A Jaguar is a car that wants to be driven, and my '67 Mark II has been on the lift far too long. I bought it in January of this year, a dark blue with red leather car with excellent cosmetics, but in need of a complete brake system rebuild and some minor mechanical tweaking. It is a right-hand drive car that spent much of its life in England, then Canada before coming to the states. It still has its original English license plate on the rear.
We have published previous articles on this car, including when we removed the brake calipers and how they were rebuilt (see www.southernwheels.com and go to the Archives section). In this article we will conclude the brake rebuild, and rebuild the master cylinder. Since the car is right-hand drive, the master cylinder is located under the hood on the right side at the firewall. Two types were used on the Mark II's: Dunlop and Girling. Ours is Girling. We got a rebuild kit from our buddies at Vintage Jag* as well as some beyond-the-manual information on the rebuild.
We removed the two steel lines, one going to the reservoir and the other to the calipers. Then the two mounting nuts and lock washers and the cotter pin that secures the push rod to the brake pedal. To do this, you have to get in the car, pull the pedal up and remove the pin.
REBUILDING THE GIRLING MASTER CYLINDER is a relatively simple project. With the master cylinder off the car, we removed the dust cover at the mounting end of the master cylinder, then the circlip which releases the push rod and dished washer, then pulled the piston from the body. Using a knife point, we pushed down on the spring seat on the valve. This allows the support spring to come off and the assembly to come apart. Then we removed the two old seals, one from each end and lubricated the new seals and the bore of the cylinder with LMA brake fluid. We then fitted the new seals into their grooves; the large one in the piston and the small seal in the end of the valve, then inserted the piston/valve back into the spring support and pushed the complete assembly into the cylinder body, being careful not to twist the seals, put in the dished washer seating it on the shoulder at the head of the cylinder, and fit the circlip, making sure it was fully in the groove. We filled the rubber dust cover with grease and installed it around the head of the master cylinder. The master cylinder like the calipers were assembled using Castrol "LMA" brake fluid. It is imperative to use LMA (low moisture activity) fluid on vintage British cars because of the type of rubber their seals are made of. Petroleum products or regular brake fluid will swell the rubber and lock up the pistons. I think that was part of the problem with this car. The seals were swollen and were so locked up it took a lot of prying and turning just to get them apart.
With the master cylinder back together we put it back on in the reverse order as above, leaving the line from the reservoir off until we poured fluid into it and cleaned it out, then reconnected it. Now we had fluid supply and it was time to put the calipers on. Before doing this, we checked the newly-rebuilt calipers with our photos that were taken before removal, and, of course, checked them with our parts manual. What we found was the manual showed the bleeder valve was on the front side of the caliper in the top position. Ours had been on the back side of the caliper in the top position. After researching this, we couldn't find any other cars with the bleeders on the back side of the calipers. We found that many Mark II's have wire wheels and the front bleeder allows the brakes to be bled without taking the wire wheels off of the car. You just bleed them through the wires. These cars from day one were and still are performance cars and were raced. Brake work could be done in the pits quickly with the front bleeders without taking the wheels off of the car. Our car is a steel-wheel car, and by back side bleeding, they could be bled without removing the wheels. We found a steel-wheel "gold standard" very low-mileage original car, expecting it to have rear bleeders, but it had front ones. So, we decided to set ours up for front bleeding, (which is a good reason to get a set of wires later on).
The calipers consist of 2 piston assemblies; one on the front and one on the back side of the calipers, a steel line coming from the master cylinder, a crossover steel line that connects the back piston assembly to the front and a ball and bleeder valve. Here is the way the "front" bleeder caliper is piped. The line from the master cylinder goes to the bottom of the back piston assembly; the top of the back piston assembly is the crossover line to the bottom of the front piston assembly, and the top of the front piston assembly has the ball and bleeder valve. The bleeders in the parts manual have the bleeder valve with a ball bearing. We removed the bleeders, making sure the balls were in the fluid holes. We found one was missing! This was a simple fix. We took an old one and matched it up with a new one from Ace Hardware. I wish all parts were that easy to find! When bleeding with foot brake applied and bleeder open, fluid pushes the ball up and flows around it in and out of the bleeder valve. When the foot brake is released, the ball sucks back into the hole and bleeder's concave end locks it in place when tightened.
BLEEDING THE BRAKES: We first checked that all connectors were tight and filled the reservoir. The manual states to bleed the nearest caliper to the master cylinder, on our right-hand drive that's the right front, then the left front, right rear, then left rear. When bleeding, the brake pedal should be moved slowly up and down in its full stroke until only fluid comes out without any air bubbles, keeping the pedal depressed until the bleeder is closed. After we bled the system twice, we re-filled the master cylinder to the correct level marked on the reservoir and held the brake pedal down for 2-3 minutes to check for leaks. There were none, and our pedal stops about halfway.
With everything on and working, we adjusted the emergency brake. This has to be done with the wheels off. The emergency brake assembly is attached to the rear calipers and has its own pads. Our pads showed almost no wear so we didn't replace them. To adjust, fully release the hand brake, remove the cotter pin from the adjustment screw (front side of caliper), insert a feeler gauge between the hand brake pad and the rotor, then screw in or out the adjustment screw so that there is .004" (.10 mm) distance between the pad and the rotor. With the feeler gauge in place when the rotor is turned, it should just touch the feeler gauge. Repeat on the other side. If further adjustment is needed, the hand brake cable can be adjusted, screwing the adjustment screw in to lock up the rotor, then with the hand brake lever fully released, remove the cotter pin, securing the fork. Back off the lock nut on the cable and adjust the position of the fork end so that with the cotter pin fitted there is no slack in the cable. (The cable can not be under tension.) Reset the hand brake pad-to-rotor clearance to .004 as described above. Put the locking cotter pin in the adjustment screw and you're done.
The Mark II's are known for great handling and for performance, and have many engine and suspension similarities to the XK-150's and early XKE's. I can't wait to get this one back on the road. Look for an upcoming drive report.
Fall is here! A great time for going to shows. The Glidden Tour just rolled into town and Marty Roth, the AACA National Director is at my door--got to go! Enjoy your cars, and keep 'em driving!