Challenge Questions

Yes, I agree, and Did not even Consider this except in a Half-*ss manner and so I appreciate the Final truth on something I left out and I may have left out even More and some other worthy Contributor or maybe Even Yourself may contribute more to this answer then You Just Obviously Did, and So I left More out then I thought But I learned even more from your answer so I am Glad I left out what I had not Considered cause if I had Considered it I had Not learned in such a Kind Considerate Manner, Thank you for your Kind Manner too,

Not diffrent types! Started out drum ! Some didnt work!So split systems started ! half and half hydroulic systems. then disk and rotors.With drums on the back. all have several difrent types of draking in the drums drums. Then four wheel disk was achived because of the knowledge of applying the parking brake was manufactured into the disk callapier on the back.The real question is why not electric brakes?

I would say the drum brakes are still used on the rear of the car because they are cheaper than the discs up front and only require a lever to make a parking brake. If discs are used on the rear, they would have to build a separate mechanism for a parking brake, adding to complication and costing more money. Drums have more braking surface area than discs, however they are unable to dissipate heat as well, so the disc is more effective in the front where it does most of the work.

I always thought that one of the reasons drum brakes fade worse than disc brakes is that as the drum heats up it's internal diameter increases. This means the brake shoe has to move further to contact the drum.

Just wondering if I'm on the right track.

Lew

The drum expansion is a major factor in brake fade. As the drum expands, the shoes will have to travel further to contact the drum. While the shoes will probably still reach the drums, the brake pedal may travel so far that the pressure required to force the shoes against the drum sufficiently to slow the vehicle can not be reached. in that case, the pedal reaches the end of it's travel before you have developed sufficient stopping power.

Boiling the brake fluid, and friction changes from the brake shoes are also a concern.

You wrote:-

Boiling the brake fluid, and friction changes from the brake shoes are also a concern.

This is seldom a problem with drum brakes, which is why DOT 1 was ONLY for drum brakes.

For disc brakes where there is more heat transfer into the fluid, it had to be made to accept a higher temperature.

There is good info on DOTs and their meaning here.

Good information on brake fluid on that site. Thanks.

Many years ago, there were metallic brake shoes used on police brake packages. There was a warning slip in the replacement shoe box about flushing and upgrading the brake fluid.

take a plastic brake drum, most plastics decrease their length if the temperature rises!

Plastic brake drums are very scarce on the equipment that I see regularly.

I've never seen one before - but they are very cheap!

if the brake drum has to be repaired - the whole cycle has to be replaced, the brake drum isn't really cheaper!

I missed the question in last entry ! The answer is cost to produce.

the Price of Drum Brakes vs Disc Brakes is Really a Factor, and an Important one, Both For The Cost of Warranty Repairs and for Manufacturing plus the Maintaining of Old Relationships with Manufacturers of Car Parts if One is a Manufacturer and has Friendly Regional Relationships they love to Maintain as This affects the Economy of the Region where the Brake Parts are Purchased both For Initial Cost of Manufacture and for Stocking Parts for Future use where Loss becomes a factor and Reuse of Same Parts for Other Models if one wants to Keep costs down for Brakes and Spend more for other Costs such as Environmental Pollution Control Products which are Required both for Unconstitutional Use of States' Environmental Requirements impressed on Detroit like the and Equipment Required on Autos Sold in California, Re: Cafe Standards as Used in California. So Brakes which are Less Advanced so that Detroit may keep costs of some items used in order to be able to meet other Requirements put on them such as Safety and Pollution required by Various Federal Agencies and Even States Laws for Environmental Protection.

At one time cars had drum brakes on all four wheels (eg. my '67 Camaro) Braking was poor, and lock-ups were common. Disk brakes were designed to increase overall braking effectiveness (stopping power, heat dissipation, reliability..etc.) In this arrangement, lock-ups occurred in front before the inferior and less-relied upon rear drums would (maintaining vehicle control). Drums were simply kept because they were cheap to produce, worked fine for their purpose, and because the cable-operated emergency system didn't need to be changed. Later, with portioning valves installed (to maintain front-end stopping power) rear disc brakes were used......at least that's how I see it!

Welcome to the insanity. I agree with you on the comments you made. I believe for a few years rear disc brakes were more of an advertising gimmick than a real improvement. Especially with front drive cars.

Editor's Note: As you've probably noticed by now, the answer to this challenge question wasn't posted on August 4th. We have a good excuse, however. (No, it's not "the dog ate our homework".) The author is on vacation. Hopefully, we'll have an answer when he returns next week.

Oha, he's on the trip to pluto!

...guess we're not going to get this answer.