Hello everyone,
Quick question:
I own a '73 and I am planning on bleeding the brakes, does my car have a proportion valve?
If not then what year does this valve start?
I thought it was '75 but wanted to ask you before I tackle the bleeding of the brakes.
Also, any specific sequence of brakes to go by on this year?

Thanks for the help.

 

IF you want to bleed these brakes ONCE and get it right, do it the easy way....

drill one 1/8 hole in the m/cyl lid per section...install it normally on a full m/cyl, everything hooked up...open a front caliper, put your shop compressor line/air jet on the hole, pressure will force the rubber down and push the fluid through to the open caliper, then when it's flowing out the open caliper, make sure the m/cyl stays full enough....close the caliper, open the mate to it on that end....do the same with the m/cyl...full of fluid, pressure above the rubber seal....again make sure m/cyl don't run dry...let drain with gravity after fluid comes out....hammer on calipers as fluid drains to encourage any bubbles out of the calipers.....

same for the other end of the car....

then you can do the pump and bleed as per 'normal'.....

seal the small holes in the lid with RTV....

 

You don't have a proportioning valve it is actually a distribution block with a switch that makes the dash light go on if there is a brake problem.
I bleed starting closest to the M/C which is LF RF than LR RR, in the rear do the inners first.
If you want to be totally confused read the sticky at the top. PG.

 

mrvette,
I am sorry, I CAN NOT buy into drilling ANY hole in the lid of a master cylinder...for any reason. AND then filling it with RTV. That is so dangerous for potential failure. This is the brake system we are talking about and find me text where it is done that way...you won't be able to because it is total B.S.

miguel1973, IF your system still has fluid in it and all you are wanting to do is bleed the brakes. There is a safer way of doing it WITHOUT damaging your master cylinder lid.

Depending on how much crap you have in the master cylinder reservoir now. BY this I mean sediment. IF you take a clean Q-tip and LIGHTLY wipe the bottom of each reservoir and it comes out with a bunch of crap on it. You may want to remove the fluid and then carefully wipe out this sediment/crap. You can remove the fluid by using a suction pump or siphon it out using a long CLEAN clear hose so you can see the fluid.
Now mind you, that if your brakes are spongy now, and you thinking that bleeding them will correct this problem you are partly true in this thought.
With this crap and sediment in your system, it is displacing the fluid, causing the hydraulic effectiveness of the fluid to be compromised. Removing the sediment and crap will gain some of the hydraulic properties back to the system. BUT... the circuitry of the master cylinder that you CAN NOT get to is probably seriously filled up with this sediment. It is the nature of the system and the DOT 3 brake fluid and the lack of keeping the system changed out with fresh fluid occasionly.
SO...with the reservoir cleaned out as best as possible. Add FRESH DOT 3 fluid from a SEALED container, not fluid that you have had around for some time.
Fill the reservoir to about 1/4" from the top and re-install the cap. Making sure that the lid seal is back to its original configuration and not extending downwards. MAKE sure that the bailing straps are securing the cap and that the sealing surface on the master cylinder was clean and dry BEFORE installing the cap.
Now , using a six point socket...if possible...carefully loosen the bleeder(s) on one caliper and then tighten thehm back right away. Do ONE at a time. This is to make sure that they will loosen and not be seized into place, (like they can often do).
Now this is where this can be a bit messy, unless you go out and buy some clear hose from the hardware store that will fit snugly over the end of your bleeder. You will only need one hose about a foot long.
If you have the hose, you can fit it onto the end of the bleeder and then using a wrench. You will now be ready to bleed the brakes WITH THE AID OF A FRIEND.
WITH your friend in the car, have them lightly apply pressure to the brake pedal several (2-3) times and then apply pressure like they are trying to stop the car. WHEN they have the pedal DOWN. AND have them say"DOWN", so you know it is down. LOOSEN the bleeder and fluid will start to come out into the clear tube that you can have routed into a jar or container. Then when the pedal is all the way down and stopped at the bottom of travel, have them say "ALL THE WAY DOWN", while they still have their foot HOLDING THE PEDAL DOWN, ***which is very important***, tighten the bleeder and tell them that it is "TIGHT". At this time, they can lift their foot off of the brake pedal and you can repeat the procedure about three if not four times BEFORE you have to STOP and re-fill the reservoir with fluid and correct the cap seal.
FOR NO REASON SHOULD YOUR FRIEND LIFT THEIR FOOT OFF OF THE BRAKE PEDAL, AFTER YOU HAVE OPENED THE BLEEDER, AND THEIR FOOT IS AT THE BOTTOM OF PEDAL TRAVEL, AND YOU STILL HAVE THE BLEEDER OPEN. thEY CAN ONLY LIFT THEIR FOOT OFF TEH PEDAL WHEN YOU KNOW YOOU HAVE TEH BLEEDER TIGHT. IF THE PEDAL GOES UP WHEN THE BLEEDER IS OPEN, AIR WILL BE SUCKED INTO THE SYSTEM AND THAT STEP WAS FOR NOTHING.
You can also find a shop that has a pressure bleeder and bleed the system for you. I bleed systems at my shop for about $50.00 barring any complicationms with the bleeders or other issues that I may find.
You are trying to get the fluid coming out of your caliper to look like what you are putting in. CLEAN, that is why you use a clear hose, plus it doesn't make it so messy.
Last but not least, Don't get to "froggy" and try to bleed a caliper more than 3 times, before you check the fluid. The LAST thing you want to do is cause your reservoir to run DRY.. When that happens you just caused a MAJOR problem and lost everything that you did earlier because there is air in the system. SO play it safe, check your reservoir after three bleedings.
On the rear calipers you are only dealing with the bleeders that are at teh TOP of your caliper, NOT the ones at the bottom..

DO NOT DRILL HOLES IN YOUR MASTER CYLINDER LID....PERIOD!!!!!!!!!!!!!!!!
"DUB"

 

There are already small vent holes in the lid.

No need for drilling.

 

I don't recall seeing them on my '72, but have on other cars...

oh well....thanks, Noonie....

I was smiling over the above post...

 

There are three bleeder screws on the rear calipers, do you bleed them all?

 

No! Only the top ones. PG