The V8 Owners Forum -

I know many folks swap over to the XJS calipers, but those things look really, really heavy!
I’ve just pulled a set of 4 pot Calipers and discs off a ‘97 LS400 for £27 and am looking for a comparison to stock vitesse and jag stuff as regards piston area and unspung weight increase (of jag and Lexus stuff) over stock.
The Lexus discs are about 12.4” dia And as you might expect for the size, are very heavy around 22lb / 10kg each. The calipers though, are only 7lb / 3.1lg each (with Pads, pins, etc) and are very, very sturdy looking, yet quite compact (minimal overhang radially from the disc outer diameter) for what is quite a large caliper. Pistons are 42.8mm diameter.

And as a final reference, the Lexus is close to 3800lb, which is 25% heavier than the typical SD1

The Jag cast iron 4 pot calipers are around 7kg each. They have 48mm pistons and maximum brake disc thickness of 24mm.

Do the Lexus discs have the correct PCD, Centre bore and height/offset for your application?

I really appreciate the input, wow, 48mm, its no wonder folks find these impressive, despite the not overly significant increase in disc diameter; that's a 17% increase in pad clamp force for the same pedal effort!

I've decided the Lexus calipers, while fantastically cheap, simply don't fit very well with the mounting bosses in the shape they are in; they interfere in every way with the bosses on the SD1 hub.

I'm now going with Wilwood superlights, and using the 325mm dia x 28mm disc from the 2002-ish XK8, or the 320mm dia x 28mm from the charger/challenger/magnum as these have 5mm more inset than the jag disc, allowing more room for the caliper to squeeze into the larger part of the rim. These discs will both need the ID opening up to suit the rover hub, and either slim nuts or (as I'll likely do) simply machine the existing rover disc down in the area with the threaded mount holes, leaving a strong threaded "nut ring" that will also aid in clamping the disc to the hub with surface area.

Or, I may just jump on the wilwood 106-11862 ($56 ea) / 160-12206 ($104 ea) discs at 310mm x 28mm with the 8x7" mounting PCD that will require a custom bell. These discs are easily available and pretty cheap all said and done; only the bell is the pricey part.

Blank alloy bells from Wilwood arent a terrible price...although by time you then pay to have them machined to suit it does add up.

Some custom bells really wont be that much more expensive from the likes of BG Developments or other brake makers.

Although if making brackets for the calipers there are quite a lot of OEM discs around that size these days if one might be a similar offset you could work with.
Some brake part websites allow you to search for disc via dimensions.

Unless you have full workshop facilities always at your disposal, I'd not want to have to modify a stock disk each time replacements were needed. So some form of bell or adaptor would seem best. Much the same applies to the callipers, but less so.

Tell me what dimensions you need for the disc:
PCD
Centre bore
OD
Thickness
Height/offset

I'll have a look in my files. I work for brake supplier.

Drilling new mounting holes is fairly straight forward, but machining the centre bore needs to be accurate H9 or better and don't even think about machining the friction surface/thickness even on a CNC lathe.

The Brembo site allows you to search by disc dimensions.

https://www.bremboparts.com/europe/en

Yes that is useful but does not include:
PCD or Centre bore.