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How To Rebuild Your Sonett Brakes
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How-To:  Rebuild Your Sonett Brake System
Bruce Turk

(please click on the diagrams for a closer look)

Please note: The following mechanical advice is offered to enhance the overall knowledge of the automobiles owner only. Any and all work described in the following article should be performed by a licensed mechanic only. The author shall be held harmless in the event of injury or accident by the automobiles owner and occupants, should the work be performed by an unlicensed mechanic.

See Bud Clarks brake system interchange data at the end of this article to determine if your car (Non- Sonett) uses the same parts as mentioned in this article.

After twenty plus years your Sonett is probably ready for a complete brake system rebuild. Some of the more common symptoms of a tired brake system include:

If you don’t want to chase these kinds of problems from one end of your car and back again, you should go with a complete system rebuild.  A rebuild of the brake master cylinder is covered here.  Use that article in conjunction with this one for a complete rebuild of the brake system.

Parts List and Availability 
(parts availability may have changed since the time of this writing)

Other Parts Sources

Description

Part #

Retail Price

Caliper rebuild kit   

784913

$13.00 set

Caliper piston   

7323793

$25.00 each

Front brake pads   

8817140

$35.00 set

Front pad clip L.H.   

7323900

$7.50 each

Front pad clip R.H.   

7323918

$7.50 each

Rotor (brake disc)   

7328057

$70.00 each

Rear brake shoes   

8817157

$59.00 set 

Front brake hose   

7395254  

$35.00 each

Rear brake hose   

7285166

$35.00 each

Rebuild kit, wheel cyl.   

7849805

$14.00 each

Rear wheel cylinder   

7328099

$44.00 each

All of the above parts should be available directly from Saab


Motor Sport Service 
1400 East 2nd Avenue
Jamestown, NY  14701
Tel    (716) 665-4200 
Fax    (716) 665-4202

Contact: Jack Lawrence


Ashtech 

4305 Dark Hollow Road
Medford, OR  97501 
Tel    (541) 779-0731 
Fax    (541) 779-0788

Contact:  Jack Ashcraft


J & B Imports 

2296-A N. Batavia Street
Orange, CA  92865
Tel    (714) 282-7378
Fax    (714) 282-0457
Contact:  Bud Clark

 

Keep in mind that the following instructions cover a complete brake system overhaul. Many of the steps can be skipped entirely if only a partial job is being performed.  You will note that I have left out most reassembly instructions from this article. Where no reassembly instructions are given, simply reverse the disassembly instructions.

If replacing the rotors (brake disc), remove the axle split pin (cotter pin) and castle nut before jacking up the car. Jack up the car, remove the wheels. Flatten the ends of the long split pins that secure the spring retaining clips and remove.


DISC BRAKE COMPONENTS FROM MODEL 1967

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Front Brake Disassembly

Pull out the retaining clips; if they are rusty they should be replaced. Pull out the brake pads; note that the friction material is beveled. The new pads must be installed with the bevels facing the same way. The inner pad may or may not have a metal shim clipped over it. Saab added the shims at some point to prevent squeaking. If you’re just replacing the pads, you must compress the caliper piston with a flat bar to make room for the new thicker pads. Be careful to keep the piston square in the bore during compression. Keep an eye on the brake fluid reservoir to make sure that it doesn’t overflow during compression. Helpful hint: If compressing the piston is a problem, open the bleeder to allow the fluid to escape during piston compression.

Caliper Piston Removal 

After removing the pads, pump the brake pedal to force the pistons out of the bore. Have a pan ready under the calipers to catch the brake fluid. If the pistons will not come out completely (they usually don’t), they can be twisted out by hand or blown out later with compressed air. Open the rear bleeders, pump the brake pedal until fluid stops running out. Unscrew the rubber brake hose from the back of the cylinder body just enough to loosen it (1/4 turn). Bend back the locking tab washers on the two bolts that secure the caliper assembly to the driveshaft carrier, remove the bolts. Spin the entire caliper assembly to remove it from the brake hose.

Brake Hose Removal

Working from inside the engine compartment, remove the nut that secures the steel brake line to the back of the brake hose. Now remove the nut and lock washer that holds the brake hose to the inner fender well. Warning-The area above the brake master cylinder is notorious for rust. This, combined with a very confined work area, almost always makes for a less than satisfying experience.

Steel Brake Line Replacement

If the outside of the brake lines have deep pitting or scale, they should be replaced. Even if the lines appear to be all right on the outside, they are often lined with scale or sludge. No amount of bleeding will remove this and it can cause leaking calipers and wheel cylinders over time. To replace the steel brake lines you will need a flaring tool capable of “double flares” and a tubing cutter. Bring your old lines to an auto parts store and buy new tubing of the same diameter and longer in length. Cut the tubes to the correct length after bending them to fit the car. Be careful that the threaded connectors on the new lines have the same thread as the old ones. If you can’t find the correct threaded connectors (I never seem to), don’t worry, just remove the old connectors and reuse them on the new tubing (condition permitting of course). If you have never used a flaring tool before, be sure to have someone with experience give you a few lessons before trying it yourself. The tubing can be bent very easily to match the originals. To prevent kinking the lines, bend them over a hard cylindrical object like a coffee can.  Always deburr the inside diameter of the lines after cutting to prevent flow restrictions. Never bend the lines after they are installed, as this will put permanent stress on the connectors.
 
Rotor Replacement

With the caliper assembly already removed, use a wheel puller to remove the hub (with the rotor still attached) from the splined end of the axle. The rotor can now be unbolted from the hub and replaced.

Caliper Rebuilding

Make a note as to how the two springs that secure the cylinder body to the caliper assembly are fastened before removal. With the springs removed, the cylinder body can be slid out of the caliper assembly. Sometimes a good smack with a rubber hammer is needed. The caliper assembly pivots on a hinge pin, the assembly can be opened up, pivoting on the pin to gain better access to the cylinder body. Clean and lightly oil the area around the pin before reassembly. If the piston is still stuck in the cylinder body, compressed air can now be used to blow it out. Be careful, the piston will shoot out like a champagne cork! If the caliper piston’s chrome plating is pitted or cracked, it should be replaced. Pry out the wiper seal along with its metal retainer. Remove the piston seal noting its beveled edge. Clean out the cylinder body with brake fluid paying special attention to the wiper seal-retaining groove. Install the new piston seal. With the groove facing inward, press the wiper seal inside the retainer. Tap the retainer inside the cylinder body being extra careful not to bend it. Do not hit the retainer directly with a hammer. Place a wood block on top of the retainer to prevent it from being damaged. Saab made a special installation tool for the retainer and you will probably wish you had one. Lubricate the seals with special brake lube or brake fluid. Press in the piston leaving about 1/4” sticking out.

Rear Brake Drum Removal

Tap off the axle end cover using a screwdriver and hammer. Remove the cotter pin, castle nut and washer. Make sure the emergency brake is released, and then back off on the brake adjuster located on the rear of the drum. Using a drum puller, remove the drum.

Brake Shoe Removal

Remove the two spring retainers by grasping them with a pair of pliers, pushing in, and turning 90° to release. Before removing the shoes, note the attachment of the return springs and the position of the friction material on the shoes. You will notice that the friction material is offset to one end of the shoe. The new shoes must be installed the same way. Remove the shoes by forcing the top of them apart, against the pressure of the return springs. This will allow the shoes to be removed from the adjuster mechanism. Pry the bottom of the shoes out of the wheel cylinder while simultaneously removing them from the hand brake link. With the shoes removed, the adjuster should be completely unscrewed, taken apart, cleaned and oiled.
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Wheel Cylinder Removal and Rebuilding
Remove the nut that attaches the steel brake line to the rear the cylinder. Press off the locking clip that holds the cylinder to the backing plate. Tap out the cylinder. Remove the dust covers and pull out the pistons. Using a small two stone hone with plenty of brake fluid as a lubricant, hone the bore just enough to smooth it out. If the bore is pitted, the cylinder must be replaced. Clean all parts with brake fluid. Install new piston seals with the bevel facing correctly. Lubricate seals with special brake lube or brake fluid. Press in pistons and install new dust covers.

Brake Fluid

I really don’t want to start a debate on the use of silicone (dot 5) brake fluid, but I’ll put in my two cents worth anyway. Here are a few facts that you should know about Silicone brake fluid. Silicone does not absorb water like dot 3 or 4. This can help prevent leaky brake cylinders in cars that are stored for the winter. Silicone fluid can make your brake pedal feel squishy. Silicone fluid will leak past worn rubber seals more readily than dot 3 or 4. I would not recommend using dot 5 unless all rubber seals have been replaced (including the ones in the brake master cylinder). All of the old fluid must be bled out before using Dot 5, never mix fluid types.

Brake Bleeding

The One-Person Method

The Two-Person Method

Buy a six foot long piece of clear fish tank tubing. Make sure the tube fits over the bleeder nipples tightly. Tape one end of the tube to the top of a broom handle or shovel. Lean the shovel/broom up against the car near a wheel. Slip the other end of the tube over a bleeder nipple and open it up a turn.  The idea is simple. While sitting in your car you can slowly pump the pedal while watching the brake fluid rise inside the clear tube. The air bubbles simply escape out of the top of the tube. When you stop seeing bubbles, close the bleeder and move on to the next one. Use the same bleeding sequence as mentioned in the “two person method”. Close all of the bleeders accept the passenger side (right) rear. Place a clear plastic tube over the bleeder, put the other end in a clear bottle or glass. Fill the brake fluid reservoir. Two people are required, one to slowly pump the pedal and the other to open and close the bleeder with each pump of the pedal. The tube must be kept in the bottom of the glass, immersed in fluid. When the pedal is depressed the bleeder is open, when the pedal is raised, the bleeder is closed, the “pedal person” must call out “up” or “down” so that the other person knows when to open and close the bleeder. The idea is to get all of the air out of the system. When you stop getting air bubbles move to the left front, followed by the left rear and right front. Don’t forget to refill the reservoir as needed. You probably will have to make the rounds two or more times before all of the air is removed.  Remember, patience is a virtue!

Brake Adjustment

The front brakes are self-adjusting, as the pads wear down the caliper piston moves out, maintaining correct pad pressure. To adjust the rear brakes, jack the wheel up off the ground. Spin the wheel while tightening the adjuster until the wheel stops spinning. Back off the adjuster just enough to allow the wheel to spin. Pump the brake pedal a few times and readjust. New rear shoes will “bed in” quickly, throwing the brakes out of adjustment. Check them again after a thousand miles or so.

Drive it!
So there you have it, not a small job by any means, but then what is, on a vintage Saab! Just one last suggestion, before you rush out and start ordering parts, do a little comparative shopping, you might save a bundle.

 

 Bruce Turk, 7/01

 

The following information was contributed by Bud Clark of J & B Imports. jandbimports@abac.com
Well, this is the way I see it-----all of the GT850 cars, starting in 1962, had the 4 bolt hubs, and dual piston caliper front disk brakes---these were also used on all MC850s and the Specials, and the first 28 Sonetts.  Although the MC850s and Specials went into 1967, only the 1966 Sonetts used this system.  No V4 cars had this system from the factory, but a lot of them are equipped this way now.  

When the V4 cars came out, a new single piston pivoting caliper was introduced---I think it was a cost issue. This is the same exact system used on the all Sonetts, starting with VIN 000029---the first 1967 car.   The Sonett is also the only stroker car to come from the factory with this particular system.  All of the cars mentioned above use basically the same shoes and linings in the rear.  The cars up through 1966 had 3/4" diameter rear wheel cylinders, and a little pressure regulator for each circuit under the rear seat. They are located under the gas tank in the first 28 Sonetts.  After that, the rear cylinders are 5/8" in diameter.  Even though the 95s had the same brakes as the 96s, they used the larger rear cylinder without the pressure regulator through 1969----in 1970, they got the 5/8" diameter cylinders like in the 96s and Sonetts.  

Even though the standard cars had drums on the front, the rear brakes were the same on all models at the time of manufacture---and the cars produced from VIN 135,000-96, and VIN 3131-95 have the same rear brakes----this was sometime in late 1961, according to the parts manual.  The 1964 95s and 96s used the same master cylinder the Sonett used.  1965-1968 master cylinder are the same mechanically, but the brake lines connect to the opposite side.  In 1969, the 95s and 96s got power brakes, and a re-designed master cylinder.  The rear drums on the 96s are the same as Sonetts-----because the 95s use larger bearings in the rear, I'm not too sure if the drums will fit a Sonett. 

Take care, Bud.


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Last modified: February 29, 2016