I would guess that most of you on here know that I write articles and stories for Mike Siewert's FSRA bi-monthly newsletter. Although I haven't done much for the last 6 months due to moving to Arizona and being busier than heck. What follows is a reprise of a disc brake article I did for the newsletter some time back. I thought perhaps it would be useful for some since there seem to be a lot of disc brake questions for solid axle cars lately. I am a big fan of disc brakes and make no apologies for using them. That said, I'd probably run drums if I built a particular style of car. A set of well detailed F100 drums on an A modified would do the trick. The right set of linings would give you all the brakes needed for such a lightweight car. Twisty mountain roads or not.... In a small way, a hot rod is like an airplane. You don't have to take off, but you always have to land. Which is . . . most times, very safe. Unless you're unlucky or incredibly dumb, then it becomes the riskiest part of the whole flight and can sometimes end in disaster. For the hot rod, if it's running you don't have to take off, but you always have to stop. Patently obvious, no doubt, but some of the things I've seen, back in the day as well as now leave me wondering. Darwinism at it's finest I suppose. So, the article will comprise 11 parts with photos et al and it's gonna take a while to get it all down. Hang in there a bit before posting if you would. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Le start.... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Front Stoppers Heres the rundown on two different disc brake installations for the solid front axle Fords. One for Camaro discs and one for Mustang discs. With a list of applicable ChryCo rotor part numbers as well. Hot rod parts suppliers for these projects are listed as well as the remaining front end parts and sources are noted. Stock parts are noted as well. Two cars are involved, a 31 A on 32 frame rails and a 32. Both cars highboy roadsters with the 31 being built for the dry lakes and the 32 an everyday street runner. Camaro Discs The Magnum brake kit used on the 31 is the #4475 Econo Disc Brake Kit. It allows GM rotors and calipers to be bolted onto 37-48 Ford spindles with a minimum of additional work. A small amount of grinding on the calipers is required and a small bit of machining or grinding may be required on the spindle nut. The kit includes: A pair of cast brackets to mount the calipers. Two bearing adapters. Two spacers that go between the outer bearings and the stock tabbed washer that fits the keyway and goes under the spindle nut. One spacer per side. Eight bolts and eight nuts to mount the caliper. Two grease seals. Two inner bearing cups/races. Two inner bearings. Note that the kit uses an earlier series of rotor than calipers. Rotors: GM part number EIS #D5214 70-78 Camaro 73-77 Chevelle 73-77 Monte Carlo 73-77 Malibu 75-78 Nova 73-77 Buick Regal 73-77 Buick Century 73-78 Buick Skylark 73-77 Olds Cutl*** 70-78 Firebird 73-77 Grand Prix 73-77 Le Mans 73-77 Tempest 73-77 GTO Calipers: 78-85 Buick Regal 82-84 Camaro 78-85 Chevelle 78-85 Monte Carlo 78-85 El Camino 78-85 Malibu 78-85 Cutl*** 78-85 F-85 78-84 Grand Prix 82-84 Bonneville 82-84 Firebird 78-81 GTO 78-81 Le Mans 78-81 Tempest Additional parts required are the spindle nut, tabbed washer and bearing dust cover. New rotors and rebuilt calipers were purchased at the parts house. The rotors come with 7/16" lug studs already pressed in. The lug stud boss cast into the back of the rotor has sufficient material to drill for larger ½" lug studs, but you will have to remain with the 4 3/4" Chevy wheel pattern. The larger studs are required by SCTA. For street use on a light car like the 31 roadster I wouldnt worry about the larger stud. If GM considers the 7/16" stud big enough for the 3500# and up cars listed there shouldnt be any problems using them on a 2200-2500# roadster. The reason the GM rotors - at least the Camaro ones I have - will not drill for the 4 ½" Ford bolt pattern is that the rotor casting is hollowed out between the Chevy pattern lug stud bosses. The area where you would drill for the Ford pattern is too thin to properly retain the ½" lug studs. Perhaps not a problem with other GM rotors in the series listed for use with this kit. If you can find a rotor thats solid on the back youre in business as far as drilling for a different bolt pattern. I would not be surprised to learn that there is a solid back GM rotor in the series listed. Youll have to grind a relief on one corner of the caliper brake line mounting boss. Pretty self explanatory when you get there and its shown in the Magnum instruction blueprint below. (Front Stoppers was the original ***le.)
Priest's Hat Dust Cover A lobe on the underside of the caliper casting will have to be ground off to clear the mounting bracket. Thats shown on the blueprint as well. Besides the grinding required on the caliper, theres one other small trick that enters into it. Obtaining sufficient clearance between what I call the Priests Hat bearing dust cover and the spindle nut. The spindle nut, tabbed washer and dust cover were purchased right out of the Dorman bolt supply drawers. They are an in-stock item at most parts houses. With the Dorman spindle nut there is insufficient clearance between the outer edge of the nut and the inside of the Priests Hat dust cover. You may be able to find a taller, more standard appearing dust cover that fits, but maybe not. I never did find a dust cover that would fit my stock 50 Plymouth coupe and ended up turning out the brake drums where the dust cover fit and using easily obtained utility trailer dust covers. I ended up turning a 45 degree chamfer on the outer edge of the spindle nut and rounding off the 45 degree corners. I note that parts illustrations for the GM spindle nut have the spindle nut shoulder cut sharply back so it will clear the inside of the dust cover. Purchasing the spindle nut at the Chevy parts counter may be a good idea. Im guessing a genuine GM part would be cut to fit and ready to go. Said Priests Hat dust cover in the photo so you can see what Im talking about.
The Mustang disc brake blueprint shows the later square faced spindles being used with the Mustang Super Bell cast caliper bracket with the notation that a little grinding is required on one of the corners. The round faced spindle is a bolt-on with the Mustang bracket and the Camaro bracket as well. Looking at the Mustang instructions leads me to believe that the same amount of grinding on the later square faced Ford spindles may work on the Magnum Camaro cast caliper bracket. Better check first though. See Mustang blueprint further down the page. Other than that, using the Camaro disc brake kit with Camaro parts has a couple of advantages over using the Mustang disc brake kit. For starters, the Camaro cast caliper bracket is more exposed than is the Mustang cast caliper bracket. Which means if you chrome plate the Camaro bracket a lot more of it shows than does the Mustang bracket. Camaro Caliper & Rotor pic
The Mustang bracket was plated and for the most part its well hidden. Not so with the Camaro bracket and chrome plating it would be a worthwhile expenditure. The Camaro rotor is 10 ½" in diameter and it looks to have more than enough braking power on a light car. The Mustang rotor is 11" in diameter and has a considerable amount of braking power. Considering the flat-out venue the 31 is slated for, I dont see any disadvantage in using the slightly smaller rotor. Overall the Camaro disc brake setup is better looking than the Mustang. Especially so on a highboy roadster. The Mustang disc brakes look ok, but to my eye the less bulky appearing Camaro caliper looks better. One big advantage is parts cost. I paid right around $300. back in 1985 for all new parts. New rotors, caliper, pads, bearings and miscellaneous small parts. That was with a fairly good discount. Note that the cost of the Mustang kit is not included in the $300. price. About the tail end of 1999 I bought roughly the same parts for the Camaro kit. New rotors, rebuilt calipers - loaded, meaning with pads - the outer bearing, spindle nuts, washers and dust covers as well as a few small parts. With the same approximate discount at the parts house as before, the Camaro stuff ran just a touch over $200. The only real disadvantages I can see with the Camaro disc brake kit is the 4 3/4" bolt pattern which may be less of a problem for some than it was for me. Id prefer to have the 4 ½" pattern on both ends, but since a spare tire on a race car is generally not required thats not really a problem. Some brands of wheels may rub against the top of the caliper. That easily cured by a little grinding and probably only a problem when using 14" wheels. Im running 15" steelies on the 31 as you can see and there are no wheel/caliper conflicts.
Mustang Discs The 32 runs 68-73 Mustang disc brakes. These are an 11" rotor as noted. Master cylinder for this installation is a 7/8" bore FoMoCo dual cylinder. These discs and calipers are also found on the 68-69 Comet, 68-69 Falcon, 68-73 Cougar, 68-71 Fairlane and 70-71 Montego. The Mustang disc brake install is made easy using SuperBell's disc brake kit which includes hub and shoulder collars (stepped bushing). The collars allow bolting the stock Mustang rotor to the SuperBell hub. The Mustang rotor has the standard 4 1/2" Ford wheel pattern. The kit installs on 39-48 Ford p***enger car spindles and 39-56 Ford pickup spindles. The blueprint shows the square spindle face, but I'm running the round face Super Bell 37-41 spindles. They do note that some spindles - the square ones I'm guessing - require a little grinding from the bottom of the spindle boss. The area to be ground is shown in the SuperBell blueprint.
Mustang Caliper & Rotor Super Bell makes a nice kit and the whole thing pretty much fell together. As for the so-called safety feature of the through bolt kits, the ones that have the steering arms drilled all the way through so as to use nuts, they look to me to be not necessary. I used Loc***e - blue - as recommended and the steering arm bolts have never come loose. Loc***e makes excellent products and I recommend them highly. Even so, use the correct product for the application. Use the red Loc***e and youre going to need a heat source to dis***emble them. Additional parts required for the Mustang kit: Inside bearing cup - p***. cars - Timken #15250 48-56 truck - Timken #14276 Inside bearing - p***. cars - Timken #15118 48-56 truck - Timken #14130 Grease seal - p***. cars - National #471316 48-56 truck - National #472179 Outside bearing cup - Timken #09196 Outside bearing - Timnken #09074 No difference noted for p***. cars or trucks. Listed below are the FoMoCo part numbers for the small pieces required to complete the package along with quan***ies noted in parenthetics. Rubber bushing - #C8AZ-2B299-A (4) Pad, retaining clip, anti-rattle - #7C8AZ-2B164-A (4) Grease cap - #A8AZ-1131-A (2) Caliper mount bolt w/washer - #C8AZ-2B296-A (4) There is one small Caveat you need to be aware of when you plate, powder coat or paint the disc brake components. Plating the cast caliper bracket doesnt make the ID of the bracket proper small enough to create problems. Powder coating and paint on the spindle itself - at least on the exposed areas - can create an interference problem when the caliper bracket is ***embled to the spindle. Powder and paint will decrease the ID of the caliper bracket to a considerable degree as well as increase the OD of the spindle register about the same amount. Register defined as the step on the spindle that locates and centers the caliper bracket. The register is easy enough to mask off when painting and its also something the powder guy can do before the spindle or caliper bracket is powdered. I chrome plated the Mustang caliper bracket and powder coated the spindle. Which created a problem when it came time for the final ***embly. What I did and I dont recommend it, was to hit the corners of the spindle register with a file. Very carefully as I didnt want to cut into the powder on the face of the spindle and give rust a place to start. Then I used some grade eight bolts to pull the whole thing together evenly. Once that was done, the kit supplied bolts and steering arms were installed. It all came out square and its working well, but I fear the day I try to take it apart is the day Im going to pay for my transgressions. I've read that some think this brake package is too much braking for a lightweight car such as a roadster and it was really designed for heavier cars like fat fendered coupes and sedans. Im not sure where that idea came from. Seems to me the more brakes the better. The non-boosted pedal on the 32 with its 7/8" bore dual master cylinder along with the standard 11" Ford drum brakes in the back make for an excellent braking package. Pedal effort is entirely reasonable and stopping distances are very short regardless of speed. Little brother used to run the very same brake package on his - at the time - 2700-2800# stock framed drag racing Henry J when it was running 125 mph and he could make the first turn off at every drag strip we went to. I expect brake performance for the two roadsters to be very similar. Both cars have the very nice Deuce Factory pedal bracket and brake pedal arm. The 10 ½" Camaro rotor doesnt look to have any particular performance disadvantage as compared to the Mustang 11" rotor. The 31 runs a 7/8" bore dual master cylinder as well. Aside from the 4 3/4" Chevy wheel pattern, the big difference is in appearance. The Camaro brakes are not as bulky appearing and make for a better appearance up front. One small point of interest and perhaps convenience is a better word, the FoMoCo dual reservoir master cylinders can be found with the outlets on either side. The great majority of the Ford products that use this style master cylinder will have the outlets pointing at the transmission when the master cylinder direction is reversed as it is for most hot rod installations. The Torino is the model to get for hot rod use if you want the outlets to point at the frame. This cylinder is available in a 7/8" bore and a similar model is available in a 1" bore. The 7/8" bore master cylinders running sans power booster - which is not needed on these lightweight cars - will have a pedal effort very similar to a non-boosted Pinto. Im pretty sure most all hot rodders know this, but Im gonna say it anyway. Power brakes do not give you a more powerful brake. All they do is lessen the pedal effort for a given situation. In fact, during a panic stop it takes longer for the power brake system to lock up the brakes than it does for a non-power brake system. Reason being, in an abrupt depression of the brake pedal you have to overcome the resistance of the power braking devices. Granted, locking up the wheels is not the way to go in almost all cases, but we all do it during those little surprises that happen when were running in traffic.
ChryCo Discs I have no experience with this installation although I understand it works quite well. Magnum Axles #4450 kit is required to use the ChryCo discs. This kit uses Camaro calipers as listed above in the Camaro Discs listing. Mopar rotor parts number EIS #17032 This particular rotor is found in the following cars: 80-83 Cordoba 78-83 Imperial 78-80 Le Baron 84-85 Fifth Avenue 73-76 Challenger 73-76 Charger 73-76 Coronet 73-76 Dart 76-80 Aspen 73-76 Demon 77-84 Diplomat 80-83 Magnum XE 80-83 Mirada 73-74 Roadrunner 73-74 Satellite 73-76 Duster 73-76 Scamp 73-76 Valiant 82-85 Gran Fury 76-80 Volare Please note that a great deal of care was used in listing the parts numbers and car models that would be good donors. Like always though, when you get the parts and small pieces to finish the job, its going to be up to you to make sure that what you get is what you want.
Brake Pedal Return Spring As long as were talking about brakes, heres a simple return spring setup thats compact, easy to set up and out of the way. You definitely need an external brake return spring so as to push the brake pedal up far enough to obtain sufficient free-play. Without free-play the M/C port that allows make-up fluid into the cylinder chamber proper will remain closed off and not replenish the cylinder chamber proper. As the photos show, theres not too much to building one of these. One thing to note is the spring end has been opened up a touch to wrap around the master cylinder mouth. Dont open the spring end up too much, you want it to grip the master cylinder mouth casting fairly snug.
Exploded view of the M/C return spring The M/C rod that usually comes with the M/C's will have to have the ring sawn off and the end threaded 3/8-NF so the Deuce Factory supplied Heim end will thread on. The threads dont show too well in the photo, but theyre there. Note the shallow step in the aluminum seat that is retained by the nut on the end of the Heim joint. The spring used is a Century product #C-812. These are available at most any well equipped hardware store as well as Home Depot and similar places. You do require a stop for the small brake arm where the Heim bolts. Make it adjustable to allow dialing in the proper amount of brake pedal free-play. Without a stop and depending on how far the pedal comes up, you stand a chance of pulling the brake rod out of the M/C and then no brakes. The stop bracket was made from a piece of 1 1/2 x 1 1/2" x .120 angle, cut about 1 1/2" wide. The rounded piece you see is simply a threaded weld bung with a step in it and it's welded to the stop bracket on the brake arm side. A nut welded to the stop bracket would work just as well. Specially if you machine a step in it. Besides the convenience of a threaded receptacle for the stop bolt, the threaded weld bung or nut needs to go on the outside of the angle bracket due to lack of room on the inside as well as having the bracket well supported. Easily seen in the next photo.
Return spring installed on the partially ***embled D.F. bracket A pair of 1/4-20 stainless allens hold the stop bracket to the Deuce Factory pedal bracket. The base of the stop bracket is threaded to accept them and the bolts just barely stick out of the stop bracket. Short bolts are required because the brake arm will drag on the mounting bolts if they're too tall. Some of the M/C's you get will have a triangular shaped flat spring that seats into a notch machined into the M/C end of the actuating rod. Once inserted, that's it. they get damaged if you try to remove the actuating rod. These do pretty well in the retainment dept., but I'd go for the positive stop bracket instead. Some of the FoMoCo M/C's come with a simple rounded end on the M/C end of the actuating rod. The stop bracket - as noted - prevents losing this style M/C rod out of the M/C.
Brake Light Switch Heres a photo of an easy to install brake light switch. This one installed on the 32 and a similar setup will be installed on the 31. The actuator is a 1/4-20 allen. The brake arm is tapped for the bolt and a plain nut is used for the locknut. The brake light switch is one of the Chevy underdash ones with the arm cut short. I realize you have much wetter weather in the Great North than we do here in Sunny California, but I get caught out in the rain now and then. So far no problems with the - originally destined for interior use - brake light switch. Ive spent a couple of days in the rain with it and driven through a couple blocks of 3" or so deep water on a flooded street and from what I can see the switch never got wet. Granted, slow driving. A bit of a requisite for a fenderless hot rod now and then. Even so, you might need a protective cover for the switch as you guys seem to drive in tougher weather than I do. And for longer. Maybe a smear of silicon glue on the switch would help, but youre on your own here. As far as hydraulic stoplight switches go, they seem to work fine when using regular brake fluid. Using silicon brake fluid will eventually fail the switch. What happens is that the silicon fluid gets past the stoplight seal and into the area where the electrical contacts are and insulates them. Eventually so much pressure on the brake pedal is required to light the stoplights that during normal use you will not have stoplights. At least not until a panic stop when youre really laying on the brake pedal. Look close in the photo above and youll see a zerk for lubing the brake pivot. An important little piece I left out on the 32. I greased it when it went together and forgot to drill and tap for a zerk before final ***embly. Five-six years after the 32 was up and running, I got worried that the pivot or pedal bore was getting egg-shaped, tore it apart and did the zerk bit installation. Only trouble was, this time around it took about three hours to do it....... In case youre wondering, the two different disc brake setups on the roadsters were due to the donation of a Magnum Axle Camaro disc brake adapter kit. This done when the 31 project was nothing more than fodder for a bench racing discussion. The Magnum Axle kit was donated by a friend to get the project started. Once I did a little thinking about it and looked around my garage at some of the leftover parts sitting in there, I realized that a lot of the parts needed for another 455 Buick powered roadster were already on hand. Now that I had a perfectly good disc brake kit I couldnt not build another roadster. The disc brake kit was simply the boot in the backside to get it started. Too far down the line to turn back now. My excuse anyway.......
Heres a photo of the 31. Next step, get the tubing, take it to the speed shop and get the roll cage bent up.
Then the fun stuff starts. Engine, trans buildup, safety equipment install, wiring, plumbing, get the right tires for the lakes, all the stuff you need to go fast. Its taken a while so far and costs havent been too bad to get the 31 to the point where its just about a running street roadster. Hitting the dry lakes though, hitting the dry lakes is gonna take some of that green stuff. Green like in $$$. Like they say, Speed costs money. How fast do you want to go? The answer, as always, in any automotive speed contest is very simple. Faster........ Thats all......... just faster........ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ That was the end of the original article. Written perhaps two years ago. Things change and sometimes the destination gets changed. True in this case, but like always, it's all about the journey. I got the 31 to a point where I had to decide whether I really wanted to run it on the lakes - which would entail a delay for more building and maybe another $3000. - $5000. for a car with a beginner lakes engine. I like the way the 31 turned out and aside from the $$ factor, decided to put it on the street. Albeit with a stronger engine than the 32 runs. The 32 has about 400 HP and is a lot of fun to drive. The 31 should end up around 460 HP - conservative numbers - and be even more fun to drive. Next stop for the 31 will be in my friends shop shown below. We've just about got his new shop up and running and the next steps for the 31 will be to bend up some different - a little bit - cycle type fender brackets for the front end. Not to mention take advantage of the new 4-post hoist to take care of some small details. After that, it comes home for the drive train rebuild, plumbing and wiring. When will it be running you ask? It's a hobby right? What will be will be....
Thanks for the post C9. Perfect timing with the return spring set-up. I'll be installing one on my Model A this weekend.
[ QUOTE ] I'm printing this............ [/ QUOTE ] ditto and please add to techomatic. Great info. Thanks
excellent - I need to get my dust caps and MC cylinder return completed! perfect timing. I like that spring idear - thanks, Tudor
Absolutely fantastic brake tech. First, is it copywrited or can i use it on another hotrod site that gets alot of questions about what your talking about? And secondly, you mention the Magnum kit. Where can one get this kit? Thanx again.
[ QUOTE ] First, is it copywrited or can i use it on another hotrod site that gets alot of questions about what your talking about? [/ QUOTE ] The article is in print in a magazine, but you may post a link to the HAMB on the other site if you wish. [ QUOTE ] you mention the Magnum kit. Where can one get this kit? [/ QUOTE ] Magnum Axles. SuperBell sells a similar kit. Pete and Jakes carries SuperBell stuff and is an ok outfit to deal with. As is Magnum Axle.
Great tech post!!! thanks C9 I work on a spring shop so the spring is easy Need a spring give us a ring
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