Hi,
I needed new rear brake pads and replaced them along with the emergency brake shoes. The car was on jeck stands for @ 2 weeks while I worked on some other projects but last evening my neighbor came by to help me bleed the brakes. I started with the rr then lr then rf then lf. The only air I got was two tiny bubbles out of rr. I noticed that when I bled the lr the pads didn't close on the rotor. I pulled the caliper and inspected, saw nothing askew then had my neighbor press the brake pedal (a small amount)...the piston did move outward. I then reinstalled the caliper+pads and when he pumped the brake pedal the pads clamped onto the rotor. I assumed it was good and finished bleeding. When I installed the wheels I noticed that the lr brake pad was not tight to the rotor. Mounted all wheels, dropped to the ground, test drive and if feels as if the master cylinder is bypassing. No real braking to speak of, of course a no abs light!
Where do I go from here?
thanks for any insight


wj

 

I had to bleed the brakes on my 2000 XK8 and had no issues. According to the workshop manual you bleed the brakes the opposite of what you think. You actually start with the nearest wheel, drives side front for US and work out. The passenger rear is the last to be opened. I don't know if this will solve your issues but it worked for me.

 

 

thanks David,
I bled the brakes last fall when I replaced the front pads...no issue.
I will bleed them the 'correct way' but something else is at play here, I'm hoping others have experienced this and would share their means of resolving.
Prior to replacing thee rear pads the braking was fine but I knew the rear pads were getting thin.
wj

 

Ask the designers at Jaguar I am sure there is a reason for it.

 

I'm a little confused. If all you were doing was changing the pads on the brakes why would you need to bleed the system? Wouldn't you just compress the piston on the calipers and install the new pads.

 

Like many things in Jaguar documentation, I suspect this may have been carried over from earlier models (e.g. XJ40 with two separate hydraulic circuits where the order of bleeding was critical) by their technical authors rather than their engineers. I've deliberately bled XK8 brakes the "right" and the "wrong" way round and found no difference when using a pressure bleeder..

The fluid acting on the piston will gradually get a build up of minute rubber fragments from the caliper seals. On an old system that has not been regularly flushed, the fluid coming out the the calipers can be almost black. Driving this out from the bleed screw whilst retracting the piston instead of pushing it back into the lines is preferable. Fresh fluid is then added at the reservoir to bring it back up to level. I must confess to NOT being this fastidious.

As Jaguar have reduced the recommended fluid change interval down to 2 years on recent models, it doesn't have time to get contaminated!

Graham

 

You might have answered your own question. It could be the half of the master cylinder that works the rear brakes could be leaking internally (by the seal). I assume you don't see any brake fluid leaking anywhere. Do you get a good squirt of fluid out of the bleed nipple on the rear brakes ? Even so, it might not hold the pressure you need for solid brakes. Maybe someone else will chime in on how to verify the master cylinder is good.