Just replaced rear brake pads S type 2003. Released electronic brake. did not need to release cable at caliper. Removed 2 bolts holding calipers.,,15mm. you have to pry the pads out of the calipers. Then rented the tool from Oreilly's to compress the caliper cylinder. Great tool worked easily...interesting both my calipers were right hand thread...I had read that the driver side was counterclockwise/ passenger clockwise...no matter it is easy to figure out and the tool with a 3/8 socket adapter can turn left or right. If you turn the wrong way it just comes loose. I used a channel lock to turn the cylinders a few turns to loosen them up so they moved easily. opened bleeder screws prior to depressing cylinders...bleed the brakes...about 2-3 hours...

 

kudos, nice job and welcome to the forums!

 

Good job, quick question for you though.

Why did you open the bleed screws before you pushed the calipers back? You could just take the cover off the master cylinder reservoir, there is room for the fluid to go back in. As long as you don't disconnect the lines, you won't introduce air into the system, so no need to bleed the brakes.

Take care,

George

 

Opening the bleed screws:
1. bleeds old fluid out
2. avoids pressures going back up into the system (people just ignore this but arguably shouldn't)

 

Unless you fully purge the system and replace all the brake fluid. (At which point you're much better off disconnecting lines and not using the bleed screw), and using a pressure brake bleeder to feed fresh fluid into the cap, you're only going to drain a negligible amount of fluid.

If you open the reservoir cap, the system has no pressure.. It's not pressurized unless it's sealed.

George

 

I didn't say or mean that you'd fully bleed that way, but you do bleed some out and it's (some of) the worst stuff. You avoid back-pressuring the system. You wouldn't take the reservoir cap off. It IS pressurised (a little) as you push the piston back in, if you don't undo the bleed screw.

 

I think we're misunderstanding each other here.

The brake system is under pressure as long as it's sealed, if you open the reservoir cap, the system is no longer under pressure (even residual pressure since the engine isn't running).

We're also using the terms bleed and flush interchangeably.

Bleeding is the process of making sure there is no air in the system by forcing fluid through the lines and making sure no air bubbles come out of the bleed screw.

Flushing is the procedure of replacing the brake fluid with new.

What I'm saying is this:

Whenever I have done rear brakes whether at home or at my brother's shop, we don't bleed the brakes unless the system is opened, and air has the possibility of entering the system.

What we do is remove the pads then open the reservoir cap. (This alleviates the pressure in the system). Then push or screw the pistons back. The fluid level will freely flow back to the reservoir and the fluid level will rise in the reservoir due to the fluid being pushed back into the reservoir. As a matter of fact we place a rag over the reservoir opening for 2 reasons. First to avoid anything falling in and contaminating the brake fluid, and second, just in case the system is overfilled and it overflows.

Replace the pads, reinstall the calipers. When you start the car, the pedal will immediately go to the floor without resistance (because the system isn't pressurized). You pump the brake pedal until it is once again firm, and you are all set.

If you open the bleed screw, and leave the cap on the reservoir the fluid that would be pushed back into the reservoir simply comes out of the bleed port. (Because the reservoir is still pressurized).

Then you have to bleed the brakes and add fluid accordingly to make sure you didn't introduce any air into the system. The only time you can introduce air into the system opening the bleed screws is if you allow the reservoir to empty and suck air into the lines (this is VERY bad for the master cylinder seals, as pressures spike and blow seals, because air is much more compressible than brake fluid).

Now I see your point of you may get out some of the old brake fluid with this method, and subsequent bleeding, but you wont get out an appreciable enough amount to make it worthwhile. If you're going to open the system, might as well disconnect the lines and properly flush the system to replenish all the fluid. Brake fluid is cheap..

Take care,

George

 

Wordman good job! Welcome to the forum. You did pads only, not pads+rotors?
Did you happen to notice if you'd need to disconnect the park-brake cables for a rotor change? I did pads+rotors on my daughter's 03 a coupla years ago and could swear I needed to remove the cable from its trigger. On the other hand, the cable on one side was hanging by a strand or two and eventually let go and I KNOW I had to pull that side...maybe the other as well to make the change. Anywho....gotta do the wife's rear end...er...uhmm...I mean the 05...pads-n-rotors, soon so I guess it'll come clear by then...just curious if you noticed whether the cables would be an issue on rotor change?

Jag/George, no air introduced and thus no need of bleeding if you coordinate the compression of the piston with the opening/closing of the bleed screw (put a bit of pressure on piston, open screw, drive piston to compressed position but close bleed screw before you bottom out) and check/top off the reservoir after each caliper. Actually a pretty good method to begin the renewal of the fluid, particularly if you have a small child handy who works for grub and can follow basic directions and not release the break pedal prematurely in your follow-on attempts to purge the rest of the old fluid.!

 

I was under the impression that there's no or very little pressure in the brake fluid reservoir, but regardless of that the idea of opening the bleed nipple is simply to avoid back (reverse) pressure. I've seen it stated several times over the years that the seals/valves (in the master cyl?) don't like / aren't designed to cope with that direction of pressure.

People generally ignore that issue of back pressure, rightly or not, and instead do the thing with the reservoir & cloth.

The jag system has (or is said to have) an explicit facility to open the valves (via OBD) for bleeding (or flushing or something) purposes. I don't know exactly what that (i.e. opening the valves) does or exactly when it's supposed to be used. IDS can do it. Maybe a jag tech such as Brutal will know and explain.

Any fluid that comes out of the bleed nipple is a by-product and not the goal. It happens that it will be some of the most cooked and contaminated fluid so it's good that some comes out. Whether you do a full flush or a partial one to get more out depends when you last flushed (replaced all of) the fluid. I wouldn't expect any air to enter in any of this.

 

For what it worth team.. I have done this trick for years... I have never had an issue one.. Actually my dad showed me this when I was 15, 30 cough years ago..

It’s the easiest, quickest, cleanest way to do a pad swap hands down IMO..

 

The valves are OPEN when you aren't pressing the brake pedal. (otherwise your car would apply the brakes and not release them when you let go of the pedal) When you press the brake pedal first the valves shut to stop the fluid from going back into the reservoir due to pressure, and instead down the brake lines.
The master cylinder pressurizes the brake fluid and it compresses the calipers. It releases the pressure and opens the valves when you let off the brake pedal.

The hydraulic braking system is a sealed system - it has to be to maintain pressure. If you keep the reservoir closed and try to compress the piston, you will create pressure in the reverse direction, just as if you were pressing the brake pedal to compress the caliper, only the fluid flow is reversed..

Opening the reservoir unseals the system, same as the coolant system therefore not allowing it to pressurize.

NEVER try to compress a piston with the brake pedal pressed - you will destroy the master cylinder in short order, and that is the reverse pressure that will cause damage.

IDS Does have a bleed and flush procedure. It does not electrically release the brake bleeder screws (there is no solenoid or actuator, it's just a screw), but cycles the ABS one wheel at a time, so you can bleed the brakes without an assistant in the car working the brake pedal.

Have you ever had a bleed screw open and pressed the pedal without a hose or catch can on the car? You'll see brake fluid shoot out 3-4 feet instead of the drip you get from an open bleed screw with no pedal pressure.

Take care,

George

 

Yup I do the same thing. You "should" be bleeding the caliper every time you change pads anyway. That's where most of the moisture is pulled in. It doesn't really take all that long if you're experienced at it. But it's not strictly required either. I just find it easier. The Brembo calipers on the STR are very much like miniature versions of the racing Brembos on my track car so I felt completely familiar with them.

More than one way to do things. Just do it safely. Brakes are GD important.

 

George,

Just to mention I'm not doing any of the bad things you mentioned!!

 

thanks for all the info and input....regarding bleeding...I opened the caliper bleed screw because I did not know for sure if it would cause too much pressure. I would much rather it push back into the reservour under the hood because the brake fluid looked clean, but new fluid is got tobe better. Finally I noticed that the spring clips were dropped through the caliper and not seeted correctly. So I took it apart and fitted it again...I went too fast..really important to go slow and careful...check everything. when dismantled noticed the *** on the inside brake pad did not fit tight into the cylinder..so reversed cylinder 180 degrees and fit perfect... details details... does anyone have exact procedure to reset electronic brake? also I did not need to release the cable on the electronic hand brake. did not replace rotors or turn rotors... better to turn or replace...the rotors drop off when you remove caliper...I used the wheel lug nuts to hold rotors in place ( two) otherwise they flop around. wordman

 

A cheap open ended lug nut is best for keeping the rotor on.

To reset the EPB, start the car, it will give you the error. with the car in park, pull up on the brake handle until the error in the dash goes away. All done.

Always replace rotors. Stock rotors are cheap ~ $30 each.

Hint - go get brakes for a 2003 Lincoln LS so you don't pay the "Jaguar Tax".

For future reference, you can just pop the cap off the reservoir and screw back the pistons. Personally I like to use disc brake quiet on the back of the pad, but the Jag's are ok with out it.

Take care,

George

 

I agree with jagv8, it may or may not apply toJags but it my understanding that it is possible to cause problems by pushing the fluid backwards.
As always there is more than one way to skin a cat.

 

george...thanks for the EBC reset info...did what you said...worked puuurrrfect....took 40 seconds...wordman

 

Just to say that what I do can't hurt so long as anyone also doing it - or any other brake work - understands to keep air and contaminants out of the brake lines (we say brake "pipes") and to make sure that the reservoir is properly filled.

My suspicion is that it's not actually necessary because I think most people don't do it - and they apparently achieve working brakes.

 

thanks all,,,brakes done...moving on to temperature sensor for climate control...system not responding to changes in temp setting....wordman

 

Just reading through this and find it quite funny if i'm honest...

When changing brake pads you only need to remove the res cap and then push back the piston, install the new pads and put the cap back on...then pump the brakes to build the pressure back up and settle the new pads into position.

all this talk of damaging the system by pushing back the pistons is complete and utter rubbish.

The other comment about its a good idea to bleed it a little at the caliper because its where the bad stuff is usually drawn in is again complete rubbish. Its a SEALED SYSTEM...if anything gets drawn in then it means there is a leak and therefore fluid would already be coming out, not water going in. If anything you are more likely to draw air back into the system if you push the piston in whilst having the bleed nipple open.

The system is designed to cope with high pressure and under extreme load, so why do people believe that pushing the piston back in by hand can cause any type of damage?.... unbelievable