Power Brakes addition to A/C Car

[DKheld]

Todd - just to be sure since I see your car and Tim's are not equipped with factory A/C.

This is the bracket that will clear the factory A/C evaporator on the firewall?

Thanks,
Eric

edit:
ABS has this listed as a 9787 bracket too

http://www.ebay.com/itm/Frame-Mount-8-Universal-Booster-combo-w-pedal-assembly-/281302746053?hash=item417ef343c5:g:S7AAAOxyeZNTPyqp&vxp=mtr

[Deanj]

Assuming confirmation this clears the evaporator, I'd install the front discs if stock wheels work with them.

You have been great help (on a car I'm finding something to either restore, repair, or upgrade everyday). I leave that for different posts.

[toddgilroy]

I THINK it will clear the evaporator...but that is based on other threads and not personal experience.

http://www.squarebirds.org/vbulletin/showthread.php?t=10943

Regarding using stock wheels, you should be able to find 14 inch wheels that will clear the calipers, but I don't think the OEM wheels will work. There are numerous threads that have a lot of information about the disc brake conversion process, including information on what wheels will work. Summit Racing sells new 14" steel wheels that worked for ~Daleo56.

http://www.summitracing.com/parts/WVI-12-461204

[jopizz]

As mentioned the stock rims will not work with discs. Look for 14" steel rims from a 90's Ford Ranger. They will work fine and are relatively inexpensive.

John

[YellowRose]

Power Brakes addition to A/C Car

IF you are considering going the disc brake route and doing that conversion, the OEM 14" rims will NOT work. Back then, they were not manufactured to be disc brake capable. You will have to find some disc brake equipped Fords from the 70's and get 14' rims off them, or do what Daleo56 did and buy them from Summit Racing. Or find some 15" rims that should be disc brake capable.

[Deanj]

I ordered ABS part #9787. It has the correct bracket, (I hope, but that's the issue: clear the evaporator and valve cover.) No proportioning valve needed if drums are kept.

[simplyconnected]

I ordered ABS part #9787. It has the correct bracket, (I hope, but that's the issue: clear the evaporator and valve cover.) No proportioning valve needed if drums are kept.

Let me clarify my last posts.
You can purchase the booster/master W/firewall bracket and all the hardware that connects to your brake pedal.

New Master Cylinders come with dual pistons so you will divide your present system into front and rear systems THROUGH a combination proportioning valve...

I keep posting this so I am only saying it this last time.
If your brake system is split (front and rear) you need a combination proportioning valve.
This applies whether you have disk/disk, disk/drum OR drum/drum brakes because the valves are different. Disk/Disk and Drum/Drum use the same valve because they don't need to proportion pressures. The problem is with FLOW when the brakes come out of adjustment. One system will need more than the other. - Dave

[Deanj]

Alright, thank you. Let's just say ABS gave me the wrong advice.

[RustyNCa]

Alright, thank you. Let's just say ABS gave me the wrong advice.

I've dealt with them before, that does not really surprise me.

[DKheld]

Purely speculation here but.....

Original system has a single line single chamber drum master cyl. Fluid leaves the master cyl via a single line and is directed to the wheels via the line splitter on the frame - no proportioning.

Here's the speculation part...

Install a new booster and dual circuit drum/drum master cyl. Join the master cyl output lines so that both master cyl outputs combine and route to the original splitter then out to the wheels as original.
Assumptions - no proportioning needed, the new drum/drum master cyl chambers are not valved differently (front and rear).

This option wouldn't give any benefit as far as safety is concerned by splitting the system and giving a dual circuit but may work for this application? (and possibly what ABS is recommending?)



Eric

[Tbird1044]

Just an additional note to confuse things a bit more.
On the original bird, the front wheel cylinders have a 1 1/32" bore and the rears have a 29/32" bore. This is how Ford proportioned the braking action between the front and rear. All of the master cylinders have a 1" bore, whether single or dual action. I believe the original master cylinder had a 1 1/8" bore, but those have pretty much been phased out.
I converted to a dual master cylinder and put in the proportioning valve so I could connect a warning light if one side of the cylinder failed. There is a proportioning valve and a pressure differential valve that can be installed. I went with the combination proportioning valve because it was actually cheaper.
Just some more food for thought.
Nyles

[simplyconnected]

Eric, you're throwing out the baby with the bath water.
The whole purpose in having a dual master cylinder is so your brakes are split into two circuits. If one fails, the other does not.

The original system supplied one power source that fed a distribution block, so all the wheel cylinders were in one circuit.

Hydraulics 101:
'Pressure' IS 'resistance to flow'
Pascal’s law says, pressure is equal in ALL parts of the same system.

So you step on the brake pedal which moves a M/C piston. Flow begins moving the shoes off the springs. The first one hits the drum but no pressure yet, the second set hits the drum but no pressure and your foot keeps going down. After the last shoe hits the drum pressure builds because all shoes are resisting flow and they all see the same pressure. This is the original setup with all brake lines connected to the tee; flow keeps going to the last set of shoes until they all resist flow.

Now, let's split the system into two separate systems using two separate pistons on the same pedal shaft:
The first system to have both sets of shoes stop against their drums will create pressure but the other system isn't there yet. So pressure builds in one system more than the other.

A combination proportioning valve puts a sliding piston between the two systems. If one system needs more flow, your pedal keeps on going and the sliding piston simply moves until pressure is equal on both sides. If the sliding piston moves all the way over to one side it senses a ruptured line and shuts that side OFF so you don't lose brake fluid then it shines a 'BRAKE' dash light.

Front brakes wear out twice as fast as rear brakes so they will eventually need more flow. You won't see it right away but you will down the road. Without a combination valve, this situation will ONLY operate the rear system since it is the first to stop flow.

Keeping all your brake shoes adjusted helps a lot but eventually they all come out of adjustment (except for disk brakes). - Dave

[Deanj]

Can we agree on some specific proportioning valve that I should order? From ABS or anywhere that is compatible with the 9787?

[simplyconnected]

You get two choices. Either is fine but it must be for drum/drum (disk/disk is the same). You can buy the Ford-style or the GM style.

ABS sells them, eBay sells them and Pirate Jack sells them (as well as every good brake company).

I prefer the GM style because it has through holes for mounting right in the casting. BTW, neither Ford nor GM ever made these valves.

Understand that if and when you go to disk brakes you will need a combination valve designed for a disk/drum system because disk brakes require much more pressure than drum brakes.

As long as you keep drum brakes in the front they will always pull to one side, fade and take forever to dry out when wet. - Dave

[YellowRose]

Power Brakes addition to A/C Car

Here is what a Ford Style Combo valve looks like, followed by a GM Style Combo valve. As Dave said, many of us like the GM style for versatility sake.