I’m working on upgrading the brakes on my Jaguar. My 1976 XJ6C with performance built 400SBC has more go than wo. With my 235 series 17” wheels I can no longer lock the wheels when stopping aggressively so a brake upgrade is warranted. The weather is turning colder and the days are getting shorter so I’ll be passing the time until spring in the garage like I do every year listening to the radio wondering why my ancestors left the warm climate of Sicily to settle up north instead of further south here in America..


The Plan....
Bigger rotors and calipers for the front and rear with ABS so I can get my high powered kitty to stop better. I'll be using 12.15 inch Wilwood 2 piece rotors and matching calipers for the front and Late XJS outboard brakes with vented rotors for the rear. 80's style Bosch ABS will be retrofitted because that system was standalone. Bosch designed and marketed it to manufactures as an add-on. Many vehicles foreign and domestic had ABS as an option back then so it will integrate easily.

The Stuff....
Front Calipers and Rotors... I already installed the Wilwood calipers on the stock rotors with no improvement in brake performance. A testament to the Jag caliper design. Bigger rotors from Wilwood with custom milled aluminum rotors hats fresh from my local machine shop machined to my specifications should help slow the Jag down. The whole kit weighs significantly less then all steel factory setup despite being much larger.

The Rear calipers and Rotors...I found a complete rear suspension from a low mileage 1996 XJS. The XJS that year had outboard brakes with vented rotors. The cost complete was 900$ delivered and since a vented rotor kit costs 630$ plus shipping the complete XJS rear represented excellent value. The XJS rear suspension solves other problems for me too....the outboard brakes with vented rotors are just the start. I'll also get 3.54 power-lok rear gear ratio, ABS rings, stronger reinforced rear hubs and since the brakes are outboard I'll have much more room for larger exhaust pipes to help the worked SBC 400 breath.

The ABS parts....Front knuckles from a 1989 XJS bolt right up to my XJ6C. They have the ABS reluctor rings on the hub as well as a spot machined for the sensor. The junk yard I got them from was nice enough to leave the ABS sensors in place which is a big plus. I also bought a complete stand alone Bosch ABS computer, pump and wiring from a C4 Corvette on Ebay. The rear hubs from the late XJS has a spot for ABS sensors too.

After planning, researching and ordering parts for this upgrade over the last 3 months I’m off to a humble start…picts attached. If anyone is interested is doing these upgrades let me know.

 

Which Wilwood rotors did you use? Also, did those hats start as Wilwood pieces as well?

Quote:

Originally Posted by icsamerica

The Rear calipers and Rotors...I found a complete rear suspension from a low mileage 1996 XJS. The XJS that year had outboard brakes with vented rotors. The cost complete was 900$ delivered and since a vented rotor kit costs 630$ plus shipping the complete XJS rear represented excellent value. The XJS rear suspension solves other problems for me too....the outboard brakes with vented rotors are just the start. I'll also get 3.54 power-lok rear gear ratio, ABS rings, stronger reinforced rear hubs and since the brakes are outboard I'll have much more room for larger exhaust pipes to help the worked SBC 400 breath.

Good deal! If your XJ6C is anything like my XJ6, it has only one brake line going to the rear of the car. I guess you're going to have to run a second brake line?

Awesome! Where did you learn about the whole stand-alone Bosch ABS computer system? Is there a forum/website/etc?


This is a really awesome project. Make sure you keep us updated and post more pics!

 

I made some more modest progress in the Garage with my ABS project tonight.

Rotors = WIL-160-11862
HATS = WIL-170-8589 are close.they need drilling and machining to make them right. I dropped them off to my local CNC shop and they used the factory rotor as a pattern to re-drill them.

You would think so but this is not the case. The Corvette, just like my Jag has limited slip and one fluid channel for the rear brakes.

Googled it and read some other people did it to early Corvette and Camaro's using the C4 system. I origionally considered a 85 Mercedes 300SD system but it needed a hall effect crank sensor for some reason unknown to me. The GM system is really a proven Bosch design that was used in all sorts of sports cars. It was a good option for me since I'm a GM guy and the system is well documented.

Ok, thanks...stay tuned.

 

Love this and will be keeping a close eye on your progress!

As you have said already, the std brakes are pretty impressive but, they are heavy. A move to a lighter Caliper and Disc/Rotor assembly will get you a decent weight saving and thereby reduce the unsprung weight.

The obvious benefits are more responsive suspension as there is less inertia which will aid both handling and ride comfort. You'll probably get even better braking performance too!

 

Wow, interesting stuff. Initially I was surprised that it was a one-channel system in the rear, but now that I think about it more, I can think of at least one RWD GM vehicle that had a 1-channel rear brake system when equiped w/ABS and a 2-channel rear brake system when equipped w/ABS + traction control.

I'm really looking forward to future posts/pics/results!

 

Got back in the garage Monday night and finished the driver side front caliper and rotor setup. I also installed the XJS 7/8 sway bar and poly end links. Even with the stiffer front sway bar, KYB shocks, 17" wheels the the ride is still very compliant. I'm amazed how much you can stiffen up the suspension and yet the ride stays compliant. It seems as if the handling improves 100% and the harshness increased just 10%.

I also finally recieved the 1996 XJS rear suspension with the 12 inch vented rotors. It's going in this weekend and I'm tracking down calipers today. You can see the yellow where I marked the rotor to verify the differential ratioits...3.54 power-lok... Good times!

 

I've made a bit of progress. Origionally I planned on concealing the ABS pump behind the headlight under the driver's side wing but once I got under the hood and planned it out it became clear that wasn't a good place for it becasue its too difficult to wire and plumb. So I took inspiration from the 1994 XJ12 I recently sold and relocated the battery to the trunk and placed the ABS pump in the battery area. This turns out to be an ideal spot becasue running the brake lines along the firewall actually shortens and keeps them out of harms way while making the ABS pump and computer easily accessible for installation and servicing. I was not excited about the extra work or expence of buying a sealed and tube vented battery but it had to be done. In the end it wasnt very diffucult and I guess the 50lbs of weight transfer rearward certainly wont hurt. I also installed stainless steel DOT flex lines leading to the rear cage. The stock flex line is very soft. Since i could not find male threaded 10mmX1.0 stainless steel flex lines I hade to use standard -3AN and reflair the tubing for the rear branch.

I'm making progress....slowly...lately I dont have much time with my needy pregnant wife and the kids have colds and need more attention. An hour here and there isn't the greatest way to get things done but it the only way I can right now.

 

Looks good!

What's that round thing above the battery - a sub?

 

Yes there are a pair of free air 12" inch subs installed in the rear shelf. They sound great but it's a bit much. If you look closly you can also see the cooling fins of the amp mounted to the underside of the rear shelf.

 

It was my 2nd attempt out of the garage with the ABS system installed and this time as I drove at speed, the ABS telltale warning light didn’t come on. I was full of hope it would work and it did. This night it had been raining lightly for hours so the roads were slick and as I got up to speed and crested a hill, I looked in the rear view mirror and depressed the brake pedal hard. No slide and the familiar ABS pulse in the pedal. Success! It had been done and it works right. The XJS spindles and C4 Corvette computer and pump (Bosch) were working. It all sounded and felt right and just like some of the older cars that I’ve had with ABS. The pedal pulses, the sound of impending wheel lockup and steering twitch. It felt just like the Porsche 928S4 I had many years ago, same feel and immediately that car popped into my head. The 928 probably had the same Bosch system and thus similar characteristics. There is still lots of finish work to do on the ABS systems. I have the front sensors wired crudely since I don’t have the proper female side electrical connections. I have to find a final place for the ABS telltale warning lamp. The rear sensors are from a Corvette with makeshift shims to get the reluctor air gap close enough. I’m really surprised it works as well as it does with the hodgepodge group of parts. Now I’ve got to hunt down some XJS or XJ40 rear ABS sensors and the proper electrical connectors.

The overall stopping performance is much improved too. I’ve learned that ABS cars have more rear brake bias by design so the rear brakes do more actual stopping. Vehicles with out ABS have much less rear braking bias because for safety sake the rears cant lock before the fronts in a wide variety of driving situations or the car will spin around. So by design, the rear brakes are basically just along for the ride and do very little actual braking. At this point its manifest for me to say installing ABS was easier that I expected. The whole project cost me about $1600… IMHO that’s money well spent for the control and stopping power ABS delivers. My test drive was a bit long tonight and uninhibited by the wet conditions.…I really enjoy the driving dynamics of this classic car.

 

Nice photos and writeup

 

Very good work there. Thanks for the write up.

 

Just a quick update....This is all still working great and the ABS system has been problem free for almost 2 years now. I recently replaced the rear calipers because they were leaking. I'll be redoing some of the brake lines strictly for cosmetic reasons soon.

 

Good to hear.
Hadn't noticed the thread was 2 years old, but worth knowing it's a great option.

 

Hello, really nice pics and work
Which Wilwood calipers and brake pads did you use? Wilwood part numbers ?
What mounting brackets did they need - any pics or drawings ?


thanks

 

Wow. really great work. and, a great presentation in words and pictures.


I had not realized that ABS allowed more braking effort on the rear. Adds to the total picture.


I learned the front/rear bias lesson early on. In late forties, I had a 31 Studebaker four door Commander sedan. Much warmer in winter than my T roadster. Dates with chicks in winter got more possible!!! But, it had cable brakes. Not that great. Lots of effort and little stopping power. And, when I got it, a decided jump to one side!!! so, I read up. I got the cables to work. One or more was frozen in it's sheath. But, in my efforts to get more braking power, I go too much rear bias. A quick stop and that big sedan swapped ends!!! Aha, the rears are working!! A bit of readjusting, and while not great, it would stop.


My 94 Jeep has ABS. It will stop quite nicely, just short of lock up. And, that is the best.


Even in non ABS cars, the best braking is just short of a four wheel lock. and, my Jaguar with good rotors and pads has never locked all four. It just squats and stops.


In my former profession, auto accidents always involved skids. It always bothered me that the lack thereof was considered a a bad thing by most.


In LA freeway driving, I had to brake hard from time to time. I tried to use all available space ands brake as hard as I could, short of locking 'em up.


Nice work


Thanks for sharing.


Carl

 

A good ABS system is a real safety enhancement. The primary safety benefit, obviously, of keeping the wheels rolling is that you can still steer the car and thus stay in control !

Cheers
DD

 

You may also be interested in this thread. Part numbers are In here.
https://www.jaguarforums.com/forum/x...-advice-98494/


There is no bracket. The new caliper ears are welded on to the spindles. At first I had a bracket fabricated but it flexed too much and pedal feel was poor.


If you would like set, send me a set of spindles. The rotor discs and calipers are off the shelf. The custom parts are the spindles and rotor hats. It costs 750$ for the 4 custom parts to be made.

 

Found this Thread!

Rusty

 

Ahhhh... my first coupe, a rusted hulk too gone to save but I tired my best. AKA The Development Mule. I did a lot of trials on that car and many bits were done and redone. What worked make it to my 2nd red coupe.

Here is partial list of what worked and got transferred.

1. The Color... simply never got tired of "Red Brown Mica" and I still love it.

2. The Brakes, front and rear. The whole rear cage was swapped over retaining the Auburn locker wth 3.54 gears and vented rear rotors. Just the front spindles were swapped to the 2015 Red Coupe and on to an XJS cradle. A late XJS/ XJ6 ABS system was used instead, becasue it's more advanced and compact.

3. Glass... as most of it was new and sourced at great expense.

4. The transmission and driveshaft. Built by a 30 year veteran, The transmission still works perfectly. I'm going back to a two piece driveshaft for more smoothness asap.

5. The engine concept, a new all forged 406 was built for the 2015 Red coupe. The Mule's cast 406 setup sits in storage perched on an engine stand wanting for light duty.

6. The Euro bumpers, door handles and various chrome bits as most were new.