My car: 1999 jaguar XJR Completely stock

The issue: The front driver side pads are worn much more than any of the other pads and the rotor looks considerably more worn, along with an excessive amount of brake dust. I've also experienced vibration in the steering wheel when braking hard, along with poor gas mileage (15MPG) and slower than usual acceleration.

I am pretty confident it is a stuck caliper. Instead of buying a rebuilt one I would like to rebuild the one I have. Now for the questions... Does anyone know of a rebuild kit specifically for the X308 stock caliper? Also does anyone have the diameter of the piston so that I can potentially buy a more generic rebuild kit? Anyone have any experience in rebuilding these calipers? I searched the forum and could not find the answers I'm seeking, but they may be out there. If the answers are out there post a link top the thread please! Any help or advice would be much appreciated. Thanks!

 

I rebuilt one on a Volvo a couple years ago and found it more trouble than it is worth. The kit was 25% of a rebuilt caliper and the rebuilt one was all purdy compared to my rusty one.

You certainly can do it if you can find the parts.

 

You may want to check the caliper before jumping into a rebuild or laying out for a recon unit.
Remove and check the slider pins (8mm hex key). These can get dry/pitted although I doubt whether they will seize in the rubber bushings enough to stop the brakes from engaging, but could contribute to a lazy braking action.
They will probably need honing and a fresh lube of silicone grease.
Can you manually retract the piston by hand (the caliper will have to be removed from the bracket by undoing the slider pins), does the piston move on application of the brake pedal.

Also if a front caliper was sticking it would probably affect the steering - does the car pull to one side at all.
With the car jacked up spin the wheel, it should spin quite freely with just a little scraping noise from the disc/pads.
After a drive, is the wheel/disc hotter than the rest.

Thats all I can think of - a caliper rebuild is relatively easy but time consuming so cost out the parts and see how that stacks up with the cost of a recon unit. The fronts have 60mm bores I think.
Theres a knack of reassembling the piston to the caliper if you decide to rebuild, let me know if so.....

AndyP

 

Thanks for the info. The car does have a slight pull to the driver side, but it is not real noticeable. During braking there is no noticeable pull. However when stopped at a light when releasing the brake pedal the car does not move forward until pressing the accelerator. Normally it would creep forward when the brake pedal is released. I think it may be just sticking when stopped, but once it gets rolling it only rubs where the rotor is warped. I bought a centric rebuild kit along with the 2 front rotors and pads. I plan on working on it this Thursday after I get the parts. I will definitely check the sliders to be sure the caliper is able to freely slide back and forth. I don't have a thermo tester, but I can definitely observe considerably more wear on the driver side rotor. All the other braking components are visibly fine. I have not had a chance to take the wheel off or put it up on a jack to spin the wheel. I will keep you updated on what I find. I feel rebuild is pretty straight forward. Thanks for the replies

 

Also the rebuild kit was $5 compared to a $70 minimum rebuilt caliper. I'm not worried if it is shiny, just has to work properly. If I can get mine to work for $5 ill be a happy camper.

 

buy a new one.. better for you.
best to do OEM new parts.. NEVER pay money for USED items unless the new ones are out of production.
always buy NEW.. I have restored many cars its worth it.
peter

 

Good luck then, a couple of tips though :

- You will need a compressed air line via the brake hose port to remove the piston .
- Clean out the stripped caliper by immersing in methylated spirit (it will dissolve brake fluid and dries quickly)
- Check the caliper housing where the pads sit for excessive pitting / corrosion. Flatten any high spots with a grinding stone. Clean the rest with a wire wheel (not the bore though !)
- On refitting you will have to remove the brake hose completely from the brake pipe if you hadn't already, trying to screw the hose back by turning the caliper is very difficult and could result in a twisted hose. Be prepared for some fluid spillage from the pipe. Screw the hose into the caliper first, then fit to the pipe tube.

 

That was some good solid advice. I totally failed today trying to accomplish it. My first issue was the hex head. Apparently it is not a 8mm, maybe a 7? I didn't have a 7 to try but a 6.5 was too small. Next the 17mm bolts on the back of the caliper would not budge. I'm not a very large guy, 130lbs, but I put all my weight in it and couldn't get any response. Even with a 2 plus foot breaker bar, or my electric impact gun. The impact broke the lugnuts no problem, but couldn't do anything to either of the two 17mm bolts in the back of the caliper. At that point I called it for the day. Tomorrow I'm going to try taking it to Monroe for a free inspection and ask if they can break those two bolts for me then snug them up again for later removal. Plus it never hurts to have the steering components checked while its on the rack. I'm also purchasing a hex head set that is more complete so I can figure out what size those 2 bolts are. Also with the brake line you mentioned, it has one end that sits under the little bracket followed by a nut on top of the bracket and finally a longer brake line nut that sits on the flange on the brake line itself. My top longer nut does not seem to turn either, it was starting to twist the metal brake line so I stopped cranking on it . I gave everything a healthy dose of pb blaster before putting the wheels back on and calling it. I didn't even get to the pass side. I'll give everyone a follow up tomorrow, hopefully a little more positive news.

 

Today I got the calipers off and changed the pads/rotors. The driver side front caliper was froze shut in the back and it took many attempts with a BFH and my handy crow bar against the old rotor to get the caliper off. After removing the caliper with the 7mm hex socket, I turned the wheel to the side and had just enough room to get my breaker bar in to break the 2 17mm bolts holding on the rest of the caliper. I thought for sure I was going to bust the heads off or the breaker bar. It was really bent! After removing the caliper I broke the bleeder valve off and had to reverse drill it out and install a new one. After that little fiasco I managed to get the piston out with air, honed the cylinder and replaced the seals. I relubed the hex bolts and reinstalled it all. One of the only things that seemed to go smoothly. I installed the new rotors and pads with the calipers. I had disconnected the calipers from the brake line at the caliper and had the lines drip into a catch pan. I reinstalled the lines to the caliper and went to bleed the brakes. This is where I again failed. I tried first bleeding just the front brakes with the vehicle off. Seemed good until I turned the car on and the pedal repeatedly went to the floor. I could pump the brake and get pressure, but it would sink to the floor eventually, and if I pumped the brake and let it sit then pressed it again, it would go to the floor. So I tried bleeding the brakes with the car running. The brakes would not hold pressure at all that way. I then attempted to bleed the rear brakes as well, out of lack of things to try. I bled from the farthest and worked my way to the driver front bleeding them with the car off. The brakes felt great until the car was started. So I again tried with the car started, and again no luck. I was doing the 2 man method which I have always used successfully in the past. I read about turning the bleeder valve up by rotating the caliper but I don't see how that is possible. The caliper only seems to fit one way and the bleeder is angled slighlty down, and if I loosen the top hex and remove the bottom, it wont rotate enough to have the bleeder facing up. At best it is slightly above level with the ground. With the 17mm top bolt loosened and the bottom removed the caliper hits the dust shield and wont rotate enough to angle the valve upward. I'm thinking there is air in the abs maybe or the brake booster? Everything functioned properly when I started and I don't see how the master cylinder could have went out when it was never even touched except to remove the cap at the start. I will be able to get back to work on it thursday hopefully. Any input would be greatly appreciated. Maybe some elaboration on the bleeder valve trick. Thanks for all the advice and suggestions thus far. Next on the list is shocks, but I dont want to get ahead of myself here.

 

I should also mention I inspected the calipers and there is no leaks in the system that I can see. There is no brake fluid leaking at least. I also tried bleeding them with the cap off the master cylinder. I went through about a quart of brake fluid. Thanks again

 

wild guess ... because the hose was open for so long air got into the ABS.

Apparently the cure is pressure bleeding.

You were using the traditional 2 man method, and that method comes with the danger that if you overstroke the pedal into an area that is normally unused in the master cylinder, the seals can score on corrosion in the master cylinder bore. Doesn't happen every time, but it's happened to a bunch of people regardless of make.

The 17mm bracket bolts are known to be tough. They generally have permanent thread lock on them. Permatex bottles of the stuff have instructions to heat the joint before disassembly.

 

Thanks for the guess. I hope I didnt mess up the master cylinder. The fluid never got emptied completely, it didnt even say low brake fluid on the dash, so it was above the sensor the whole time. I'm going to try going through the complete system starting at the master cylinder, next to the abs and each of the brake lines coming off it. Finally I'll bleed all 4 lines again and see if I can get it to work. Hopefully I can get it figured out Thursday. I'll keep everyone posted.

 

I see you removed the brackets from the hub as well as the caliper - I know the bolts can be tight !

When bleeding I use the Gunson Eezibleed kit, which is inexpensive, allows a one man operation and works really well. It will push fluid through the system from the resovoir at roughly 20psi. You can push through as much fluid as you want in one smooth operation, eliminating any trapped air. I use a foot pump instead of a partially deflated tyre to pressurize the system but it works just as well.
If you have no brake pedal pressure there must either be a leak or trapped air in the system. There should be no need to alter the angle of the bleeder screw.

Just a thought .....
AndyP

 

BTW, light tapping on the caliper with a *small* hammer can help free up air bubbles as well as tapping on hoses and lines with your fingers or screw driver handle.

Due to the amount of brake fluid you will use in trying to clear up the ABS, making or buying a pressure bleeder is probably cheaper and more likely to lead to success. The usual brand recommended at the hobbyist level in the US market is the Motive bleeder. DIY can be as little as $10.

Of course ... even a mountain bike inner tube stretched over the reservoir opening can do the job.

 

Okay, sorry for the late update, but the Jag is back on the road. I ended up bleeding the system from the ABS and each caliper. Went through an additional qt of brake fluid but it was well worth it. The brakes are good and solid now. I put centric ceramic pads and Reliance rotors on. No complaints yet. Here is the link for the $120 kit Front Kit Reliance OE Replacement Disc Brake Rotors Plus Ceramic Pads F2013 | eBay
pads and rotors for the price of a single rotor at autozone/advanced. They are not real "bitey", but I got brake checked today on the highway going 65-70mph and they worked great. I will report back on the brake dust, but being ceramic pads the dust should be pretty minimal. It took about a hour to bleed all the lines. I stuck with the 2 man method, my brother and I eventually got everything bled. The rebuilt caliper seems to function well also. I feel like an expert in the brake dept after disassembling and reassembling my brakes at least 5 times haha. Might get around to the shocks this weekend. Looks like I will be in for more fun with those. I noticed a pretty loud rattle when I hit any sort of bump in the road coming from the driver side front wheel. I also noticed the front end has been repainted, so I'm pretty sure it has been in some sort of collision and that is the source of my issues with the front driver side of the vehicle. Any suggestions on what I should look at for the rattle? I know the shocks are shot, but this sounds like it is coming from the wheel area related to the suspension. The car also makes a humming noise when driving over any type of grating on the highway i.e. bridges. Almost like the toe in on the alignment is messed up. Thanks again for all the suggestions and help troubleshooting on the brakes. I'll update you guys on anything I find out on the suspension.

 

Do you happen to recall the exact thread size on the bleeder you replaced?

What do you mean by "bleeding the system from the ABS"?

Is it more a rattle or a clunk?

 

The bleeder was a "coarse" thread type. Don't remember the exact thread count, but I had to go to 3 autoparts stores to find it. I bought 4 of them and replaced them all. I bled the ABS from the main line going to it from the master cylinder, then each of the 4 lines coming from it.

The noise in the front suspension is definitely a rattle. Not a clunk.

 

You mean you cracked open the pipe connections at the hydraulic control unit?

 

Yes, each one starting with the one coming from the master cylinder to the abs. I had pressure applied to the brakes, then turned the connector until fluid came out, then tightened it again. It was a bit messy, but most of the fluid fell down to the catch pan. I then did the same for each line coming from the abs. Then I proceeded to bleed each caliper starting from rr going to lf. Then tested the brakes and they were solid

 

Thanks for the confirmation. Not a whole lot of people get into it that deep.

For the rattle, the first and cheapest stops are the sway bar bushings and the end links.

Then there are the bushings at each end of the shocks.