2006 S-Type 3.0, Cannot Retract Rear brake Caliper Piston
#41
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My rear 07 rear calipers are made by ATE and are the same as the units on my wife's Audi. IMOH opinion the resistance to screwing in the caliper piston is due to the ABS pump valve body. At one time there were thoughts floating around the ether that you should not force fluid backwards through an ABS unit as it can cause damage. Perhaps it's just another urban myth, but...........
#42
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Loosening the cap achieves nothing.
If the cap is not vented, how does air get in to replace the fluid as the level drops with pad wear?
#43
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Please re-read what I actually wrote. The brakes are not serviced with the pedal depressed.
Sorry, disagree. The reservoir cap is vented to atmosphere. Newer (generally post '60s) have a flexible diaphragm separating the fluid from the air to lessen moisture absorption, older cars do not.
Loosening the cap achieves nothing.
If the cap is not vented, how does air get in to replace the fluid as the level drops with pad wear?
Sorry, disagree. The reservoir cap is vented to atmosphere. Newer (generally post '60s) have a flexible diaphragm separating the fluid from the air to lessen moisture absorption, older cars do not.
Loosening the cap achieves nothing.
If the cap is not vented, how does air get in to replace the fluid as the level drops with pad wear?
As for the rest of your arguments.
I'll, carry on doing what I've always done on bikes and cars when changing the discs and pads because it works.
Glad to see the OP got it sorted.
Last edited by Busa; 01-18-2017 at 02:25 AM.
#44
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My rear 07 rear calipers are made by ATE and are the same as the units on my wife's Audi. IMOH opinion the resistance to screwing in the caliper piston is due to the ABS pump valve body. At one time there were thoughts floating around the ether that you should not force fluid backwards through an ABS unit as it can cause damage. Perhaps it's just another urban myth, but...........
The main point, that might have gotten lost, was that the latest poster has left himself low on brake fluid by bleeding the contents of each caliper and did not replace it.
This will almost guarantee a low fluid warning as the new pads wear. It's important to keep the system fluid volume within certain min/max limits.
Last edited by Mikey; 01-19-2017 at 08:00 AM.
#45
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Just a few comments. You can't force any fluid back thru the ABS. What the ABS does is have a reservoir of high pressure brake fluid ready at all times to be directed to where ever the ABS computer says to put it. If no signal is received the ABS valves are locked closed at all other times.
In fact no one has mentioned it but technically you are not fully bleeding your brake system unless you have the factory service tool to cycle the ABS pump (remember this pumps job is to keep a small amount of brake fluid under high pressure at all times for emergency use). Since most people drive such that the ABS is not triggered you can see where you have a small isolated bit of brake fluid that never gets changed.
On a previous car I had I did have the correct service tool. Some people claimed that you could acheive the same thing by driving on a gravel road and stomping on the brakes making the ABS kick in to cycle the pump. Can't say if that works or not but I have done it.
The reason the rear calipers are harder to push in is just geometry. There is more distance and more turns and twists back to the master cylinder. So you are attempting to move more fluid compared to the front caliper so it's much harder. If you watch you will see the fluid level in the master cylinder rise as you crank the calipers back in.
Also one thing to check. As our cars age the flexible rubber brake hoses decay from the inside. This restricts the brake fluid mainly from draining back after a brake application. It's very common on some cars for this to happen and the main symptom is you can't push the caliper back in and the rear brakes drag.
Agree with making sure your slider pins are greased and moving too.
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In fact no one has mentioned it but technically you are not fully bleeding your brake system unless you have the factory service tool to cycle the ABS pump (remember this pumps job is to keep a small amount of brake fluid under high pressure at all times for emergency use). Since most people drive such that the ABS is not triggered you can see where you have a small isolated bit of brake fluid that never gets changed.
On a previous car I had I did have the correct service tool. Some people claimed that you could acheive the same thing by driving on a gravel road and stomping on the brakes making the ABS kick in to cycle the pump. Can't say if that works or not but I have done it.
The reason the rear calipers are harder to push in is just geometry. There is more distance and more turns and twists back to the master cylinder. So you are attempting to move more fluid compared to the front caliper so it's much harder. If you watch you will see the fluid level in the master cylinder rise as you crank the calipers back in.
Also one thing to check. As our cars age the flexible rubber brake hoses decay from the inside. This restricts the brake fluid mainly from draining back after a brake application. It's very common on some cars for this to happen and the main symptom is you can't push the caliper back in and the rear brakes drag.
Agree with making sure your slider pins are greased and moving too.
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.
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#46
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I replaced my pads and rotors on the rear for the first time. I fought with the c-clamp until I read through all of this thread. Using the loaner tool from Advance Auto Parts and cracking the bleeder got the pistons all of the way back in. I could see that using one of those cubes and a ratchet would be very difficult. After I was all done I pumped the brakes a few times before and after starting the car and there was no squishy brake pedal, so I did not bleed the brakes even though fluid was lost during the pushing of the pistons back. I also did not reset the electric parking brake at that time since I got no warning indicator. I went for a short drive around our hilly neighborhood and it seemed that the brakes were applying themselves. I took it apart again to push the pistons back completely this time. I drove again and seemed fine in the neighborhood. Again, I did not bleed or reset the parking brake. A couple hours later I drove a mile or so to the grocery store and the brakes were applying themselves again. The rotors were very hot to the touch. After I let them cool for a while, I went through the procedure to reset the parking brake, but each time it beeped on the last step, releasing the parking brake. My theory is that either I should have bled the bakes regardless of the absence of a squishy pedal or I should have reset the electric parking brake before driving. What did I do wrong? What will I need to re-do?
#47
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What TonyX means is found here in the link provided, go to post #54 thru #57.
https://www.jaguarforums.com/forum/s...ewed-up-53653/
https://www.jaguarforums.com/forum/s...ewed-up-53653/
#48
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I'm not sure if you have your issue sorted. If not, my hunch is that you may have installed your pads flipped; inside pad to outside position and vice versa. This matters as the inside pads have dimples to engage the parking brake paws but not the outside pads. Let us know how you make out with this issue nonetheless.
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