Hello everyone,
does anyone here have experience putting the XKRS 380mm brakes onto the 2006-09 XKR to replace the stock 355mm/326mm?

Thinking about this I have the following questions:

• How does the ABS controller react after the swap?
• Do you run into problems cause of different ABS rings between XKR and XKRS?
• Is a change of hubs mandatory?
• Is the XKR power brake booster strong enough for the upgrade?

My reason for considering the upgrade: Autobahn, Autobahn, Autobahn and alpine roads. After bringing the car down from 270 to 100~130 a couple of times you instantly feel a fade while the temperature of the brakes went up pretty much. For fast driving even the XKR might need more brake diameter to dispense heat.

I appreciate any help or hints

 

Instead of experimenting with XKR-S Brakes, why don't you ask Arden in Krefeld, Germany. They sell a performance braking-system for XKR's.
Their system is TÜV approved, I doubt you will get a positive signal from TÜV for the Jaguar system from a XKR-S

 

Talked about that already with guys from the TÜV and Dekra here in bavaria. They see no problem at all with putting the XKRS brakes into the XKR. They said its not an issue while the parts were sold on the same chassis even when it was a different model.

 

I'm interested in this as well. Looking at the photos, apart from being red I'd say those calipers may well be the same as the 4.2 XKR items. If they are then maybe the only change needed would be to get the different caliper-to-hub brackets and the larger discs. As far as I'm aware, that's the only difference between 5.0 cars with 355mm discs and ones with the 380mm discs.

Anyone able to shed any light on this?

 

The non-Alcon systems on both the 4.2 and 5.0 cars are different, but they're both made by Continental Teves. So they may have similar mountings - sorry, don't have any definitive answer.

 

I know I don't have an XK but I've just retrofitted the Alcon brake system to my X358 from the X150 Portfolio. It's a fairly involved conversion on the rear, necessitating a change of hub, hub carrier, handbrake cables etc.. The fronts however do just bolt on if you purchase the brackets for the calipers. Just another option to consider if you're looking for ultimate performance the 400mm 6 piston & 350mm 4 piston Alcons would probably be the best option - Carbotech offer everything from street pads to full on race only pads to fit the calipers. EBC also offer the Yellowstuff pad which I've previously been impressed by.

If you're interested in fitting the 380mm & 376mm 5.0L Teves brake system ( Fitted to XKR, XKR-S, XJ Supersport, XFR & XFR-S) They should just bolt onto the existing hub carriers, they may require new brake lines - the Alcons certainly did - The calipers are different from the 4.2L R brake system, they had a single piston on the front whereas the 5.0L caliper has 2 smaller pistons in the front caliper. The rear caliper is of the same design as the 326mm one fitted to the 4.2L models, but the bracket is much larger as is the action for the handbrake cable.

I did look into this conversion and if I was going about it again I would most probably go down that route due to the work involved with the Alcon retrofit, the obvious advantage to the 5.0L brake system is that the rear caliper retains the handbrake functionality.

To answer your original questions, the ABS is unaffected as the reluctor rings are mounted to the inside of the hub which can be retained. The disc shields will also need to be changed but they are only riveted to the hub carrier. I've not noticed any issues with the brake booster on mine - The brakes just bite and bite...

May I ask if you're still running the OEM pads and brake fluid? Perhaps before replacing the calipers try Yellowstuff pads and a brake fluid change with Castrol SRF, I'm running SRF in mine with the Alcons.

Hope this helps - If there's anything else just shout, I have an excel sheet of all the parts you'll need to retrofit the Alcons should you wish to explore that route.

 

Hi SimonXJ,
You mention Castrol SRF and EBC Yellow pads. AM not familiar with the SRF's use in our XK-Rs. Is it compatible with all of the components?
I am familiar with EBS, as I run them on my high performance street warrior. They did make a difference in the braking performance of my old technology disc drum combo. I'm looking into EBC's for my daily driver Venza.
Thanks for mentioning...and Happy Motoring

 

Thanks guys, appreciate it.

Simon, I'd love to do the Alcon upgrade but it's very expensive. I was really just looking to see if I could just swap the caliper brackets for the ones to suit the 380mm disc. I've just had a look at the workshop manual for the 4.2 X150 and I realised that the bracket that the caliper attaches to is also the one that attaches to the hub. I guess if the front vertical links are the same then the bracket will fit to that, but whether the caliper will fit into the bracket is another matter entirely. I guess I could upgrade the calipers too but that pushes the cost up considerably.

I am still on OEM pads and discs at the front, with Pagid discs and EBC Redstuff pads on the rear. Fluid is OEM, not sure what the dealer used last time. I was thinking of switching to Black Diamond discs and EBC Redstuff all round and got to wondering about switching to 380mm discs at the front while I was at it.

Just wish I could get a good look at a bracket for a 4.2 XKR and one for a 380mm-equipped 5.0 XKR side-by-side.

 

Hi guys, the Castrol SRF is comparable with all DOT 3 & 4 fluids. I got mine from;
Opie Oils - car oil and motorbike oil sales and recommendations

I had a poor experience with the redstuff pads but that was a couple of years ago now and others have had positive experiences with them recently with the ATE brake system and the compound has been revised a number of times since so they may now be excellent. I will be replacing the OEM Ferodo Alcon pads with Yellowstuff when they wear out, the OEM pads are so much dustier than the standard 355mm set up.

But to answer your question about fitting the 4.2L calipers in the 5.0L carrier to fit the bigger disc, I have some bad news,



4.2L Front





5.0L Front





Alcon Front

I've attached the above pictures which look to put that idea to bed, due to the wider pad mounting lugs - which are located in the carrier for both the 4.2 & 5.0L cars.
But I think it should be possible on the rear. Possibly best trying an up-rated brake fluid and some up-rated pads, to begin with. When I fitted Yellowstuff pads to my Mondeo ( which uses the same brakes as the X-type ) I was really impressed by the difference the pads and better brake fluid made, with the caveat being I did not know how old the fluid was already in the system.


This isn't the most scientific comparison below but it illustrates the differences between the 4.2L & 5.0L calipers. The red one is off a 5.0L car.





5.0L Caliper





4.2L Caliper

Hope this helps.

 

Thanks for that Simon, I never thought to check pads. I guess then to upgrade to 380mm fronts it would be necessary to change the calipers as well as the carriers, plus stone-guards and discs (and maybe other stuff besides).

 

Certainly looks that way - but I'd say it's a choice between upgrading the calipers, carriers, discs, pads and lines and upgrading only the pads, discs and fluid. When I last looked the Yellowstuff pads were about £100.00 per axle, with discs varying in price from approx. £80.00 to £200.00 per axle. Compared with £1200.00 ish to fit the 5.0L brake system it may offer similar performance. Of course if you can find a bargain set of Alcons or the 5.0L brakes that makes the conversion that much more attractive.

 

Thanks again, Simon.

I'm sure I would benefit from some better fluid and front pads and discs, I was just thinking that the difference in brake diameter between 355mm and 380mm was quite large, so if it'd been fairly simple/inexpensive to do then that would have been a good bang-for-buck upgrade. Maybe I'll see if I can get a test drive in a car with the 380mm brakes first and decide whether to pursue this further from there.

 

Also, consider the challenge of brake pads. I have a XKR175 with the 380mm brake pads(I have been told--if someone can confirm), and there is NOTHING available in aftermarket ceramic pads from all my searches so you are left with one choice... the extremely dusty stock pads. If anyone has news to the contrary for me(which I would be thrilled to find out), this would once again show how very useful we are in our Jag community.

 

FYI: Premium Cross Drilled & Slotted Brake Kit
I use their rotors and pads. Even on the track. Much, much better than OEM.

 

Greek175 - If you're looking for low dust EBC make the Redstuff pads for both the 355mm & 380mm brake systems. I've attached a link below for the front pads for the 5.0L supercharged cars. I prefer the Yellowstuff but they are about the same dust level as the OEM pads. ( Which are also made for both braking systems )

A number of the guys on the UK forum have been impressed with the Redstuff pads on the 355mm brake systems especially the lower dust levels.

 

I thank you for the info. Unfortunately, I keep getting conflicting reports on what size my XKR175 has? I was hoping someone could definitely tell me what I have. I have not through my resources been able to figure it out. I have used Red stuff on past vehicles and they work as advertised. Low dust and good braking. Really hoping someone can let me know,


Thanks guys,
Greek

 

All 5.0 XKRs (including R-S) have Continental ATE 'high performance brakes', which are 380mm front (floating 2-pot calliper), 376mm rear (floating 1-pot calliper). The R-S GT is the only exception; it has a Brembo ceramic disc system.

 

Ngarara,
Thank you very much for the clarification. So my 2011 XKR175 has the same brakes as the standard 2011 XKR? If that is the case, I am a happy guy as your info always seems spot on. I will be happy to put on the EBC red stuff pads. One other smaller issue I deal with and also on my previous 07XK was when turning at slow speed(like to park) you would hear what sounds like the front suspension springs binding but have been told by Jag it is in fact the brakes? Service manager stated that a grease or something needs to be put I think he said on the back of the pads. Lived with it on the other but now that I am going to change pads, would like some input as to what I need to do. I am sure others have the same issue.
On a separate note, I have attached pictures of the new caliper covers front and rear. Notice I also changed our the rear bolts to polished stainless and it looks Worlds better. I took the new covers and clear coated them with high temp clear and then wet sanded and buffed. Anything short of battery acid will not affect them and they clean up easily.

 

Yes, the 175 is basically a Speed Pack upgrade, i.e. bodykit, & limiter increased to 174 mph. It has no performance/handling upgrades. You guys were short-changed; we got the 75, which does have the go-faster stuff (more HP, lower/stiffer suspension, revised steering). But even the 75 and the R-S have the same system as the other 5.0 XKRs, which means they're pretty decent brakes.

Nice work on the callipers!

 

does anyone know which models came with the 355mm vs 380mm