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Brake pad and rotor replacement details

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Brake pad and rotor replacement details

  #1  
Old 01-02-2019, 01:22 PM
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Default Brake pad and rotor replacement details

Hi all,

I replaced all my rotors and pads two days ago. This was my first time doing a brake job. I did many many hours of research and think it went pretty well. However there were a few details that I couldnít find or that differed from the way my setup appeared. The previous brake job was clearly not done by Jaguar, so I donít know how much to trust the current setup. Could you please weigh in on the following questions? Feel free to answer only the questions you know.

1) Do the springs on the brake pads (that hold the wear sensor) go under the caliper, being compressed? Or do they reach from the outside of the caliper in, not compressed? I would assume the former would apply unwanted spring tension on the pad that could affect pad travel. I ask because I found my old pad springs compressed by the caliper and my braking was definitely strange.

2) Do the caliper retaining bolts (~25 ft-lb ones) really need silicon lubricant on them? The bolts on three of my wheels were bone dry. The fourth one had some grease but also lacked the plastic cover over the bolts, so perhaps some grease/grime got in there. If I should grease them, is there any concern about the grease getting on the bolt threads?

3) Does the front brake pad wear sensor use a spring to hold them on too (similar to the rear)? The front brake pads I bought didnít have them, whereas the rears did. The old sensors that were on my car werenít held in place by springs at all.

4) I found out from somewhere else that for at least the rear rotors you donít need to remove the caliper retaining bracket to remove the rotor, it can slip out around it. This was very helpful, but I only found this info after I had completed the fronts. Does anyone know if this trick works for the front 380mm rotor as well?

5) In using the piston re-wind tool I found both rear pistons required clockwise twisting to rewind it. Is this a US version thing? All other forum posts seem to be in conflict with each other.

Thanks in advance for your help.

- Nick
 
  #2  
Old 01-02-2019, 04:19 PM
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Okay, so I got some answers by contacting R1 Concepts (the company that sold me the pads and rotors). They said the springs on the rear pads are supposed to be on the inside of the caliper, providing downward pressure on the pad. One spring-containing pad is used per side of the vehicle (the inboard pad). The sensor happens to clip in there, but sensor retention isnít the main point of the spring.

This probably explains the lack of springs on the front pads, because they already have anti-rattle clips keeping them in place. Let me know your thoughts on this.

Also, Iím still interested in answers to the other questions.

Thanks!

-Nick
 
  #3  
Old 01-02-2019, 05:19 PM
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Originally Posted by Nedoerr View Post
Hi all,

I replaced all my rotors and pads two days ago. This was my first time doing a brake job. I did many many hours of research and think it went pretty well. However there were a few details that I couldnít find or that differed from the way my setup appeared. The previous brake job was clearly not done by Jaguar, so I donít know how much to trust the current setup. Could you please weigh in on the following questions? Feel free to answer only the questions you know.

OK, I'll have a go at answering your questions.
Firstly I assume you have the same brakes as an XFR, 380 mm front and 376 mm rear. Or maybe you have the 326 mm rears?
I have changed the brake pads and/or the brake rotors on my XFS, XFR and F-Type many many times now so there aren't too many things I am yet to discover or work out.


1) Do the springs on the brake pads (that hold the wear sensor) go under the caliper, being compressed? Or do they reach from the outside of the caliper in, not compressed? I would assume the former would apply unwanted spring tension on the pad that could affect pad travel. I ask because I found my old pad springs compressed by the caliper and my braking was definitely strange.

As you already found out the springs on the rear brake pads go inside/under the caliper and are compressed slightly.
The rear brake pad wear sensor is on only the RHS inner pad and it clips into the middle of the spring. The easiest/best way to fit it is to remove that spring from the pad (it pulls out easily with pliers), open up the central "hole" a little by pressing the ends of the spring together, then inset the wear sensor. Then replace the sensor cable (with pad attached) by feeding it back through the hole/gap in the caliper before you put the caliper slide pins back in.


2) Do the caliper retaining bolts (~25 ft-lb ones) really need silicon lubricant on them? The bolts on three of my wheels were bone dry. The fourth one had some grease but also lacked the plastic cover over the bolts, so perhaps some grease/grime got in there. If I should grease them, is there any concern about the grease getting on the bolt threads?

Not sure exactly which bolts you are talking about, there are two different sets of bolts - the caliper slide pins (9 mm hex on the front and 7 mm hex on the rear) and the caliper bracket retaining bolts, 15 mm front and rear.
If you are changing just the pads there is no need to remove the caliper brackets at all and you simply remove the caliper slide pins. Once you remove those pins the caliper slides off the rotor and you can access the brake pads. Some prefer to remove the caliper retaining brackets instead (the 15 mm bolts) and take the whole assembly off the rotor but I have always found that on the 380 mm front brakes it's damn near impossible to remove the old pads or insert the new pads with the caliper bracket in the way.
If you remove the caliper slide pins you should clean them off and give them a very light coat of high-temp ceramic brake grease before you re-insert them.
The caliper bracket retaining bolts should have a tiny bit of Locktite on them up near the head, and in theory you should renew this when replacing them.
I bought new rear calipers for the F-Type (upgraded from 326 mm to 376 mm) and they came with four new caliper bracket bolts already pre-coated with Locktite.


3) Does the front brake pad wear sensor use a spring to hold them on too (similar to the rear)? The front brake pads I bought didnít have them, whereas the rears did. The old sensors that were on my car werenít held in place by springs at all.

Yes, the front brake pad wear sensor has a tiny little metal clip/spring on the very end which almost always falls off or breaks when you remove the sensor, and it won't stay in place without that little spring.

4) I found out from somewhere else that for at least the rear rotors you donít need to remove the caliper retaining bracket to remove the rotor, it can slip out around it. This was very helpful, but I only found this info after I had completed the fronts. Does anyone know if this trick works for the front 380mm rotor as well?

No, to remove the front rotors you need to take the caliper retaining brackets off.

5) In using the piston re-wind tool I found both rear pistons required clockwise twisting to rewind it. Is this a US version thing? All other forum posts seem to be in conflict with each other.

Not as far as I know, ie zero difference between the NAS and ROW versions of the XJ brakes.

Thanks in advance for your help.

- Nick
See suggestions above.
 
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  #4  
Old 01-03-2019, 12:43 AM
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Thanks OzXFR for the excellent post. Yes I have the same rotors as your XFR (380 fronts, 376 rears).

Fortunately I happened to put the springs under the caliper, but only because that is the way I found them. Glad to hear that this is normal. Strangely my old right rear inboard pad had a sensor in place but lacked a spring. This furthered my confusion about the function of the spring and got me nervous.

As you suspected, I was referring to lubricating the slide pins. Its surprising that 6 out of 8 of my slide pins were completely dry. I wonder if they were lubricated properly during the last brake job. Now that I'm doing it myself I won't have to wonder.

It's interesting that the front and rear rotors are similar sizes and yet the fronts can't slide past the retaining bracket (after the caliper is removed). It's not too much of a hassle to remove, but those bolts are torqued pretty high, and I do love a great short-cut.

It's also interesting that no one can seem to agree on the direction of the piston wind-back. I assumed there must be a straight-forward reason for the disagreement, but I guess not. It wasn't too difficult to tell though; one direction was highly resistant to turning, so I tried the other direction.

Thanks again for your suggestions, they are much appreciated.

-Nick
 
  #5  
Old 01-03-2019, 01:29 AM
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Originally Posted by Nedoerr View Post
Thanks OzXFR for the excellent post. Yes I have the same rotors as your XFR (380 fronts, 376 rears).

Fortunately I happened to put the springs under the caliper, but only because that is the way I found them. Glad to hear that this is normal. Strangely my old right rear inboard pad had a sensor in place but lacked a spring. This furthered my confusion about the function of the spring and got me nervous.

As you suspected, I was referring to lubricating the slide pins. Its surprising that 6 out of 8 of my slide pins were completely dry. I wonder if they were lubricated properly during the last brake job. Now that I'm doing it myself I won't have to wonder.

It's interesting that the front and rear rotors are similar sizes and yet the fronts can't slide past the retaining bracket (after the caliper is removed). It's not too much of a hassle to remove, but those bolts are torqued pretty high, and I do love a great short-cut.

It's also interesting that no one can seem to agree on the direction of the piston wind-back. I assumed there must be a straight-forward reason for the disagreement, but I guess not. It wasn't too difficult to tell though; one direction was highly resistant to turning, so I tried the other direction.

Thanks again for your suggestions, they are much appreciated.

-Nick
As you would have seen the front brake calipers (and therefore the caliper brackets) are hugely bigger than the rear brake calipers which even on the 376 mm rear brakes are fairly small, and this is why you need to remove the front caliper brackets before you can remove the front rotors. Also you would have noticed that the rear 376 mm rotors don't have anywhere near the swept area of the 380 mm front rotors, because those rear rotors have a big blank area in the middle.
Lastly, yes those 15 mm caliper bracket bolts can be a bit tough to crack (partly due to the Locktite on them) but I have found that using a nice big and boofy 1/2" socket wrench does the trick no sweat, whereas it's a struggle with a weedy 3/8" socket wrench.
 

Last edited by OzXFR; 01-03-2019 at 01:31 AM.
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  #6  
Old 01-04-2019, 07:36 PM
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Originally Posted by Nedoerr View Post
Hi all,

I replaced all my rotors and pads two days ago. This was my first time doing a brake job. I did many many hours of research and think it went pretty well. However there were a few details that I couldnít find or that differed from the way my setup appeared. The previous brake job was clearly not done by Jaguar, so I donít know how much to trust the current setup. Could you please weigh in on the following questions? Feel free to answer only the questions you know.

1) Do the springs on the brake pads (that hold the wear sensor) go under the caliper, being compressed? Or do they reach from the outside of the caliper in, not compressed? I would assume the former would apply unwanted spring tension on the pad that could affect pad travel. I ask because I found my old pad springs compressed by the caliper and my braking was definitely strange.

2) Do the caliper retaining bolts (~25 ft-lb ones) really need silicon lubricant on them? The bolts on three of my wheels were bone dry. The fourth one had some grease but also lacked the plastic cover over the bolts, so perhaps some grease/grime got in there. If I should grease them, is there any concern about the grease getting on the bolt threads?

3) Does the front brake pad wear sensor use a spring to hold them on too (similar to the rear)? The front brake pads I bought didnít have them, whereas the rears did. The old sensors that were on my car werenít held in place by springs at all.

4) I found out from somewhere else that for at least the rear rotors you donít need to remove the caliper retaining bracket to remove the rotor, it can slip out around it. This was very helpful, but I only found this info after I had completed the fronts. Does anyone know if this trick works for the front 380mm rotor as well?

5) In using the piston re-wind tool I found both rear pistons required clockwise twisting to rewind it. Is this a US version thing? All other forum posts seem to be in conflict with each other.

Thanks in advance for your help.

- Nick
You must be pleased, having never done a brake job before. Did you have any issues with emergency brake re-calibration?
 
  #7  
Old 01-05-2019, 12:03 AM
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Originally Posted by jp11 View Post
You must be pleased, having never done a brake job before. Did you have any issues with emergency brake re-calibration?
Yes, it definitely felt good when the job was finished. It was also nice to get a clear understanding of how it all works.

The calibration wasnít too bad, someone posted how to do it on another thread. Disconnecting the battery did result in some temporary electrical gremlins (i.e. the one-touch power windows wouldnít reset without multiple attempts and the trunk/boot lid would periodically forget how to close and Iíd have to reset that too). But now everything seems to work again.

Iím still trying to track down a slight rubbing noise (sounds like a wobbly rotor rubbing against the pad) issue that was also present before I did the brakes. I was hoping it would go away when I replaced my rotors and pads. It gets worse when I turn to the right, making me think it might be a left hub and/or bearing that is bad. I measured the runout on my front hubs and they were fine. I couldnít measure the rears with the car in park (wheels wonít turn), so my best guess would be the left rear hub. I was planning to buy a wireless microphone to see if I could confirm which wheel is making the noise and move forward from there. Iíll be really happy when Iíve got this one figured out.

Apologies for the rambling reply.

- Nick
 
  #8  
Old 01-08-2019, 08:56 AM
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I'm having a similar issue on my XF (X250). Check out the thread on 'R1 Concepts Issue'.
Suggestions are brake rub (as you indicate but unlikely if all new), dust shield rubbing the rotor, or hub

Jack up each corner in turn and free spin the wheels (you will need to put car in N for the rears) and see which is making the noise

Both fronts for me. Now I have to wrk out the cause...
 
  #9  
Old 01-08-2019, 11:28 AM
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Originally Posted by BritCars View Post
I'm having a similar issue on my XF (X250). Check out the thread on 'R1 Concepts Issue'.
Suggestions are brake rub (as you indicate but unlikely if all new), dust shield rubbing the rotor, or hub

Jack up each corner in turn and free spin the wheels (you will need to put car in N for the rears) and see which is making the noise

Both fronts for me. Now I have to wrk out the cause...

Thanks for the reply. I ended up using Cassis-Ear [sp] to diagnose where the noise was coming from. It is indeed the left rear hub (though there was no play in the hub and no ABS light turned on). I figured this was the problem because my front hubs had no sound or runout (using a dial test indicator) and the sound got significantly worse when turning to the right whereas it went away turning to the left. Now I just need to replace the bad hub/ bearings before it warps my new rotors. I can't wait to be done with my list of to do items. Best of luck on your X250.
 
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