Spring Brake Tune-Up

Freshly tuned carburetors, proper running adjustments, an oil and filter  change; these are just the start of a successful driving season. Making sure  that your car will stop is probably the most important part of the spring maintenance routine. This year, why not give your car a safety check?

1.

    Excessive pedal travel and/or excessive handbrake movement indicates an overdue adjustment or the need for new pads or shoes.

2. Sticky wheel cylinder pistons or incorrect master cylinder push rod adjustment will result in a 'dead'
feeling pedal. Air in the system is the most common cause of 'spongy' pedal. These are the most common
of storage-related brake problems.

3. An obvious and serious brake problem is indicated by the abnormal loss of fluid once the car is put in
service. Do not just keep on filling the reservoir; clean and tighten the brake fluid connections. Look for
fluid seeping out of the cylinder seals. Pay special attention to the master cylinder. If wheel cylinders leak
into the brake assembly, the fluid quickly ruins the shoes.

4. Leaky rear oil seals are also a prime source of brake contamination. Often, both leaky wheel cylinders
and oil seals rob your stopping safety. Determine the culprit and correct the problem.

5. Shoes that have been soaked with brake fluid and oil may sometimes be  reclaimed with a proprietary brake cleaner, but it is usually necessary to replace them, as rear axle oil will soften the friction material, greatly reducing its  efficiency and safety.

6.  As brake fluid is susceptible to water contamination, it is essential to bleed the  brake system once a year. Worn seals will allow air to enter the system without a sign of fluid leak. The need for repeated bleedings is a sure indicator of this fault.

N.B. Absolute cleanliness is essential when servicing brake systems. Be sure that the master cylinder top is clean before it is opened, so no dirt or grit enters the system. Small rubber caps (Moss 031-300) are
available to cover bleed screws, and are an inexpensive and convenient way to keep dirt out of the
bleeders. Wash the backplates and any other gritty areas before anything is disassembled for service.
Remove the drums and clean the parts with brake cleaner or soap and hot water. Do not use an air blast
to clean brake assemblies. The asbestos particles are a proven carcinogen. Do not handle the clean parts
with dirty hands.

7. Carefully inspect the cylinder bores. Units having rust pitting, score marks, and 'rings' left by corrosion
must be replaced. Internal parts must also be in good order. Disc brake pistons that are rusted or corroded
will not hold a seal, nor will plungers and pistons that are scored or worn on one side.

8.  Examine the rubber hydraulic hoses. The connections to the metal piping are commonly covered in grease. This area should be kept clean so any  indication of cracking or swelling can be observed. An uncommon problem  with rubber hydraulic hoses occurs when the inside of the hose swells and cuts off the fluid flow. No problem is apparent on the outside. If you are bleeding the system and no air or fluid passes from the cylinder in question,  consider removing the rubber hose for close inspection.

9.   It is preferable to visually inspect front drum brake systems where two cylinders are used. Back off the adjusters to permit the removal of the drum. Get a helper to push the pedal gently. Observe the action of the cylinders' pistons - only one cylinder may be working, while the other may be stuck. That will stop the wheel, but not very well. If the cylinder does not retract fully when  pressure is released you can see right away that it will have to be rebuilt.

 Tech Tip: Stuck pistons can be forced from cylinders by air pressure. Clean the cylinder; remove
 corrosion in the exposed bore. Use an air nozzle to force air into the cylinder, covering the open end with
 a rag to prevent damage from flying pistons.


A Plug for Calipers

When rebuilding disc brake calipers, your shop manual or other service instructions probably recommend removal of the pistons by using pressure from the hydraulic system. This method is not only messy, but inhibits the work by allowing removal of only one piston at a time. It also forces you to work on the caliper under the confines of the fender while it is tethered to the chassis by the brake hose.

However, there is an alternative mechanical method which permits removal of both  pistons at once, while allowing you to do the work off the car. Remove the caliper  assembly from the car, disconnecting the hydraulic hose at the caliper. Determine the  inside diameter of the caliper piston, then visit the hardware store and find a  plumber's "test plug", or try the auto store for the rubber plug used to replace the steel expansion plug in a cylinder block core opening. Both are rubber sleeves with concave washers at each end and a center bolt used to compress and swell the  rubber sleeve. Choose one of a diameter as close as possible to the piston bore.

Now cut a piece of 1/4" x 1" steel strap about 6" long and drill a hole in the center that will fit the bolt in
the expansion plug. Install the strap on the center bolt with the nut finger tight and cut off the bolt flush
with the nut.

Insert the plug in the piston bore, install the strap and tighten the nut securely to cause the plug to grip the
inside of the bore. If the plug should prove too small to expand enough to grip the piston, securely wrap a
few turns of rubber tape around it until it is large enough to grip as needed. Rubber tape is far better than
plastic or electrical tape because it will expand with the plug, having good friction characteristics.

Once the plug is tight in the bore, grasp the caliper and tool assembly with both hands, placing the thumbs on the back of the opposite cylinder and the fingers around the strap. Squeezing the hands closed will extract the piston from the bore. Then repeat for the opposite side. Either this tool or a C-clamp can be  used to install the pistons following the rework.



Tightening Bleed Nipples

It is a very common fault to find  brake bleed nipples over-tightened (sometimes to the point where they shear or crack the alloy casting). Girling states that "a torque of 4 to 6 lb. ft.  should be applied, which is sufficient to lock the bleed screws up without damaging the orifices of the ports. If the orifice has been enlarged and the  tell-tale black ring can be seen on the conical seating, then this is a sure sign  of over-tightening."


Brake Cylinder "C" Clip Installation Made Easy

There is easier way to install the large "C" clip that  retains the rear wheel brake hydraulic cylinder of the  in place. With the wheel and the brake drum off, you will see that the axle flange sits almost directly above the hole through which the slotted "neck" of the wheel cylinder is  installed. Clamp a large vise grip wrench to the bottom of the axle flange with the  head of the wrench pushing against the wheel cylinder (as shown), and you will now have your own two hands free to install the "C" clip.

The concave side of the clip is positioned against the inner side of the brake shoe backing plate. Insert one flanged end of the clip into the slot of the wheel cylinder, followed by the middle  flange. Use a flat screwdriver and hammer to ensure that these first two flanges enter into the circular slot  of the wheel cylinder.

The screwdriver is then used to lift/pry the third flange of the clip up and over the neck of the wheel
cylinder to snap it into the circular slot. Check that all three flanged areas of the clip are fully within the
circular slot, and voila, you have completed the job with no damage to the "C" clip itself, and almost
faster than it takes to read this how-to-do-it.


Brake Adjustments

Adjustment of most British brake systems is a simple operation which should be done regularly. The
general method is to turn the adjusters clockwise until the shoe comes up against the drum, "clicking
back" until the wheel turns free. Most manuals recommend one click to free the drum, but two or more
are usually needed. Rotate the wheel by hand to check the adjustment. A slight "scuff" is permissible, but
no drag must be present. Check the drum for concentricity if the adjusters must be backed off an
excessive amount. On twin cylinder systems, adjust each shoe in turn.
It is advisable to remove the brake drums at least once each year to inspect the linings and drum surfaces.


Routing the Safety Brake Cable

All Morgan hand brake cables are the same length.  The cable is routed over the crossmember at the back of the transmission then UNDER the left transmission mount leg then in between the body of the transmission and the end of the mount ear.  The cable should then be more then long enough to reach the safety brake junction.
.
The brake shoes are pulled off by the shoe return springs that are inside the brake drum when the hand brake is released.  There is  no other return spring nor is one necessary.

There is supposed to be one cable clamp that holds the cable to the left battery floor as it comes out of the drive shaft tunnel and before it reaches the attachment on the rear axle.  The cable passes over all the crossmembers.


Maintaining Wire Wheels

One of the less popular aspects of wire wheels is that they tend to go "out-of tune" and need occasional
straightening (or "truing"). This is caused by the spokes stretching and by the spoke holes wearing, both
of which result in a change in spoke tension. This causes the rim to run out-of-round.

Consider that the weight of the car is suspended on the few spokes that are uppermost in each wheel and
that they are constantly moving into and out of this weight-bearing position when the car is moving. Add
side loads from cornering and you can understand the stresses that cause the spokes to stretch and move around.

A wheel which is tuned to run true may be kept this way by a monthly checking of spoke tension. Run a pencil around the spokes and note  whether any make a sound which is markedly lower in pitch than the
others. Tighten these "flat" ones with a Moss spoke wrench (#385-800) and you will maintain the wheel in a nice, round condition.


Old Wire Wheels

If your wheels have not been trued for some time, simply tightening the "flat" spokes will not necessarily
make them run true. You might just tighten them permanently into their buckled condition! An old wheel
should be properly trued to eliminate radial and lateral run out before being put on the monthly
maintenance program. see Tuning Wire Wheels.


New Wire Wheels

When the wheels are assembled at the factory, they are laced so as to be within factory tolerance for
radial and lateral run out. Since the hubs, rims, and spokes are new, this tolerance can be achieved
without the spokes necessarily being tensioned evenly! Result? When a new wheel is subjected to a load,
it may go slightly out of round. Even when the spoke tension is correct, some settling will occur during
the first couple of hundred miles, as the spokes and nipples bed into their seats. A good practice with new
wheels, therefore, is:

A)  Check spoke tension before mounting new tires. Tighten any loose spokes, check for excessive run
      out and remedy by tightening appropriate spokes.

B)  Drive gently on new wheels at first, allowing them to settle in without severe stress.

C)  Re-check spoke tension and run out after new wheels have been used for a couple of  hundred     miles or so.

Following this procedure, and remembering to clean and re-grease the hub splines every 4-6 months, will
give you years of trouble-free life from your wire wheels.


Dissolving Hardened Wire Wheel Grease

Because servicing them is a dirty job, wire wheels are perhaps the most neglected components on a
British car. Many times I've bought or worked on a car and found it nearly impossible to remove one of
the wheels! This is likely due to very hard, dried-up grease which essentially freezes the wheel on.

I've heard about many techniques for removing stuck wheels with torches and chisels, and even trying to
drive around without the knock-offs installed to loosen the the wheel. Before resorting to such drastic
measures, try using a can of carburetor cleaner to dissolve dried up grease. Jack the car up, remove the
knock-offs and spray well up into the cavity between the wheel hub and the splined extension, The carb
cleaner will dissolve hardened grease in short order.

Be sure to place a pan or tray under the wheel to catch the dissolved grease and carb cleaner. Let the
carb cleaner soak in for a few minutes and repeat the process while wiggling the wheel around to help
break up hardened grease.


Remounting Knockoff Wheels

The second most frequently asked question about our cars must be "how do I take care of my wire
wheels?" "Should the car be off the ground to hammer the knock-off, or should the wheel be on the
ground?" Well, that's two questions, but the problem remains...Whether you call it a knock-off, a
knock-on, a nut or a locknut, BMC felt inclined to issue a Technical Service Bulletin on the matter. In
short, you should always hammer the nuts on or off with the wheel off the ground and free to rotate.
While they don't say so, many people believe this will decrease the force transmitted into the spokes from
each blow. If the wheel is not free to turn, then the spokes take the full brunt of each hammer blow.

The rest of the information is definitive! If you do as BMC says, your wheels should last much longer
than if you don't. How many of you have had to hacksaw off a wire wheel, as it had become rusted to
the hub? A few of you have. So inspect, grease, and check your wheels at least once a year, preferably
before the rainy season. As an added precaution, why not use an anti-seize lubricant that comes in a large
can with a brush in the lid. One can should last a lifetime and isn't all that expensive at a local auto parts
store.

One final word, don't forget to use RTV silicone inside the wheel hub on top of the spoke heads - to seal
out water and prevent grease or anti-seize lubricant from being spun out onto your spokes and wheels.
Several of us have used this technique for years and it works great!


Index