Brake Question

All right. So I just got the bike back from having the new exhaust installed, carbs synced, and so on. I took my fiance out for a ride on it and about 7 miles into our 10 mile ride I noticed the front end diving. I then noticed that at the lights you didn't have to apply the brake. I knew right away what was going on. The front break had seized. The front caliper was frozen onto the rotor. I limped it back home and pulled the caliper off and trashed the pads (kinda scared). Luckily the rotor looks to be in great shape though. I was wondering if anyone had any idea what this could be. Is there any way to tell if it's the caliper or anything?

Thanks,

Graig

 

could be gunk in the master cylinder... there's a tiny pinhole next to the bigger one inside the reservoir, if it's not clean it will make your brakes drag.

 

From what I understand, there are small passages in the master cylinder and resvoir that can get plugged ... and result in the brake grabbing like that. I would completely clean out all the old brake fluid, flush/clean out the master cylinder and fill the entire system with fresh brake fluid.

I would fill it fthen bleed from below via the bleed screw and pump fluid up into the resevior. Rig somthing up to cach the overflow. A hand pump oil can works good (that's how I do it on my plane).

This is a project I have scheduled for my XJ650 next weekend. No telling when it was last done if ever.

 

Sounds good. I'm going to Pepboys now for brake fluid and a bleeder tool. I'll order new pads today......I really want to ride!! Is there anyway to tell if this works before getting the pads installed?

Thanks!

 

Ok, so here's the deal. I drained all of the fluid out of the system and cleaned the crud out of the master cylinder.

1. I hooked up a brake bleeding tool that goes into the bleeder hole and drains into a little bottle. (there isn't a pump or anything. The tools says to put fluid into the master cylinder and keep pumping the brake and all the air will come out.

2. I've done this and it's full of air and no fluid is coming out. The brake has no feel either (goes all the way to the floor or grip?)

I love this bike, but I can tell it's going to be a love / hate relationship.

Thanks!

 

Close the bleed nipple and pump the lever.
Hole the lever tightly pulled and open the bleed screw.
Close the bleed screw.
Do this process until the fluid begins moving through the lines.
Once the fluid is pushed through the lines some ... the bleeder will work.

Unless:
There is an air leak breaking vacuum.
Wrap the bleed screw with vinyl thread wrap ... don't block hole.

Possibility of worn-out Master Cylinder seals exists.
All the pumping in the world won't move fluid if the seals are shot.

 

So should I have the master cylinder cover installed when I do this?

 

You'll need the cover off so you can top it up when the fluid starts coming out.... Won't make any difference to the way it operates if the cover is off or on

Just watch you don't spill any brake fluid on your paint.

 

be patient, it may take some time and lots of squeezes of the lever to bring the pressure back up, make sure all the holes in the master cylinder are clean and not plugged.

 

So here's what I've done:

I installed the new pads (they came in the mail today)
Open and closed the bleeder screw (as adivsed for about a half hour and nothing was coming out!
I then wraped the threads (leaving the hole open) with plumbers tape and still nothing.

Could it be the master cylinder? If so how should I go about getting one. I guess what I'm asking is what is the best bet.

Thanks

 

Master Cylinder Rebuild Kit.

Everything you need comes in the package.

You know you need the kit if the Master Cylinder looks like Old Faithful when you are pumping the lever with the Cover off.

Get the Master Cylinder on the bench.
Pry-out the Dust Cover
Remove the circlip.
Let the guts out being mindful that they're spring loaded.
Line-up the guts on the bench.
Clean-out the bore using Brake-Kleen.
Inspect the bore for scoring and pitting.
If the bore is free of pitting within the travel of the seals ... install Kit.

If the bore is pitted ... you have to hone the pitting out.
Duct tape some 800 to a rod. Make it a snug-fit.
Chuck it in the drill and move it in and out at medium speed.
Lubing the 800 with WD-40 will give you a nice new finish in there.

 

With the cover off, there is a little burst of fluid not a lot. You can see almost like a little could of smoke (but under fluid) come up everytime you pump the brakes. Is the master cylinder rebuild kit very involved? I'm pretty mechanically inclined but I'm not sure if just going with a whole new aftermarket set up is better something like these?

http://cgi.ebay.com/ebaymotors/FRONT-BR ... enameZWDVW

would that even fit?

Also what about this?? Would it fit?

http://cgi.ebay.com/ebaymotors/80-YAMAH ... enameZWDVW

or should I just rebuild it? What is my best bet?

 

I had the same trouble after rebuilding the master cylinder. I could not get brake fluid out of the brake calliper. I got a large syringe from a vet's office. Using a small hose (clear works well) connect one end to the bleader screw the other end to the syringe, open the bleader and pull the plunger on the syringe till you see fluid. This will prime the system. Now do a reguler bleading of air from the system.

 

I'd say ... giving that you see the contamination trail ... that your seals are gone and you need to rebuild that Master Cylinder.

It isn't a complicated job.

It one of those "Sooner or later" situations we all face.

If you haven't done preventative maintenance and flushed-out the old fluid; the job come-up sooner rather than later.

Either way ... right now you got no brakes. So, you have to do "Something."
Take the Master Cylinder apart and evaluate the situation.
Get back to us with what it looks like in there ... and, we'll take it from there.
If you score a used one ... there's no guarantee you won't be rebuilding that one -- too -- sooner or later.

 

Ok so I ordered the master cylinder and caliper rebuild kits. I only think I need to do the master cylinder, but since I'm tearing into anyways why not? I atempted to take the master cylinder cover off (again) and one of the screws stripped. In trying to get it out / prying on the cover. I snapped the side off of the cover.....but got the screw out no problem then. Does anyone know where I can get another cover?

Thanks!

 

Just buy one of those "Designer One's"

Or, fix the one you got!

DuraFix Aluminum Brazing Rod ... Propane or MAP Gas heat source.

http://durafix.com/

 

Are all the covers the same size?

 

Why not buy a new master cylinder? Item # 08-0255 is only $69, shipping included, from mikesxs.com. I bought one for my 82 Maxim 650,and it works great!
Best of luck to you !

 

I ordered the new master cylinder from mikesxs.com and it works great! I was going to rebuild it, but why not. I got a clear sight glass and so on. I even got to ride it work today! I'm so excited! The riding season isn't the longest in Chicagoland and I plan to take full advantage!!

 

Hey, graig:

How's she runnin'? Are you all "Tweaked-Up" and "Dialed-in"???

 

Pretty much. I bumped up the idle a very little bit, I'm now idling around 1200 or so. She seems to be running good. I don't work unti noon tomorrow. I might wake up and just early and just go ride! I do need to take the mirror off of the old master cylinder assmebly though.