[PontGuy]

At this point I don't know if I have a problem or not. I have no bubbles from the passenger side rear, but still got a few from the drivers side the last time I bled. I have been bleeding and seating/tightening the rears every now and then while working on everything else. The pedal seems plenty hard and the rears are definitely engaging, but without vacuum on the booster I can't tell for sure what I have.

But I am quite sure I don't have a residual valve anywhere. And like I said the rear porting on the proportioning valve that I removed is wide open, so as far as I can tell there never was one on my car. But if I do have problems I plan to follow your lead if the residual valve gets yours working right.

Walt

[Shiny]

It's better !!!

I put the residual pressure valve between master and combo valve, pumped a lot of fluid through the lines after.

Drove it around the block and it was way better. Bled it again the next day and got more air, and drove it again today with no change in pedal.

I won't say it's right yet, but I've got brakes !!! yoo-hoo !!!!

I am moving to another state to start a new job and won't be able work on it for a while now, but next time me and the car are together, I think I will replace the rear cylinders with known new ones, as this success tells me it is definitely something wrong with the rear system.

[PontGuy]

Great news!! Now I have a plan "B" just in case I do have ongoing problems with the rear brakes.

I got my cam broken in Sunday without any problems (more great news!!) I gave my buddy Bill the gas pedal and gage-watching duty while I checked for leaks, etc. We started it up on a 2 gallon gas can feeding directly to the fuel pump- and just about dried it up by the end of the break-in and had to shut it down, so I still haven't felt the brakes yet. Bill said the brake pedal seemed normal. But I don't think he wasn't really paying too much attention to it and he also said the brake light stayed on the whole time.

This weekend I will finish painting the inside of the fenders and front-end sheet metal so I can assemble it all. Hopefully I should be able to take the first test drive within a week or so. I am really hoping the engine pulls hard, and the new trans works good, and that I have reasonable brakes!

Did you have to make your own flares or were you able to get pre-made connectors to put it all together? I have all-new stainless brake lines and would rather keep it all looking nice if I have to go your route. Oops, just re-read and saw that you did have to flare the lines. Something I never did before and definitely would not be looking forward to trying- just one more learning experience to add to a bunch over the past six months.

Walt

[Shiny]

Walt - Nice work on the break-in ! You must be excited about that new engine.

I have been slowly getting my LeMans driveable for the past few years... the brakes were the last barrier. I started by putting a new posi carrier and 3.55 gears in the back, added a sway bar, new springs, bushings, etc. Then my son and I did the same on the front suspension, put in a quick-ratio box, and all new steering stuff and control arm bushings. Then we did the change to front discs. Car still has the original 350, but we put in a mild Summit cam and a quadrajet with a lot of help from Cliff. Today, for the first time, I had enough brakes to actually give it some gas and it actually broke the tires loose !!! That was fun.

Since I can't work on it for a while, I'll have to hold onto the fun from today.

Why don't you start a new thread on your car. It is gorgeous and I'd like to hear how it goes for you.

Mike

[PontGuy]

Mike,

Sounds like you and I have been on a similar path, I didn't realize that your brakes were part of a bigger project. You mentioned that you were moving- hopefully you will get time to enjoy it some during the coming weeks between that and the winter weather.

Background on my LeMans-

My wife's first car was a 71 Lemans so the body style is special to her. And I had a lot of fun racing the A bodies on the dirt track back when I was young and foolish. So years ago we decided to see if we could find a late 60's convertible Lemans to fix up. It actually took a long time to find one I liked, and I found out later that they actually made very few of them and it might actually have been easier to start with a vert GTO. When I finally found the car 11 years ago the body was sound and it looked OK but it was a mechanical disaster. I patched it up to make it drivable but didn't have the money to do it right, and put restoration on the "to do" list. Then the kids started graduated high school and we went through the college payment era and the car slowly went downhill.

Anyway the kids are finally out and on their own and I finally have plenty of money in the bank. And when the brakes went completely bad earlier this year that got me motivated, and all I have done in my "spare time" since then is work on the Lemans. I am about $15K into my $30K budget for it. The car will never be worth anything close to that to anyone else, but I'm not building it to sell.

Next on the list is to pull the dash and steering column for rebuild/detailing, and new glass, chrome, etc. at the front windshield. Then on to bodywork, paint and the rest of the interior... I imagine I will be posting on the board for a good while to come.

My goal is to make my LeMans a stock-looking sleeper. I am keeping it very original looking on the outside, quiet exhaust etc. And I don't have a huge cam in the engine since I want to keep the idle smooth. But I am hoping that all the cubes will make the car get up and go!

Walt

[PontGuy]

Update-

Ran the engine again and this time sat in the drivers seat. So I got to feel the brakes with the booster. They held good enough to put the car in and out of gear (the trans is brand-new too so that was another first.) The pedal did not go to the floor, but it definitely felt spongy. I bled some more afterward and still getting bubbles from the drivers side rear, but the fluid is still clear at the other wheels. I checked over all the fittings and can't find any leaks except for the banjo fitting on one of the calipers which was a little wet after feeling full pressure. Also the brake light is still stuck on.

I called Inline Tube and the rep confirmed that there never was a residual valve in the '69 design, and there isn't one in the replacement stuff that I bought from them. I told him about the like-new condition of the drum surfaces and that the adjuster knockouts were never "knocked out", and he said he had never heard of that in such an old car. He agreed it is probably air getting past the seal in the wheel cylinders and suggested replacing them. But if it is a design weakness then it is likely to gradually go bad again, so I am also looking into the residual valve option.

What I want to try is fitting a residual valve between the master cylinder port and the existing flare fitting on the new SS line. The IT rep said that would probably work OK, at least to try, and bending the tubing a little to make room would be easy. But all of the residual valves seem to come with 1/8" NPT pipe threads so I will need to search out fittings to connect it up this way. I can find some flare-to-flare adapters, but for some reason flare-to-NPT is not at all common. And I don't want to use an assortment of adapters on both ends of the valve to make it work.

I also picked up another wheel cylinder, this time from Napa. I will go ahead and replace the one on the drivers side and see if it changes anything. I also still need to "unstick" the brake sensor, but first need to get full pressure on the rear lines in order to push the piston back.

All of the front end sheet metal and bumper assy pieces have now been cleaned up and painted, and over the weekend I got it all ready to put back on the car. So the brake system is now the big hold-up to road testing. I can't believe just how much trouble it has been.

Walt

[Shiny]

Sounds like you are almost there in record time !! Nicely done.

Based on my pain, and still unknown confidence in the residual valve as a solution, I would recommend you start with the rear cylinders. I think a zillion people get by without the residual valve, and if I had a leaky rear cylinder as root cause, then I still wouldn't know it because I did not replace them. The residual pressure valve for me was an act of desperation, but the improvement at least told me my problem was in the rear system. I may have bought rebuilt or "old stock" or similar cylinders off eBay when I did the rear brakes, which could be my real problem....

If you really have the original cylinders, it seems a basic starting point to replace them now before you get any more frustrated. I looked at my local parts stores and they had "house brand" only, so it may be best to order a name brand online or maybe somebody like NAPA would carry a higher quality new part.

If you are determined to put the residual pressure valve in just in case, I agree it seemed odd to have an NPT fitting on the inlet. Mine came with a flare-to-NPT adapter fitting, so I guess that saved me another major hassle, but that pipe fitting leaked and I had to tighten it beyond what I thought rational to get it to stop. Another place to leak, which is another reason to avoid it if you can.

My experience bleeding also told me not to expect to do it once and be done. I was told by many on this forum to let it sit and do it again, and I think that is good advice. Bleed it 2 or 3 times with a day or two between before you draw any conclusions, although I agree with your one conclusion about it being a seemingly ridiculous hurdle in the scale of what you are doing.

I still think you will be driving a rocket sooner than you know and am excited to hear about it.

[PontGuy]

Mike,

Glad to see you are still watching out for me! I just finished replacing the rear brake cylinder. The NAPA unit certainly looks much nicer than the one that I removed (bought at one of the local cheap chain stores). Higher quality casting, better seal arrangement, and it has "USA" and some numbers cast into the housing which may not mean anything but it makes me feel better. Hopefully I am going to find that quality of the rear cylinders is the key to making it work without a residual valve.

My wife fell sound asleep so I won't get to bleed until tomorrow evening. One thing I am a little worried about- the brake line and fitting back there have gotten a little bent up from being loosened and re-tightened on the other wheel cylinder so much. I really never thought that fitting leakage was causing the problem since it stayed dry, but the air had to be coming from somewhere... Hopefully it is sealed up OK to the new cylinder.

I know the bleeding drill very well. If everything is working right it has never me taken too long to get an acceptable pedal in the past. But it does take bleeding several times with some waiting time between to get it really good.

I think you are pretty safe with the residual valve as long as you don't develop any leaks. As long as your master cylinder level holds steady you should be good to go. Hope you are finding some opportunity to drive!

Walt

[Shiny]

Walt,

I'm thinking you got it now. I'm glad to hear the NAPA cylinder looked good to you. I think it would be smart for me to get new ones too, so if yours works, it will be easy to find. I really don't think I was getting air into my system through any fitting. I think it was coming in past the cups inside the rear cylinders. They look like check valves if you think about it... and if you pulled even a little suction on them, I can imagine air being ingested. I really want to hear that a good quality cylinder solves your problem. My residual pressure valve isn't going to hurt anything, but it just feels like a band-aid and if new cylinders are the fix, I would finally and truly understand the source of all my grief (ok, at least some of my grief).

I was layed off in May, had no luck finding work locally, so had to move away from my wife, house and LeMans to find a decent paycheck and health insurance. I am lucky to have found something at all, but until something changes, I won't be driving my car for a while. I'll be back at Christmas, and if it's not too cold, maybe I can at least drive around the block. I still have the front bumper, nose, and hood off. I had to repair a crushed front fender, which was my first attempt at bodywork. It turned out OK, so next is to repair a crack in the fiberglass nose and straighten the fascia a little. I have a dinged up GTO hood I am going to try and salvage, cause I like them, but it may be too difficult. I would rather try to fix it than buy a new one, though.. since that's what this is about for me. My car is hardly a gem, will never be a gem, but it's fun for me.

So post the results when you get it bled. I'll bet it will all fall together for you finally... oh yeah, except for that stupid switch that needs to be centered. I'll bet it pops right back once you can build pressure in the rear system.

Good luck !!

Mike

[PontGuy]

Mike, sorry to hear about the job. Hang in there, I am sure things will eventually get better. I have been very lucky- my company is doing well and our sales are actually up this year especially in my division, so work has been very busy and the money has been good. I have family and friends that have been hit by the economy though, and know that it can be tough.

We just finished bleeding the wheel with the new cylinder with excellent results. It only took a few refills at the master cylinder to push out all the air I got in the rear line, and then no more bubbles. And the pedal is the best it has been. Unfortunately I got a very late start this evening, and flying out on business tomorrow for the rest of the week so I won't get to give it a real test until Saturday. I need to bleed both rears again and then fire up the engine to see how it does with vacuum on the booster to be absolutely sure, but now I am 90% convinced that high quality wheel cylinders is the solution. If the light switch re-centers I will really celebrate!

If it works I am going to go back to NAPA and get another wheel cylinder. The cheap looking one on the passenger side finally seemed to stopped leaking air in by itself, but I will never trust it. Also I think the residual valve is still a good idea. Even with quality wheel cylinders I bet some air will eventually get back past the seals again.

Your car may be a "diamond in the rough" but nothing wrong with that. I've certainly had fun working on them over the years. Now I am building my car into something that will probably never be worth much more than half I am putting into it, not even including all the labor. Not sure it really makes sense, but my philosopy- its all about the enjoyment and satisfaction you get out if it.

Walt

[Shiny]

Yoo hoo !!!! that is really good to hear. Given your success, I will replace my rear cylinders next time I can. I'll look for a report when you get back. If you think of it, post the part number and/or brand of the cylinders.

And thanks for the encouragement and empathy on the job thing. I really am glad to hear you are doing well. I was part of a RIF that clearly targeted older workers with bigger paychecks and higher medical costs. I went from being treasured (biggest bonus I have ever imagined in October) to worthless in less than 6 months. I was lucky to find a job, and like you, have many friends in worse shape, so I try to view it as positively as I can.

As far as my car goes, I agree with you - it is there only for the satisfaction when I actually make progress and for the learning experience. If it had to make financial sense, it would have to be gone. This brake problem has been by far the most frustrating thing I've run into. When I declare victory on this one, it will feel like the Prize Patrol is knocking on my door.

[Blk 76]

I was having a real difficult time getting the switch to re-center and had read about using a small sledge hammer to hit the brake pedal. I was very skeptical about this method but nothing else had worked for me so I figured I had nothing to loose by trying it. I used hammer about 2-3 lbs and only had about 16 inches of swing so I was not concerned about hitting it so hard it would damage something and it really worked and it took a couple of days to get my brake problems figured out and I needed to re-center the switch few times but the hammer trick worked every time. I think part of my problem had been the switch was not centered and was causing a problem with bleeding the brakes. My master cylinder tested good but I was told that it could still be bad so I put another one on. I am not 100% sure if I had just one problem or if there was more than one but the brakes on my truck are better than they ever were.

[PontGuy]

Interesting, I never heard of the sledge hammer trick. What kind of truck was it and did it have power discs? If so did you hit it with vacuum on the booster or with the engine shut down?

In my case the valve does not seem to be restricting flow to the rears and I am hoping that I will be able to pop the switch back using rear brake pressure. But the GM switch is really not supposed to stick so it may take a shock to get it to free up.

I think mine got stuck when I put pressure on the front brakes with the rear system bone dry. If you read way back into the posts you will see that the cause for this was a master/booster rod problem.

Walt

[Blk 76]

My truck is 1990 Chevy Z-71 4 Wheel drive with front disc and rear drums that had the rear ABS and the brakes had always been real bad, I took it to the dealer and they told me nothing was wrong. I replaced everything but the metal lines at one time or another. I finally took out the ABS for good a few weeks ago and that's when I had trouble with the combination valve. When I tried the hammer on the brake pedal the engine was off and I did not worry about whether the booster was connected or not. Once I hit the pedal with the hammer my light on the dash went out immediately. I was afraid to bleed the brakes using the brake pedal method seeing that I had so much trouble with the switch in the combination valve so I used the small mighty vac hand pump to draw fluid down from the master cylinder and out the wheel cylinders. I can actually hear the rear shoes release now. The truck brakes feel good now, they are not as responsive as the ones on my 76 TA but they are better than ever.

[PontGuy]

So its an entirely different design, but the same principle would apply. I'll keep that as a backup plan in case mine refuses to free up using regular pressure.

[ELKHORNAOG7]

I changed my brakes over from drum/drum to disc/drum and put on a new m/c and booster and some new lines I think I just may put on some new wheel cyls. once I find out what kind was used from napa. before I bleed them I hope I don't run into the same prob. but the luck I have I know I'll be back in all these threads looking for something lol-----BOB

[Shiny]

Blk 76 - thanks for posting that hammer info. I had not read that anywhere either. My switch is the only thing that has NOT given me fits, but I will remember that trick.

I think about a hundred posts ago, I relayed a recommendation from Inline Tube to open BOTH front bleeders so pressure can't build up in front system, then press pedal to pressurize the rear system while watching the light (or measuring switch contact) and stopping the pedal when the light goes out or switch opens. They basically are saying to reverse the imbalance that caused the switch to trip in the first place. I think if both systems are building pressure (front bleeders are tight), there will be no pressure differential to center the switch again and it will just stay where it is. Sounds good, anyway....

PontGuy is going to eliminate the folklore and give us the facts soon !!

[PontGuy]

I am at the Charlotte airport between flights catching up on things- I had absolutely no time the last day or so. Can't wait to get home and work on brakes tomorrow.

On so many levels that sounds just wrong...

What I am really looking forward to (now with some degree of confidence) is getting to give the car a test drive some time before the Thanksgiving weekend ends!

Walt

[PontGuy]

Here's the update..

I re-bled the drivers side wheel with the new NAPA cylinder. No bubbles. Then bled the passengers side with the "cheap cylinder" and got air bubbles that would not completely stop. I tried to work most of it out then started the engine. The pedal still was still a bit spongy. So I drove over to NAPA and bought another cylinder and installed it on the passenger side, then bled it. Absolutely no air after quickly working out what got in during installation. Then bled the drivers side again. Still no bubbles.

I started the engine and for the first time the pedal is perfect- not spongy at all. So the next step is to actually test drive and see what happens.

With the cylinders from the other local parts house (Advance or A-Zone, don't remember which) I always got some bubbles no matter what I did. With the new NAPA cylinders I am getting no bubbles. There definitely is a big difference. I posted pics of them side by side, with the NAPA box behind the NAPA cylinder. You can see the difference in the design and the numbers cast in the NAPA cylinder. The NAPA cylinders are only $7 and change each so I don't think that you can tell anything by the price tag. I am not yet sure that this is the end-all solution, but I am now positive that it takes quality cylinders to get the old disc brake systems to work right.

I also tried centering the switch, both by opening up both wheel cylinders in the font and trying the hammer method. No success but I think I will leave that for another day- actually I am sort of hoping it will magically free up when I test drive.

It will take a couple of days work to take care of odds and ends up front and get the fenders and bumper back on the car, but I should be able to report back on street testing results by next weekend.

Walt

[Shiny]

Congrats on getting this far!! Major good news for you and perhaps me too... Pat yourself on the back freely.

You are definitely holding my interest. If you go back through these posts, you will see pics of my rear brakes, with my cylinders being the same style as your "leaky" ones.

I don't think I believe in coincidence right now... so I will choose to believe if mine look like yours, mine are bad too. You have convinced me to replace them. Thanks for posting the pics and the NAPA part number.

Sorry to hear the switch is still stuck. I'll vote with you for the magical fix approach !

Can't wait to hear your report when you finally get to drive with new engine.