Rear Master Cylinder

[froche]

So ready to rebuild MC
Got the kit
Started to take it off!
Gave up and put tools away, went inside and washed up
Looked up in Honda manual!
According to the manual i have to take off the swing arm.

Has anybody removed and replaced the Rear MC without doing this?
Also they say (cavalierly) remove the hard lines, as if they were just put in loosely!
Any thoughts on this?

[Charlie1Horse]

I have the OEM Honda manual open to page 13-14. It states,

On Aspencade, remove the right passenger foot rest.

Drain the brake fluid from the brake line.

Remove the cotter pin and the clevis pin.

Disconnect the brake rod clevis from the brake arm.

Place a drip pan under the brake line.

Disconnect the reservoir hose from the master cylinder,
and remove the reservoir.

Remove the two master cylinder bolts.

Disconnect the metal brake lines from the master
cylinder.

Remove the master cylinder.

Absolutely nothing about removing the swingarm. I have my 86 Aspencade master cylinder off and didn't have to remove the swingarm. Hope this helps.
Russell

If I don't do Facebook or Twitter, do I still have to do Social Media Distancing????

[froche]

Here is a screen shot of my manual.
Note what it says on second line

[Charlie1Horse]

Oh Well!!! Take it off if you want but mine is off now and the bike is still sitting on it’s wheels.
Russell

If I don’t do Facebook or Twitter do I still have to do Social Media Distancing????

[froche]

Did you take it off by pulling back and upwards?

[gerald collins]

Hey Guys, I took off the rear M/C from my 1984 Aspencade because it had no pump pressure. Disassembled, cleaned all orifices, assembled and put back on bike.

Still no pressure and doesn't move any fluid. I'm absolutely certain that it is clean. Could there be a problem inside the pressure control valve, which the manual says to not mess with or try to disassemble? I pumped fluid from the front and rear slave cylinders to the master cylinder, so there should be no air in the lines. The only explanation I can come up with is that the fluid is being pumped through the pressure control valve instead of out into the pressure lines.

And yes you can get the cylinder off without taking the swingarm off, but it ain't easy. Most difficult part is getting the brake lines off. I took a box end wrench and ground a slot in it so I could get the wrench around the brake line. Take the cylinder attach bolts off so you can move it around a bit to get a better attack on the brake line 'nuts' for lack of the correct name. Then it will come out over the frame member there.

I look forward to hearing from some of you who know more than I do.

Gerald in Atlanta

[froche]

Well first of all I got mine off, rebuilt, reinstalled ( a friend had to help because my right hand/arm doesn't work at 100% since 3 strokes in 4 days, but all he did was reattach the brake lines), and bled.

Boy Honda really did a bad job engineering the brake lines attachment. A bump in the gas tank to make it easier, or a different method of attaching the lines really would have done the trick! Oh well, it did last 35 years before needing any attention except for bleeding and flushing!

I have Speedbleeders on my calipers, and had both front and rear under negative pressure, pumped 1 reservoir of new Dot 4 through the front, and 1 through the rear. Then closed the front and did the same again through the rear, closed the rear and opened the front and did 1 more then closed the front. Great brakes!

So no pressure...
Do you have Speedbleeders? When open they allow pressure to flow through and exit without getting air back in. If both front or rear or both are open no pressure, close them all, pressure!

Because you have both front and rear brakes one one MC you won't really feel pressure until they both are mostly bled. if one of them has a large air pocket the hydraulic fluid will compress that air rather than build pressure. if you have a MityVac tool (or a similar one) you can suck the fluid from the reservoir and with the brake bleeding attachment you can see air bubbles in the line as you pump it.

Are you sure you got a kit that fits, cleaned EVERYTHING out, put the seals in facing the correct direction using fresh DOT4 as a lubricant, replaced the o-ring under the reservoir attachment seal and checked to see if the MC is leaking at all?

And lastly are you 35 year old rubber lines cracked and leaking at all?

[gerald collins]

Hey, thanks for the reply. After my post yesterday, I took the master cylinder off, sure that the cup in the cyl. was stuck in the forward position and not moving at all, or was cocked and not sealing. Neither was the case. Operating it manually it shot fluid out of both holes, more from the front line than the rear. So, I guess the problem was air in the lines, but hard to believe since I had pumped fluid from each slave to the master. Perhaps it wasn't enough fluid to get rid of all the air.

BTW, the m/c comes out the back and not the side as I said it did. The reason I said the side is that is how I put it back in. But when I first took it out, it came out the back. Strange how it went in the side but would not come out the side for me. It took me 20 minutes to get it out this last time but many times that the first time. Practice makes perfect.

No, I do not have speed bleeders but will look them up. Yes, I have a mityvac but it would not pull fluid yesterday. Will investigate that further. Thanks again for replying.

[froche]

If a Mityvac can't pull fluid something is wrong!

My Mityvac was able to pull 15 lbs of pressure before opening the front caliper bleed valve. it took about 1 full reservoir to pull new fluid from the rebuilt rear mc to the front and bleed all the air.

[gerald collins]

Hi, The mityvac obviously had aa bad connection or the lid was not screwed on tight, because it was pulling vacuum at the pump itself. I had to quit before I could check it out further.

Yesterday I took off the m/c and set it up in a vice with the reservoir attached, and it pumped fluid like a geyser. Put it back on and the situation is the same.

I will get the mityvac set up today and do a better job of getting the air out.

[gerald collins]

Hi, I just tested my mityvac, and it pulls a vacuum, but only as long as I hold the handles closed. Let go and the vacuum goes to zero. I think my mityvac is defective....Not to be defeated, I used the mityvac,s hoses and catch bottle, and I sucked on the line with my mouth. Lots and lots of air came out before fluid started flowing. Presto, I got a firm pedal. Front brake works as it should, but the rear doesn't move the pistons. I previously took it apart and cleaned it up, but something is wrong.

[froche]

Got to bleed front then rear then front then rear to be sure!