Willwood calipers for Jag Front End

[Tenrocca]

The square tube classic revival uses Jaguar xj6\xj12 series 2\3 front end like a lot of other kits out there. The brakes work pretty well with decent pads, but the calipers themselves are very heavy - about 8kg each. The question has been asked a few times about fitting lighter aftermarket calipers using the stock rotors, but I could never find a definitive guide to doing this on this or any other site.

There are different big brake kits that can be fitted, but I do want to put 15"s on my car eventually so that is a no go.

I chose the Wilwood Dynapro radial mount model 120-8545. The specs are as follows:

Piston Count 4
Piston Area (in²) 4.80
Piston Type Stainless
Rotor Dimensions
Rotor Width(in) 1
Rotor Diameter(in) 12.19 (max)
Pad Dimensions
Pad Area (in²) 6.36
Pad Volume (in³) 3
Duty Rating & Material
Material Aluminum
Weight(Lbs) 4

The piston size is very similar to the old jag 4 pots. The stock jag rotor is 24mm so the 1" rotor width is fine. Pad area is a little smaller but with decent pads should go OK. AS long as they stop as well at the old jag ones Ill be happy as the 6kg per wheel in unsprung weight saving is significant.



I have access to a 3d printer and printed up a model before ordering so I could mock up and ensure it would fit. When you compare the 2 calipers side by side you can so the Wilwood is Physically much smaller.



Here is the printed version of the bracket I machined up to mount. The radial mount is easier to adapt than the lug mount and my research indicated the radial mount caliper is a bit stiffer than the lug mount version anyway.



Here they are mounted:



Heaps of clearance on my 17" wheels. 15's will fit no worries. I know a few had to modify the jag calipers a bit for their 15's



Inside:



Bracket drawn up in autocad:



First drive the brake feel pretty much the same as the old jag ones. Just a test run around the block so far. Ill give them a good run in this weekend.

Disclaimer - I am not an engineer.

[spookypt]

Andy, great pics. Side note question. What pad compound are you running and where are you buying them from when required?

[Tenrocca]

I had EBC Yellow stuff on the old calipers and on the rear. Probably get them again or maybe Ferodo DS2500. These calipers use a standard wilwood 7816 pad type - just have the wilwood ones (BP-10) that came with the calipers on there now.

I dont want to sound like the ad but I always check Ebay - UK site as well. Helps locate dealers even if the exact ones you want aren't listed.

[kyleb]

Great setup!!
I used the Wilwood 120-7380 calipers so that I could use the 160-7103/4 Rotors and 171-3755 Rotor hat.
The radial mount I machined up was exactly the same as yours which made it easy to adjust and centre the caliper on the disc.
No dust boots on the 8545 which makes them (correct me if I’m wrong) technically illegal on the road.
The difference in un-sprung weight is huge.

[Tenrocca]

Correct - Track only setup. I can change and bleed in 30 minutes.

[Gav]

Looks great Andy, the 3D printing of the caliper and mount for design and fitment is next level.

[spookypt]

don’t forget the insurance Andy.

[Tenrocca]

On the to do list Matty

[Treeve]

Dust boots aren’t a requirement of your calipers can resist the elements (ie stainless pistons). This is another hangover from a bygone era of over effacious Australian regulators.

[Modena]

looks like there's plenty of meat in the bracket, so why didn't you tap the holes for the radial bolts instead of use nuts?

[Tenrocca]

Originally Posted by Modena

looks like there's plenty of meat in the bracket, so why didn't you tap the holes for the radial bolts instead of use nuts?

A few different reasons I went that way. Used Nordlock locking washers. Someone told me Pace use them on their calipers so they must be good.

[gjkrv8]

Well done Andrew. Wish I had a 3D printer when I was doing mine. Great work.

Maybe you should subbie out as a pattern maker :-)

I have 120-9750's on the Rears on mine - works a treat.

I am chasing a right front lock up problem at present. Going through process of elimination. Dont want to ruin a front tyre again. cheers Gregg

[Gav]

Paint your printed proto type mounts silver and start flogging them on eBay Andy.

[Gaz64]

Originally Posted by kyleb

Great setup!!
I used the Wilwood 120-7380 calipers so that I could use the 160-7103/4 Rotors and 171-3755 Rotor hat.
The radial mount I machined up was exactly the same as yours which made it easy to adjust and centre the caliper on the disc.
No dust boots on the 8545 which makes them (correct me if I’m wrong) technically illegal on the road.[/color]
The difference in un-sprung weight is huge.

Originally Posted by Treeve

Dust boots aren’t a requirement of your calipers can resist the elements (ie stainless pistons). This is another hangover from a bygone era of over effacious Australian regulators.

Dust boots perform another function of keeping brake fluid off the brakes, if the piston seal weeps.
Hopefully a mechanic finds it before it becomes an issue.
I have found many on road cars.

[Tenrocca]

Just back from a spirited run to test out the new brakes.

I've got some yellow stuff pads on the way. Gav pointed out you really need to run the same compound front and back. That said, even with the basic wilwood pads the brakes feel great. Pulls up quickly and straight, better feel from the pedal and you can feel the reduced weight. Best upgrade I've done since the hardtop

[LoBelly]

Thanks for Posting this info Tenrocca - I will be looking at a brake redo in the future and will put this information to good use.

See you at the Nationals

LoBelly

[LoBelly]

dooble-oop

[Treeve]

Originally Posted by Gaz64

Dust boots perform another function of keeping brake fluid off the brakes, if the piston seal weeps.
Hopefully a mechanic finds it before it becomes an issue.
I have found many on road cars.

Whilst this may be the case, this was not the reason they were regulated for. Once the regulation was changed and allowance made to not have dust boots, on the proviso of suitable corrosion resistance, there was no longer a mandated reason to have to have them - provided the corrosion protection requirements are met.

Treeve

[Rebel1]

Andy, Great thread and which reminded me to post this option for lightweight alternatives for Jag XJ6 front calipers:

Kit 6: Billet aluminium vented front kit | cooper

Bolt on alloy replacements for the heavy cast iron XJ6 units. Comes in choice of anodised colour, with stainless pistons, seals and competition pads.
Simple bolt in replacement.

Edit: fits 15" rims

[Tenrocca]

Gday Les - Been so long mate. We've missed you