Brake conversion
 

Has anyone ever converted there disc brakes on there honda civic to drum brakes? Drum brakes are have no drag when set properly.

No. However, while disk brakes will always have a small amount of drag (the design prevents you from totally eliminating that drag), you can non-the-less make a HUGE difference in how much drag you get by how you take care of (and how you adjust) your brakes. Sadly, most of the "quick lube" type mechanics do a "brake job" easily/quickly, vs taking their time to do a job that is designed to minimize undesired brake drag!

The last time I needed a brake job (on my Honda CRX), I paid my independent mechanic a little extra to take his time to do the "brake job" right. In addition to changing the brake shoes (which every place does), he also very carefully lubed up the moving parts of the disk brakes and adjusted exactly where the pads touched the disk with the goal of having the minimum drag when the brakes were not in use (a step that many brake places don't do). And since virtually ALL old brake fluid increases problems with brake "sticking" (even if only by a small amount), we also replaced the brake fluid with decent synthetic DOT 3/4 fluid (thereby cutting down on any "sticking", since all "brake sticking" results in at least a little extra brake drag).

And just for good measure (since we had the wheels open anyway, in order to work on the brakes), we also used a grease gun and a hypodermic needle to inject high quality (slick and very sturdy) synthetic grease into the wheel's bearings. While the wheel barrings aren't part of the brake system, they non-the-less are one significant source of drag in the wheels, and so I figured we might as well do something about that as long as the wheel was open (for the brake job) anyway!

Of course, even with all these steps, a disk brake system won't go to zero brake drag, because some drag is inherent in the disk brake design. However, if you properly take care of disk brakes (i.e. properly maintain/adjust them, such as my mechanic did for my car), you cut your "disk brake drag" to a small fraction of what it is with many cars. So while the drag from disk brakes will never go to zero (a little drag is inherent in the disk brake design), it's also true that properly maintained disk brakes (and many quick brake change places do NOT go to the effort to properly maintain the brakes when doing a normal "brake job") makes the disk brake drag pretty low/trivial indeed.

NOTE: Don't underestimate the drag built into the wheel itself (such as the drag in older wheel barrings). Not only can that wheel drag be significant, it can sometimes be larger than the drag from the brake system. So if your goal is to get lower wheel rolling resistance (a valid goal for FE), be sure you also keep the moving parts of the wheel (especially the barrings) properly lubricated. i.e. Don't just look at the brakes, when looking at things that cause the wheels to spin less freely!

Are you talking about the bolts that are inside the bellows at each end of the caliper?

How did he adjust the pads? To my knowledge there isn't any adjustment like you described. The only thing holding the pads in are the metal clips.

Ever had drum brakes fade to pretty much no stopping power? I have. Going down a steep hill. Not for the faint of heart.

I'll trade a couple 1/10ths mpg (if that much) for being able to stop when I need to. If your brakes are dragging enough to cause much mpg loss, they are probably getting hot when you are driving, and there is probably a problem with them.

A better choice would be opposed piston calipers. Single piston calipers have more drag.

Disc brakes CAN be made to be free running (without the pads in permanent contact with the disc) BUT there will be a delay in operation while the pad travels the necessary distance to the disc.

This is the main reason why it is not normally done.
There are others related to costs and brake disc runout but "pedal feel"is the main one.

Oh yeah , there are probably some legal issues as well car makers simply don't want to know about.

On the topic of converting to drums and the fade problems.

Rolls - Royce had drum brakes on the Silver Cloud series which would stop the car
without fade repeatedly until the linings totally wore away. They were self adjusting as well and Rolls - Royce cars are not light cars so the issues can be resolved so long as the makers are willing to put in the development time and costs.
Sadly most are not and a lot of the bad reputation drum brakes had related to poor design and cheap build quality.

Pete.

A drag free disk brake could be made if there was a way to place a small adjustable spring between the top of the two pads to push the pads apart 1 mm more than when they touch the rotor- this is like Pete said- but as he mentioned, there would be a little of the pedal stroke that would be used to take up that 1mm of slack.

You would not want to push the pads/pistons all the way back- then the pedal would go to the floor before all of that slack was taken up

I agree 100%!

Just converted my VX to have rear discs, helps it stop so much better!

If anyone wants some VX brake parts PM me. I'll let it all go for very cheap.

Yeah, the cheap stamped parts on the S15 we had were a real hair tearer, always twisting out of line and screwing up. Not had much problem at all with the rear drums on Marvin, chrysler used a design that had been working well for them for years.


On trying to stop the disk pads dragging, one idea I've had on that was to saw a few 45* notches in the leading edge, to attempt to get a little bit of air under the edge at speed and make them "fly" over the disks. However, this may impair wet braking performance slightly. Was going to round off the leading edge, but thought that might be real bad for wet performance, with just a few narrow slots, they should "squeegee" the water off fairly well still. Wondering if those grooved rotors would be better for allowing air under the pad at speed, while still being good in the wet.

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