I think that I want better brakes........

[themechanic]

Thanks. These rear calipers are from a Ford Mustang as part of the Dr Diff kit.

I have Cass's front and rear kit on my Coronet. It stops okay. But not as good as my 2016 Frontier and the El Camino, which has drums in back.

 

[themechanic]

https://www.streetmusclemag.com/features/muscle-car-braking-systems-what-to-consider-when-upgrading/

 

[themechanic]

Makes sense.

 

[Kern Dog]

I have Cass's front and rear kit on my Coronet. It stops okay. But not as good as my 2016 Frontier and the El Camino, which has drums in back.

Isn't that odd?
My car stopped about the same when I had a disc/drum setup but the 10" drum looked tiny through the wheel spokes.

 

[themechanic]

Isn't that odd?
My car stopped about the same when I had a disc/drum setup but the 10" drum looked tiny through the wheel spokes.

I have 18" wheels all around on the El Camino with stock disc and drums and booster/MC combo. They look small but stop very well. That's why I don't want to spend on big brake kits just for looks. The trucks are lighter than a big b body, which explains some of the better stopping performance.

 

[rikkitik]

Thanks. These rear calipers are from a Ford Mustang as part of the Dr Diff kit.

Interesting, looked at the Dr Diff caliper, definitely looks like a hydraulic parking brake actuator, so not much help there, sorry.
Different M/C's can have ports drilled in slightly different locations, creating a BIG difference in "dead travel". It's a "thing" on sportbikes for sure. Factory brake M/C's are usually spec'ed with different port location/dead travel than aftermarket. Both might be Brembo, but the dead travel can be a lot less with the aftermarket Brembo offering. Wouldn't have a clue which automotive M/C would be an improvement though.
Just out of curiosity, can you tell if the "dead travel" is in linkage (free play) or M/C?
It seems like you believe it's the M/C, just trying to verify though.
Braided s/s lines can give firmer feel when braking, but won't do anything for "dead travel".

 

[themechanic]

Forgot to mention I have a Wilwood 1 1/8" MC on the Coronet and the distribution block, all new SS hard lines and braided ss flexible lines. I think I need more vacuum but don't think I will spend on a vacuum pump since I don't drive it hardly ever.

 

[DeltaV]

Mine work fine but after driving late model cars, I want what they are having!

The Charger affectionally known as Ginger....

View attachment 1162727

The current setup is the 1975 A body knuckles, 12" Cordoba discs with a 2.75" F-M-J body iron caliper, a 10.7" rear disc with a 1.5" single piston caliper and a 1975 Dart power booster and disc/drum master cylinder. Drum/drum distribution block. It fits, it works but it could be better. When I changed to the 5 speed earlier this year, the brake pedal had to be changed. I had modified the old pedal with the pushrod hole up higher; this resulted in a more favorable pedal ratio. Now there is a slightly greater amount of free travel before the brakes start to bite.
I don't know if a bigger set of rotors and calipers would make the difference. It isn't as if I am overheating the brakes from hard use. I don't think that I have ever had brake fade with this car with this setup. I have heard suggestions that old brake hoses can bulge out under pressure. This "lost motion" would result in the calipers "seeing" a delay in pressure or even some reduction of it.

View attachment 1162728

My brake hoses were replaced about 5 years ago so they should be fine. I'll check though.
I remember reading an article in Hot Rod or Car Craft many moons ago about a car that had what they called a "Quick take up" master cylinder. I have never heard of that since then.
In short, I'm wondering if there is some type of master cylinder, power or otherwise, that reacts faster than what I have. The pedal has more free play than before but when it starts to bite, it works. The pedal never gets near the floor. It never feels spongy either.
My system has no leaks. The car stops fine, it just used to stop better. I know that the disc/drum master cylinder sounds like a mismatch but it worked quite well before the pedal swap. I could pull the pedal and modify it like I did with the automatic pedal but I'm curious if there is something available that feels more like a modern car.
In 2012, I wanted to switch to a manual master cylinder. I had 4 to choose from, with three different bore sizes and all of them resulted in a similar fashion: Hard pedal and poor stopping force. I like the idea of a manual braking system for the weight savings and for the less cluttered look. I'd try that again if I could be reassured that I could make it work.

Have you tried contacting Craig @mobileparts? The guy is an invertible walking-talking encyclopedia of brake (and suspension) parts for old Mopars and those other American car brands.

He is a super nice and helpful guy. Send him a pm...get his telephone number and call him.

 

[themechanic]

FYI, Mike Finnigan's El Camino videos tested 2 or 3 sizes of Wilwood brakes before he ended up with the 14", which was the largest.

I think they're on Hot Rod Magazine or one of those YouTube channels.

 

[1 Wild R/T]

Mustang rear calipers have the parking brake integrated into the caliper, as mentioned you need to use the parking brake to keep them adjusted.... I think your problem has been found...

 

[440 PHIXX]

My ‘70 Charger still has the 11” drums on all corners.

I’d love to have your current setup. But I’d like to keep the 15’s

 

[1 Wild R/T]

My ‘70 Charger still has the 11” drums on all corners.

I’d love to have your current setup. But I’d like to keep the 15’s

What Greg is running will fit with 15" rims... I run the same front brakes, the rears he's running are smaller...

 

[Kern Dog]

I'll restate what my situation is. I may have left something out.
Brake leverage is the only change that I have made in years.
Several years ago, I took out my stock brake pedal and hogged out the hole higher on the brake pedal arm/lever then welded a washer over it. This made a nice change in the pedal ratio and made it so less effort was needed to get the brakes to react.

From the pivot pin center to the brake pedal pushrod hole, the automatic transmission pedal was 1 1/2"

The Manual trans pedal was at 1 3/4". That 1/4" seems to be the only difference that I can remember doing.
In 2012 with the same front and rear brakes I have now, I tried 4 different manual master cylinders and they all were terrible. I even used a Dr Diff 15/16" aluminum one. It wasn't a matter of air in the lines. The pedal was firm in all 4 instances. The problem was that even with me standing on the pedal, the tires wouldn't even skid on gravel. Imagine how a power brake car feels with the engine off and the vacuum all used up.....the pedal is super firm but the clamping force of the calipers just wasn't adequate. That is what I had going on back then.
The easy fix as far as I can see is to modify this brake pedal lever the same way I did before. I do wish that I could find a manual master cylinder just to drop some weight and clean up the engine bay.
By the way....These Mustang calipers use a traditional cable operated parking brake.

 

[1 Wild R/T]

But the cable acts on the caliper... Not on a separate drum brake setup inside the rotor... Therefore you need to operate the parking brake in order to adjust the pads out closer to the rotor.... If you don't the symptoms are a low pedal and minimal rear braking...

 

[themechanic]

I'll restate what my situation is. I may have left something out.
Brake leverage is the only change that I have made in years.
Several years ago, I took out my stock brake pedal and hogged out the hole higher on the brake pedal arm/lever then welded a washer over it. This made a nice change in the pedal ratio and made it so less effort was needed to get the brakes to react.

View attachment 1163185

From the pivot pin center to the brake pedal pushrod hole, the automatic transmission pedal was 1 1/2"

View attachment 1163186


View attachment 1163187

The Manual trans pedal was at 1 3/4". That 1/4" seems to be the only difference that I can remember doing.
In 2012 with the same front and rear brakes I have now, I tried 4 different manual master cylinders and they all were terrible. I even used a Dr Diff 15/16" aluminum one. It wasn't a matter of air in the lines. The pedal was firm in all 4 instances. The problem was that even with me standing on the pedal, the tires wouldn't even skid on gravel. Imagine how a power brake car feels with the engine off and the vacuum all used up.....the pedal is super firm but the clamping force of the calipers just wasn't adequate. That is what I had going on back then.
The easy fix as far as I can see is to modify this brake pedal lever the same way I did before. I do wish that I could find a manual master cylinder just to drop some weight and clean up the engine bay.
By the way....These Mustang calipers use a traditional cable operated parking brake.

View attachment 1163196

I'll send you the manual mc off the Cuda that needs to be cleaned/rebuilt for the cost of shipping.

 

[Kern Dog]

Randy...Please explain it like I am S-L-O-W......
What is the procedure?

 

[themechanic]

But the cable acts on the caliper... Not on a separate drum brake setup inside the rotor... Therefore you need to operate the parking brake in order to adjust the pads out closer to the rotor.... If you don't the symptoms are a low pedal and minimal rear braking...

Agree. But you only need to apply the parking brake a few times to achieve the desired adjustment. Those Ford calipers also require a special tool to screw the piston back into their bored to replace the pads.

 

[1 Wild R/T]

Back when I worked on cars regularly I would frequently get vehicles with low pedal & poor braking complaints.. Pumping the parking brake about five times then pumping the regular brake pedal & repeating that cycle 20+ times usually cured it.... Occasionally you'd get one with stuck adjusters & you'd have to put the calipers & screw the piston out.... Then you explain to the owner about using the parking brake so it doesn't happen again...

 

[Kern Dog]

What size master cylinder bore do you have?

The master cylinder is a 15/16", stock for a 1975 Dart with power brakes. I had this setup with the front disc-rear drum, then when I added the rear discs, I switched the disc/drum proportioning valve to a drum-drum distribution block to allow the calipers to determine the proportioning.

 

[1 Wild R/T]

Agree. But you only need to apply the parking brake a few times to achieve the desired adjustment. Those Ford calipers also require a special tool to screw the piston back into their bored to replace the pads.

Maybe only a few times on the newer stuff... The old Mk7 & Continentals took quite a bit...