70 Dart manual brake to power brake swap

-
Sublime Swinger

Sublime Swinger

Well-Known Member
Joined
Sep 15, 2013
Messages
166
Reaction score
33
Location
Minnesota
My Dart has 73 conversion disc up front and stock 10" drum in rear with manual brake, my question is has anyone bought a 73+ master cylinder and booster to convert to power brakes? If you removed the master cylinder studs off the firewall and installed that booster setup would everything line up or would I need the 73+ brake pedal assembly also?
 
There are no modifications needed. I ask... Why make the change? A manual brake setup works great and weighs less. It is simpler and makes engine service easier because the power booster takes up some much needed space.
I swapped a 75 Dart power booster and master cylinder into my 70.Charger in 2001. I'm now in the process of swapping in a manual brake master cylinder.
 
Kern Dog said:
There are no modifications needed. I ask... Why make the change? A manual brake setup works great and weighs less. It is simpler and makes engine service easier because the power booster takes up some much needed space.
I swapped a 75 Dart power booster and master cylinder into my 70.Charger in 2001. I'm now in the process of swapping in a manual brake master cylinder.
Click to expand...
Personal preference mostly for the piece of mind to update to today's braking power. I also think it would look alot cleaner than having that conversion bracket that come with some of the kits nowadays, would rather use Mopar parts as replacement than buy one of those kits.

But I would need to remove the firewall studs and make some sort of backing plate to bolt it to correct?
 
original booster just bolts on to studs. everything is quick and easy. should purchase new lines to TEE as they are farther forward and longer length is needed.
 
j061093409 said:
original booster just bolts on to studs. everything is quick and easy. should purchase new lines to TEE as they are farther forward and longer length is needed.
Click to expand...
Okay, I was under the assumption by looking at the picture on Rock Auto's website that the booster is studded for the 73+ style.
 
I understand because people are selling replacement master cylinders on ebay with studs. they must be for a non-mopar application. just knock the studs out as the a-body brake pedal assembly has studs welded on to housing.
 
My disc/drum manual master cylinder 67 Dart stops better than my power equipped 70 Charger. That is why I question messing with a system that is working. Maybe try a more aggressive disc pad and drum shoe ?
 
The pedal leverage in a manual setup is more than with the power setup.
 
j061093409 said:
I understand because people are selling replacement master cylinders on ebay with studs. they must be for a non-mopar application. just knock the studs out as the a-body brake pedal assembly has studs welded on to housing.
Click to expand...
This is what Rock Auto is showing for a 73+ booster setup.

506101-LEF.jpg


506101-TOP.jpg
 
Sublime Swinger said:
Personal preference mostly for the piece of mind to update to today's braking power. I also think it would look alot cleaner than having that conversion bracket that come with some of the kits nowadays, would rather use Mopar parts as replacement than buy one of those kits.

But I would need to remove the firewall studs and make some sort of backing plate to bolt it to correct?
Click to expand...

This is a misconception. Adding power brakes does not necessarily increase braking power. It reduces pedal effort, which is not the same as increasing braking power. A-bodies are a little unique, the pedal ratio does change slightly because of the linkage needed for the power booster (because the booster has to sit higher for clearance. The factory made up the difference in ratio by boosting pressure with a smaller master cylinder bore. But, without a change in ratio or master cylinder diameter the booster just makes the pedal easier to push, it doesn't make the brakes do any more.

I have found on my cars that a manual disk set up with a 15/16" master (same diameter as an A-body power brake master) gives better braking feel than any of the stock power booster set ups. I actually converted my Challenger to manual disks from power after driving my manual disk Duster. Even on the larger E-body I found the manual disks to be an improvement in braking feel. I wouldn't add the stock power booster to any of my cars.

Here's a picture of the booster from a '74 Dart, it shows the stock booster and A-body linkage that's needed...
IMG_2740.jpg
 
Last edited:
The gold anodized bracketry is the only way to attach the booster in A body cars. The brackets put the master cylinder up and away from the firewall. The brake lines have to be longer as well. They had to mount the setup up and away so it would clear the engine.
 
There are other boosters which do not require the bellcrank. They would sit lower of course.
Wait, now you got me thinking; do I or don't I have the bellcrank? Hmmmmmmmmmmm Update, I do.
It looks like the dual-diaphragm wouldn't fit either
 
Last edited:
OK, thanks. That's what I wanted to know. I wasn't sure if the booster could be directly mounted to the firewall.
 
I've seen earlier A body cars, 1967-70 maybe?...That had a smaller diameter booster that still had brackets that made it stand off of the firewall by some amount. I don't recall seeing any A-body that had a booster directly mounted to the firewall.
 
You must log in or register to reply here.
-

Back
Top