Hello all ... Attempting to get the 1969 Camaro SS on the road after many years of sitting and restoration ... The brakes need attention to include the brake light on the dash is lighting up ... Okay, today was the day ... Started in the rear passenger side ... Bled away with no problems, then the driver's side ... Then the passenger's side ... Allot of bubbles came out ... Hmmm went to the driver's side ... Many more bubbles came out ... Small tiny ones like a "foam" ... Regardless, we worked at getting the bubbles out with some success however, the brakes are still rather "spongey" and the light still comes on when they are pushed to the floor ... Okay, now we begin speculating ... Bad brake calipers ? or bad master cylinder ... Any suggestions or help would be appreciated ... Kevin (kmg1969ss)

Assuming that the calipers and wheel cylinders are bone dry, this is a sure sign of a faulty master cylinder!.....Check for brake fluid leakage at the rear of the master.

Years ago I was having a difficult time bleeding the brakes on my ’67 with front disc brakes. No matter how much brake fluid I pumped through the system, I couldn’t get the air bubbles to go away.

The problem turned out to be the hold off valve (the small round valve under the master cylinder) was sucking in air. I by-passed the hold off valve with some steel brake line and was able to easily bleed the brakes without any problem.

I have no leakage anywhere ... Not at the rear of the master cylinder, or the brake calipers ... The guy that was helping out, told me that he had to replace his calipers and that helped him out ... Then in the 1973 Motor's Repair Manual, it notes that for Chevrolet when there is a disc and drum brake combination (as the Camaro is), there is a spring loaded pressure differential valve ... Which must be held in the open position ... Okay, where is the pressure differential valve anybody ? ...

I looked, and cannot locate a small hole / valve of which you are referring to ... These are power assist brakes with the booster if that helps out with more information ... Kevin

The plunger is on the back of the hold off valve (round one under the M.C.) Just because it's bad does not mean it will leak. It still can suck air.

Bubbles out with "some success"? I think that's your problem. You need to get the bubbles out with total success. If there is air in the system the pedal will feel spongy. Bleed, bleed, bleed.

PS If you were able to get fluid to the front brakes, you don't need to worry about holding in the button on the hold-off valve. (The button is on the back side - it's the roundish thing just below the MC)

I got a flashlight ... I am not understanding where the plunger/ hold off valve is located ... I am looking on, around, under, and over the master cylinder ... What do you mean round one under the master cylinder ... On the booster ? ... I shall look here again ... But ... ??? ... Kevin (kmg1969ss)

I don't know ... The distribution block ... That is under the master cylinder ... I am still not understanding the "round button thing" ...

This attaches to the fender side mc to booster bolt. If it's not there, in my opinion it's just one less thing to worry about. Someone probably removed it.


http://img.photobucket.com/albums/v61/gort69/dscn0232.jpg

My helper went home already ... but I shall try to blled bleed bleed again some other day ... And yes, fluid is coming out so ... I don't need the plunger, round button thing ? ...

How are you bleeding ? Pumping and holding down the pedal ? If you have a air compressor, Vacula makes a great bleeder that moves alot of fluid fast and really gets the air out. It will pull bubbles downhill.

Uhhh ... There is something that looks simular to what it is that you are talking about ... But, no button ... Plunger thingey ... Rather instead, this (mine) looks as thoug it is "hard" lined into the front of the master cylinder ... Does that sound right ? ...

Yes, pumping and holding th "old" fashioned way ... I do have a compressor here ... Is that Count Vacula ? ... I am assuming I can find one at a local automotive store ? ...

The button is the black thing you see in the picture. Acually it's a rubber dust boot. The pic on the right shows the actual button. Using the foot pump method creates enough pressure to open the valve, and if you are getting fluid to the fronts it's opening. Yes - it is plumbed with steel brake line, 1/4" to the front port on the MC and then back out to the front port on the distrinution block.

Okay, I got that cleared up ... The "button" is located next to the booster with just enough clearance to get a finger in there ... Hmmm ... It doesn't really depress ... Should it ? ... Easily ? ... But, as mentioned, it must be working because I am getting fluid to the front brakes ... Now about my "problem" ... Spongey brakes ??? ... Keep bleeding and bleeding and bleeding ? ... Kevin (kmg1969ss)

The hold off valve serves a purpose in the origional style system:The function of the round metering valve (or "hold-off" valve) is to allow the rear system to see 30-40 psi (which moves the rear drum shoes out into contact with the drums) before the front discs see any pressure, to avoid disconcerting "front brakes first" on pedal application, which causes "nose-dive" at low speed.

And like the others said if you have fluid depressing the button is not neccessary. Mine bled fine without depressing it.

Is there something malfunctioning, possibly sucking air, causing the "foam" bubbles ... Or would that be a common thing after nearly 13 years off of the road ? ... The brakes worked fine when I parked it, and began the restoration many years ago ...

Last thing anyone ... I shall/ will get back to bleeding the brakes ... But what about this Dot 3 brake fluid ... The stuf coming out is rather dirty (brownish) while the new dot 3 by Pyrol, is clear ... The older stuff has more viscosity, while the new Pyrol is rather fluid ... Any responses to that ? ...

i'd keep bleeding till all the brownish crap is gone...dot 3 is fine.

Not to set off an S storm but I used Dot 5 silicone and have for many years.

Is there something malfunctioning, possibly sucking air, causing the "foam" bubbles ... Or would that be a common thing after nearly 13 years off of the road ? ... The brakes worked fine when I parked it, and began the restoration many years ago ...


My hold-off valve was sucking air in past the button. It never leaked a drop of fluid but I could not get the air out of the system with the valve in the car. I removed the valve and “temporally” replaced it with a short steel line. After removing it I was finally able to easily bleed my brakes. This was over four years ago and my pedal is still nice and firm. I have not noticed any ill braking effect with the valve out of the system.

If you can’t bleed the air out of your brakes I would suggest by-passing or replacing the hold off valve.

Here is a picture of my bypass line with the hold-off valve removed.

http://geocities.com/sdampier@sbcglobal.net/Team_Camaro/Master-cylinder-AD.jpg

Yes, pumping and holding th "old" fashioned way ... I do have a compressor here ... Is that Count Vacula ? ... I am assuming I can find one at a local automotive store ? ...

http://cgi.ebay.com/ebaymotors/Basic-Brake-Bleeder-Vacula-18-0051_W0QQcmdZViewItemQQ_trksidZp3286Q2em20Q2el1116 QQhashZitem390026047120QQitemZ390026047120QQptZMot orsQ5fAutomotiveQ5fTools

Had a discussion about my brakes with my neighbor yesterday ... And then I took him over to inspect the brakes ... He decided, that the seal on top of the master cylinder (the cap and seal) seams a little corroded and he thought it would be a good idea to replace ... It could be a problem ... Then he was at the local auto parts store and noticed the owner has a vacuum pump that we shall see if he will rent out .... Next thing, he suggested ... Was to remove ALL of the old brake fluid and then to add NEW brake fluid ... So that is where I am at ... On my next day off (next week), I shall try all of the above and see where that gets me ... Kevin (kmg1969ss)

I bleed brakes myself. I use a canister and attach a neoprene line to it which fits over the bleeders. I start the engine and use a vacuum source to create a vacuum in the canister and pinch the neoprene hose. Ensuring the master has fluid and does not cavate, bleeding brakes can't be anymore simpler. You can see when there are no more bubbles in the line.

If your neighbor thinks the cap and seal could be the problem you are talking to the wrong guy. If you have a air compressor the Vacula type can be used to flush all the fluid out and even suck it straight out of the top of the master cylinder. The best part is it is not messy at all. I've used pressure pots, Mighty Vacs , foot bleeding etc and nothing comes close to the Vacula type setup. The hose goes over the bleed screw, open the screw, suck fluid out into the sealed jar, close bleed screw. There are also Vacula knock offs on Ebay that are alot cheaper and might be fine but I haven't used them.

Try clamping all flexi hoses . But clamp hose a the female end closest to brake pipe (all at once). Whats the pedal like?? Hard or still spongey??? If hard nothing wrong with m/c if spongey yes may be problem with m/c.now if pedal is hard start by releasing rear clamp but you must have someone hold pressure on brake pedal at all times!!.what happens?? Now go to the r/f wheel release clamp what happens?? Now go to l/f wheel whats happens??. The pedal will drop but only by a small amount but if it drops to the floor (rear or front) this will point you to the problem (bad shoe adjustment/sad wheel cylinders/worn calipers etc. Another one is brake hoses check there is no deforms in hoses if so replace (hoses can cause a valving affect causing spongey pedal) i hope you can make some sence of all this !!! Cheers kabrka

The hardest brakes to bleed on any car are the 4-piston 4-wheel disc brakes on '65-'82 Corvettes; they trap air everywhere. The solution to that is the Motive Power Bleeder (www.motiveproducts.com); makes it a one-person job, in less than ten minutes, with one trip around the car, and a high, hard pedal every time. Has worked for me for many years. I wouldn't even THINK about using any other method again (gravity bleed, pump-and-hold, vacuum-bleed, Phoenix Injector, etc. - have tried them all at one time or another, and none of them work anywhere near as well as the Motive bleeder. :thumbsup:

http://img.villagephotos.com/p/2002-2/13522/BleederTank.JPG

:beers:

Thank You for more suggestions ... I will post an update on my results after I get an opportunity to work on the brakes on my next day off ... Anyone else go to the Good Guys car show at the Alameda fairgrounds in Pleasanton this weekend ? ... I particularly looked at Camaros and Chevelles ... There were a couple over very nice Chevelles ... I think there was at least one original Camaro ... Other than that, allot of mistakes on the restorations that I noticed (bad emblem placements, a Z/28 with an automatic ughhh, improper stripes, rocker panels missing the blackout, wrong colored grilles) ... Well anyways things that bug me ... So to whom it may concern, pay attention to some of the details ...

Kevin, wishing you the best.
But remember, there were hundreds of thousands 69 Camaro's produced. Some of us liked our cars to look like WE wanted them to, not just the way the factory built them. Now the new Camaro's are stealing some of our ideas. Note the stripes, and the mirrors are a vast improvement, if you don't care for 'factory'.
http://epitomesrebuild.com/images/247.JPG

I had the exact same problem. It was the Master Cylinder. Bleed the master cylinder and problem solved???

The hardest brakes to bleed on any car are the 4-piston 4-wheel disc brakes on '65-'82 Corvettes; they trap air everywhere. The solution to that is the Motive Power Bleeder (www.motiveproducts.com); (http://www.motiveproducts.com);) makes it a one-person job, in less than ten minutes, with one trip around the car, and a high, hard pedal every time. Has worked for me for many years. I wouldn't even THINK about using any other method again (gravity bleed, pump-and-hold, vacuum-bleed, Phoenix Injector, etc. - have tried them all at one time or another, and none of them work anywhere near as well as the Motive bleeder. :thumbsup:

:beers:

John, if you come back to this I have a question. Will the bleeders on an original master bleed the air from the master?

Quick thing to check - make sure that the calipers are installed on the correct side. The bleeder valve should be facing up. If they are on the opposite sides, the valvles will face down and you will not be able to bleed them.

I appreciate the idea about the master cylinder may need bleeding ... I shall give it a look (on my next day off) ... Brake calipers had not been removed ...