I've been researching doing a disc brake swap for my 1958 Buick, and this is where I'm starting to collect all of the technical info I've been able to glean. For the rotors and calipers, there are three basic approaches I've learned of plus one that is a research-in-progress, each is detailed below. There are also master cylinder, power brake booster, and proportioning valve concerns - they are listed below as well.

Kit from Scarebird Mechanical

I stumbled across this place at a local swap meet and talked a good bit with the owner who is a very nice fellow. They have a decent website up with details - check out http://www.scarebird.com/ and they have their kits on eBay as well. The kit includes a custom caliper mounting bracket plus details on specific rotors, calipers, pads, and brake hoses to use. This kit does not require welding. The cost is currently $115 and appears to include any shipping fees.

The basic approach is to use a custom caliper bracket with later model GM calipers and a set of rear brake style rotors that slips over studs mounted to your original drum brake hub. You drill out the rivets that mount the drum to the hub, mount modern style studs in the hub, and slip the rear brake rotor over the studs, just like you would do on a rear brake car. You may need to machine the hub once to get the rotor to fit over it and sit properly, but other than that one-time machining job, everything is a bolt on.

Kit from Mike Pemberton

I originally hadn't found a website for this, but Mike had posted various details online and I've emailed him a bunch for details, as well as talked to him on the phone, and he is a nice fellow. Various websites I found with Google listed his contact information - I was searching on "mike pemberton disc", "mike pemberton brake", etc. to find out more about this. The best details I found were here. I emailed him and talked to him a bit, and out of the conversation, I ended up creating and hosting a website for him - check out Disc Brake Mike for all the details. His kit includes a custom caliper bracket, plus details on specific rotors, calipers, and brake hoses to use. This kit does require welding. The cost is currently $195 and includes free shipping to US addresses.

In this case, Mike has found a specific rotor and hub setup that will work on the original spindle, and it appears no machining is required. If true, this would be good because it would (hopefully) allow you to convert to the more modern roller bearings in place of the older (and hard to find) ball bearings. He has good coverage on various years in this era for Buicks and Oldsmobiles. Not only am I going to get one of his kits, I liked his business enough to make him a website! :-)

I've received some email from Joe Braun who read this  page and was in the process of installing Mike Pemberton's kit plus a custom dual master cylinder and power brake booster setup on his 1957 Buick. Joe was kind enough to give me details about the swap and take a few pictures which he has graciously allowed me to post here. The photos of the master cylinder work are below. He did mention that he ended up using different hoses than what was specified because the original ones were too short in his application. He said late 70's Chevette front brake hoses were a bit longer and worked out well for him.

Joe says that the calipers and rotors went on quite easily with this kit and has high praise for the kit.

Kit from RRS

I found this while searching about online a while ago and they have a decent web page about this conversion. It claims 1961 and up, but I've seen reports that this kit will fit back to 1957, though you should contact them and be sure before you buy anything. The kit is pretty expensive, and is shipped from Australia, but it is also the most complete of all the options. It includes the caliper brackets, calipers, pads, hoses, custom machined rotors, and all hardware to complete the conversion. This kit does not require welding. The cost is currently $1875 and includes shipping.

The only potential hitch here is the custom machined rotors. They are a wear item, and will need to be replaced eventually. Having to order new rotors all the way from Australia is a bit of a disincentive for me, and so is the price.

Research-In-Progress

I found this info through a friend who was contemplating creating a kit. He claimed that the front rotors from a 1969-1978 Cadillac Eldorado or Oldsmobile Toronado (Hollander interchange #1298) and calipers for the same (Hollander interchange #177), and a custom caliper mounting bracket would get the job done. This may be the same rotor Mike Pemberton is using - I'm not sure yet. I have no idea what the brake hoses would be as of yet, though I suspect they all would end up using similar hoses.

Kit Comparisons

Rotor Size

It looks like the Scarebird kit ends up with an 11" rotor, and the RRS and Mike Pemberton kits end up with a 12" rotor.

If you want a more powerful braking system that can take more abuse and stop better, going with a 12" rotor could be worth it. For me, I won't be road racing my 1958 Special, but the added braking power in a panic stop is nice to have. Your interests and mileage may vary, though, and I wanted to mention it here. For example, the later model Riv's are much heavier than my Special, and if you do any spirited driving in one of them, you may very well require the added braking power that a 12" rotor provides.

Cost

It looks like Scarebird is the cheapest, followed by Mike Pemberton, followed by the RRS kit. Mike's kit seems to offer the best balance overall of price vs. performance, and Mike is a car enthusiast just like the rest of us, so I really like to support that.

Calipers

Both the Scarebird and Mike Pemberton kits use factory style single piston floating calipers from a 1970's era GM. The RRS kit uses a dual piston floating caliper from a 2004 Pontiac GTO. In terms of performance, the 2004 Pontiac GTO caliper likely gets the edge, though I'd be skeptical if most folks will ever notice the difference.

Master Cylinder and Power Brake Booster

This swap generally requires the use a modern dual reservoir master cylinder and power brake booster arrangement, which in turn requires custom brackets to mount it to the firewall. Some folks say you can get away with running the original single master cylinder, but I think that's playing with fire. You really have to keep an eye on the fluid level and add more fluid as the pads wear - disc brakes consume much more fluid behind the pistons in the calipers as the pads wear - and that's easy to forget and leave yourself with no brakes.

I believe all of the later model GM power brake boosters and master cylinders use a common mounting pattern, so fabricating mounts for one will suffice for all of them. This is important because the simple first step would be to convert to a modern dual reservoir master cylinder and power brake booster setup for drum brakes, and then to later convert to a disc brake setup, this focusing attention on one simple piece at a time. It also helps that I happen to have a complete master cylinder and brake booster setup sitting around from both a 1970 Electra with 4 wheel drum brakes and a 1973 Electra with front disc brakes and rear drum brakes, so I can afford to do this one piece at a time to verify what works and what doesn't. :-)

I've received some email from Joe Braun who read this page and was in the process of installing Mike Pemberton's kit plus a custom dual master cylinder and power brake booster setup on his 1957 Buick. Joe was kind enough to give me details about the swap and take a few pictures which he has graciously allowed me to post here. The photos of the rotor and caliper work are above.

Joe opted to remove the air plenum entirely in his conversion and replace it with a flat piece of 16 gauge steel cut to be the same size and dimensions as the base of the air plenum. Joe said that in his case, the original 1957 Buick master cylinder refused to come off until a Sawzall was used on it, so salvaging anything from the original mounting was not possible. He took this opportunity to create a custom access hole in the firewall to get at the power brake booster mounting bolts from the interior side. (I gotta hand it to him for taking the lemons life handed him and making lemonade! :-)

I would be a bit concerned about the 16 gauge metal flexing under heavy braking, but Joe said it's working fine for him so far. I've heard horror stories about fatigue cracking the firewall over time in disc brake conversions on early Mustangs, especially power brake conversions, so I'm really leery of how the power booster is installed. In later GM models, the factory tied the booster mounting directly into the brake pedal support assembly (which also holds up the steering column), and they became one large assembly with the firewall sandwiched in between the booster and the pedal support bracket. The firewall could not flex independently of the brake pedal bracket flexing or moving in relation to the firewall, an unlikely occurrence.

Below are some scans of the notes I made on booster dimensions and how to build a custom adaptor plate to mount a later model power brake booster in the original location. I used a 1969 Riviera booster as the basis for my "later model" booster dimensions. The one possible hitch here seems to be the need for the very long pushrod for this to work. Some boosters have a threaded end on the pushrod to allow for adjustability, and I can use that to add an extension to the pushrod. The problem is that none of the Buick boosters I have laying around use the threaded end. My Suburban appears to have a booster that uses the threaded end on the pushrod, but it uses some very tall brackets to allow the booster to "stand off" the firewall to clear some things. I need the threaded pushrod end without any standoff brackets. It looks like I'll have to do some parts hunting to find one that will work right. Master Power Brakes makes aftermarket units that look good for this, but they are brand new and thus much more expensive than a remanufactured unit at the parts store - $200+ vs. $80-$100.

I compared my pictures and notes to what Joe Braun did for his 1957 Buick, and it appears that on the 1958 Buick there is much more room and that extra room makes it look like it's possible to do this without removing the original plenum as Joe did. I haven't tried it yet, so it may or may not work, but so far the planning looks favorable to not having to modify the actual firewall. If the plenum turned out to be too thick to make this work, my next ideas were to mount the booster right to the adaptor plate (and drill holes in the plenum to make it work) and thus gain another 1" to 1.5" of clearance. If that wasn't enough, next up would be to create a "recess" in the plenum that would allow the booster to sit back further - all the way to making it flush against the firewall behind the plenum if need be. This would still provide a way for some air to flow into the plenum and thus into the car for ventilation. I would still need the adaptor plate, and I would have to modify the plenum extensively, but I do have a "spare" plenum laying around so this isn't such a bad thing for me. This might not gain me much clearance, but then again, it might be "just enough" to make this work if space turns out to be really tight.

Hydroboost Brake Booster

This is a a new idea I'm messing around with to see if it will work. Many GM trucks, especially newer ones, came with what is known as a "Hydroboost" brake booster instead of a more traditional vacuum operated brake booster. The hydroboost units use hydraulic power from the power steering pump to provide the extra braking boost. They are smaller in most dimensions than a vacuum booster, though they might be a bit longer than some vacuum boosters. They mount to their mounting plate with a single large nut, which is a possibly large advantage for this conversion - if that nut will fit into the existing triangular opening in the plenum on the '58, and I can make a custom mounting plate for it, and I can somehow create an extended mount with a nut on the end, much like was done on the original 1958 brake booster, then this could work out reasonably well without any cutting of the factory parts being required. I'm trying to get a junkyard Hydroboost unit out of an 1990's Astro van (or the like) to compare to the 1958 parts I have sitting in the garage to see what might work here.

The Hydroboost units use a standard GM master cylinder, so there are no issues there.

There is the issue of running more hydraulic hoses and using the original power steering pump in a way it was not really intended, but it could work. I've seen lots of folks say that the Hydroboost units should use ATF instead of power steering fluid, and the 1958 power steering system uses Type A ATF fluid, which has been (more or less) superseded by later Dextron ATF fluids. That means that I should be able to use Dextron ATF in the existing power steering system, and it should be compatible with the later model Hydroboost system. I would have to modify the hydraulic lines, but I can save the originals and make up new lines "just in case" I ever want to return the car to stock condition.

Proportioning Valve

I have not sorted out the proportioning valve and plumbing needs, though it's reasonably obvious that the plumbing between the master cylinder and the proportioning valve would need to be custom bent and flared hard-line. Some folks say a proportioning valve is not needed, but I tend to not believe that. An adjustable unit would seem to be the best choice.

I would also like to use a later-model warning-light-equipped combination valve as a starting point since it adds the ability to hook up the existing parking brake warning light just like a later-model car. After all, if half of the braking system fails, you really want to know about it right away via a big red light coming on inside the car. To do this, either get a factory-style unit that does not have the proportioning valve in it, or simply take it apart and remove the springs and such that form the proportioning valve part of the assembly. Then you can mount an aftermarket adjustable valve in the rear brake line after the combination valve.

Comments? Kudos? Got some parts you'd like to buy/sell/barter/swap? Nasty comments about my web page so far? You can email Mike or Debbie.

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Page last updated 01/02/2009 01:51:39 PM