Bad breaking

[nchrome]

Okay guys l read it some where but can't find it. For a while l had a fair brake peddle now if l need to do a panic stop better get a large anchor cause she's not going to stop. Everything is new master, vac booster, front disc, new lines, new wheel cylinders, everything is new except for the rear drums. Some where l read someone had the same problem and found out it was the booster. Any other ldeas that may help. Or should l just replace my booster and see what happens.

[b5blue]

Sounds like bad booster, shockingly hard to stop!

[Back N Black]

I has pretty much the same problem, rock hard pedal and required to feet on the brake to stop. My problem was the proportion valve was stuck and only allowing fluid to the front brakes. Worth checking out.

[Mopar Nut]

I has pretty much the same problem, rock hard pedal and required to feet on the brake to stop. My problem was the proportion valve was stuck and only allowing fluid to the front brakes. Worth checking out.

I had the same problem, mine was the distribution block. I rebuilt mine and it stops on a dime.

[LaOtto70Charger]

Where do you find the components to rebuild the distribution block?  Mine never stopped right. I did get decent braking with ssbc disc setup but the master went out. I have a new double spring to put but converted to manual. It is ok right now but not great. Booster may help but have been wondering about the block also.

[Mopar Nut]

Where do you find the components to rebuild the distribution block?  Mine never stopped right. I did get decent braking with ssbc disc setup but the master went out. I have a new double spring to put but converted to manual. It is ok right now but not great. Booster may help but have been wondering about the block also.

https://www.musclecarresearch.com/

[LaOtto70Charger]

Thank you!

[Kern Dog]

I has pretty much the same problem, rock hard pedal and required two feet on the brake to stop. My problem was the proportion valve was stuck and only allowing fluid to the front brakes. Worth checking out.

There is a video on Youtube where a guy in a 1300 HP red '64 Mercury wrecked the car when his brakes overheated and failed.
I'm looking at upgrading my brakes and after seeing that, I'm aiming to really do it right.
When you piece something together like I have done before, you can have a mismatched system that should work but doesn't or a system that really hunkers down and stops the car.
I have never felt that the brakes in my car were that great. Decent, but not impressive like I have felt about a few manual disc-drum A body cars that I have driven.

[Mike DC]

            
I've seen that video.  It's like that guy was going out of his way to make mistakes.  He had a sticking throttle and he kept driving it.  He was riding the brakes nonstop and somehow it took him by surprise when the brakes finally overheated & failed.  Then he had an out-of-control car with a sticking throttle and he didn't even turn off the ignition key or get it into neutral.




There's a lot of options for brakes out there these days.  I'm leery of the aftermarket stuff because I would rather have replacement parts at the local store.    

IMO the main reason why modern car brakes feel so much better is because the rotor diameters are bigger.  (Now that we're using 17+ inch wheels on everything.)  It makes more practical impact than the drilled/slotted rotors & other unobtainium parts.  It's just easier to stop a spinning disc by clamping it at the outer edge.  Trying to clamp onto it near the center is less effective.  

 

[Kern Dog]

The past week, I've been pondering about brake caliper sizing, rotor diameters and master cylinders. Our classics used large single piston brake calipers with 11 or 12 inch rotors. New cars use huge rotors with calipers that have a lot less surface area. The 2.75" caliper used in all Aspen/Volare and other FMJR cars has a surface area of almost 6 inches. The Ford Mustang Cobra kit offered by Dr Diff uses a 13" rotor with a 2 piston caliper that when added together, add up to about 4 inches of surface area. I'm still fuzzy on how a caliper with smaller clamping surface area can be more effective that the 2.75" caliper. One theory is that the smaller surface area 2 piston caliper requires less fluid volume to move the pads. I'd  love for someone with an engineering background explain it to me. I do see that the larger rotor offers far more leverage to stop. Maybe that is the whole story....Maybe the caliper doesn't have to work as hard when the rotor is so big?

[472 R/T SE]

           
I've seen that video.  It's like that guy was going out of his way to make mistakes.  He had a sticking throttle and he kept driving it.  He was riding the brakes nonstop and somehow it took him by surprise when the brakes finally overheated & failed.  Then he had an out-of-control car with a sticking throttle and he didn't even turn off the ignition key or get it into neutral.




There's a lot of options for brakes out there these days.  I'm leery of the aftermarket stuff because I would rather have replacement parts at the local store.    

IMO the main reason why modern car brakes feel so much better is because the rotor diameters are bigger.  (Now that we're using 17+ inch wheels on everything.)  It makes more practical impact than the drilled/slotted rotors & other unobtainium parts.  It's just easier to stop a spinning disc by clamping it at the outer edge.  Trying to clamp onto it near the center is less effective.  

 

The rotors were installed 15 years back.  Dime size compared to nowadays silver dollar size.  He had the wheel size for bigger.

You can see in the video he put it in park and can hear shit grinding.  That was momentum, not drive.  Turning it off wouldn't have helped in that situation and with a temperamental throttle it would have kept running for a bit...  Perhaps a kill switch woulda shut it down.
Still wouldn't have mattered.

We weren't there so we can only speculate.
But I know what youre saying.  I taught the EX and daughter how to drive on snow and if youre in a slide coming to a stop, put it in neutral to stop the drive.

Such a beautiful car and what a shame.  Felt bad for the guy.  

Emergency brake with your hand on the release.  For you able bodies, lol.  Id prolly be f'ed, lol.

[472 R/T SE]

Okay guys l read it some where but can't find it. For a while l had a fair brake peddle now if l need to do a panic stop better get a large anchor cause she's not going to stop. Everything is new master, vac booster, front disc, new lines, new wheel cylinders, everything is new except for the rear drums. Some where l read someone had the same problem and found out it was the booster. Any other ldeas that may help. Or should l just replace my booster and see what happens.

Was the motor cam changed out by any chance?  Big ass cams don't produce the vacuum.

[Mike DC]

The past week, I've been pondering about brake caliper sizing, rotor diameters and master cylinders. Our classics used large single piston brake calipers with 11 or 12 inch rotors. New cars use huge rotors with calipers that have a lot less surface area. The 2.75" caliper used in all Aspen/Volare and other FMJR cars has a surface area of almost 6 inches. The Ford Mustang Cobra kit offered by Dr Diff uses a 13" rotor with a 2 piston caliper that when added together, add up to about 4 inches of surface area. I'm still fuzzy on how a caliper with smaller clamping surface area can be more effective that the 2.75" caliper. One theory is that the smaller surface area 2 piston caliper requires less fluid volume to move the pads. I'd  love for someone with an engineering background explain it to me. I do see that the larger rotor offers far more leverage to stop. Maybe that is the whole story....Maybe the caliper doesn't have to work as hard when the rotor is so big?

The trend of more pistons isn't about total piston size, it's about spreading out the clamping load across a big brake pad.  Once the pads get more than a few inches long they are flexing too much.



The amount of brakes that is "enough for a street car" is one of those opinions.  Some guys will tell you with a straight face that 4-wheel drum brakes are enough.  Others want 14" rotors and 6-piston calipers.

The huge stuff is a legit gain for a fast autocross-type car.  But by that logic you also need bigger wheel bearings and a differential oil cooler.  



Me, I think 13" (front) rotors and 2-piston calipers are plenty for the street (like, to feel sporty).   It does commit you to 17" wheels though.  

If you just want something safe in traffic then the old 11.75 rotors & single-piston calipers still cut it.  In the 1990s some smaller sports cars were still using "12-inch rotors" with pride.

[Kern Dog]

"The trend of more pistons isn't about total piston size, it's about spreading out the clamping load across a big brake pad.  Once the pads get more than a few inches long they are flexing too much."

Now THIS makes sense. The large single piston is probably limited to a pad that is maybe 3 1/2" long, whereas two 1.59" pistons with a small gap in between can use a longer pad, maybe  4 1/2" or so. That would help.