I really don’t think it’s that simple, it may help for a while but it won’t stop the brakes from warping.

 

well, you see here is where the disconnect is. Your brake rotor is not warped. It never was. We are talking about a massive chunk of steel alloy that is extremely thermally stable because it’s designed that way. The alloy is homogeneous all the way down to the molecular level. The rotor does not get hot enough (forge temps) to allow it to bend and take a new form. The vibration you believe is from the rotor being warped is not from the rotor being heated to a forge temp and bending. It is actually just a uneven buildup of pad material on the rotor surface.

So yes bedding is only a temporary fix but so is replacing them or like when you turn your rotors. Bedding is only a temporary fix because as soon as they are put back into use the pad material starts to build up again and over time the vibration comes back. But the rotor is not warped. Race car teams around the world have investigated this and come to the same conclusion.

You gotta realize that the steel alloys used on rotors are extremely dimensionally stable over temperature. Temperature will cause the metal to grow a very specific scientifically calculable amount (cte) I’m out and when it cools down it will shrink down to the exact same scientifically calculable dimension. And it will do it again and again and again and again and again and always come back to the same dimension. Just like your cylinder walls in your vehicle. It does not retain an odd shape after heating to 600f. You gotta realize that science backs this up. Temperature will cause the metal to grow by a very specific scientifically calculable amount and when it cools down it will shrink down to the exact same scientifically calculable dimension it was. It does not retain an odd shape after thermal expansion and contraction. If they did they would be warped after the first time you applied your brakes

 

Ok I’ll bow to your knowledge, but even manufacturers refer to discs warping eg (Haglin automotive) amongst others. It’s an interesting subject to have a discussion on.

 

Distortion of brake rotors can be caused by uneven heating, by uneven cooling and even improper torquing of wheel nuts. There are other potential causes braking vibrations such as run out on the wheel hub, wheel run out, improperly installed wheel (hub centric or stud centric).
Ask any technician who has machined disc rotors if they have ever machined distorted rotors and the answer will be yes.
Having said that, in this case I would be looking for run out on the hubs and wheels.

 

so let me ask you- how does a brake rotor get unevenly heated? It’s not like when you apply the break the rotor turns a quarter of a turn and then stop turning (there by heating up that quarter of the rotor). The rotor is going to turn many many times under friction as you come to a stop. Hundreds of times probably so that is going to create an even heating of the rotor. The only time that they Would see an uneven heating Is when you have just come to a stop and you’re sitting at a stop sign or a stoplight with your foot on the break. Then you get a small increase at the place the pads are because the rotor cant dissipate the heat to the air bc the pads there. And guess what happens at that point? that’s when you have the brake pad transfer to the rotor that causes that vibration. The increase in temperature under those brake pads is not significantly higher than the rest of the rotor and it’s certainly not enough to cause the disk to warp. Braking doesn’t cause the disk to warp. Hell have you ever seen a car that’s been in a major accident? even the case where the entire front suspension is destroyed you don’t see warped rotors from the impact. Maybe cracked. But not bent. But you want me to believe that normal breaking he’s going to cause a disk to warp?

look I was in denial too when I first heard this concept. I didn’t want to believe that I wasted my money all those times getting my rotors turned. I knew that getting my rotors turned solved my problem of vibration so I was sure that my rotors must have been warped. Wake up and stop being hesitant to new ideas or scientific concepts. Everything I said could be easily proven we’re backed up if you just do a little reading on the Internet and stop listening to the guys who want you to spend money turning your rotors at the parts store. If uneven heating cost disc brake rotors to warp think about all the other parts in your car that are unevenly heated. Why aren’t those things warping as well? Turning a brake rotor is great to get rid of grooves and surface flaws or glaze. But it’s not needed for vibration.

Until I went at it with an open mind and decided to try bedding my brakes. That was over 10 years ago and it has worked every single time.

and also to prove out the concept Google search for a “brake rotor Hone”

It’s a little tool that has the small abrasive bars attached to a packing plate that you can put on the end of a drill. You spin your rotor (by hand) while you operate the brake hone and it will remove the same built up pad material without going through the process of bedding the brakes. It’s a neat little tool and I have one and I’ve used it and it works great
Brake rotor hone

 

Remember folks brake rotors are not made of cheese

 

How many brake rotors have you seen turned on a brake lathe? How many rotors have you actually turned on a brake lathe? How many shops do you know who do not have brake lathes? How many technicians have you talked to about turning brake rotors? How many brake calipers have you seen with sticking pistons? How many brake calipers have you seen with frozen slider pins? How many cars have you seen splashing through water?

 

I find fewer and fewer shops/parts places that will turn rotors these days.
Most repair shops just replace rotors now and many will not do a brake job unless the customer will pay for new rotors.

Did learn something new with that brake hone too. Not sure I need it but will keep it in mind for sure. Thanks much for posting something I was not aware of!
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I’m having the same problem with my jag 2014 it’s started 2 years ago and I’ve changed so many parts on it and not the smallest difference

 

Read post #4.

 

Have you found the issue? I’m having same problem

 

Read this. JagRepair.com - Jaguar Repair Information Resource

Gus
JagRepair.com - Jaguar Repair Information Resource

 

I've had a quick look at the brake parts last year and they didn't seem like to much wanted replacing but I always overhaul my brakes when I get a new vehicle. The pads were just over half way down, so I took the decision to replace the lot this summer and clean them up, overhaul and paint the callipers as it looked like there could have been a leak from the bleed point on one. I had a little look at the guide pins and cleaned them but didnt lubricate and it solved the problem each time i did it but it came back shortly after. It mainly does it when the brakes are up to temperature, and its not apparent when the brakes are cold. I'm just going to run through a process of elimination as Ill upgrade everything when Im doing it so be happy to share info. It does look like its a common problem though.

 

As many of you have experienced, I too experienced the same pulsing of the brakes when they are applied. Many things went through my mind. Is it part of the suspension, worn brakes pads, stuck caliper and the most common warped disks? So I checked all four wheels for the quality of my brake pads and calipers and checked the entire suspension system and found no abnormalities. All looked good. Now I did not remove the disks to check the trueness of them because I at the time did not believe they were warped. They looked new and I felt I had a few other checks I wanted to make based on a hunch.

What I was experiencing was that I could feel the pulse and feel it in the steering wheel and brake pedal. The brake pedal in normal driving had the pulsing and the steering felt like the brakes were shifting pressure from left to right. But when extra pressure was applied to the brake pedal the pulse was near nonexistent. It made me direct my effort to the ABS and or an out of adjustment caliper.

This is What I Did to Correct the Brake Pulse

First I want you to know I had driven the car for several miles with this problem trying to figure it out. I also searched the internet and found MANY with the same issue were replacing the brake pads, calipers and disks. When I inspected the brake system I did notice that the rear disks were not as polished as I thought they should be from normal use. I should also mention that I am light on the brakes when backing and driving. With that in mind I took my XF to an area that I can back up safely and applied the brakes several times while backing and to my surprise the pulsing disappeared when driving normally.

The XF is equipped with self adjusting brakes on the rear wheels like many other cars. But because of my light braking when backing they were not adjusting. My best guess is that when the brake pulsing was taking place the braking / ABS was not seeing all wheels braking and it was pulsing searching to correct the problem. Now that I have adjusted the rear brakes I have driven the car well over two thousand miles without the pulsing.

I am in no way suggesting that this will eliminate your brake pulsing but it might and this process fixed mine. Should you still experience the pulsing after this adjusting process you should have your brake system checked.

 

The problem with blanket statements like "brake rotors are not made of cheese" is that someone on the internet will come along and show you a brake rotor that's definitely made of cheese....



Modern rotors are pretty good, but it's not all that long ago that they were just a solid disc made of some pretty average steel, and absoluely could warp if they got too hot. The size or thickness of the material has nothing to do with it - a 100mm thick steel plate will pull itself out of flat just from welding - it's about how quickly the part can shed heat. If heat goes in quicker than it can get out, eventually it'll get too hot and sometimes when steel gets too hot, it pulls itself in weird ways. This often happens when something has gone wrong in the process of making and heat treating the steel.

Steelmaking and heat shedding have improved so much over the past 20 years or so that it's very difficult to warp a rotor these days, but it's definitely not impossible. It would be much more accurate to say "If you think you have a warped rotor, it's probably something else."

 

Very interesting @Gus , I can produce the tiniest judder if I creep the car forward at about 5-10km/h with very light pressure on the pedal... as as soon as you're doing more than 10km/h or you apply normal braking pressure it goes away, so I never really worried about it. Will be nice if a few reverse stoppies gets rid of it 😁

 

If you check the Jaguar Service manuals ( from 2004 S-Type up to 2015 XK 150) you will find that the standard material used for Jaguar brake rotors is CAST IRON. The only exception I am aware of are the exotic brakes on some XK 150.

 

And the carbon ceramics on the F-Type (same as those on the X150 XK I think).

 

If you're talking to me that's a fair catch - unless I need to be specific (i.e. buying stock, having something made, etc), I have a bad habit of saying "steel" for cast iron and a couple of other things 😣

 

Does this work on older breaks as well then as the link spoke about new breaks? breaking s so bad i dont really want to be performing multiple emergency stops.....

Iv just picked up at 2010 3.0D V6 and the shuddering is very bad under breaking, very occasionally on motorway today i felt the steering wheel vibrate slightly but as it wasnt consistant i put it down to the road - or the higher speed induced it. along with a slight pull left i think i can tell theres uneven wear on the disks and unever tyre wear too, along with balancing and tracking could be my fix

Not to mention finding out today that the skid pan was held on by cable ties, then it almost being ripped off the car later in the journey. Fixed it back to a strut and nursed her home at under 55 and in dynamic mode to stop any further damage Yet to inspect for further damage to suspension, arns etc from the incident where the pan was originally damaged