I looking online and only the stats for the small brakes were listed. It was something like 165 ft 70-0. I am wondering how much better the Brembo brakes are. I have the R1 with the large brakes.

 

It's tire traction that's the limiting factor, not braking force.

 

I thought I've read that the performance of the "regular" brakes is comparable to the Brembo big brakes and as such don't really offer any performance advantage.

Perhaps the Brembos were less prone to fade over heavy use due to their increased size/mass?

.

 

The Brembos actually work better at higher speeds. The normal 305 mm brakes go rather spongey of you decellerate hard from a higher speed (greater than any other speed limit in any other country on this planet, apart from Germany). When I brake from 200 kph (125 mph) the brakes tend to fade... The initial bite is great, but it gets worse the longer you apply them. The Brembos work equal all the way to a stop.

In every day driving the brakes are more than sufficient.

 

Agreed. From what I've heard (I haven't actually fitted my Brembos yet) they're more about better heat dispersion and fade resistance than an actual increase in braking performance.

Obviously there will be a slight increase in actual braking performance, with the larger pad area, larger diameter disks, and more even spread of braking force from having multiple pistons, but the main limiting factor in your stopping distance in a car this weight will be the grip level of your tyres.

 

You can get the ABS to kick in faster with the Brembo system, a more consistent pedal and shorter stopping distance but I've not seen a side by side with the ATE system..I don't think Jaguar would have fitted them if it didn't offer more braking performance. Having said that I wasn't that impressed with the Brembo, combined with ABS there's not that much benefit.

The braking performance leading up to ABS activation is what I needed, so fitted a better system (Alcon) which is happily far better in all respects. Not everyone will want/need a brake upgrade and the standard system is fine for almost all driving. I will say braided hoses are a good addition if better pedal feel is the goal.

 

With cold brakes I doubt the difference between them is significant in a single 80 MPH to zero stop. A key indicator of this is the behavior of the ABS. Both types are capable of triggering the ABS with good tires on dry pavement - the ABS indicates the traction limit of the tires has been reached - moar brake here won't improve things. The difference is the heat dissipation in the Brembos will allow them to be more consistent in hard brake application after hard brake application such as on a race track.

I recall when car shopping that the Brembo cars had a better feeling brake pedal and I didn't have any issues with brake heat running my XJR Milan (R1) on a race track here in Texas in the middle of the summer using OEM quality Mintex pads. The standard brakes would likely be okay on the track with track pads. The stock brakes on the X308 are sized correctly, the Brembos are just a bit better, have better pedal feel, and have better looks. A penalty of these is poorer wheel selection w/o having to resort to adapters.

-Mike

 

In my experience that is demonstrably false and the probability of a catastrophic failure of a braided brake line is many times higher than for rubber. I had the left rear factory braided line fail on my 2003 XJR Milan with the Brembos. No warning. I was doing a max braking demonstration at a car control school when it popped. It felt like I popped a zit with the brake pedal. I've never seen a rubber line fail and I've been driving a long time.

I replaced the factory ss lines on the XJR with factory rubber lines and it feels exactly the same.

'99 BMW M3 replaced an after market set of SS lines with rubber and it feels exactly the same.

'97 BMW M3 race car, replaced the rear after market set of SS lines with rubber and it feels exactly the same. The front Stoptechs were not compatible with rubber lines so they stayed SS.

Faulty rubber lines can cause a soft pedal, but new rubber lines are cheap, will last for a long time, will fail gracefully and will provide the same pedal firmness as SS lines.

-Mike

 

A few days ago I drive from Bistrita to Vatra Dornei 82km in the mountain about 42km with heavy braking from 140 km to 20 km, I have 325mm in front 305 in the rear, very good brake, no failing. ATE pads in front Brembo pads on rear, new brake fluid.
I am interested to to compare two cars with the same tyres and different brake system but this will be impossible because in my town are only two XJR and the other one have the same brakes no brembo.

 

My experience from the earlier post is based on 2 XJR's back to back and both on Michelin PS2 tires (one ATE 18" other Brembo 19"). I didn't care to measure stopping distance, but roughly by side makers and the Brembo was shorter from 100mph to stop. Both dry and ABS activated. What I didn't like was the ABS potential to put you through a wall. Reapplying the brake isn't what you want to do at high speed, but for performance sake that's how it felt. My system now stands the car on it's nose without the ABS light flashing most of the time, I can concentrate on stopping without panic.

And for the braided hoses are not better than rubber comment, why do all racing cars and bike uses braided hoses instead of rubber? And why did Jaguar fit BFG hoses to the Brembo/Alcon cars? I only use BFGoodridge, not HongBangHudini. Rubber expands under pressure = soft pedal, braided don't = firm. pedal.

 

The braided hose that failed on me was a factory Goodridge. Part of the reason for braided hoses on race cars is debris protection. They also change those hoses often.

Jaguar fit braided hoses because marketing. New rubber hoses do not expand under pressure. An old hose will and long before it truly lets go. A braided hose won't expand, it is just fine one second and not the next. Braided hoses on street cars is because vanity.

On track cars, the general recommendation is to swap braided hoses every 2 years. For as nice as the Jag Brembos are, they pale compared with the binders on Porsche GT3s. GT3 brakes are very powerful and controllable with excellent feel and come with, wait for it, ... rubber hoses.

-Mike