Those of us with one of the 61-63 F-85/Cutlass/Jetfire cars know that the go-kart sized drum brakes are kind of marginal. Ever since I got my 62 wagon, I've been working on a four wheel disk brake conversion that retained the 4 x 4.5" wheel bolt pattern. Yes, I know Scarebird sells a bracket for this, at least for the front, and while I'm sure it's a good product, I've never been thrilled with it for two reasons. First, I wanted to retain the vintage 14" aluminum slot mags I have on the car currently, and even hoped to be able to run the optional factory 15" steel wheels with dog dish caps (the standard 13" wheels are a lost cause unless you settle for 9" rotors). Second, I've never been a fan of any aftermarket disk conversion that used a flat plate mount for the sliding caliper. I know lots of kits do this, but as an engineer, I realize that the factory brackets are designed to react the braking loads from the outer pads; without that, all this load goes into bending the caliper mounting pins, which were never designed for that.

I've been compiling a fairly extensive list of rotors with the 4 x 4.5 bolt pattern. There are a lot more than you think. Unfortunately, most of them are FWD cars, with very little offset from the wheel mounting surface to the rotor friction surface. For example, here's the Galant rotor that Scarebird uses:



Here's the one I went with for the front:



Note that the offset on this one is about 2", vs less than 1" on the Galant rotor. That pushes the caliper inboard, away from the wheel, allowing more flexibilty in wheel selection. It's also about 11" in diameter, which is about the size of stock A-body rotors. Note that it is only 20mm thick, but vented, and the Saab that it comes from weighs more than the 2700 lbs of my wagon.

Rear rotors I picked are from an RX-7:



Front calipers are from a VW Jetta, and rears from an RX-7, both designed for 20mm vented rotors. The rears have integral e-brake features. The nice thing about most foreign car calipers is that they come with the sliding bracket, so all you have to do is fab a simple steel plate adapter to mount that bracket to the spindle or rear axle flange. Since the factory style sliding bracket is included, all the critical dimensions and mounting hardware are done. The adapter plate is not dimensionally critical and thus easy to make with a cutting torch and drill press.

Since I will retain the manual brakes, I'm likely using a 7/8" master cylinder, maybe even 3/4". The Y-body needs an M/C with right side ports, which limits options a little. For now, it looks like the Ford Granada M/C is the way to go, but I'll need to extract the residual pressure valve from the rear brake port.

There's a lot of work to do, like machining adapter rings to go between the pilot on the hubs and the bore on the rotors, as well as making the mounting brackets. I'm hoping to have this done by nationals. Stay tuned. In the mean time, here are some teaser photos of the front rotors and calipers inside the factory 15" drum brake wheels.

 

-Excellent post, Joe! Any updates, or more details? I'd love to improve my 63 Cutlass manual drums.

 

Unfortunately, nothing yet. I got sidetracked by other efforts.

Still working on this, though. Once the 67 is running I can take the 62 down to finish this.

 

Nice sleuthing Joe.

I'd love to see it when you finally bring it to the Nationals.

One minor point--those who have worked with computers for a long time think disks. But hiding behind those wheels, cars have discs.

 

Sorry, but every single dictionary in the English-speaking world shows "disk" and "disc" as acceptable alternate spellings for the same thing.

 

Yes, it's one of the few words in modern American English that have two equally acceptable spellings, without background connotations.

Only other one I can think of is "grey" and "gray."

There are others, such as "color" and "colour," that are American vs foreign,
and others, such as "catalogue" and "catalog," that are "old" vs "new,"
but "disk / disc" is one of the rare ones that carries no baggage.

- Eric

 

Thanks, Joe! I too have many projects and my 63 is not the top priority, so no rush on this!

 

No offense intended Joe. Just pulling your chain. It's all good.

 

You'll have to try a lot harder than that to offend me.

 

It seems to me that gage and gauge were interchangeable.

 

Not really.

"Gauge" is a word associated with measuring, either as an instrument for measuring, or as a unit of measurement that is inversely proportional to size.

"Gage" is an old word for a deposit, something left for security or pawned.
It is also a word invented by General Motors because they thought their own mechanics weren't smart enough to read English.

- Eric

 

I had a Websters dictionary that I usually keep by my computer (can't find it since I moved), that I used to look it up one time when I thought that someone in print had used gage when they should have used gauge. It gave the same meaning for both.

 

Both dictionary.com (which is based on the Random House dictionary) and merriam-webster.com show different definitions for gage and gauge. The latter is the one we usually mean on this site.

 

The only place I've ever seen "gauge" consistently misspelled as "gage" was in GM manuals.

It's really kinda weird, when you think of it. Why that one word?

- Eric

 

GM has misused "galley" when they meant "gallery" in reference to the oil passages in the block. The Olds CSMs all use "gallery" but other GM manuals I have sometimes use "galley".

FYI, one definition of "gallery" is a long narrow space. "Galley" has no such definition that would relate, despite the fact that it is often used that way.

 

Well... A boat galley tends to be a narrow space, but I doubt that's what they were thinking of.

- Eric

 

Great info, I can't wait to hear an update.