So I've had a "brake pads low" warning popping up and when I checked it out during a service at the dealership, they said the rear pads were low and they quoted me $900+ to replace the rear pads, rotors, and sensors.

When I asked about replacing the rotors and sensors in addition to the pads, they said it was standard because the sensor comes in contact with the rotor (or something along those lines which honestly sounds like BS to me).

Anyway, does anyone have an insight into this? I mean, I could see replacing the sensors, but if the rotors still have enough thickness, that just seems excessive to me.

 

It is excessive. If the rotors are serviceable, they're serviceable.

 

Cool. I have yet to check with my local Jag specialist too.

Same thing with the sensors?

 

No on the sensors. When the pads get too low, the sensor grinds against the rotor, cutting a groove in the plastic sensor head, that groove severs a wire inside the plastic. Once they "trip", the sensor needs to be replaced.


They are cheap, same as the Ford sensors. Should be somewhere around $20 US Dollars at any auto store.

 

That's an insanely high price too. If you have even a little mechanical knowledge it's a 60 minute job in your garage. The rear brakes on these cars are the easiest I've ever done. I swapped out rotors and pads on all 4 corners with aftermarket units for $500.

If the sensor is left too long and grinds against the rotor it can be damaged and need replaced (or you can ground it to itself and not use them at all if you are one who inspects your own brakes now and then) I can't see the sensor damaging the rotor at all.

 

The stock XF rotors will generally last for two sets of pads before they get near minimum thickness. And that's the stock Jag soft and dusty pads, with ceramic pads I would expect longer rotor life.
So you need to work out if the rotors will go below minimum thickness before the new pads wear out, and if so you should replace the rotors as well as the pads.
If not and you have enough meat still on the rotors, simply get them machined before you fit the new pads.
As Maddshadez says, replacing the pads and rotors on these cars is fairly straightforward and if you have an ounce of mechanical smarts it's an easy DIY job. There are only four "tricks or traps":
- You need a 9 mm hex driver to undo the front caliper bolts, and they can be hard to find
- Make sure the EPB is not engaged when you do the rears
- You need a tool to wind in the rear brake pistons, plenty of kits available in Fleabay or at a pinch you can get away with a pair of needle nosed pliers
- The pad wear sensor on the rear (passenger side in NA) can be a little tricky to remove and replace, it clips into a spring on the pad so you have to remove the pad and sensor (with cable) first before you remove the sensor.

 

Most auto parts stores will "rent" the rear brake compressor/screw tool.

You put it on your credit card, then return it for a full refund.

Save yourself $50-$100 on buying a tool you most likely will only use once.

 

So, your offbrand parts are $500. and the $ 900.d ealer charge is "insanely high"? I don't think so. If you actually did the 4 wheels in 60 minutes, your skills are wasted in whatever profession you are in if is not auto mechanics. I agree it is cheaper and straightforward to do it yourself, as I do, but to say $900. for 4 corners of rotors , pads, and sensors from the dealer is too high is just not realistic in todays market.

 

Except that the $900 was for rear only, versus $500 for all four corners.

And, I suspect that the dealer is specifying rotor replacement without
regard for whether it is justified. Shops like new rotors because it
avoids comebacks. Good for the shop, not so good for the customer.

 

Actually mine are name brand parts, and as previously mentioned, these are rears only. It took me about 2 hours to do all 4 for pads plus rotors, but I've also done a good 30 brake jobs in my time so i have practice. Still, rear brakes are quick and easy. Jack up car, remove wheel, remove 2 caliper screws, screw back piston using rented tool from auto zone (or buy from Harbor freight), then reverse procedure. If replacing rotors it's 2 more screws holding the caliper mounting bracket. It's not rocket science.

 

That's not quite how it works. The min thickness for the rotor is a go/no go specification for returning the piece to service. If the rotor is at or above the min thickness at pad replacement, it's acceptable for continued service.

There's no way for a mechanic to know how fast rotors will wear, how many miles are already on them or how many sets of pads they've seen.

 

Thanks, I didn't know that, I always assumed that once a rotor went below minimum thickness then legally it must be replaced, if for no other reason than insurance claim purposes.
The wear specs for the Jag rotors also seem pretty fierce, for example the 36 mm thick front rotors on my XFR have a specified minimum thickness of 34 mm. That's only 2 mm or 1 mm each side wear allowed, which seems almost nothing when you look at them. I bet they would still be perfectly good and safe at 32 mm thick.

 

Double post

 

Yeah, I missed that. Well, assuming they were only doing two, I agree it is high
As to the minimum thickness, I make that "bet" on my own rotors, but the dealer mechanic, nor anyone else, should make the bet on someone elses car.
__________________

 

The concept can be surprising at first as it's obvious that a rotor that re-enters service right at it's minimum acceptable thickness (say 34mm) will fall below that value at some point in the future.

It's important to understand that the 34mm point is not the minimum safe thickness of the rotor. That would be some lesser dimension as you've suggested, say 32mm or probably less.

If the above were not true, how could a mechanic who's never seen the car before possibly calculate whether there is still enough meat left on a rotor to last another set of pads. Not all rotors start life at the same thickness, not all brands wear at the same rate. Not all cars 'eat' rotors at the same rate and not all pads wear rotors at the same rate. No two drivers are the same. No two mechanics would use the same calculations or make the same decisions, etc. etc.

There is a situation where this system can work against the car owner. If the brakes are disassembled and the mechanic is holding the rotor in his hands and it's below min. thickness, he must replace it no matter the reason for disassembly or how new everything else is..

The go/no go decision on rotors has been around since the mid-70s and follows the same strategy that's always been used on machined parts that wear. All internal engine parts follow this system, new or used.

 

Wow, that is a much bigger reply then I was expecting, and a lot of great information. Thank you all.

- Yes, I have replaced/upgraded pads and rotors before, so nothing too complicated there.
- Good call on the caliper piston compressor.
- The car has about 18k miles on it, so I should be able to get another set of pads out of the current rear rotors. I'll measure the thickness (> 34mm). I think the value should also be stamped onto the edge of the rotor.
- Obviously, the dealership is going to charge a lot, and I'm not spending over $900 on rear brakes.
- This is my first car with brake pad sensors, so there is, understandably, a little confusion over how big of a role they play in rotor life, especially if the dealership is trying to goad me into buying new rotors.

 

Always go strictly by what's written on the rotor.


They play no role in rotor life. They trip the warning when the pads are simply getting thin, usually quite a bit before they're worn out.

I'll never understand the business model used by some Jag dealers in quoting 'worst possible case scenario' prices without looking at the car. Experience should tell them that a car with only 18K miles will most probably only need pads and a sensor. Possibly some but certainly not all customers would drop $900. without batting an eye. All the others go running for the hills, never to return.

 

Also know that the sensors come on quite early. Mine came on at 4mm, which is still a bit of meat to leave on the bone in my opinion.

 

Also, 36 mm down to 34 mm are the specs for the 380 mm diameter XFR front rotors.
The rear rotors on all XFs are a lot thinner than that, and the specs are:
All except 5.0 SC (326 mm diameter rotors): 20 mm down to 18 mm
5.0 SC (376 mm diameter rotors): 26 mm down to 24 mm.

 

I wonder why the rear pads are worn after 18,000 miles? Mine made 45,000.