XJS Big Brake Kit

[simon-9x8gj]

I recently found a UK based company, Compbrake, who list a big brake conversion for the XJS /XJ Front Hubs. The discs are 330 mm diameter so brings it up to the size that Lister used to fit on their modified cars. Took the plunge and have to say very impressed by the quality and certainly value for money compared to the Aston DB7 upgrade root, 5 kgs weight saving per side and OE XJS 16 inch wheels fit no problem.
Thought this may be of interest to any owners looking to upgrade those 50 year old Girlings!

[alabbasi]

Interesting. When I first pulled the wheels of an XJ, i thought the front calipers looked huge compared to anything German from the same era.

[simon-9x8gj]

The calipers are similar in size but its the weight saving that is so noticeable, the Girling caliper is cast iron against the aluminium of the Compbrake , and it’s designed to take a far larger disc.Also to anyone who has struggled to fit the steering arm shim when re fitting the original type caliper will appreciate how easy it now is with the separate caliper mounting bracket .

[simon-9x8gj]

Photo of caliper sizes

[V12 Migaloo]

After last years shenanigans on the AutoRoute back from Le Mans classic, my brakes where awful, couldn't do more then 2 or 3 high speed stops... big brake kit I thought.... then one day when I pulled her out of the garage I notice one of the rear seals had gone on a calliper. I couldn't stretch to the prices I saw on big brake kits (£2,000 +) so I replaced both rear callipers for rebuilt items and fitted new pistons and seals on the front. I also fitted EBC crossed drilled disks and new yellow stuff pads and I haven't found a situation where I wished I gone for a bigger brake kit...… OP Simon, What size wheels do you need for that Kit and give us an indication on price, thanks, I presume front and rears kit?

[simon-9x8gj]

Hi, all the details are on the Compbrake website, the kit I went for was the ‘smaller’ 330 mm diameter disc kit(£1199 plus vat) and all OE XJS 16 inch wheels will fit.
What appealed to me was the 5kilos per side unsprung weight saving and the heat dissipation provided by the aluminium calipers , bells and the directional cooling vanes in the discs. I reckon all of my brake issues in the 40 years plus of running v12’s have been caused by heat, either warping discs, perished seals , boiling brake fluid etc. Albeit that was many years ago when you could use the v12 to its maximum in France without fear of getting your car impounded and a spot of porridge!
As an added bonus with this kit fitting the steering arm to caliper shim is a piece of cake, I think in the past a lot of mechanics have fiddled for ages trying to refit the shim only to give up and just bolt the arm straight up, judging by the number of XJ’s I have seen were it’s missing.
Regarding the rears, I have a set of vented inboard discs and modified calipers so will be keeping that set up for the moment but Compbrake have said they could probably supply a suitable rear caliper in Aluminium if I supply them with a set, only issue would be the handbrake set up.

[V12 Migaloo]

For me its the rears that need upgrading before the fronts, my Arden spoiler feed adequate amounts of air to the fronts to stop them from over heating, its the rears for me that always needed assistance...

[alabbasi]

The inboard rears are typically neglected given that it requires the subframe to come out in order to change them, If you felt that they needed more attention, it was probably because they did.

[V12 Migaloo]

No more attention then the fronts, the rears always overheat first....