len. Master cylinder went together well as did the caliper. I got new lines and copper washers, all torqued properly. This should be best case scenario. I have a mighty-vac and have been pulling brake fluid through the system. I know because it's collecting in the mighty-vac holding container (and I've emptied it once). I still fail to get any pressure when I squeeze the brake lever. I see some fluid shooting up through the tiny hole in the MC. I watch the spiral part of the plunger go past the bigger hole.

 

Secure the brake lever to the grip.
Grab a vibratory sander.
Work your way up the system from the caliper to the top of the brake line.
All the air will have been forced up and out.

The calipers have places where air bubbles like to hide. Vacuum just won't do it when bleeeding a freshly filled system.

 

I did grab my Makita and took off the sand paper. Should I spend, what, 30 seconds on caliper and every 6in or so on the brake line?

 

I think there must be trapped air in the upper hose. It comes up from the L and then dips down and then back up where it connects to the MC. Tomorrow, I'm going to get the MC off the handlebar and raise it up to be higher than the entire hose and see if I can get that air out (while depressing the plunger).

 

I take about 5 or 6 minutes to run the sander along the entire length of the system. Getting that dip out of the hose will help.

 

I thought I'd wrap this thread up by saying I've ridden the bike 25 miles so far and the front brake feels great. Grabs smoothly and no spongy feeling. So far the MC w/ the black engine paint is holding up well. A new seal for the lid sure didn't hurt keep things clean.