This article, which I have been threatening to write for WINGS for some time now, will outline the braking system service that was done on my BJ8. The reader should understand that I am not a professional mechanic, and that there are differing opinions on certain of the procedures and on the pros and cons of using silicone brake fluid. If you have any hesitation about personally servicing the brakes on your own car, I strongly recommend seeking the advice and, perhaps, assistance of a professional mechanic, as your safety is involved.
As many of you know, I do not hesitate to drive my Healey(s) on trips, both by myself and in the company of other club members, to various events. I knew that the brake fluid was old, and when the brakes were applied, the car had a tendency to pull slightly left and then straighten. I was also concerned about the health of the clutch hydraulics. We decided to replace all of the rubber parts in the both systems (brake hoses, clutch hose, brake and clutch master cylinder kits, clutch slave kit, calliper kits, calliper pistons as necessary, rear wheel cylinder kits or replacements). We ignored the servo, as it was known to be new just prior to my buying the car. Of course, we would carefully examine the brake pipes, and would put the reservoir right. (A previous owner had chromed it and had used rubber washers to seal the bottom fittings, and the rubber was all but rotted away.) I obtained Girling kits, as they were noticeably better than the others when compared side by side.
This component is fairly straight forward. Examine the bores carefully to determine if replacement is needed; also check the internal metal parts. A major consideration here is the repair or replacement of the clutch push rod. The holes in the fork end are probably worn, and the pin is certainly worn. This means that the plunger assembly's travel in the bore is greatly reduced. Correcting this problem makes a tremendous difference in the way the clutch feels and works; the piston will now move the correct amount of fluid and fully disengage the clutch. Check the brake cylinder's fork for the same problem. It probably will be okay; it doesn't go through anywhere near the travel of the clutch, and likely won't be as worn. Wet the seals with the brake fluid that you will use, and coat the insides of the dust covers with rubber grease. This will help reduce corrosion on the dry side of the seal. Read and follow the appropriate sections in the workshop manual, and follow the instructions that come with the kits.
Now is the time to strip and paint the reservoir, as it probably looks like hell as a result of the brake fluid de-painting it endlessly. (See comments on silicone brake fluid.) (When my mechanical mentor Fred Falkins spoke of "windage", he wasn't talking about medical condition, but rather the tendency of high-speed driving to draw a fine mist of brake fluid out of the reservoir cap's vent hole.) Use copper washers to seal the threaded adapters. (A new rubber cap gasket was included in my calliper kit.) Remember that the centre section of the dual reservoir is the clutch section when you re-install it. (4-cylinder Healeys have mechanical clutch actuation. Early BN4s have separate brake and clutch reservoirs integral with their respective master cylinders.)
CLUTCH SLAVE CYLINDER
Assuming that the bleed screw will come out, it may be re-used if the bore and the plunger are not worn or corroded. Don't forget the rubber grease inside the dust cover. When the new hose is installed, I recommend protecting it from the inevitable road abrasions it will get. I used Teflon spiral wrap - 2 layers - commonly available at electronic supply stores. My hose was badly worn, and would have let go at any moment!
CALLIPERS and DISCS
Again, hopefully, the bleed screws and pipe fittings unthread. The book says not to split the calliper halves. In my case there was no choice; one piston was seized solidly in the left calliper. The kit contained the o-rings necessary for re-assembly. Do them separately, as they are mated pairs. I had to replace all four calliper pistons, as there was pitting in the chrome surfaces.
The discs should be checked as per the workshop manual, and should be resurfaced only if necessary. Surface rust, usually a result of the car sitting for a long period of time, can be removed by hand sanding. (Apparently, some early disc-equipped cars had thinner discs installed by the factory; these should definitely not be turned as breakage could result.) I took advantage of the opportunity to replace my front bearings, as there was a slight roughness when they were checked.
Again, use rubber grease (carefully) to protect the dry side of the calliper pistons inside the rubber boot. Make sure the boot is properly fitted to the grooves in the calliper and in the calliper piston on re-assembly, and that the anti-squeal shims, if present, are installed with the arrows pointing in the direction of rotation of the wheel. Some of the replacement front hoses come with a wire protector on them - mine didn't. I used the spiral wrap as described above. I replaced my pads (Repco Deluxe) and have had no problems with them. Owners of cars with drum front brakes should pay attention to the specifics of those brakes, including the paper gaskets on some of the earlier cars (supplied in the Girling kits).
REAR DRUMS and WHEEL CYLINDERS
Here is where you are most likely to break a bleed screw. If everything unthreads, the cylinders can be sleeved for about half the price of new ones. This involves machining the bore to accept the sleeve, reaming the sleeve to the original bore size, and then drilling open the fluid passageways. The sleeves must be solidly lock-tited in place; they must not come adrift. Former A-HOABC member Ziff House did this operation for me, and so far I have had no problems. In most cases it is probably better to replace the assemblies; I believe they come complete with pistons, seals, and dust covers. Use the rubber grease again! Make sure that the locking plates that hold the cylinders to the back plates are in good condition, or replace them, and that new rubber boots are installed around the handbrake levers where they exit the drums.
Rick Regan advises that drums should not be turned. The working surface is factory hardened, and the machining process destroys this. Try and locate replacement (used) drums if yours are very bad. (I turned mine at the time, not realizing that I shouldn't have. So far they're okay. Other club members that I have spoken to have routinely turned drums and have not had problems.) Another thing to watch for - the Healey brake shoes are designed to have a lining thickness of 3/16 inch. Most shops use 1/4 inch friction material. My drums would not go on until the linings were 'arched' down to 3/16! Best bet is to get your shoes from a Healey supplier on exchange; he is wise to this quirk. Pay attention to the routing of the new rear brake hose. It must not contact the car body at any point in the travel of the rear suspension.
There are differences of opinion here. I spoke to Vern Bethel of False Creek Automotive. They specialize in vintage vehicles, and use silicone fluid almost exclusively. Fellow A-HOABC member Dan Doucette has used it in all of his Healeys over the years, as well as his Jag XK-120, and has had no problems. Good friend and E-Jag owner Mark White has had it in his car for ten or so years, and drove the Jag daily until very recently. Club member Craig Wallace has it in his BJ8, and endorses it (a rear brake problem turned out to be a fault in the turning of the drums - nothing to do with the fluid).
Yet some that I have spoken to have had problems. I suspect that if one installs silicone fluid without renewing all of the rubber parts that it contacts, trouble will result. The greatest single advantage to us, whose cars are used seasonally and intermittently is the fact that SBF is non-hydroscopic. It does not attract moisture, as does alcohol-based brake fluid. This will tend to reduce or eliminate the build-up of moisture, hence corrosion, inside the system. Another advantage is that SBF won't remove paint if spilled. Some claim they don't like the feel of their brakes with SBF installed. My car has an excellent feel, on both the brakes and the clutch. Bear in mind that a servo-equipped car will tend to mask any difference in the feel of the brakes.
Disadvantages? It's expensive. And it takes greater care to bleed the SBF equipped car. Personally, I recommend its use. I believe that the advantages far outweigh the disadvantages, but only if the braking system is in top shape before SBF is installed. One caution - there have been failures on the track in vintage racing cars using silicone braking fluid. Gunther Pichler had such a brake failure in a longish racing event in his E-type Jag. The entire system had been carefully rebuilt. He feels that extreme heat caused the problem. The brakes were fine when they cooled and they seemed fine in a shorter event later on. Discretion in cars used for competition is definitely advised.
Once everything had been checked, we did a 'gravity bleed'. Open all 5 bleed screws and gently pour from a 'settled' container of new fluid, keeping the reservoir topped up as the fluid slowly settles. It took a surprisingly long time, about three beers as I recall, for fluid to appear at the first fitting. Close each bleed screw as fluid appears until all five are closed. Now do the usual 'two-man bleed' starting at the wheel farthest from the reservoir, and then the clutch slave. Check for leaks (we had a couple) and you are done.
It is likely you will have to bleed the system again after a few miles. I think the trick is to flush plenty of fluid through the system in order to get rid of any old fluid or debris. Unfortunately, for a servo-equipped car, this is going to require two containers (quarts) of fluid. The instructions on the container from Dow-Corning are excellent; follow them and you should have no trouble.
In conclusion, I would like to thank the people (named herein) who have helped me with this article. Also, I would welcome any additional input, even if it is critical, from readers. A letter to the editor would not only shock the editor, but it would add to our collective information on brake servicing, and perhaps prevent our members from making mistakes while learning about their Healeys.
Austin Healey Brake Service
by Earl Kagna