Weak feeling brakes

[gto64gto]

I have a 65 Satellite that I installed front disc brakes from The Right Stuff and it came with a 15/32 piston dual master cylinder. I replaced the rear brake shoes, all brake lines,(braided up front and the system has been very well bled. The brake rod is in the top hole of the brake pedal. The brakes seem to be weak and take longer to stop than they should. There's no leaks in the system. Has any one had this problem and found an answer. I've worked on cars as a hobby my whole life (73) and never run into any thing like this. I'm stumped. I know its been a long time since 65 when I had a 65 Belvedere and I know today's new cars have very good breaks but it just seems that I should be able to stop quicker. Thanks for any help you can send my way. (both the 65 Belvedere and Satellite don't have power brakes)

 

[gto64gto]

I have a 65 Satellite that I installed front disc brakes from The Right Stuff and it came with a 15/32 piston dual master cylinder. I replaced the rear brake shoes, all brake lines,(braided up front and the system has been very well bled. The brake rod is in the top hole of the brake pedal. The brakes seem to be weak and take longer to stop than they should. There's no leaks in the system. Has any one had this problem and found an answer. I've worked on cars as a hobby my whole life (73) and never run into any thing like this. I'm stumped. I know its been a long time since 65 when I had a 65 Belvedere and I know today's new cars have very good breaks but it just seems that I should be able to stop quicker. Thanks for any help you can send my way. (both the 65 Belvedere and Satellite don't have power brakes)

I made a mistake. My piston is 15/16, not 15/32.

 

[69L48Z27]

How many miles do you have on them? I did a conversion with a 15/16” MC, disc and factory drums non- power. Took about 30-40 miles to have them start working as I expected. First time out I thought it was a big waste of time and money. 11” drums seemed way better at that point. After those initial miles it was finally right. They worked good and pedal feel was great.

 

[khryslerkid]

It will take a little to break in the non asbestos linings. Don't ride them to speed up the process, that will cause glazing. Keep after the rear lining adjustment for awhile until they seat in. You can tell they need adjustment when a double pump of the pedal will give you a full pedal.

Keep your distance for awhile like we used to do back in the day.

If your pedal is spongy you still have air in the line.

If you are using Dot 5 it will cause a bit more brake pedal travel until the pedal gets hard.

 

[kiwigtx]

If your pedal is spongy you still have air in the line.

This.

 

[hunt2elk]

I installed my first 15/16" master cylinder recently, and am not quite certain I really like the longer pedal travel yet. I went through the same thing, bleeding the system many times, going through 1 1/2 quarts of fluid. Swore that there couldn't be any more air in the lines. Drove it 300 miles and decided to bleed again. Was very surprised to get 2 very small air bubbles out. That helped the pedal feel tremendously.

 

[66Satellite47]

"Back in the day" I had the new shoes" arched" to the actual diameter of the drum. That was common practice. Doesn't seem like done much now. Minimizes break in time on new shoes.

 

[khryslerkid]

"Back in the day" I had the new shoes" arched" to the actual diameter of the drum. That was common practice. Doesn't seem like done much now. Minimizes break in time on new shoes.

I had my rear drums off not that long ago and the shoes are only showing contact from the middle and up to the top.

I've seen the machine that is used to arch them at a couple of the older shops that I frequent but they haven't been used in a long time!

 

[bc3j]

FWIW I have a disc drum system modeled after the disc-o-tech article. I use a 15/16” Dr Diff aluminum master on a manual system. Replaced my pads and shoes with FF friction coefficient ratings. Took about 200 city miles for really good stopping.

Re bled the rear lines after replacing some faulty wheel cylinders (i.e. Made in China) by using just a clear tube in a clear container with the end of the tube submerged in brake fluid. With a full master and with the cap on, I just pumped the brakes while my helper watched for bubbles. After a clear stream was present I held the pedal down. On the final push with the pedal held down my helper closed the bleeder. Had the rears bled in 10 minutes. I was surprised at the firmness in the pedal and it was a little higher than before. The 15/16” MC works good without a lot of pedal travel.

 

[66Satellite47]

I had my rear drums off not that long ago and the shoes are only showing contact from the middle and up to the top.

I've seen the machine that is used to arch them at a couple of the older shops that I frequent but they haven't been used in a long time!

With the rear drums, if the shoe matches the drum right away, you get the correct "feel". If the shoe has 60 -70% contact area, you don't get the stopping power. DUH! Next time I change shoes I will be sure to have this operation done. I'll start looking for the shops to do it.