Putting my calipers back together... HELP!

Okay so calipers cleaned o ring slots scraped out. Brake rebuild kits purchased from chacal. As well as EBC pads. I greased the pistons, and the rings, and bolted them back together.

I then slid the retaining pins part way in to hold the pads and put the steel clip in. I then slid them the rest of the way through and put the retaining clips on the pins. The question that I have... Is it's been awhile since these have been together. What makes the pads retract as opposed to sticking to the rotors? If I just let them sit the pads fall together. When I slide them onto the rotor they appear to be almost touching it.

Forks are off the bike so I can't put them onto test if they're dragging or now.

Second question.


system is completely dry. How do I add fluid? And bleed. How do I "open the bleeder nipples"?

 

Answer, nothing, clearance is notional.

 

Okay so based on my description everything sounds good? They just don't drag "on their own"?

any advice on the filling the system side of things?

 

Keep the res' topped up, I tape a piece of plastic tube onto the shop vac' hose, loosen the bleed nipple, fit the pipe on & suck away, watch your level.

 

It's kind of counter-intuitive, but yeah, they don't just stay there closed. If you look closely at the pads on the rotor, you should be able to squeeze the lever, then release it, you should see a tiny gap open up between the pad and the rotor, immediately.

Wait, forks are off the bike? Lol, never mind. But when you have it together, try it

Anyway, the master cylinder piston pushes fluid down the lines against the piston when you pull the lever. You can't compress fluid, so the piston moves. When you release the lever, the piston in the master moves back and fluid makes its way back into the reservoir. Since it's a closed system, I mean assuming there's no air in there, now there is less pressure on the piston in the caliper.

That's all it takes. It takes pressure to get the brakes to push on the rotor, as soon as the pressure reduces they don't "spring back" but they do stop pushing, that's enough. With the seals and everything the piston is sort of resisting being pushed out, so if it isn't being pushed, there's a certain "retraction" effect. If everything works right and you don't have a seized piston, of course.

Edit: Just did some research on this. It seems like this is quite a thing on many forums, This is why the piston seals are square in cross-section. the piston pushes them out of shape, they want to go back to their original shape, hence the force to get a little movement out of the piston. Between that and the drop in pressure behind the piston, there ya go. Apparently bicycle hydraulic brakes have a little spring arcing across the rotor to push the pads away for better retraction, since any rubbing would suck away so much energy on a bicycle.

 

Wow thank you guys very much. I have never been satisfied with just knowing I like to know why as well! Is there a way to do this without a vacuum? I think my roommate would be pissed if I used his dyson....

 

You can do it without the vacuum. It's like the system on a car. Just takes a lot more time: squeezing the brake, holding it, opening nipple, closing nipple, repeat like 30 times.

You still have to do this after the vacuum, but vacuum pulls in a bunch so the method above is just a fine tune. You know, its not hard, just time consuming.

Do a search and you'll find the "inject from the nipple up" method, and also the "fill and leave for a day or two" method. And check my recent topic - I used a gas siphon to get it started.

Also about the piston, when you have it filled/bled, you can squeeze and release the brake and see the piston move in and out (before you cover it with the little condom thing). The pads kind like to hang with it as it moves. Scientifically it's called FM (f***** magic).

 

Easy alternative to vacuum (when also replacing hoses):

Fill MC, add hose from MC to distribution joint, put finger over hose end, pump lever until fluid comes out.

Join to Dist joint, add line from dist joint to caliper, do the finger thing again, then join hose to caliper.

This gets the system full of fluid, then you just have to squeeze/hold/open valve/close valve, repeat until all bubbles disappear.

Make sure the MC stays as full as possible until you are done bleeding the system. It is easy to get a little fluid out of the MC, but if you introduce any air into the system you have to start the bleed all over.

I did this on my dual disc system and had it full in about 5 minutes, then another 5-10 minutes to bleed.

Don't forget to re-bleed after about 200 miles or so, the system will still have minute bubbles that will develop and need to be released after a few heat cycles.

 

The TOOL for the Bleed-Job is the "Mighty-Vac Brake Bleeder". Gets the job done, ... quickly.

But, the "Old School Method" of PUMPING Brake Fluid through the System through a CLEAR HOSE which has its bitter-end submerged in Clean Brake Fluid is a trusted age-old method.

The process depends on having a healthy Master Cylinder that will PUMP Brake Fluid OUT, ... under good Hydraulic Pressure.

The Bleeder needs to Vinyl Taped to insure that the connection is AIR TIGHT.
Pumping the Fluid down and out through the lines and caliper. A HIGH-QUALITY "One-Man Bleeder" makes the job even easier.

 

This will probably be the best for me. Stupid question... How do I open the bleed valve? Just back it out a few turns? or......

 

Righty tighty, lefty loosey. From fully seated it should take less than a quarter turn to open the valve enough to bleed.

 

The Bleeder only needs to be loosened approx. 45-90 degrees. You only need to lift there orifice off the seat.

Teflon Taping the Bleed Screw makes the Threads "Air-tight" and aids in preventing Seizure.

After applying a couple of wraps of Teflon Thread Tape to the Bleed Screw; be sure to PUNCTURE the Tape covering the orifice to allow Fluid to exit when the Bleeder is loosened.

 

Wonderful thank you guys for teaching me so much. So Rick I just wrap it in that and then puncture out the hole before putting it back in? Then just screw it in? Teflon tape would be at an auto parts store? or hardware I assume.

 

You'd do well to shop at a well-stocked hardware store like ACE.

After you get the tape; get Hose supplies.

Bring a Bleed Screw.
Buy 6" of Rubber Hose with an I-D that fits tightly onto the Bleed Screws Bubble-end.
A long length of Clear Vinyl Hose to join to the Rubber Hose.
A Hose-connecting "Union" ... (splice).

Fabricate a Hose that fits the Bleeder air-tight and won't slip-off.
2" Rubber Hose <> Union <> Clear Hose length.
The Rubber Hose is Chem-resistant and won't harden or stretch when exposed to the Brake Fluid or repeatedly fitted to a Bleeder.

 

I opted for the mitty vac as its relatively cheap and should get it done faster can anyone give any tips or anything? I tried putting fluid in the master cylinder and leaving the bleeder closed while flexing it to "built pressure" The pressure didn't build and the level didn't even go down lol.

Just got the mitty vac will give it a go in a few hours.

 

With the Mity vac. Tape the brake lever back to the grip to hold it open. attach the mity vac to the bleeder screw and pump a few times to create a suction. Once you open the bleeder screw keep pumping the mity vac until you get a steady flow of fluid without air bubbles. Make absolute certain that the master cylinder stays full of fluid while doing this.

Start with the left caliper. Then move to the right.

Ghost

 

Thanks a ton man for answering on all of my threads. What do I do with the resivoir it came with?

 

I am assuming that you got this setup.

With this setup you will attach a length of the hose from the bleeder screw to the reservoir. Then a second long length from the reservoir to the vacuum pump. The reservoir is for catching the brake fluid that comes out.

If there are two tubes stretching down into the reservoir from the cap. The end with the shortest tube gets attatched to the pump. This keeps the brake fluid from contaminating the pump.

If the reservoir gets full. empty it out before sucking any brake fluid into the pump.

Ghost

Ghost

 

If the Fluid Seals in the Master Cylinder are incapable of making Hydraulic Pressure and "Pumping" Brake Fluid out of the Master Cylinder down into the Brake Lines and Brake Caliper, ... attaching a Mighty-Vac and drawing Brake Fluid down through the Bleeder will be a waste of time and Brake Fluid.

Pad the Jaws of a pair of Vice Grips so they won't damage the Brake Line.
Clamp the Brake Line close to the Master Cylinder outlet.
Determine if the Master will develop Hydraulic Pressure.
"Pump" the Brake Lever and see if the Master Cylinder Fluid Seals are capable of generating Hydraulic Pressure.
If the Lever gets firm and "Pumps-up" ... go ahead and Mighty-Vac.
If the Lever is spongy and does not firm-up, ... Rebuild the Master Cylinder with a Replacement Set of Fluid Seals, Piston, Cup and Spring.

 

I took off the top bolt by the mc it won't let fluid out of the resivoir is it stuck somehow? I even Mitty vac up to the whole at around 20. Nothing not a drop doesn't matter if the lever is opened or closed. It pressurized when I first out everything then It stopped after I realized I'd been sucking air in with releasing with the bleeder open still. What do I do? This is my first time doing anything at all brake related.

 

The Master Cylinder MUST -->PASS<-- the Hydraulic Pressure Test.
The Master is a PUMP.
Unless the Pump is MOVING Fluid; there will be NO Brake Pressure.

With a Bleeder OPEN; the Master Should PUMP-OUT all the Fluid in the Reservoir.
If the Brake Fluid is "Push-Pulling instead of "One-way" Pumping; the Master Cylinder's Internal Seals are not developing PRESSURE and are no longer capable of FORCING Fluid OUT the Cylinder to make Hydraulic Pressure develop.

Without a healthy Master Cylinder that has Fluid Seals PUSHING Brake Fluid OUT if the Cylinder with the integrity to SEAL the Cylinder such that the FLOW is ONE-WAY causing Hydraulic Pressure to develop; the process of Bleeding the System is just a waste of time. Even with the System free of ALL Air Bubbles, ... unless the M-C can INCREASE PRESSURE within the Hoses and Caliper, ... the Brakes won't have enough PRESSURE to force the Caliper Piston to act on the Brake Pads.

 

I read that from pumping the lever with the bleeder open it can lodge air inside the mc. Making it unable to properly pump. When I pull the lever I do see some bubbles coming up in the master cylinder. Is it possible it's just got an air pocket inside it? Can I just pull it apart and clean it?

 

The Bore of the Master Cylinder needs too be inspected.
Build-up or Pitting will render the MC inoperative.

Build-up will have to be scraped clean.
Pitting will have to be Honed-out.

Tape Finishing Paper to a Hardwood, Fiberglass or Brass Dowel.
Wrap the Finishing Paper tightly and stuff it into the Bore.
Spin it with your drill.
Move it in and out.
Refinish until the Bore has a restored finish to it.

Clean.
Install Rebuilt Kit. New Seals and Piston Parts.
Start from scratch.

 

Question I left it over night and just went and felt it and it was firm like built up pressure even when I squeezed it a few times... Does that change anything?

 

Yes.
IF the MC will develop Hydraulic Pressure AND "Pump" Fluid down through the Lines, through the Caliper and OUT the Bleeder, ... you're good to go.

If you Mighty-Vac all the Bubbles of Air out from the System and the Brakes are still spongy like there is Air still within, ... the Seals are weak and you need to rebuild the Master.

 

Are you seeing bubbles in the MC, or a small gyser of brake fluid? If the return port is blocked the MC will not develope much pressure.

 

If there is a miniature "Old Faithful" geyser in the Reservoir when the Brake Lever is operated, ... that means the MAIN Fluid Seal isn't doing the job and needs too be replaced.

Fluid that gets pushed back into the Reservoir is the result of the Main Seal NOT forcing Fluid OUT of the MC.
The REAR Seal causes the Increase in Pressure and the Fluid gets forced OUT the replenishment orifice under Pressure from the Rear Seal on the volume of Fluid in the System.

 

Yes I was getting a little geyser. and little bubbles. I got brake fluid all through the lines but the caliper pistons aren't pushing out yet. Do I just need to keep bleeding and when there's less air it will pressurize them out?

 

It would also drain fluid faster with the brake lever not engaged and slower when it was. Is that another sign?


This Damn thing.... Went from just the pads to literally the entire freaking system lol. I guess I'll know how to redo an ENTIRE brake system now.

I'm pulling it off the bike now.

 

How do I get the brake light switch off the master cyclinder? Do local shops normally carry the rebuild kits or is that a chacal only type of deal?

 

Brake light switch: there is a tab on the side of the switch where it clips into the MC, just depress it with a small screwdriver (or something similar) and wiggle it out.

Quite a few places carry the rebuild kit, but if you have to mail order, might as well go with chacal.

 

I do believe we might have told you this more than once going in...

You can't just replace one part. Replace the lines, you'll need to rebuild the caliper and master cylinder. Rebuild only the caliper, you'll discover you still need to do the master. Do just those, you'll need new lines.

The brakes are only as good as the weakest component in the system. As soon as you rebuild/replace PART of it, the remaining bits will fail.

BLEEDING is such a ringtailed PIA that it really is best to only have to go through it once.

And the way to do it only once is to do it right and do it all the first time. An "incremental" brake overhaul on an '80s Yamaha is an exercise in frustration. (A whole lot of us here learned that the hard way.)

 

That being said, ...

IF the Master Cylinder isn't in tip-top condition ... then Bleeding the Front Brakes will be an exercise in futility.

What "Feels" like AIR in the system is really Fluid seeping-by the MC's Main Seal causing Hydraulic Pressure NOT to develop in the system after the Main Seal.

The "Squishy-feeling" is Brake Fluid being allowed to flow over (around) the Seal and not be compressed to apply pressure to the volume below the Seal.

At 30-years old; you're due for an overhaul.

Caliper Seals.
Stainless Steel replacement Brake Line Kit w/ New Banjo's & Washers.
Master Rebuild Kit
-or-
New or Reproduction Master Cylinder.

::: The Stainless Lines from chacal fit like a glove and are engineered to have the correct geometry needed to bolt-on without a fuss. :::