Malibudave, thanks for joining the discussion. To be positive, you had some good information. However, I disagree that 1/4" brake lines were stock in a late 70's car. Fred Puhn, a professional engineer wrote in my 1985 edition of his
Brake Handbook that 3/16" tubing was used in "most" modern cars because it "stiffer, lighter, and easier to bend". (I would add that it is also cheaper for the auto makers to buy, and for a collector/restorer, it has less internal surface area to rust and damage the cups and seals.) Puhn noted that the 1/4" tubing is less restrictive of fluid flow, and less likely to get damaged in handling, but were only found on older vehicles. So the 1/4 lines might be useful for off-road vehicles where the lines might get kinked from rocks and debris, or they might be considered as a way to get more fluid to disk caliper cylinder in a modified system that needs more fluid than stock. Why would that be the case for rear drum wheel cylinders? That just doesn't make any sense. The one explanation that I can give is that the fitting nuts from the 1/4 tubing sold for fuel lines fit in the m/c port, so some DIYers saw a way to avoid reflaring a line. I redid all of the lines in a 75 Ford and they were all 3/16", as is every car I can remember. Puhn recommends 3/16" for the entire brake system, and I can see no good reason to change that.
Yes, well why is that since these were originally two different parts? Maybe a guy who has a website about brakes could get an answer from the reman companies and tell us what they are actually selling people, and what they do with the cores that are non-conforming to their intended design?
An opinion is like a belly-button. Everyone has one. A bigger problem is getting one reman caliper that is standard, and a second that is low drag. Most certainly, the traditional will grab first and the car will pull to that side in a hard brake. I had an experience around the time of that Bendix letter I gave the link for when the car did a 180 into the incoming lane avoiding a deer in the wee hours of the morning. Fortunately, there was no one else on the road, but I don't doubt that kind of thing was happening. Not checking the grooves might save money short term, but it would open them up to a nasty product liability class action lawsuit.
So, do you link the link with the Bendix letter is a fraud, or was Bendix wrong? What's your opinion on that? Here's that link again:
http://www.remaninc.com/pdfs/lowdragcalipers.pdf
Here's another link stating that the difference is between a 15 degree grove on the standard calipers and a 30 degree grove on the low drag calipers with diagrams for those who need a better visual:
http://www.idmsvcs.com/2vmod/brakesystem/hydraulic/disassembly/calipers/pdfs/mpbrakes_lowdrag.pdf
For your opinion to be correct, both of these links need to be wrong.
Well, since the reman companies and the vendors won't tell us, we really don't know what's inside the calipers. Since its possible to get the wrong ones for the m/c, or worse yet, a mismatched pair, it makes more sense to buy a new set. Raybestos still makes them new, no core needed, and listed as having "residual drag torque", which I assume is the original standard version:
http://www.rockauto.com/en/moreinfo.php?pk=8467976&cc=2002800&jsn=455
If not, they should be at least a matching pair.
[Edit to note that a series of small changes to a hydraulic system can have a negative sum result, or could multiply small problems created by each.]
Thanks for stopping by Clutch. When you get a chance, how about peeking under the hood and tell us what size the brake lines are coming out of the m/c?
