I'm wondering what it consists of?

Is it a simple bolt on un respect to just calipers and rotors? Or is there more involved like a master cylinder etc?

 

You Need different wheels...I have the stock R1...bigger calipers and routers with stainless lines and Milan wheels...I also think the mount for the calipers is different too...

 

yeah you need different wheels to clear the bigger caliper, that's what has kept me back, I like the asteroids too much to get rid of them. Most of what I have seen has reported that the difference between normal XJR brakes and the brembo setup isn't very noticeable, but it would still be cool and technically better even if it is only a small difference.

Eurotoys company seems to sell the actual factory Jaguar brembo brake kit on their website
Jaguar XJ8/XJR Big Brake Kit (Grey Calipers)

you could probably get everything cheaper from a junkyard or other used parts source

 

Not really sure why anyone buys brembo for road use, you can get crossdrilled rotors and carbon fiber brakes from no-name companies online for less $ then OEM and they should perform in the ballpark of the brembo setup. I have driven cars with crappy brakes that need a power upgrade, but the Jag is definitely not one of them and there is no normal street-use that requires bigger calipers than stock XJ8.

If you are taking your Jag to the track (or street racing, lol), then that is a whole different story.

 

my car came with the Brembo's as standard, I junked them for Alcon 6pot/4pot monoblocs, the Brembo's aren't worth the effort to retrofit, the main reasons being only a slight performance upgrade from the Ate calipers, super expensive oem discs cost (do not recommend anything else as Brembo discs from Jaguar are the real deal, cryo treated)
The work to get them to fit a standard stub axle, warping if abused, ABS kicks in before you can enjoy the benefit, squeaking/screeching coming to a halt, added dust, etc etc plus the aforementioned wheel upgrade.

The drilled discs look nice though, but I could argue all day about plain over drilled rotors...

How about a pair of specially machined Ate calipers that accept the 32mm width brembo disc, along with EN42 adaptors and goodridge braided hoses? All you'd need then is some 355mm discs and you'd have similar performance, oh and I'd chuck in a near new set of DS2500 pads, I know the Porsche boys love them. This setup doesn't need the wheels too .

 

Some of you guys need some schooling ( Brake 101) on how brakes work and therefore why the R1 is better than the Ate and the Alcon better than the R1
ready for the lesson.............

1/ Floating VS fixed calipers

Floating calipers, such as the ATE have piston (s) only on 1 side of the caliper and in order for the opposite side pad (s) to clamp on the rotor, the piston side pad has to push against the rotor in order for the caliper to move on it's carrier.
Pro: CHEAP to manufacture, do not require high manufacturing tolearances, do not neeed to be centered perfectly on the rotor
Con: unequal side pads loading/pressure, mucho flex, very heavy( unsprung weight) and very ugly

Fixed calipers such as the R1 or Alcon have pistons on both sides and do not need a carrier.
Pro: Equal side pads loading/pressure, reduced flex, lighter,( less unsprung weight) pistons have different diameters to balance clamping torque from the leading to trailling edges of the pads
Con: more expensive

1 piece VS 2 pieces fixed calipers.
as the name implie, 1 piece caliper are made of 1 block of aluminum and 2 pieces calipers of 2 pieces bolted together
Obviously a 1 piece caliper ( such as the Alcon on my race car) will flex less but are way more expensive to manufacture

OK, now that you know better about the varied caliper designs and their pro and con, let's move to the rotors:

beside the various material ( iron, steel and carbon) there are 2 main designs, either a 1 piece rotor ( such as 99% of cars have or, a 2 pieces rotors, with a hat and the rotor itself bolted to it ( all bikes use this design as well than race cars)
2 pieces rotors can also be of the fixed or floating design.
There are 2 main advantages to 2 pieces rotor, they are lighter ( again less unsprung weight) because the hat is made of aluminum and a lot less heat is transfered to the hub

Rotor diameter:
It is the most important factor in braking performance and it's a case of where bigger is better.
Due to leverage, for the same braking force, a caliper will need a lot less torque/pressure on a larger diameter rotor than on a smaller 1
BTW, Sean, I disagree with you 100% on the purpoted benefit of cryogenic treatment ( I don't even believe that factory R1 rotors are treated), it's mostly marketing BS.
The most important factor in rotor longevity is proper bed-in with the correct heating and cooling of the metal in order to change it's property at the molecular level.

OK, now let's compare the ATE and R1 system:
ATE: Floating calipers, 13" front rotors and 12" rear and rubber line all around.
R1: Fixed 2 pieces aluminum calipers, 14" front 1 piece rotors and 13" rear 1 piece rotor with Teflon/stainless steel braided lines

Alcons ( such that on my race car, a 1991 tube frame Roush Mustang Trans-Am) remember the Jaguar XK Trans-Am from Paul Gentillossi??

Fixed 1 piece( monoblock) calipers, 15" and 14" floating 2 pieces rotors, water cooling and driver adjustable bias ( yes, I can even adjust the front and rear sway bar on-the-fly, from my driver seat)

I wonder why race cars do not use floating calipers??????????

Obviously for 99% of jaguar owners, the factory ATE is good enough but we also know that 99% of drivers ( not specifically Jaguar), don't know how to drive ( I should re phrase that and say that they only know how to use 20% or 30% of their car performance potential
Put some DOT race tires on a XJR and you will have to re-calibrate your notion of handling. Same with brakes

 

Great contribution luc. Now we want the pictures of the Mustang and the watercoed brakes.

Btw. My BMW bike has fixed rotors

 

Sean, would that Alcon setup fit inside the 18" Asteroids?

 

I think Luc has some reasonable points on the basic description of the differences but real world experience of all three systems on an XJR is sadly lacking.....

I have had the benefit of using all three on various XJR's and speak from experience, not comparing a race car with cabin adjustable bias, school, I did 4 years at Kingston University to gain an Automotive systems Engineering degree and have over 25 years experience building and restoring Jaguars in various states of tune.

Let me clarify what I mean by using o.e.m discs. They're made by the people who designed and installed the R1, they have the correct steel properties along with the pads to keep within specification - using aftermarket brands might be alright for a sprint race but over 40,000 miles this means using the correct parts. Cryo treatment isn't marketing bull, in fact I use this to treat some steel items to get the correct level of transformation of austenite to martensite, i.e. the mounting brackets for the brake calipers, it releaves stress. If you do this to a brake disc the benefits are obvious. Brembo do it to match all discs in their properties and cryo treatment allows them to do this time after time, no variation from disc to disc, as against untreated. This is why you buy them in pairs, this is why they're expensive.

@ Adam - I can supply either the custom Ate fronts, or a full set of R1 Brembos or a full set of Alcon, or a full set of AP Racing, you take your choice and pays your money.

@Luc - read up on cryo treatment and get back to me. (consider the little wear resistance graph for homework)

@JKo - no, they need 19" minimum. If using 385 to 415mm disc, 20" minimum.

by the way, I've an XJR sat here that brakes from 120mph to 0 in 5 seconds, not bad for a 1.8 ton car.....developed over a period of 2 years. Why don't we start a proper brake thread?

 

I think that it would be good to define what is a good braking system:

Obviously the most important is brake fade or the capacity of the system to deal with very hard and prolonged braking, such as on a race track or downhill on a montain road
After that "feel" would be #2 and #3 would be weight ( once again unsprung weight is bad for handling)
Assuming the correct pad is used, by correct i mean the pads that are designed to work in the temperature range that the braking system will experiment, brake fade is the result of overheating the brake fluid.
Therefore, different strategies are used, cooling duct, water cooling, 2 pieces rotors, fluid recirculating valve,etc

"feel" come very high in the list, it is the combination of master cylinder design/bore size, rotor diameter, brake lines, caliper design and temperature management and it's what the stock ATE system sorely lack, too soft and not enough feedback

Sean: I didn't say that cryogenic treatment do nothing, simply that the cost/benefit ratio is not good. In the US most racers use custom made Coleman rotors that are anywhere from 50% to 80% cheaper than most manufacturer rotors and offer 90% of the quality/longevity.
For example, the Alcon rotors on my race car are $500 each and the coleman $170.
sure, the Alcon will last a bit longer but not that much
Same thing on my R1, I use the british made Eurospare rotors and after proper bed-in they work as good that the brembo. Will they last 25K miles compared to the brembo 30K miles? I don't know but i can get almost 3 eurospare for the price of 1 brembo
I like your idea of a specific brake thread

 

I guess Jaguar was stupid for putting Brembos on cars for street use. Same with many other manufacturers that use Brembos on their street cars.

But I may be biased since I have a set for sale:

https://www.jaguarforums.com/forum/p...xkr-xk8-54781/


Here's what I wrote a while ago concerning the swap:

'Otherwise, the brembos fit right on with minor modifications. You will have to tap threads in the front spindles/knuckles where the holes are for the caliper to bolt on. I believe the size is 14mm by 1.5 pitch. Or you can buy spindles from an XJR/ XKR with brembos. You will also need to get the correct caliper bolts. The brake dust shields will need to be trimmed to fit the bigger rotors, or buy the proper ones. I don't know if you can use the stock brake hoses; if not you'll need the stainless brake lines from Goodridge.
If you have the stock wheels, you will need 20 mm spacers to clear the bigger calipers, at least for the front. Or get wheels that clear the brakes.'

 

Wow, guys. Tons of good info from everyone. I think there really should be a dedicated brake thread for the XJR.

I'm not ready to start swapping parts just yet, but I was just wondering if I can ****** the parts somewhere for a decent price if I should go for it.

 

@Luc
Eurospare is just a marketing name under which it is sold, the rotors seem to come from an Italian company, although not brembo…

@Sean B
If the original brembo rotors are already cryogenically treated (is that a fact?). Then it can explain why I didn't notice any difference in a set that I treated and an untreated one (assuming cryogenic treatments does make a noticeable difference).

Am now going with stoptech/centric rotors instead of the brembos, as the original brembos are just too expensive.

Personally I found the brembo set a very good improvement over stock ones (street driving/autobahn).

 

you guys might want to look at www rockauto com for rotors. I believe they ship overseas, and the have the best prices hands down on centric/wagner/bendix rotors.

They don't list brembo discs for some cars, but if you search by the part# (I think 25485 is the correct part# for XJ8 & XJR fronts )they come up for $66 each.

 

once you can lock up all four corners, you cannot use any more braking power.

The brakes might be prettier, and carry more bragging power, but will not stop the car any quicker.

 

http://www.drivingfast.net/car-control/braking.htm

 

The specifications may indicate a big difference -- but the the R1's don't give you much over the stock R's very good brakes. If we are talking about a standard x308 -- I would look into adding stock XJR brakes to it.

The need for different wheels, rotors and pads - all with limited availability and higher cost stopped me from ordering mine with the R1 back in 02.

I know we have had a least one post about aftermarket rotor problems on the R1's -- I not sure I see the point in the upgrade and then go cheap on the rotors/pads .... although I see that Centric is now touting that they are now using a model specific OE comparable compound setup ..... funny they said that before.

The standard brakes on the XJR are very good and you can have many miles of trouble free use for and extra couple of hundred dollars every 35k for the fronts.

 

No over-braking here, that's what the ABS is for...

 

These so called prettier brakes (Alcon, Brembo, Wilwood etc.) are easier to modulate while braking, which is crucial when threshold or trail braking, and with larger discs they are able to slow down the wheels (and lock if necessary) faster from high speeds. There is no question whether they are better at stopping your car. Cost is probably the only reason for not having these in a road car.

 

That’s odd, the difference in my car was very noticeable, maybe because it is heavier or there was something not right with my original ones.

If you assume that the cost for the Jaguar Brembo is directly related to the quality, then I can understand your comments, but I can buy original Brembo rotors 360mm for a RRS for about 170 euros, and Jaguars 355mm Brembos are about 600 euros, and I doubt the difference in price is only quality, stopping a beast like the RRS is something else again…

So far no one has yet explained why these things are so much more expensive, but am curious of course to know, also if you have facts that the centric ones are to avoid, please share, I am not aware of any issues with these.

I only bought them as there was no alternative (except for non-brand rotors), and didn’t though they would be bad.