63 Metallic "Drum" Brake Replacement

[Stuart F.]

Prior to shipping my 63 Vette from Illinois to our new residence Florida, I decided to finally change to Radial tires as I expected to drive the car more and show it less. I went to a Goodyear shop where a Corvette mechanic worked part time in order to get the proper alignment front and rear. While he was in the process, I asked him to let me pop the drums to check the condition of my Sintered Metallic linings. WOW! There it was; at least one pad at each wheel had rusted off a shoe and was just floating in the drum. A number of other pads were chipped and/or disintegrating. So, I knew I had to plan on a brake job soon after moving, BUT! What to use in place of these metal brakes? I asked around at many shows and dealers, even wrote into a couple Corvette magazines. No one could give me a better alternative than to go back to standard brake shoes. I was told by one manufacturer that they tried to tool up to make replacement shoes, but were shot down by the EPA. I finally came across an ad by a manufacturer in Texas that made a material they called "Matrix Ceramic" (they once called it Kevlar, but stopped using that name as it may have been a Trademark issue). I called them and got their literature, and decided to go with their material. They claimed stopping force equal to metal when hot and similar to standard brakes when cold (I liked the sound of that). I talked it around our local 63-65 Vette owners and they liked it too, but left it as; "let me know how they work out for you".

Well, I have finally completely the installation and have had about a 300 mile test with them. It took me a while to get things sorted out; first there were some incorrect parts issues (I changed every thing from the hoses out). They had sent me a couple of incorrect "star wheel adjusters", and I used some new U.S. made replacement drums. These did not work out well as they don't have grooves for the Anti Chatter springs (minor), and they don't seem to engage the backing plate properly (not deep enough {?} for the shoes to seat on the inner braking surfaces). Every time I did an initial adjustment to them, they would work well for a few stops, then start pulling. I replaced the drums because I was told that metal brakes would chew up the original drums, specially with over 40k miles and the pad problems mentioned before. Well, I had my original drums miked and cut. They cleaned up easily, and I now have them back on the car and have got the braking balanced out real good. So far, they meet or exceed my expectations for low speed/cold braking, but I am not sure about the high speed/hot braking as I really have been trying to avoid hard stops for at least 400 miles or so during the break in period. The few times I have been forced into heavier braking (more than I could do with down shifting), they seem to have the same "No Lockup" characteristics, but I'm not sure about brake fade as yet. I also installed a sleeved correctly dated master cylinder at the same time (my original was stolen by a Corvette shop in Illinois), so I am not certain about the hydraulic cylinder sizing, etc. The wheel cylinders from the manufacturer are claimed to be oversize heavy duty (good/bad {?}). I have noticed a little pedal drop under harder braking, but it seems to be getting better as the linings get seated in more.

The vendor for these brakes is; The Praise Dyno Brake company over in Texas. 1 (972) 636-2722 or 1 (877) 606-7867. or http://www.praisedynobrake.com

[Duke W.]

Re: 63 Metallic "Drum" Brake Replacement

The only way I was ever able to get my J-65s close to the limit of their endurance was race track hot lapping. In that environment they actually did the opposite of fade - they became very sensitive and felt like power brakes because the Cf increases when the linings get very hot.

I think it would be hard to even get base brakes to fade in any sort of normal street driving, so I doubt if these kevlar linings will ever show much fade. The base C2 brake system is basically the same as used on the full sized passenger cars, which had curb weights up to 1000 plus pounds higher.

Someone asked about replacing metallic linings not too long ago, and I recommended www.carbotecheng.com I recall one C1 user who was very satisfied with their carbon-metallic linings. I talked to the proprieter on the phone a few years ago, and he was and experienced J-65 user. Normally, one would have to send their shoes back to them to have the new friction material installed.

Duke

[Stuart F.]

Re: 63 Metallic "Drum" Brake Replacement

All the time I was looking for answers about my brake problem, it appears I was looking in all the wrong places. I don't know why, after being a NCRS member since 1996, I never knew about this forum. They stuck a card in my last Driveline saying there was some new features and improvements to this forum and how to log onto it. Surprise!

Thanks for the reference to the other manufacturer, I had noticed your discussion in the archieves as well and read all the discussion with great interest.

I was kinda forced into making my brake change sooner than I'd planned, because the brakes took a quick turn for the worse. Living here in Florida, let me tell you, it is a very important issue to change out your Vette's brake fluid every couple of years. Mine looked fine when I shipped the car here in June 2004, but in just three years my pedal nearly went to the floor. I opened up the master and found "grease" and very little fluid. When I pulled things apart, the RF wheel cylinder was full of rusty water (the other 3 were fine). This time around, I put in DOT4. That's what a number of Floridians recommended for a car such as mine that sees low driving miles. I hope they are right, cause that was scary. I realize silicon fluid is best as it won't absorbe water, but I'm not sure it will work well with drum brakes. DOT 4 will mix with DOT 3 and has a number of characteristics that are an improvement including heat and moisture. We'll see. One thing is for certain, I will check the master far more frequently.

[Duke W.]

Re: 63 Metallic "Drum" Brake Replacement

I only recommend switching to DOT 5 silicone if the system is completely overhauled and you start out with everything squeaky clean and free of any trace of DOT 3 or DOT 4 fluid. The reason is that the two are not miscible, and it is impossible to completely purge the system of DOT 3 or 4 using the "bleed to flush" method.

There is no problem otherwise using DOT 5 on the drum brake systems. The only systems where DOT 5 should not be used are modern systems with ABS.

In a damp climate I recommend changing DOT 3 or 4 fluid every two years. In dry climates it's probably okay to extend this for up to four years. In Southern California I like to do brake system flushes in the fall when we get dry Santa Ana winds and the relative humidity gets down to single digits. Brake fluid can absorb moisture right out the the air!

Start by siphoning all the old fluid out of the master cylinder and clean the bottom of any sludge or debris.

Once clean, pour fresh fluid into the master cylinder reservoir and start bleeding - 6-12 pumper per corner. I always start with the LF as this is the shortest exit path for the old fluid in the m/c outlet line. Go around the car about four times until the expelled fluid is squeaky clean.

Get a feel for how many pumps it takes to bring the reservoir down to about 1/4 capacity, and refill it at this point. If you bleed down the m/c reservoir to the bottom the system will draw in air, which will require a lot of extra bleeding to purge it.

Keep the cover on when bleeding (but it doesn't need to be secured with the bail wire or screw) because everytime you push on the pedal the compensating port is covered, which causes a little geyser of fluid. It's also not a bad idea to place some clean rags under the m/c, and any spills can be wiped up with a damp rag since DOT 3 and 4 is water soluble.

Usually about a quart of fluid is sufficient for a good and complete flush. IIRC the system capacity on '63s is about 0.65 pint, so flushing a quart through means that you have flushed through over three times the system's capacity.

Duke

[Stuart F.]

Re: 63 Metallic "Drum" Brake Replacement

Duke;

Thanks for the advice. I will surely heed it. I've learned my lesson. I'm also going to try and do something with my garage (portable A/C or at least a dehumidifier) before the summer really takes hold.