NUMBER: 67-32
DATE: 2-22-67
GROUP: Clutch
SUBGROUP: Master Cylinder

MODELS: Alpine V & Minx IV
SUBJECT: Modified Master Cylinder Main Cup

A modified master cylinder main cup is now available which will correct problems of periodic loss of clutch in heavy traffic.

The new main cup can be identified by its manufacturer’s number 3842-424 which is on the cup.

All master cylinders, part number 1223548, and the new overhaul kits, part number 5044629, currently supplied include the latest cup, part number 5044628.

T.H. Bullard
Manager – Service & Parts

by Jim Morrison

In attempting to return the engine compartment in my Tiger to like new condition, I found no way of cleaning the exterior of the clutch and brake master cylinders to remove the discolorations of age. As a last resort, I lightly sand blasted them with very good results.

The first step is to thoroughly clean the part of grease, brake fluid, etc. Then tape up or plug the openings to prevent the sandblasting from damaging the bore.

After a light sandblasting, remove the tape and plugs and clean the piece thoroughly with soap and water making sure to get any sand particles out of the passages. Blow it out with an air gun and let it dry.

Further protection and beauty is added by coating the piece in a clear coating. For longest lasting results, use a coating that does not dissolve in gasoline or brake fluid. I found a spray can of Rustoleum clear to work very nicely but I would suggest you test a few brands before trying it on the real thing.

The end result is an attractive alloy finish with its glossiness determined by the type of clear coat used.

by R. Pennell

The hydraulic cylinders of my car were all rebuilt with painstaking care and utmost cleanliness. All internal parts were soaked in Castrol LMA and the completed assemblies stored in airtight ziplock plastic bags. All of this work was completed approx. 1 1/2 to two years prior to installation on the car.

Lo and behold, with everything assembled on the car, neither the brakes nor the clutch would work. So, off came all of the hydraulic cylinders for inspection. Incredibly, the internal parts were more corroded at this point than before they were originally cleaned up and rebuilt.

They have now been rebuilt for a second time, but this time the hydraulic system is filled with Dow-Corning silicone fluid, and everything seems to be working just fine. The conclusions reached from my experience are:

1. The cylinders should not be rebuilt until close to the time they win actually be installed.
2. To be on the safe side, spend a few more bucks and go first class with the silicone fluid.

by Tom Ehrhart

Rebuilding the Girling servo is a critical operation that requires cleanliness, care in disassembly/reassembly, and moderate mechanical dexterity. If you are a little weak in or doubtful about the latter, get a qualified individual to help or do not attempt this rebuild. If you are apprehensive about attempting this rebuild-don’t! The worst that can happen is the brake fluid will leak out causing the brakes to fail, or the brakes will lock up making the vehicle immobile, or the brakes will fail to release completely causing severe brake pad rotor and shoe/drum damage, or (finally) no brakes at all. YOU guess what happens next!

Now that you have been appropriately put on guard or scared, let’s start. Removal of the unit from the car is made easier by first removing the manifold vacuum line banjo fitting and the small air filter element on top of the unit. This provides more room to get a 7/16″ wrench on the input and output lines.

Remove the lines before removal of servo from mounting brackets. Follow Figures I through II for disassembly (dismantling) instructions. With the unit cleaned, examine all bores for corrosion, pitting, scoring, or ridges. Using a flashlight is one of the best ways to examine the bores.

At this point of your examination, you are bound to find the bores in need of service. Pitting is almost always a result of moisture buildup within the fluid and is usually quite severe with servos that have not been used for extended periods of time (a year or more). Scoring and ridges are a result of piston scrubbing from use.

In all cases, these bore conditions must be rectified. You are wasting your time and possibly your life if you do not restore the bores. This is the main secret of a successful servo rebuild.

Despite appearances, most bores are repairable by honing. There are three (3) bore sizes in your servo, they are as follows: Vacuum Upper Bores, Lower Bore Canister ID, Small (5″) 3/4″, 5/8″, 7/16″, 3/4″, Large (7″) 3/4″, 5/8″, 3/8″, 3/4″.

When determining booster size, check diameter of rear cover. The small is approx. 6″ and the large is approx. 7-1/2″ Commercially available hones are usually available for the 3/4″ bores, but you will have great difficulty finding hones for the smaller bores.

It is easy to make your own hones, though. With a brass rod as shown in Figure 12 (liberally coated with fine grit valve lappng compound), insert it in the bore and rotate it back and forth and out until ridges and pits are eliminated. In the absence of honing, #400 wet/dry sandpaper wrapped around a rod can sometimes be used to remove bore imperfections.

Then, with #0000 steel wool wrapped around a rod inserted in a high-speed drill, polish bores to a mirror finish. Again using a flashlight, look down the bores to verify your handy work. At this point, if all bores are satisfactory, clean one more time with a strong detergent and hot water.

Remember, if you would not eat off of it, it is not clean enough!

Now precoat all hydraulic parts with synthetic silicone brake fluid and assemble unit as shown in Figures 13 through 18. Next, prepare vacuum cylinder piston for reassembly. Using #400 wet/dry sandpaper, polish cylinder bore. With the rubber strip removed from behind the leather seal, wrap a dry rag around the leather seal overnight to absorb brake fluid. Do not use solvents to do this job.

Thoroughly saturate the leather seal with a silicone lubricant (usually in spray cans) or use lubricant supplied with the rebuild kit. Coat the cylinder bore with the same lubricant. Continue assembling as shown in Fig. 19 through 23. Just prior to replacing the cover plate, fully depress piston several times. The piston must be pushed completely out of the bore by the return spring (Fig. 21 Item 3) without sticking. If it does stick, remedy the problem by adding lubricant on the leather seal and/or using a razor blade to cut the foam seal (Fig. 22 Item 41) in half lengthwise.

NOTE: If the piston sticks, your brakes will lock up or not completely release causing severe brake rotor and caliper damage. It is highly recommended that you use a synthetic (silicone) brake fluid in your new rebuild and the rest of your brake/clutch system.

Editors Note: Silicon Fluid should not be used in a racing application due to its higher rate of compressibility.

by Tom Ehrhart

Fig 1

Fig 2

by Tom Ehrhart

The following is taken from literature from Lockheed on the installation and maintenance of flexible brake hoses: To ensure that the vehicle braking system remains in good working order and provides the essential safety and reliability, periodic checks and replacement of flexible brake hoses is necessary. At every 6,000 miles, 10,000 kilometers, or 6 months (routine service period), check hoses for chafing, cuts, perishing and security of end fittings. If any defects are found relevant hose(s) must be replaced. Take care when fitting replacement hoses to ensure that they are not twisted or kinked, and are clear of any part of the vehicle liable to cause chafing.

Fig 1 (Click to enlarge)

It is easy to see the pattern molded into the hose rubber. It must be running perfectly straight, any twisting during fitting could put a permanent torsional load at the end connections which can result in premature hose failure. Tighten hose fittings sufficient to prevent leakage, but do not over tighten. It is important to note that hoses with UNF threads use a copper-sealing washer, as illustrated.

Fig 2 (Click to enlarge)

Certain METRIC threads are similar in size to UNF threads; therefore, it is important that they are correctly identified. If any doubt exists, do not use a spanner, but first screw the component fully home by hand. If the fitting is tight or unduly “sloppy” check the thread type. Such parts as tube nuts, bleed screws and hose-end fittings, etc., with METRIC threads are colored pale gold, similar parts with UNF threads are colored silver, green, or red. It is recommended that all flexible brake hoses are renewed at least every 36,000 miles, 60,000 kilometers or 3 years, whichever occur first.

from CAT

The threads on most of the components of your Tiger’s brake system are fragile at best. It is easy to cross-thread a line into a cylinder, for example, and, once the threads are damaged, the chances for a good, leak-free connection are very small unless you can repair the threads.

One thing I do before refitting any of the brake (or clutch) lines is carefully run a 3/8-24 bottoming tap into the cylinder and run a 3/8-24 die over the fittings on the line to clean out and renew the threads.

by Stu Brennan

I remember sitting in a tech session at a United several years back, listening to some of our experts talk about silicone brake fluid. They were describing how easy it was to put silicone fluid in–just fill the reservoir and bleed until the silicone fluid came out. I pointed out that there would still be a bit of old fluid left in the wheel cylinders and calipers, but no one thought that this would be a problem.

A recent answer to a technical question in ROAD & TRACK suggests that this is not the case. They state that if silicone (DOT 5) and glycol (DOT 3) fluids are mixed, the glycol will cause the rubber swelling additives to separate from the silicone fluid, and the silicone will cause the anti-corrosion additives to separate from the glycol.

So, it seems that the best way to change to silicone is to start with a completely dry system. The article also contains some interesting comments about the various types of rubber used in brake systems and how each fluid works with them.

See pages 199-200 of the November, 1989, issue.

by Phil Lindsay

The vacuum-power brake servo unit is really a two-sided beast. Its good side provides substantial braking assistance to romping Tigers and, thus, it seems to be desirable for most Tiger owners. I’ve only heard of a couple Godzillas who don’t need the servo. The bad side of the servo can really be nasty, like engine vacuum leaks (air to vacuum chamber leaks), loss of hydraulic pressure (internal fluid leakage in piston seals) or loss of hydraulic fluid (fluid goes into engine intake due to vacuum seal leakage). Rebuilding the servo requires more effort than the brake cylinders, but the extra effort is offset by the cost of a new servo ($150).

The rebuilding effort should go well if your brake system has been cared for during the servo’s life. I think that the most important factor is periodic changing of the brake fluid. I don’t mean topping off the reservoir every year. You’ve got to completely purge out the old fluid.

Start by emptying the master cylinder reservoir with a squeeze bulb and wipe out all of the dirt with a clean cloth. After refilling with fresh fluid (half-opened cans of unused fluid are not considered fresh if there has been moisture contamination), start bleeding each brake in the usual manner.

Continue to pump at each brake until clean fluid comes out; don’t forget to replenish the master cylinder reservoir. This entire procedure will require at least two pints of fluid. No, it’s not a waste because the old fluid will corrode the internal parts of the servo, as well as other brake parts, and make rebuilding very difficult, maybe even impossible. The frequency of fluid changes probably depends more upon time than mileage: I suspect every 12 to 18 months is reasonable.

If your brake system has been well cared for, you will find the internal bores in the servo to be clean and smooth. If so, you can forget about honing the bores and concentrate on a very thorough cleaning before rebuilding.

The subject of bore honing is very controversial, especially for hydraulic systems built of aluminum such as the Girling units. If a cylinder bore is damaged due to corrosion attack or mechanical scratches, it must be smoothed out in order for the rubber seals to work without excessive wear. If the bore is bad, throw the unit out and try again! (Or, maybe get super machinist Tom Hall to make up a stainless steel sleeve.)

There are several approaches to honing and all of them have problems. Aluminum is soft and difficult to smooth out; the servo bores have small diameters that are difficult to hone and it’s difficult to thoroughly clean out the cylinders after honing. All in all, it’s a nightmare. If you can retain the bore concentricity while honing with a sandpaper-covered stick or a miniature honing stone, you will have beat the odds. Good Luck!

My point of this doomsday story is simple; Don’t hone a good bore! There is nothing harmful about the so called “glazed surface” on aluminum; feel it ? it’s smooth! There have been numerous tips on servo rebuilding, including the instructions provided with the rebuild kit. The kit directions are pretty good, but I’ve found a few modifications that have helped me.

• Good circlip pliers are necessary for removal of the output piston circlip. It’s a tight fit because the circlip is buried deep down the bore. I had to extend the tips on my pliers in order to fit.
• The spring tool for holding down the output piston while removing the circlip is worthless! It takes up space within the bore and interferes with the circlip pliers. It also prevents the piston spring from helping guide out the circlip.
• The new rubber strip that fits under the leather seal on the vacuum piston is often too large, causing the piston to bind and lock up the brakes. A great anti-theft feature, but not so convenient! Reuse the old seal if not damaged; otherwise carefully cut the new strip on one side so as to reduce its thickness.
• The leather seal and rubber strip will be saturated with brake fluid. Use clean paper towels or rags to blot up the excess fluid; keeping in contact with the strip for several hours will help.
• Silicone spray the leather and allow to soak into the seal. Be sure to use silicone (WD-40 is not silicone.) Allow silicone to soak in for a couple of hours and wipe off excess.

I use the “special servo grease” provided in the rebuild kit. Work it into the leather and coat the rubber strip. Also, wipe a thin coating over the vacuum cylinder bore. Rebuilding servos, master cylinders, etc. are big pains! Change your brake (and clutch!) fluid more often for less pain! Tiger and Alpine owners over time have experienced a variety of maladies centered on “stopping the beast”, i.e. brakes.

Contrary to common belief, the brakes on a Tiger are basically the same as those on an Alpine. Keep in mind that there are two body series for Tigers and Alpines. The Alpine came in Series IV and Series V and Tigers came as MK I and MK II. It is reasonably safe to say that at this time there are fewer than 5 percent of all Tigers and Alpines with their brakes in the best condition possible. Why so few? Several reasons: there are a number of brake service procedures that are required but almost never followed as most owners do not own service manuals or owners manuals which are needed for the necessary information. There are three items that are most often overlooked.

1. Brake fluid is hygroscopic; it absorbs water from the atmosphere and becomes contaminated resulting in internal corrosion (oxidizing) of all components, reduced braking power, and rapid brake fade under moderate use. The factory service procedure is to completely replace the fluid at one-year intervals. Start with the engine off, depress the brake pedal 3 x 5 times before bleeding to eliminate all vacuum in the booster. Bleed the rear (left wheel cylinder), first, then the left front, then the right front. Be sure to use only Girling amber or Castrol LMA (low moisture absorption).
2. To properly bleed the rear brakes, they must be adjusted out until the wheels will not turn by hand; this ensures the removal of all air that may be trapped in the cylinders. Brake pedal height is also determined by proper adjustment of the rear brakes, usually two clicks back from hard lock.
3. The brake servo air filter should be replaced every 6000 miles. Dirt in this filter or a blocked filter will result in a hard pedal or apparent lack of servo assist.

It should be noted that a Tiger or Alpine with brakes in proper condition can lock up all fours at 15-20 mph testing speed with standard 78-70 series tires and stock pads. For vehicles used in competition (auto-cross; short to medium length tracks) standard pads and shoes are fair, however, improved times may be had by using up-rated components.

As one additional point of interest, I recommend that each of the bleed screws be loosened and retightened at least once each 6 months and that they not be over tightened (5 lb. ft.). When servicing the rear brakes, the brake adjusters should be disassembled, cleaned, coated with never-seize compound and reassembled.

This does not apply to those later 1967 production Tigers and Alpines equipped with self-adjusting rear wheel cylinders. These should be checked at 6-month intervals for freedom of operation.

Still on brakes and in answer to a question from a fellow member, the blue-white smoke and heavy detonation or engine knock experienced after heavy braking is the result of brake fluid entering the engine through the servo to engine vacuum hose. This results from a failure of the servo piston rod bearing bush seal which forces fluid into the vacuum cylinder. If the failure has not occurred here, it has occurred at valve control piston either at the hi or lo pressure end which will allow fluid to enter the valve chest. In any event, the servo must be rebuilt.

Sunbeams from B9470001 thru B382991282 have small-chamber boosters that use Girling kit SP 2230; from B382001283, they have large-chamber boosters that use SP2228. If a new servo is needed due to scoring of a piston, #64049127 is for the small chamber, and #64049460 is for the large chamber. These numbers also apply to Alpine Series IV small and Series V large. To close this rap on brakes, let me say that the limiting factor on proper brakes in a Tiger or Alpine is tires, particularly on the Tiger. One can very easily overpower these tires with standard brakes. I’d suggest … well a lot of things, but for starters minimum size should be about 175/70?13 and not any smaller. Rim size and room in the wheel well determine the upper limits. LAT9 & 70 wheels and T/A 60′s (BFG) work nicely.

Editors note: A very reliable option to the brake servo is to bypass it with a brake line, replace the master cylinder with a smaller one and increase the diameter of the rear brake cylinders. Doug Jennings of Dayton Tiger can help you with all the parts.

…And it worked for me!

by Ron Rogers

I am about to divulge a secret that has been invaluable for making my car win races for the last six years. Are you ready for this one? I know that I have maximum braking power. This fact not only helps the car perform better, but also helps me be a little more daring on those “deep comers.” I’ll explain why you’re not developing full potential and more importantly, how you can, no matter how much work you’ve done on your brake system.

In the beginning, all Sunbeams were created equal. That is, equal tires front and rear, with the same width, same height and same compound. The brakes were also calibrated by the factory to stop with the front wheels locking up before the rear wheels. This is important because it prevents your rear end from passing you in a hard brake situation.

So what’s the problem? Unless your car has original tires (and even if they do) you can probably lock your front wheels long before your rears, if at all. What this all means is that your brake system is not fully balanced for maximum braking. If your car has been changed since production with different size tires front and/or rear, traction bars to prevent spring wrap-up under hard braking, altered ride height in any way, or altered weight distribution front/rear, you really are asking for it.

But wait! No need to send your car to Ralph Nader and take the bus. A simple and extremely effective solution is at hand. All we want to do is shift more of the braking load to the rear wheels. Other than changing lining, compound and/or sizes, the most effective solution is an adjustable brake-proportioning valve. The best one that I know of is made by Kelsey-Hayes and sold through Ford and Chevy dealers. The Ford part number is C5ZZ 2BO91 B and the Chevy number is 3878944. The valve will have to be installed on the brake line that you want to reduce pressure on; that is, the front brake line.

To install the proportional valve you will need the valve, a three-way tee block, three or four compression fitting connectors, five double flare ends and fittings, one brass plug, and three or four feet of steel brake line. I’ll leave the placement of the valve and tee block up to you, but you must put the parts on in the correct way. Remove the line from the servo to factory four-way tee. You will have to cut the ends off this line about four to eight inches from the fittings. The three-way tee and valve must be installed between the servo and factory four-way tee. The rear brake line must be removed from the factory four-way tee, the hole plugged and the line connected to the remaining hole in the three-way tee.

Now comes the good part, the set up. First, bleed the front brakes to remove air from the valve. Really stand hard on the brake to make sure there are no leaks anywhere. Then, go to an empty parking lot with wrenches for adjusting the valve, a roll of masking tape, and a friend. Place a strip of tape every 90 degrees on the sidewalls of the front and rear tire on one side of the car. With the valve in the “full in” position, start doing panic stops from about 20 to 30 mph while your friend watches the tires. He’ll have no trouble telling which wheel is locking up first. Gradually back out on the adjuster until the rears lock first; then back in slowly until the fronts lock up just before the rears. Tighten the lock and you’re home. When you can see exactly what your brakes are doing, there is no doubt on how they’re working. If you change your tires or brake linings or suspension, no problem, just readjust! You’ll know you’re at maximum. It worked for me.