1st Gen bolt in brake swap. Thanks to Bob C for the info...
Donor cars: 1969-1972 (possibly '68 too) A-body, including Chevelle/Malibu/Monte Carlo, Cutlass/442, Skylark,Tempest/LeMans/GTO/Grand Prix. Earlier cars are likely to have the 4 piston caliper, which is more expensive to rebuild. Later cars ('73 and up) have a redesigned spindle that won't work on a 1st gen. F-body.
1968-74 X-body, Nova, Apollo, Ventura/GTO,Omega. Again, 1975 and later cars were fitted with an incompatible spindle. Don't go there.
Forget Cadillacs or any of the big B-body cars like the Bonneville, Bel Air, Century, Olds 88/98, etc. Their spindles are too tall, and they are 5 lug on a 5 inch bolt circle most of the time.
Parts from the above qualified cars needed for the swap:
All of the above with the exception of the spindles, caliper bracket, and dust shield, can be used as trade-in cores for new or rebuilt parts from your favorite parts store. Tell the clerk the parts are for a 1969 Firebird, which is the brake system you are recreating here.
Drum brake spindles won't accept the disk brake calipers without machining. Some aftermarket disk brakes, such as Wilwood, use the drum brake calipers for their setup. If you go that way, keep your drum spindles.
Check the spindles for any scoring or other damage on the bearing load areas. Bunged up threads are unacceptable as well. A number of restoration houses such as Classic Industries and National Parts Depot are selling new spindles just in case you can't find anything affordable. They can also provide the caliper bracket, the other hard to find component. Dust shields are also being
Don't pay too much for used parts as most everything will old and worn, and very likely only useful as a core exchange item. Some of the new GM conversion setups on eBay look reasonably priced, and the parts are all new. Just be sure that they are stock replacement parts and nothing kluged together from unnatural sources. For instance, some of the dropped spindle kits use 1978 and later G-body (Malibu/Monte Carlo/Grand Prix/etc) calipers and rotors. These may not perform as well as the earlier A-body stuff, and some of the rotors use metric lug nuts and other hardware.
Also be sure that the kit includes a master cylinder, booster (if needed), and the combination valve. You don't have a complete brake swap kit without these parts.
Parts from your car to keep: 1. Steering arms (1st gen F-bodies are rear steer cars, as are the above x-body cars. A-body cars are front steer. This means that the center link and tie rods sit to the rear of the center axle line. Bolt your F-body steering arms to the A or X-body spindles, and you're good to go.
New parts to buy:
1. Brake Pads 2. Front flex hoses (from hard lines to the calipers). Do not, I repeat, do not use old, used, nasty, cracked, and spongy hoses. Always buy new hoses. Is your life or your car not worth the 20 extra bucks? 3. DOT 3 or better brake fluid (avoid silicone fluid as it is very difficult to avoid air bubbles and get a good firm pedal). Believe it or not, the Ford DOT 3 is considered about best non-race fluid around. Get it at your local Ford parts department, and take your Firebird when you go. It will improve the neighborhood. 4. Inner and outer wheel bearings, races, and seals. Get the Timken brand which are superior to anything else on the market. Most of the standard mainstream parts house brands like GMB are so lousy as to be considered junk. If the store doesn't have Timken, then find someone who does. They are that good.
5. High temp bearing grease. Pick your favorite brand. Natural or synthetic. Avoid the cheap stuff.
Again, say that all of the above parts are for a 1969 Firebird with factory disk brakes when you go parts shopping. This will simplify things, and if you ever need replacement/service parts, they are easily found.
No modifications are needed here to the above parts. You may have to rework the flex hose brackets on your subframe, but not very much as I recall.
You may find that some (as in very few) 14" wheels will rub on the brake calipers. I don't know which particular codes will have a problem, so you'll have to cross that bridge when you get there. You might be able to get away with a thin spacer, but you'll have to experiment. All 15" wheels should clear this setup. Disk brakes may push your wheels outward by as much as a quarter inch due to a slightly wider track. If your present tires are very close to rubbing on the outside, the disk brake conversion will make it worse. The stock narrow 205/80-14 or 15 inch tires are not an issue. It's only an issue when you go to fairly wide tires and wheels that this comes up as an issue. Or if you use after- market wheels with a very deep dish.
Check the condition of your hard lines. If they are rusted, kinked, or the fittings are stripped, you are better off replacing them as well. Fine Lines and Inline Tube are very good at getting you the right parts if you think that your master cylinder or combination valve require unique fittings. Both of the above companies are known to bend up a custom set of lines for any special requirements. But you should find that 1969 Firebird disk brake hard lines should work without any difficulty.
Don't forget to bench bleed your master cylinder before putting it in the car. This will make bleeding the entire system much quicker.
Upgrades to the above system:
1. Consider braided steel flex lines. Many are now DOT approved, and they reward you with an excellent firm pedal.
2. Performance pads. A good street compound from Hawk, EBC, or Performance Friction will give stopping performance, little dust, and excellent rotor life.
As usual, be careful when releasing the coil spring in the control arms when swapping spindles. There is a lot of energy in that spring and it's easy to get hurt. And use proper flair or tubing wrenches on the brake fittings. Regular wrenches are sure to round off the fittings and create problems. Sears is a good source for reasonably priced quality tools. Consult your Pontiac shop manual for the details on removing and installing the brake parts. You do have a shop manual, right? They are readily available from any of the restoration parts houses or even eBay, and are essential to any Firebird owner.
By the way. While catching up on some of the recent postings regarding disk brakes compared to drum, some folks have said that drums aren't all that bad. To be sure, on the first hard stop, you may get by with drum brakes. But repeated hard stops will soon teach you the meaning of fade. I remember a particularly exciting ride down a mountain pass in my buddy's '65 El Camino with drum brakes. After the 3rd big sweeping turn, the brakes rapidly began to fade, and each of the following turns involved a great deal of squealing tires and white knuckles.
It doesn't take a high speed road course to push one's brakes to their limit. Just a few hills, or heavy traffic on the way back from the car show. But if you must stick with drum brakes, check out Praise Dyno. They have some very good drum brake components that will really improve performance of the drum system. http://www.praisedynobrake.com/ I've been quite impressed with their products.
also, 69 hose bolts to control arm and enters line above the frame, rather than on the side. do not use the long hose with the drum lines. the correct brackets and lines are available.
Those of us who defend drums don't claim that they are better or equal to disc. I cannot speak for everyone who shares my opinion about drum brakes being adequate. I'm not trying to come off as offensive, but there is a cold hard fact of reality called the idiot factor. If you throw the idiot factor into the equasion, there isn't any room on the highway for drum brakes. The majority of the f/g/f owners aren't plauged by the idiot factor; otherwise, the f/g/f cars would have been cubed, sent over to Japan, melted down, and remolded into rice burners.
The issues of which you mention are easilly solved by driving habits. If there is brake fade in heavy traffic, the idiot factor is coming into play. Under such conditions, I have 2 totally different driving styles between my 4 drum firebird and my 4 disc sts. I noticed that when 3 birds met, there was always a huge amount of room between bumpers. On steep inclines, using lower gears will more than solve any stopping problems. With a slush box, if it's in first gear, the car will almost stand on its nose when you let off the gas.
If you really want to get a taste of drum brakes, try driving through standing water. That the one thing that cannot be easilly solved, and it will give you a major wake up call. One way to make it less of a problem is to drive through the water with a fairly healty amount of hoss on the the brake pedal.
The site looks interesting, but I wouldn't waste my money with any of the products. The shoes, and cylineders don't offer any advantage, other than needing less foot pressure. I have driven the darn things for almost 3 decades, and you have to step on the pedal if you want it to stop.
I also question the validity of the drums based on the semantics. (I know that my freeflow style/spellling doesn't reflect it, but I have a strong foundation in redrick and its inferences.) It says that they are "designed to dissipate" whatever amount of additiona heat. The problem, however, comes into play because it's more than clear that they do an effective job at skirting the facts. There is a big differenc beteen the comment "deisgned to dissipate x-amount" and "reduces heat by x-amount, or dissipate x-amount of heat." The difference is called false advertising, the reason why companies seek people trained in redrick and proofread by leagle experts.
This is a post from Glenn Uettwiller, and as usual he hit the nail right on the head. Kevin
I've gotta tell you, you're right - it ain't that simple. There are many variations to how you can build the system even with "stock" parts, whether you build a 67-68 4-piston fixed-position caliper system or a 69-style single piston sliding caliper. Also, 67 and 68 were available with or without power assist, while 69 was a package setup - all discs became power assist.
I don't know how long you've been on the list, but I know I've detailed the conversion a couple times, and explained the various component's jobs. Maybe I need to check what Geoff's got in the archives for completeness and accuracy, or he can substitute this explanation. This is probably more complete and thorough than any I've done before.
By the way, there were some earlier wheels which were designed before discs were considered, and due to the way the rim and wheel centers are stamped and welded will certainly interfere with the caliper. However, if you get the slightly later wheels, JC for 14x6 and JK, JM, JS and KS for 69 and later 14x7, they should fit just fine.
Brake basics, in order:
Never use copper tubing for brake lines - only steel. Also, all flares MUST be double-flared for strength. If there is a point that must flex between body and chassis, there should be a loop or two to accommodate the flex. Otherwise, metal becomes brittle due to what is called "work-hardening" and will eventually fracture.
There are 2 mounting holes in the brake pedal arm, one for the power booster, and one for the non-assisted cars. There are some slight differences between boosters for A-body (LeMans, GTO, Chevelle, 442, GS) and F-body (Firebird, Camaro) cars. I've actually seen a letter "A" or "F" stamped into the pushrod. There is special hose used for the power booster - 11/32"ID, and rated for vacuum - very hard to find in rolls, but I've found in 18" lengths in packs at PepBoys. It's actually PCV hose.
The master cylinder is actually 2 master cylinders, one in front of the other in one housing. If one system of the brakes should lose pressure, either the forward piston bottoms in the bore, or the rearward piston bottoms on the forward piston. This means the car will at least brake on one axle set using the hydraulics.
The residual pressure valve (there are 2 in drum brake master cylinders, just inside the bore where the lines screw in) are supposed to maintain 5-7 psi pressure to keep the wheel cylinder cup lips sealed in place. You DO NOT want any pressure on the disc brake system (it causes drag, premature wear, and overheating of pads), only the drum brake section. Disc brake master cylinders do not have a residual check valve in the disc brake side, only the drum brake side. One trick for using the old drum master cylinder is to remove the residual valve on the side you've added the disc brake to.
A metering valve (the round device mounted just under the master cylinder on most 67-70 GM disc brake equipped cars) meters the pressure to the front discs, meaning that since discs run zero clearance, and the rear drum brakes must take up some clearance. Method to do this is to hold back the initial pressure to the front discs until the rears start to build pressure, which indicates the clearance has been met. Then the metering valve is over-ridden.
Next component is the differential switch, included in the distribution block. It's also mounted under the master cylinder or just a bit down line from it (at least it is on the 69 LeMans I was working on today) When the system fails as described regarding the dual master cylinder, the resulting loss of pressure offsets the centered valve in the differential switch touching the pin of the contact, turning on the warning lamp on the dash.
The next device, the proportioning valve, does just that - it alters the proportion of braking at the front versus rear axle sets of brakes. A separate proportioning valve would be found in the line going to the rear brakes (not all Firebirds with discs had this - I believe it was only the V8 cars with AC). Method used is to reduce the braking to the rear, since drum brakes actually need less pressure - they are more efficient at braking initially, until they reach their natural limits for heat and the resulting fade problem (also prone to being almost useless when very wet).
GM wised up for the '71 model years by incorporating the differential switch, metering valve, proportioning valve and line distribution block into ONE component. If you knew the proportion was fine for your vehicle in a particular combination valve, this is a great choice. However, most conversion kits are using an adjustable valve to add in line, after the differential switch. That's what I'm currently stuck on for the LeMans, I need to go buy a double-flaring kit tomorrow to install the adjustable valve.
The other issues you haven't gotten to yet are the calipers - make sure they have the bleeder in the correct position. That doesn't necessarily mean they must be at the top, you need to know that the drilled bleeder hole is at the top inside so the air does in fact bleed out. Also make sure the hoses do not interfere with anything at full turn position. The original hoses had little crimped rings to clamp them to the upper control arms. Some later replacements did not have this feature, and if routed well will work fine. The brackets were different as well, where the steel lines met the hoses at the frame, but if routed well, this can be overlooked.
Rotors are generally no big issue unless you're using the 4-piston fixed-position calipers, then you need the RARE original 2-piece units. The original 2-piece rotors were shaped for this, the later one-piece are shaped more like a top-hat, without the necessary recess. The sliding single-piston calipers fit these just fine. I believe there's a special (read that expensive, but cheaper than new old stock) replacement available that accommodate the 4-piston calipers, somebody correct me if I'm wrong here.
Don't forget bleeding basics, such as bench-bleeding the master cylinder before anything else, then starting at the furthest wheel and DON'T have your pedal person pump the brakes or push too hard - just a steady light down pedal, then open a bleeder, close it and holler "up" at your pedal person, leaving a few seconds between strokes. Five strokes or so, then top up reservoir in master, replace lid. Repeat until done. Pumping the pedal furiously foams the fluid, and pushing too hard can lock up the differential switch to one side. DOT 5 is naturally spongy - stay with DOT 3 and remember it has a tendency to remove paint. Wash all spills and splashes away quickly.
