Hello all. I have what seems to be a slightly rare 03 XJR R1. Did not know when I bought it that the 7 spoke asteroid wheels meant "plain" brakes and the 5 spoke BBS wheels meant R1 which has the Brembo brakes. I need to replace my rotors again as they are pulsing / juddering (warped?) - whatever you want to call it. I have had trouble with the last two sets of rotors I purchased not lasting too long before they do this. I am looking at Centric rotors and semi metallic pads (can't find ceramics for the front but did for the rear). Lots of parts sites don't specifically state that the rotors are for Brembo calipers. Often they will say "Fr Ch# F39526" which seems to mean the R1 car - Brembos. The size is 355mm.

Does anyone have experience with different brands of rotors specifically for the R1? I am in Canada (but the car is American) so can't get all parts sites to ship to me. Any advice / help would be appreciated. I have searched the forums but it seems everyone is talking about non brembo.

 

Fr Ch#F39526 is for all units built after VIN number ending in F39525. My Vin or chassis number is F35063.

I had Brembos on my 08 RRS/SC: Advance Auto Parts had rotors and ceramic pads. Try their web site.

 

Hello Tibow, we sell Brembo discs at a fraction of the cost of the Jaguar boxed item. See link below, you are also eligible for 10% off this being a forum member..


www.sngbarratt.com/ProductDetails.aspx?id=f52f95f1-1c3e-47ff-a7b1-3ff1dcc352fe


please let me know if you need any further info.

 

I use Eurospare on mine. i believe that it's what Sngbarrat are selling.
good rotors and no issues.
That say the juddering/pulsing is a very common issue on the R1 brakes and correct breaking in of pads and rotors is VERY important on this system.
Before buying new rotors try to do the following:

From a speed of 80 mph do about 5 very hard braking but release brakes just before the car stop.
So basically you go from 80 to almost 0, five time in a row.
The ides is to put a lot of heat on the rotors/pads and clean any material transfer.

 

One of the main culprits with the Brembo kits are misaligned discs with hub interface, these have to be bang on, any misalignment is felt through the brake peddle as 'pulsing' naturally assumed as 'warped' discs. Extra care is needed when fitting them. I've used stack washer shims on the hub nuts and spun the disc before fitting wheels in the past to check runout.

Both internal and external faces need to be minty clean and flat. Then you can carry out the disc pad burn in process that the manufacturer suggests.

Actual warping is introduced when hauling 1.8 tons down from 3 digits and holding the pads on the discs on a dead stop, this creates a hotspot on the disc face, enough to kick it out of wack - skimming rarely cures the problem.

 

I used to use Hawk HPS Street brake pads that I purchased from Tirerack and drilled rotors from Coventry West. I would take 50 to 75 miles of gentle seating in and properly torqued lug nuts and had no shimmy or pulsation. The brake pedal pressure was a little harder, but the brake dust was less and the stopping was good.

 

I have Centrics on my R1, and they have needed skimming about every 6 months. It had OEM Brembos on it when I bought it, and they were bad too.

Sean is most likely correct about the root cause - big disc on small hub magnifies any mounting asymmetry, giving runout. Which results in the pads getting knocked back by the high spot on the disc, Which wears that point on the disk a bit thinner. Which causes uneven braking force. Fixed caliper brakes like the R1 type are worse, because when one pad is knocked back, hydraulic pressure pushes the other one forward, which then gets knocked back 180 degrees later and the cycle repeats.

If the root cause is runout (mine is) , you'll get 2 brake pulses per wheel rotation: easy enough to check by braking lightly while going slowly and measure the distance between pulses. Genuine heat-caused warpage has always seemed unlikely to me on these - they're massively over braked for normal road use, you're unlikely to get them hot enough to warp without a convenient autobahn or alpine pass.

I've been through the recommended Jag procedure to get the runout to a minimum and it didn't seem to help. Next time it needs skimming I'll probably try finding a way to measure the runout with the wheel in place and see if mounting the wheel in different orientations helps - possibly the stiffness of the wheel itself is distorting things when it's clamped up.

I'malso thinking about going to a 2 piece rotor next time in the hope a more flexible bell will make it less prone to this problem. DBA make one that fits the R1. Also I'll go hunting for a less abrasive pad. Premium manufacturers like Jag prefer abrasive pads because they reduce squeal problems. But they make disc thickness variation problems worse because they wear the disc more when the mechanism described above happens.

Or you could just live with it - Centrics are cheap, and they work fine apart from the judder.

Dave