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Power Brake Booster
https://slantsix.org/forum/viewtopic.php?t=16880		 Page 1 of 1
Author:  70survivor [ Mon Apr 03, 2006 10:01 am ]
Post subject:  Power Brake Booster
I have a good donor car that has power brakes and my 70 Valiant does not. Is it just as easy as swapping the vacuum booster and master cylinder or do I need something else? Is the power brake set up designed for use with front wheel disc?
Author:  SlantSixDan [ Mon Apr 03, 2006 10:17 am ]
Post subject: 
If you have a complete donor setup, then yes, you can just swap. But...why? Power brakes with most A-body brake setups are unnecessary at best, dangerous at worst, and objectionable in general.
Author:  vynn3 [ Mon Apr 03, 2006 12:14 pm ]
Post subject: 
Quote:
and objectionable in general.
Not to everyone, Dan. Guess I'm a weakling, because, despite owning a couple of non-power steering and power brake cars over the years and living with them for a while, THOSE cars scared me a lot more than overboosted steering and brakes.

My brother currently owns a beautiful '67 Barracuda with manual K-H disks and manual steering, and despite the VERY healthy 360 under the hood, :twisted: I'd rather drive my little PS/PB Swinger any day.

VM
Author:  SlantSixDan [ Mon Apr 03, 2006 12:39 pm ]
Post subject: 
Improper shoe/pad compound is usually to blame for "scary" nonpower brakes. The culprit is the marketeers who push "lifetime" pads and shoes that are hard as cast iron. Passable with power boost, but as you say, "scary" without. It takes extra effort but usually less money to get the softer non-lifetime pads/shoes.
Author:  70survivor [ Mon Apr 03, 2006 2:27 pm ]
Post subject: 
This car is a daily driver for my daughter. I thought power brakes would be an upgrade along with putting disc brakes up front. Am I wasting my time???
Author:  SlantSixDan [ Mon Apr 03, 2006 2:33 pm ]
Post subject: 
No, no, I don't think you're wasting your time. You didn't mention the disc brakes part, nor the daughter part. Maybe power brakes would be preferable in your situation. What kind of brakes will be on the back? 9" or 10"? Especially with discs on the front, and especially with power boost, you'll want to pay very careful attention to setting up the system to avoid premature rear-wheel lockup.
Author:  70survivor [ Tue Apr 04, 2006 8:51 am ]
Post subject: 
I currently have 9" drums all the way around. Is there a proportioning valve incorporated in the 74 brake system? Will the vacuum booster mount directly to the spot where the master cylinder is now or do I have to do some drilling? As far as brake linings go, I've had pretty good luck with NAPA Gold.
Author:  tophat [ Sun Apr 09, 2006 6:41 am ]
Post subject: 
I am starting a similar swap, putting power brakes on a 67 b body wagon
for my wife. Your master now on both cars should have 4 bolts in a rectangular pattern (aaprox3.5"x2.75") where it bolts to the firewall OR the booster. but in the PB car where the booster bolts to the firewall the ppatternis
much larger.
I have not found a way to overcome this problem yet, other then hacking up the firewall. the PB firewall looks like it is much heavier in that area, and has extra reinforcing plates form what I remember in the junkyard.

hope this helps
I'll check back if I figure anything else out
Author:  rock [ Sun Apr 09, 2006 7:58 am ]
Post subject:  here is something that might work
tophat,

I want to suggest a solution to your bolt in, but first tell you why I came it and give you the source for parts.

First, realizing a '64 D100 truck is a long way from your car in terms of weight distribution and brake size, the generality SlantSixDan mentions IS important in trucks, thus I can't see why not in cars. I had to solve the booster boltup pattern problem when I did the disc brake swap on my truck...using a power booster and new dual port master cylinder...and used a Mopar performance adjusting valve too.

In trucks all the weight is in the front, UNTIL you put a half ton or 3/4 ton in the back..thereby inducing wide swings in road grabbing in the back. If you are empty, power disc brakes WILL lock before the rear drum brakes lock and you will twirl around...unless you have run setup tests on a gravel road with someone watching and adjust the valve so that each brake system locks at same time....then mark that spot on the valve. Do it again with a load in rear, or car trunk, and mark again. Then just set valve to your load condition. I went to power disc because it being my truck, it works sometimes. A cube of red bricks in the back one day when a jerk pulled out in front of me (me going 40) made me wonder if I was ever going to stop with the good standard brakes and made me want the ability to full power stop.

So I got the now unavailable disc conversion kit from Ray at Helitools, and his power booster deal too. The power booster thing is likely still available. I would check at www.uglytruckling.com and click on that part. The bracket Ray makes from channel steel works PERFECT. Having seen it, sure I could make it, but it was awfully nice to pay, get it, and bolt right up. The site has detailed instructions with pics so you can see how to match your pushrod to the application. Not hard at all.

rock
'64d100
Author:  terryx [ Thu Apr 27, 2006 10:13 am ]
Post subject:  power breaks
HI

I am working on a similar conversion.

From drum breaks to power drum breaks all round.

As far as I can tell you just need :

The complete booster set up with the master cyl and the step up bracket.

Found new ones on Ebay $180 and rock auto has them aswell.

Then you just remover you old manual master cyl and put the new set up in its place.

because it has the step up bracket it bolts righ in place of the old master cyl.

Also because you are staying with the drum all round set up you do not need to mess with the proportioning valve.

You will probably need longer break lines though, from the proportioning valve up to the new master cyl at the end of the step up power booster.

If anyone knows different I would be interested to find out more.

T


(bad spelling at no extra charge) :wink:
Author:  green convertible [ Fri May 05, 2006 1:25 pm ]
Post subject: 
I did this conversion, KH disks, dual master, booster from a (I wish I knew right now!) 7(place a random digit here) dart and I think it was a swinger. Right now my booster is leaking and I cant find a replacement anywhere. other than that, with the kh's, make sure you get a rebuild kit, they will likely be full of compresed powder. seems like just three years ago you could find an a body donar in any yard in california.
Author:  KBB_of_TMC [ Fri May 05, 2006 1:42 pm ]
Post subject: 
To get back to the orig. question:

Besides the booster & MC, often the brake pedal lever assembly was a little different too. Don't forget to readjust the stop light switch.

MC for disk/drum are different from drum/drum, as is the proportioning valve. The rear wheel cylinders might have been different too; I'd match them to the proportioning valve or get an adjustable valve and set the ratio empirically.

I'm pretty sure all the lines & front calipers are the same.

Most of my Mopars w/ front disk came w/ power, but the one that had disk & manual worked just fine and I never felt the need for power brakes in it, so I would check that the existing components are working correctly before I replaced the system.

I would also want to use freshly rebuilt hydraulic components. I've seen a weak hose (that didn't leak a drop) in a '73 Dart render the brakes almost useless and that gave me the scariest ride of my life.
Author:  green convertible [ Sat May 06, 2006 10:08 am ]
Post subject: 
I got an adjustable proportioning valve and it works great. I would recomend it. it was summit or jegs or someting
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