Walt Zettner's Brake Upgrade

Walt Zettner's Brake Upgrade
Originally published in the Pontiac Fiero Connection magazine, 4Q97 issue. Reprinted by permission from the author.
Scans of the three required brackets are at the bottom of the article. If, when viewing them in your browser, the top edge is cut off, save them to your pc by right clicking on the link and selecting "save link as.." or by using "save as" while viewing the image in your browser. Then open the file in a local image viewer. The complete scan is in the file.

Whoa! or... Stop That Fiero
By Watt Zettner

Tim "The Tool Man" Taylor and I have a lot in common. More, bigger, better, faster...it is really easy for me to identify with him. Since 1987, I have dreamed of building a V8 Fiero. Last August, a silver metallic 1987 SE Coupe spoke to me. Very clearly, the Fiero told me that this was my chance and it may never come again. I bought the Fiero and over an enjoyable six months period I engineered and installed a 350 small block Chevy with an estimated 448 bhp. Uaargh! Uaargh!

Being the sensible person that I am, I rebuilt the brakes by turning the rotors and installing new premium pads. The stock brakes are OK, but they were not bigger or better than any other Fiero. Uarrgh! Uarrgh!

So I set out, to develop some big, efficient brakes. My goal was not to avoid paying the price for purchasing a brake kit, but to derive enjoyment from using my engineering and shop skills to upgrade the brakes to be on a par with the engine conversion.

The following brake conversion uses mostly off-the-shelf parts and a few simple fabrications. I had in mind using the largest vented discs I could fit under my street wheels, which are Chevrolet Beretta GTU 16" x 7" aluminum. This conversion was done to a 1987 Fiero and all should apply to 1984 through 1987 Fieros, all models. I do not know the compatibility with the changes of the 1988 model year.

In beginning my research for the project, I gathered some initial information from the Internet, including the Fiero List Archives and several very helpful home pages. Most valuable was a Hot Rod magazine on the Fiero Indy Pace Car published in 1984. It gave some strong hints for a starting point on the calipers. Continuing my research, I made friends with the neighborhood Car Quest Auto Parts Store. Telling them about my plan, they became very interested, and provided help the average walk-up customer may not get. I will go into this briefly, because the procedure is universal in projects of this type.

From a high shelf, they produced the CarQuest "Brakes Illustration Guide." The book is a wealth of information. The illustrations are clear photographs, in two views, of literally hundreds of brake calipers, showing all of their basic features. Likewise, there are dimensioned, two-view, drawings of all the commonly used brake discs. Master cylinders are shown in photos like the calipers, with bore sizes listed.

This book is fully 3/4 inch thick with much more information that I reference here. They also loaned me a CarQuest "Brake Buyer's Guide" which ties the illustrations to their years, makes, and models. The book I used were current through 1994. Therefore, this is the latest year referenced in the Bill of Materials. Many of the same parts carry forward to 1996 and 1997.
The search started by scanning the lists of dimensions for the rotor disks. I highlighted some twenty or so models that had the 100 mm x 5 Fiero lug hole pattern. I chose only the vented disks from that group. I settled on a disk number 5354. A check in the Buyer's Guide, showed this rotor is for the rear of the 1989-1994 Chrysler LeBaron and several other Chrysler products. It is 11.260" diameter, vented, with the 100 mm x 5 lug pattern.

A similar search turned up suitable front and rear calipers. The fronts were a no-brainer. 1982-1992 (Note 1) Camaro calipers fit the bill. The rears were a little more difficult. I wanted the front and rear pads to be identical. Having narrowed the choice, I prevailed on the CarQuest owner to arrange for me to visit the distribution center where I could look a three calipers. The features I could not discern from the photos become clear on first hand examination.
The trick was finding a rear caliper to function with the stock Fiero parking brake cable arrangement. some people mistakenly rationalize that they never use the hand brake, therefore they won't miss it. Definitely you should retain the emergency brake function.
The rear Camaro units that correspond with the front do not work because one cable would pull forward and the other aft. The Fiero requires that both pull to the rear. 1980-1985 Cadillac Seville calipers met the requirements. Be careful that the calipers you get are marked with casting numbers 020 and the other with 021. They are mirror images of each other in that one is a right and the other a left. In our application, the sides are reversed. We will re-use the parking brake levers and return springs from the Fiero calipers. No modifications are required.
The master cylinder selected is for late model Chevrolet C/K pickups and Blazer. It is made by Bendix and is of the same family of master cylinders as the stock Fiero unit. To look at the two, they are identical, varying only in bore size. Our choice is 1 1/8" bore to pump more fluid to the larger caliper bores, thus maintaining a pedal stroke equal to the original. Installation is a perfect bolt in replacement.

Using a PC CAD program, designing the caliper brackets was simple. Two designs sufficed, one for the front pair and one for the rear pair. The accompanying drawings show the simplicity. The dimensions are accurate for 11.260 inch rotors. Should you choose smaller rotors, you must make an adjustment equal to difference in the rotor radii. Thus a 10.5 inch rotor would require the caliper to be mounted (11.260-10.5)/2 = 0.380 inches closer to the hub center. The X coordinate distance between the drilled holes and the tapped holes would be reduced by 0.380 inches.

The caliper brackets are flame cut from 3/8 inch mild steel plate. Machining consisted of drilling four holes and tapping two of them, and milling or grinding the 1/8 inch machining allowance from thrust surfaces for the calipers.

The fronts require spacers 1.00 OD x .50 ID x .435 inches thick to align the calipers with the rotor. The rears require a similar space, but only 060" thick. Use a flat washer. The test is to be able to freely turn the rotor with the calipers installed. Misalignment will cause the pads to drag. Your actual spacer thickness may vary, but if by more than a few thousandths, look for something bent or deformed.

At the rear, two "boomerang" shaped brackets are fashioned from 1/4 inch mild steel plate to anchor the parking (emergency) brake cable to the calipers. The two larger bolt holes in the bracket are secured under the nuts on the forward side of the 16 mm strut-to-knuckle mounting bolts. The original washers go under the fabricated bracket. Be cautioned that if you move the strut in relation to the rear hub carrier while the bolts are loosened, you are asking for a rear wheel alignment. If your car's handling becomes strange, or your steering wheel is not centered after installation, then one or both of them moved. Carefully mark the relationship of the parts so that they may be restored to their original location.
The Fiero front rotors must be modified. Take them to a machine shop and have the rotor disk portion "parted-off" in a lathe, leaving the edge of the hub flange about 5/8 inches thick. This gives you a beautiful little hub with no brake disk. The studs are then knocked out and replaced with longer, 55 mm studs. The extra length is needed for the added thickness of the LeBaron brake disk, which is installed over the studs.
While you are at the machine shop, have them put one pass of machineable cast iron weld in the bore (center hole) of your front disks and bore to fit the hubs. You will have reduced the diameter by 0.018 inches. Conversely, the rear rotors need the bore enlarged 0.018 inches to fit the rear hubs.

The tapped caliper bolt holes in the Fiero knuckles and front spindles must be drilled out to 27/64 inches and tapped with a 12M1.50 metric tap. If you are not compulsive, you are free to drill and tap a 7/16 inch English thread. Adjust the tap drill size accordingly. The balance of the job is bolt together and plumbing. The stock rubber hoses are not suitable for a high performance brake system and they are too short. Use the stainless braided hoses referenced in the Bill of Materials.

Caution: During disassembly and re-assemble, refer to the appropriate sections of your Fiero shop manual. If you are not a "brake" person, get help from someone who is. The lives of you and your loved ones depend on the quality of the work you do during this project. Always use jack stands and an adequate floor jack when raising the car. The Fiero jack is for on-the-road emergency situations only.

Check for fit and alignment on each step of the assembly process. Check for clearance of the brake hoses. Use rubber insulated straps to secure them out of harm's way. Turn the steering, full lock to lock, watch for clearance, and beware of "banjo-string" tension on the hoses. Likewise, check for free rotation as you assemble each part, including mounting the wheels. It is embarrassing to finish up the job only to find that your wheels won't turn. I had some minor interference between the inside of my aluminum wheels and the rear calipers, which was corrected by light grinding of the caliper casting.

There is no alternative to a perfect brake bleeding job for good brakes. I recommend a small hand-operated vacuum pump that is sold in the Wal-Mart automotive department for about $20. Start with the right rear caliper (farthest from the master cylinder) and work to the caliper closest to the master cylinder. I suggest draining all of the old fluid and using all new DOT 3 or better brake fluid. Do not re-use the bled fluid.

Perform the obvious driveway slow speed brake checks first. Do several miles of start and stop driving to allow our pads to seat in before you try your 60 mph to zero test stops. I retained the standard Fiero proportioning valve and performance is perfect, with no premature locking up, front or rear.

There are several ways of doing this modification and this is but one. The cost was approximately $600 in parts for all four corners and the master cylinder. My results are very pleasing. The brakes provide a great match for the 448 bhp engine in autocross competition. I hope to be able to provide actual stopping distances in a future communication. In the meantime, I will be glad to provide additional details on this brake modification to anyone interested via e-mail. I may be reached at (email address updated 2/27/2001 - dwc).

Next comes a power steering project for my car.

SOURCES AND REFERENCES:
All of the rotors, calipers, and the master cylinder listed in the Bill of Materials following are manufactured or rebuilt by CarQuest and are available at any CarQuest store. My favorite CarQuest dealer is Mission Auto Parts, 2918 Roosevelt Ave., San Antonio, Texas, 78214, (210) 921-2803. They have a copy of the Bill of Materials for reference. Hint: Shop around for at least a 20% discount for your parts. Work the best deal you can on the cores and/or core charges when buying rebuilt. The core charges for the rear calipers is significant.
(Previously, the adapters were available from Walt's machine shop and were advertised here for sale. Walt has since moved on to full time Fiero work (ok, he sold the shop and retired) and the adapters are no longer for sale. You will have to contract with your local machine shop for fabrication. ed)

BILL OF MATERIALS

See the parts list below.

BRAKE MODIFICATION NOTES

It is possible to reuse the front hoses on the rear (in a pinch), but longer hoses are needed on the front. 1988 front hoses are 2" longer and should work in the front. The braided hoses are probably less expensive.

Wheels: sixteen-inch wheels are required to clear the calipers installed over 11.25" discs. Smaller diameter disks are available at 10.5" for possible clearance with fifteen-inch wheels. I did not research this.

If smaller rotors are used, the drawings for caliper adapters must be altered, i.e., the holes will be moved .5 x (reduction in diameter) toward the center of the hub. (See text.)

Rear calipers are installed reversed from the original Cadillac Seville application to allow the hand brake cables to pull to the rear.

Stock Fiero hand brake cables and return springs are used.

A 1.125" master cylinder is not mandatory, but is recommended to avoid approximately 1" added pedal travel that will result from using the stock master cylinder with the new, larger caliper cylinder sizes.
Click below for various pictorial views:
Front Caliper Adapter bracket Rear Caliper Adapter Bracket E Brake Adapter Arm
Bill of Materials:

4 each Raybestos P/N 7993 11.260" Vented Rotors (rear, 89-94 Chrysler LeBaron)
1 each CarQuest P/N 18-4071 Front Caliper, rebuilt, 82-92 Chevrolet Camaro (note 1)
1 each CarQuest P/N 18-4072 Front Caliper, rebuilt, 82-92 Chevrolet Camaro (note 1)
1 each CarQuest P/N 18-4138 Rear Caliper, rebuilt, 80-85 Cadillac
1 each CarQuest P/N 18-4139 Rear Caliper, rebuilt, 80-85 Cadillac
(These calipers must be identified with casting Nos. 020 and 021)
8 each Caliper bolts
2 sets CarQuest P/N D-154 Disc Pads (Front and rear are same)
1 each CarQuest P/N 2218 Master Cylinder, (92-94 Chev/GMC Blazer/Jimmy) Aluminum, 1.125" bore
4 each 3/16" X 24" Teflon stainless steel braided brake hoses. (Stock hoses are too short)
4 each Earls P/N 600773 .400" Banjo fittings for above
4 each Earls P/N 989534 Female 10mm X 1 adapter ends for above
4 each 1/4" AN-type rubber insulated clamps (to secure brake hoses)
10 each Dorman P/N 610-323 Wheel studs, 12M1.50, X 55mm X 12.67mm knurl diameter wheel studs for front hubs.
2 each Caliper adapters for front, (burned, drilled and tapped 3/8" steel plate)
2 each Caliper adapters for rear, (burned, drilled and tapped 3/8" steel plate)
4 each 12M1.50 X 40mm Hex head cap screws for front adapters.
8 each 12mm or 1/2" Split Lock washers for 12 mm bolts
4 each 12M1.50 X 25mm Hex head cap screws for rear adapters.
4 each 1" Round X .500" X .435" thick spacers for front caliper adapters.
4 each .060" thick SAE flat washers for rear caliper spacers.
2 each E-brake cable housing stops (burned and drilled 1/4" plate)
1 quart SAE 3 or better Brake Fluid
1 each 12M1.50 Starting tap
1 each 27/64 High Speed Twist Drill

Re-used Materials:

4 each Banjo fitting bolts from Fiero calipers
2 each Front hub assemblies, modified with the disc rotors machined off to leave hub flange approximately 5/8" thick.
2 each Fiero E-brake cable return springs.
1 lot Fiero E-brake cables.
Note 1 - 4/6/2002 updated application years
David