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European Car Magazine - GTV6 Project

   

 

Part 4 - Brake Upgrade and Maintenance

European Car Magazine - May 1995

Author - Paul Mitchell
Photos by the author
 

   

Since 1910, when Alfa Romeo began producing performance cars, Alfds engineers have considered braking to be one of the most critical of all performance characteristics and worthy of the extensive attention they devoted to innovative solutions. While Ford was stamping out Model Ts and As, and other European manufacturers were producing cars not much more sophisticated, Alfa Romeo was building 1750cc supercharged dual overhead cam sports cars. These Alfas were fitted with aluminum drums that provided superior braking, which allowed Alfa Romeo to win many Grands Prix and open road races. During this period, Alfa Romeo won several World Championships.

From this beginning, through the 159 Alfetta G.P car and its massive disc brakes, the 2000 Sportiva with its inboard rear drums, and the Giulietta, with its beautifully cast aluminum three-shoe drums, Alfa braking system evolution has been marked with extraordinary capability and innovation.

Among recent Alfas, the 116 chassis cars-the GTV-6 and Milano - certainly deliver on the promise of the past. Their demise in 1986 and 1989, respectively, was not due to any inherent flaws but rather was a economic decision made by the Fiat Group, which had recently purchased Alfa Romeo (along with Lancia, Ferrari and most everything else Italian).

This decision was based on the margin of profit from the production of these models. They were simply too expensive to produce. The large number of aluminum castings associated with an aluminum engine and rear transaxle, the rear inboard disc brakes, and the de Dion tube and Watts linkage of the rear suspension were all very costly items to make, usually found on far more expensive cars. It's just, simpler and cheaper to make front-wheel-drive cars, as evidenced by Fiat's entire line; or the lines of most other manufacturers for that matter. All of the things that made the GTV-6 and Milano unique in performance and personality, and make them fun to drive and own, eventually killed them.

The braking systems of the Milano and the GTV-6 are virtually identical. It begins with a vacuum booster manufactured by Alfred Teves GmbH (ATE) coupled with a simple dual-circuit master cylinder of the same brand, though occasionally one by Benditalia sneaks through. The master cylinder actuates Brembo dual-piston calipers in the front and very unique adjustable twin piston calipers by ATE mounted inboard at the transaxle in the rear. Spinning through both sets of calipers are Brembo rotors. The 116 chassis cars have 10.4-in. vented rotors in the front and 9.8-in. solid rotors in the rear.

 

 

This system is quite capable of handling velocities achieved by the GTV-6, and compares favorably when considering the swept area-to-weight ratio to that of other sports cars. The system is a forthright design requiring little special attention. With the exception of the rear calipers, knowledge of standard braking systems will carry you through most maintenance procedures.

Our testing brought two areas to our attention. First, that the factory supplied 195/60-15 tires provided a contact patch too small to match the ability of the brakes, and that the OEM brake pads, though not bad, could definitely be improved upon.

Having taken care of the tires in our previous article, our goals were to improve upon braking ability substantially, while maintaining safety and full function under all conditions found in everyday street use, such as a panic stop with cold brakes, as well as conditions most people will never experience, such as competition use. We also sought to enhance, or at least not adversely affect, ease of maintenance and reliability. Keep in mind that any ill-advised modifications, such as increasing caliper size without a commensurate increase in rotor swept area, could easily result in Racer X being well on his way to becoming Patient X. Additionally, should any regular maintenance be neglected during hard usage, such as regularly changing the brake fluid, Racer X may well become a familiar face to everyone down at ICU.

To avoid the obvious disadvantages of these concerns, such as orthopedic traction and physical therapy, stay with modifications which you know have been track tested, preferably through constant competition. Those who race wont stay with any modifications that won't help them win, and sanctioning bodies won't allow unsafe modifications. 

 

Modifications

In our testing, we employed a pyrometer and tempilables (an adhesive label which when applied will provide a temperature reading during operating conditions) to determine pad and fluid selection.

It was known beforehand that the OEM flexible brake lines would be replaced with Shankle stainless steel lines. This is a very worthy modification, even for cars which are to have no other modifications. Along with being more resistant to damage, they will provide better pedal feel. To run through our new lines we wanted to select a fluid that provided a higher boiling point than those commonly available. It was known that the brakes would be subjected to very hard use in autocross and club racing. Also desirable was a low hygroscopic rating. Other things in your life may retain water, but your brake fluid shouldn’t.

Much discussion still continues regarding silicone brake fluids. Though essentially non-hygroscopic, silicone fluids contain more air than standard DOT 4 fluids. With up to 15% retained air, silicone fluid can cause a spongy brake pedal feel, though I'm sure many people have become accustomed to this. In comparison, glycol fluids retain only about 5% air. I felt that it was an unnecessary burden, when there are high quality glycol fluids available which provide all the desired characteristics without having to replace all the seals in the entire system, a standard precaution when using silicone fluid in a system which previously used DOT 4. Also, silicone is not compatible with all seal materials, and I was not prepared to find out if the seal in the GTV-6s were of the wrong type.

 

 

A good fluid to use is ATE SL DOT 4 brake fluid (available from Alfa Ricambi of Glendale, California. Alfa Ricambi is also the source of the aforementioned Shankle stainless steel brake lines. Shankle and Alfa Ricambi provide excellent performance and original Alfa pieces, many that may be difficult to find elsewhere, and always priced within reason.). After testing several brands of brake pads, we selected Repco Metal Masters. Another pad we considered were the Ferodo brand street pad. They provide comparable performance and are readily available. The Repco pads provided consistent performance and feel through the full range of conditions we encountered through our testing. Though Metal Masters, like most semi-metallic pads, will cause your rotors to wear more quickly than organic pads, few would argue that the improved performance is worth that small price.

When it came time to decide on what to do with the standard Brembo rotors, we were faced with our most trying decision. Feeling compelled to make some kind of improvement, and with Alfa Ricambi offering cross-drilled rotors which would undoubtedly perform as intended, it was difficult to accept that no changes needed to be made. We have experienced absolutely no brake-fade with the system as it is. So we felt there was no justification for installing the cross-drilled rotors.

Occasionally, other GTV-6 owners report that they are not as fortunate and experience some degree of brake fade during extreme use. Of course, I cannot account for the unknown variables that could contribute to these complaints, but I'm sure that cross-drilled rotors could definitely help ease the pain of these anguished souls.

Though we chose not to install the cross-drilled rotors, we are including removal and installation instructions in our tech procedures for those who may choose differently or require new OEM rotors. Also keep in mind that when resurfacing rotors, a non-directional cut is preferable to a standard circular cut, though not absolutely necessary. Many machine shops are able to perform non-directional resurfaces, often using a flat wheel resurfacer. And remember that Alfa rotors may only be machined once. Minimum front rotor thickness is 20 mm and the rear is 8 mm. Replacing the rotors with new ones as opposed to resurfacing seems reasonable, particularly when one considers the cost of new components, rotor.

At this point, with the rotors off the car, would be the time to replace your front wheel bearings. Though many Alfas pass the I 00,000 mile mark with their original wheel bearings, taking such chances with a car that will be driven hard and quickly would be ill-advised. The substantial amount of safety and reliability gained will certainly offset the small investment in labor and expense.

When undertaking any of these upgrades or maintenance outlined on these pages, keep in mind that along with steering, the braking system is the most critical of all systems in your car. Any repair or modification improperly done will affect safety in an adverse manner that will likely result in injury.

When handling braking surfaces, pads and rotors, prevent these surfaces from coming into contact with any type of lubricant or hydraulic fluid. Pads which have become saturated or even slightly soiled with brake fluid or grease must be discarded. Rotor braking surfaces may only be cleaned with alcohol or a quality brake solvent.

Seals should be inspected for leaks and deterioration, and if any are found, the caliper should be rebuilt or replaced immediately. GTV-6 and Milano rear calipers can only be replaced. Due to the unique construction of the rear caliper, attempting to disassemble them is not advised. When adjusting the rear calipers, following the instructions provided here is essential. When rotating the adjusting screws, care must be taken to not go beyond the adjusting screw limits, which will result in damage to the adjusting screw seals that will cause them to leak, and necessitating replacement of the complete caliper.

The technique for bleeding the rear brakes is unique to these models and any deviation from these instructions will provide an improper bleeding, not ensuring that all air has been removed from the system. To facilitate this procedure, you'll find a bleeding bottle to be indispensable. A simple expedient one may be made from a clear plastic bottle and two 3-ft lengths of 1/8-in. I.D. fuel line. We used a one-liter bottle so that the entire system may be bled at all four corners without having to stop and empty the bottle. Simply poke two holes in the cap and insert the two lines until the ends just reach the bottom.

All pad retention pins and springs should be inspected for rust and damage and replaced as necessary. And never reuse a cotter pin. The following procedures are also found in the factory service manual I and I recommend to every owner that one should be on their workbench. They are available through Alfa Ricambi for approximately $75 and can easily save you that amount the first time it's needed.

Alfa Ricambi can also provide all the items used and mentioned in this article at prices often substantially below your dealer or local parts house.  

 

TECH PROCEDURES

Installation of the Shankle Stainless Steel Brake Line

Begin by withdrawing all existing brake fluid from the master cylinder reservoir with the syringe. Place the car on jack stands and remove the front wheels. Clean the calipers and all fittings to be serviced with brake cleaner and allow to dry. Removal and installation of the lines is essentially the same for the front and rear, so these instructions will cover all three lines.

  •  Using the appropriate fitting wrench, loosen the union connecting the steel hard line to the flexible line at the body.
  • This union will have a nut retaining it to the body. Remove this nut now. Also free the flexible line from the spring retainer on the upper control arm.
  • With the fitting wrench, loosen the flexible line at the caliper and remove the flexible line.
  • Inspect the OEM flexible line and note the rubber insulator in the middle of the line. This will have to be removed with a razor blade and installed on the stainless lines or duplicated with a suitable length of fuel line.
  • Before installing the Shankle lines, rinse the inside of the lines thoroughly with alcohol and allow to dry.
  • Begin installation by reversing the disassembly process, taking care not too over-tighten the unions.
  • Run the suspension through its travel and check for any interference with the flexible lines. If any is found, correct it and check again. Finally, refill the master cylinder reservoir with new fluid from a previously unopened bottle and bleed the system, following the instructions provided here closely, as it is substantially different than the procedures for most cars.

 

Required Tools and Supplies

  • I syringe
  • 13, 14, 15, and 17mm brake fitting wrenches
  • 7, 11 mm box open wrenches
  • 2 - 3 ft lengths of 1/8-in. fuel line
  • I clear plastic bottle
  • 3 pints of brake fluid
  • I bottle of alcohol (isopropyl, not scotch)
  • I can of brake cleaner

  

Brake System Bleeding (Non-ABS):

  • Raise the car and place on jack stands. Remove the front road wheels, rear wheels may remain in place.
  • Beginning with the right rear caliper, remove dust caps and insert lines from the bleeding bottle over both bleeding screws ( have enough fluid in the bottle to cover the ends of the lines).
  • Slacken the bleed screws with a 7 mm box end wrench and depress the brake pedal closing the bleed screws before allowing the pedal to return. Pause a few seconds between each stroke, keep pumping until the issuing fluid is free of bubbles. Tighten bleed screws, remove lines and replace the dust caps.
  • Repeat the procedures for the left rear caliper and move on to the right front and then left front, topping off the master cylinder with fluid before the moving on to each new caliper.
  • Before driving car, pump the pedal a few times to check for a full pedal, if any sponginess is felt , check for leaks, then re-bleed the system.

 

Replacing Front Rotors and Wheel Bearings

  • Using a punch, push through and remove brake pad pins, pad spring and pads.
  • Slacken the two 17mm bolt retaining the caliper. Lift away the caliper and secure it to a control arm, taking care not to stretch or twist the flexible brake line.
  • Take off the hub cover and remove the cotter pin. Slacken and remove the nut and washer. You may now remove the hub and rotor
  • Loosen and remove the two screws securing the hub to the brake rotor and separate hub from the rotor. Installing a new or refinished rotor is simply a matter of reversing the disassembly procedure including the wheel bearing adjustment procedure, outlined below.
  • To renew wheel bearings, remove the outer bearing from the hub, then remove the seal for the inner bearing and withdraw the inner bearing.
  • Using the old bearing cups or an appropriate piece of hardwood, gently tap the new bearing cups in, beginning with the inner bearing cup. Use a nylon mallet. Be sure to press each cup fully home. Heat may be applied to the hub to facilitate the cups being tapped in.
  • Lubricate the bearing cups using a quality high-temperature bearing grease. 50 grams (1.7602 oz) should be used on each hub. Lubricate the inner bearing and install, lubricate the grease seal and
  • install on the hub.
  • Place the rotor on the hub and tighten the securing screws. Install the hub rotor assembly on the axle and lubricate and install the outer bearing with the washer and nut.
  • Tighten the nut to 14.5 to 17.5 lb-ft (20 to 24 Nm and rotate the hub to settle the bearings. Slacken the nut and re-tighten to 3.5 to 7.5 lb-ft ( 0.5 to I Nm), back off the nut 90 degrees and insert the cotter pin, If the nut slot and the axle hole are not aligned, further tighten the nut as necessary to allow the pin to be inserted.
  • Tap the end of the axle with a mallet to settle the beatings and verify that the washer is not locked (ensure the washer can be moved by slight pressure with a screwdriver between the washer and the
  • hub). If the washer is locked, back off the nut 90 degrees and reinsert the cotter pin. Tap the axle with a mallet and check for washer fit again. Bend over cotter pin and install hub cover.

 

Brake Pad Removal/Installation

The following procedures are conducted with the car raised on jack stands and the front wheels removed.

Front calipers:

  • With a punch, tap out the pad retention pins and remove the pad spring. Withdraw the pads. With appropriate tool, slowly press the pistons back within their bores in the calipers.
  • Inspect the caliper seats for cracks and leaks, Rebuild as necessary. Also, inspect the pad retention pins and spring for rust or damage and replace as necessary. If you choose to use an anti-squeal compound on the pad backing plates, apply it now. Also, if new or resurfaced rotors are not to be used, lightly scuff complete braking surfaces on all discs with emery cloth to remove any glazing.
  • Install the pads within the calipers and re-install the pins and spring.

 

Rear calipers.

  • Withdraw the pad retaining pins by first removing the spring clips.
  • Back off the parking brake adjustment at the rear calipers until the cable is loose.
  • The caliper adjustment screws can now be slowly and carefully backed off. The inner adjuster is rotated with a 7mm socket and extension. The outer adjuster requires a 17mm combination wrench and a 5mm allen wrench. It is important not to go beyond the limit stops on the adjustment screws. Stop when resistance is felt. Failure to do so will cause permanent damage and necessitate replacement of the caliper. Once the caliper adjusting screws have been loosened, the pads can then be removed from the caliper.
  • The rear caliper seals should now be inspected for signs of leaks or damage. Leaking or damaged calipers will have to be replaced with new ones.
  • If the brake rotors are not being resurfaced or replaced, the braking surfaces should be scuffed with emery cloth to remove the glazing. When replacing the brake rotors, make certain to remove all of
  • the rust proofing from the brake rotors. Anti-squeal compound can be applied to the back of the brake pads if so desired.
  • The new brake pads, pins, springs, and pin retention clips can now be installed.
  • With the pads installed, it is now time to adjust the calipers. Rotate the caliper adjustment screws leaving a gap of 1/32in. between the pact and the rotor surface. Use a feeler gauge to verify the proper gap.
  • Run in the parking brake cable adjustment until the inner pads firmly contact the rotor surface. Then back off the adjustment 1-2 rotations of the nut until the rotor turns freely.
  • Re-check the pad-rotor gap to ensure that the distance between the pads and the rotors is still 1/32-in. Further adjusting may be required, Once the proper gap is achieved, the caliper adjuster locknuts should be tightened and the dust caps replaced.
  • Pump the brake pedal several times to check- for operation and pedal feel. If anything appears awry, don’t drive the vehicle until the cause can be determined and rectified.
  • After 500 miles of use, the calipers must be re-adjusted. The previous instructions should be followed, omitting the portions pertaining to the parking brake cable adjustment. The importance of proper brake pad bed-in can not be stressed enough. Failure to properly bed-in pads will result in poor braking performance caused by glazing of the pads and rotor surfaces.
  • Accelerate to 35 miles per hour.
  • Using light to moderate pedal pressure, brake to approximately 5 miles per hour without stopping.
  • Repeat this procedure at least ten times, allowing 1/3 of a mile between each brake application.

 

Having done all of these procedures to our GTV-6, the braking performance has been greatly enhanced.