I just found out that the cross drilled rotors (optional on the Car - mine is a 2003) are supposedly a different diameter than the standard brembo rotors. For some reason the pads don't fit quite the same I'm told, but to me this session odd as the caliper should be the same for either type of rotor.

Has anyone else run into this and were you able to use an aftermarket rotor that was slightly smaller in diameter?

Would the handling package option have anything to do with the different rotor diameter on my car? This is the only thing I can think of as to why mine would be a differ diameter than every other cross drilled part available.

 

All the brembo rotors should be 355mm (14")

Non Brembo rotors are 325mm (13")

how much is slightly?

 

The difference in the rotor is big enough to where the pads will overhang on a regular replacement sized rotor. I did not measure it but its a few millimeters all the way around.

I read in another thread that XKRs equipped with the handling package had slightly larger diameter rotors. As a result, that same Brembo caliper must also be placed in a slightly different location if a noticeable overhang occurs when trying to use a smaller sized rotor. Still looking for more info, but I think I've found the general answer - there is a difference.

As it happens, there are not many options for larger sized rotors other than the stock Brembos, unfortunately.

 

According to the partsgeek catalog, they sell a Centric branded replacement for the Brembo where the front is 325mm.

They also list a separate part for the 2003 model year which is 355mm (I didn't see this part listed when I ordered last time or I would have bought it)

Both parts listed here.

Are you saying ALL brembos should be 355mm? I have not measured the ones that came with my car yet.

 

My understanding is this:

The early cars all had the 305mm front rotors with single piston calipers.

When the XKR came about (1999?), XK8 and "base" XKRs all came with upgraded single piston calipers and 325mm rotors.

Separately, XKRs could later be upgraded with the Brembo 4-piston calipers. There are 2 versions I know of. The "early" Silverstone calipers came with a threaded steel bracket, and the later calipers came with built-in non-threaded ears (no bracket). Some of the later calipers could be painted in red, but normally came in silver, with Jaguar R lettering. The rotor size for this kit is 355mm. I have not read anything regarding different size rotors for the 4-piston kit. Now, some cars came with smooth rotors, and others could be ordered with cross-drilled rotors.

FWIW, in my research, I have found that, besides dealer parts, a couple of after market brands come up for cross-drilled rotors: the Centric brand makes a single-part-number cross-drilled rotor. The other brand is BrakePerformance, which, on the face of it, offers symmetric rotors (2 part numbers), just like the Jaguar kit.

At this point, it would be useful to post some specifics (part#, brand) of what you are trying to fit. Are you also replacing the pads?

Best of luck, keep us posted.

 

All Brembos are 355mm (14")


The 325mm (13") are the single piston calipers with the 1/2" taller caliper brackets. (same calipers as 305mm (12") Brakes).

 

OK, it sounds like an X100 XKR ≠Brembo brakes as standard in the early models. Never seen one without them, but I do not know the early versions well.

In addition, the Brembos at some point were offered with an option for red painted calipers as well as an option for cross drilled rotors ($500 option, according to my research). I have the silver calipers with what is a larger rotor than the $96.33 ones I ordered here: (scroll down and you will see two variants) jaguar xkr rotor | Partsgeek.com

Further down, you can see the 355mm variants for $122.33 - those did not show up in my original search. There are rear rotors also offered in that search.

In either case, is not a single part number as there are left and right variants. The only reason aside from cost that I was interested in these was because they were slotted versus cross drilled. Slotted actually offers an advantage whereas cross drilled is widely thought to be mostly for looks nowadays. I've seen slotted rotors on race cars, but lately no cross drilled rotors.

What brakes on an XKR would use the 325mm rotors if they were not Brembos? Curious what the outward appearance would resemble - bone stock, Brembo, or something else?

I did not know about the difference in the threaded versus non-threaded brackets, thanks.

I am not replacing the pads at this time as the car will go into storage immediately after this is done. I can get a variety of pads when track season rolls around again in the spring - they do not vary in size like the rotors, thank heaven.

Anyway, I can return the rear rotors as I just got them, but I still have two front 325mm slotted Centric rotors that I can't return (been too long). Listed them in the for sale section. Message me if anyone is interested.

 

You got it, you need to shop for items that list "330mm Rear; 355mm Front Disk"

FWIW, brakeperformance.com has other options, too.

All of them, really. In 1999, the brakes were upgraded to 325mm across the board (XK8s and base XKRs). They look like normal single piston caliper setups on most cars, i.e. completely different from the 4-piston setup. There is a big wire clip, and most of the caliper is behind the rotor, sort of hidden. More wheels fit this setup, and it is cheaper, too.

It seem to only matter when someone (ahem!) is upgrading from the standard to the Brembo setup. Neither the new calipers nor the uprights are threaded, so the uprights need to be tapped to fit the bolts. With the old caliper, the bracket is already tapped, so it is a direct bolt on.

Well, the pads obviously have to fit the Brembo caliper, with the locking pins setup. The earlier single piston calipers take a different pad with an "ears" setup.