XJ XJ8 / XJR ( X308 ) 1997 - 2003

R1 brembo brakes conversion on an early car

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Old 06-07-2024, 02:07 PM
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Default R1 brembo brakes conversion on an early car

I managed to snag an R1 package car for parts this past week. The car has the R1 brembo brakes with larger rotors and the Milan wheels. I want to swap these onto my 1999 XJR.

From what I've been able to find on the forums the brakes themselves and the dust shields etc. should swap over, but I have seen nothing regarding the rest of the system including the master cylinder.

I know the master cylinder and pedal configuration were updated in 2000. Will I need to swap over all of these components to run the brakes? Has anyone swapped just the brakes onto an early 98 or 99 XJR? How did they work?
 
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Old 06-07-2024, 04:44 PM
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Here is a thread for your reviewing pleasure, the master cylinder is just a hydraulic device to create pressure, so your concerns there are moot.
If yours is original, you may want to consider replacing it, but that is up to you. I'd definitely bleed new fluid throughout.

https://www.jaguarforums.com/forum/x...wanted-128967/
 
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Old 06-08-2024, 10:37 AM
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Originally Posted by Highhorse
Here is a thread for your reviewing pleasure, the master cylinder is just a hydraulic device to create pressure, so your concerns there are moot.
If yours is original, you may want to consider replacing it, but that is up to you. I'd definitely bleed new fluid throughout.

https://www.jaguarforums.com/forum/x...wanted-128967/
Thank you for that link, there is some good information there regarding the shields etc. However the brakes were swapped onto an 01 which means the master cylinders were the same updated units from the facelift that occurred in 2000. I am wondering if anyone has swapped the brakes onto an earlier car which had the older master cylinder design.

The master cylinder is a critical part of the system and is not moot in this case at all.

The design of the brake pedal arm and it's leverage over the master cylinder, the diameter of the master cylinder piston, and the diameters of the pistons at the caliper define the pedal travel as a system. A larger diameter master cylinder will displace more fluid for the same pedal travel assuming all else is equal.

It is very common to have a situation where larger brakes are swapped onto a car only for the pedal travel to increase significantly, sometimes so much so that ABS cannot even be engaged before the pedal hits the floor. This happens when the existing master cylinder can no longer displace enough fluid to properly engage the new piston(s) at the calipers. I am more familiar with BMWs and on those platforms the M3s always had significantly larger master cylinders to go with the larger brakes.

In this case the literature specifically says the master cylinder diameters were increased in 2000, but the leverage from the arm was reduced. These two changes act opposite to each other and were specifically called out as an attempt only to increase the pedal feel. It's possible that the earlier configuration will still work, I'm just looking for confirmation.
 
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Old 06-08-2024, 01:51 PM
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I have a 99 and I did the caliper swap without touching the master cylinder (well apart from a flush), and it was fine. Good enough that I don't want to mess with swapping the newer battery cylinder in.

Don't forget your m14 tap, and a jig to hold the tap square while cutting threads. And definitely get a drill bit that is the right size for the tap, to enlarge the holes slightly... some say you don't need to buy the amount of resistance I encountered without doing so was concerning.
 
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Old 06-08-2024, 02:53 PM
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I always wonder when reading these postings,,,,if the end
justified the means,
 
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Old 06-09-2024, 04:11 AM
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Wouldn't the 01' master cylinder delete the 99' cruise control? I think that was the difference in 26/27 systems not volume or stroke. Just fit the calipers, discs, braided hoses and shields, there isn't that much of a gain in braking performance before ABS interferes anyway.
 
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Old 06-09-2024, 03:58 PM
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Originally Posted by MWC
I managed to snag an R1 package car for parts this past week. The car has the R1 brembo brakes with larger rotors and the Milan wheels. I want to swap these onto my 1999 XJR.

From what I've been able to find on the forums the brakes themselves and the dust shields etc. should swap over, but I have seen nothing regarding the rest of the system including the master cylinder.

I know the master cylinder and pedal configuration were updated in 2000. Will I need to swap over all of these components to run the brakes? Has anyone swapped just the brakes onto an early 98 or 99 XJR? How did they work?
Added Brembo's to my 98 XJR, you don't need to make any changes to the master cylinder. Pedal feel wise, its about the same or the same as my 2003 R1. I did not bother with swapping hubs/dust shields; trimmed the rear dust shields, removed the front shields, and tapped the hubs (think its 14mm.x 1.5pitchx 55mm bolt (might be wrong). My earlyish 98 had 305 mm rotors that I would warp (driving a bit to fast), so the brembos were a nice upgrade. I installed solid disks from 2000-2006 brembo XKR's, were cheaper then the cross drilled rotors at the time. Be warned, the Brembo's do squeal at low speed; used EBC redstuff, Textar, and Mintex pads.


 
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Old 06-09-2024, 05:15 PM
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Yes...everything comes at a price. (sigh)
Glad that you are happy with it.
 
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Old 06-12-2024, 01:12 PM
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Sweet! Thanks for the confirmations everyone. Much appreciated.
 
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