Can't get a pedal of any kind.

[bossman2696]

Hi, I am new to the forum and actually bought my second 7 litre that I am working on to get mobile, I got it up and running after a 15 year nap, but cannot get the brakes to work, I did everything in Hulk 66's post and did use the 461 kit etc. The bore appears good and is not scored. I got a new 1" 2223502 cylinder as a backup, but haven't wet it yet. Inthe box it says to presuure or vacuum bleed the master cylinder only, no bench bleeding. Ugh. I do get seepage out the rear when the piston is used to bleed. I bench vaccum bled the master and then did the same o nthe car to no avail, The air never really seems to clean up completely either, Anybody Have any other ideas as to the problem or somethin gI have missed before I install the new cylinder? Thanks all, This one may go for sale as well once running like a car as they say. bossman2696

[7leader]

Hey Bossman,

Not an answer to your question, but I have put out an alert to all the guys to get back to you on this...

My question....do I have both your cars in the Registry, and do I have photos and descriptions for the website?

If not, please forward and I'll get you up there.

Vince
dziner55@optonline.net

[bossman2696]

Thanks Vince, I have not registered the second 7 Litre yet, but I will, as soon as I get a break, Its an 80k, emberglo with white vinyl roof and parchment interior, ac, ps pb, factory cruise, factory telltale panel and power windows, which frankly is why I bought the car, 15 years in storage in Mass. Got it running and driving all ok except the brakes when I wrote it up as I along with several good mechanics were stumped. I since had gotten a new master cylinder as that number is used i nseveral vehicles and discovered the manufacturer stated do not bench bleed only vacuum or power bleed. I since did that and vacuum bled the car as well. Result was I still had no brakes in it when I left it for the day. Here's the real kicker, The next day when I came in I thought what the heck I will step on it, Guess what I had a pedal and it held, I think the brake fairy did something over night LOL but doesn't give me a warm felling about them. If I decide to register and drive it I will redo completley but sure doesn't give me a warm fuzzy for the system and I know I have to do the other car ever eventually. If any one has an expalnation to this one I am all ears as they say. When the 7 litre thats o nthe site is done I will update the pictures ( ed Reeses old car ) I will add the other soon, I may not steal the power windows out of it either and may just elect to sell it off as it should probably be preserved as is wit hte options it has. Thanks

[thomas11]

Think of your brake system on a base level. It is a hydraulic system; you apply a pressure to a closed tube that is filled with fluid. Assuming there is no voids in the tube, the pressure has only one place to go, which is out the other end. In the brake's case, you have a mechanical interface to the tube system (brake pedal to MC), then another mechanical conversion at each wheel. So there would be two things that would cause your issue; a void in the fluid in the system, or a mechanical inability to transfer the application of pressure to that fluid.

First, when you had your MC off, did you verify that the brake pedal extends the pushrod ? The pushrod has an adjustment on the end, so you can make sure the pushrod travel is sufficient to compress the MC enough to transfer to the fluid. There is a seal on the end of the pushrod, was it in place? You could verify the function of the MC by detaching the brakeline from it, make sure the MC has fluid then have someone push the pedal while you hold a receptical at the fitting (to catch the displaced fluid - DOT3 fluid eats paint). Note the force of fluid exit, should be strong.

If this test is successful, then your issue is air in your lines, or a void in the system somewhere. Could be in a line, at the distribution block, in one of the front calipers, or rear cylinders. If you dont note any fluid trails anywhere (look on the inside of the wheels) then you may still have air in the system. Did you use a handheld pump to bleed the brakes? I will assume you know how to bleed brakes.

If you lines have any kinks, or the prop valve or any of the wheel cylinders are clogged, it still should be able to build pressure up.

You could separate the front from the rear circuit by detaching a line from the distribution block mounted on the frame under the MC and providing for a robust plug where you took the line out. That would further help in the process of elimination.

Are your rubber lines original? Check their condition...there are 3; one at each front caliper and one mounted to the rear axle.

Are you using DOT3 fluid? If you've converted to DOT5, it has a greater chance of retaining air bubbles.

Let us know what you find. Since you let the system sit for awhile then you had a pedal, it sounds like air bubbles in the system.

Tom

[bossman2696]

Thanks for all that great information Thomas 11, The answer is everything you touched upon was done, with exception to checking the push rod travel. I used the assumption method that the car was driven and parked some 15 years ago and was working. I did all your steps inclucding borrowing a vacuum pump to bleed them of as recommended by the MC people on the new one I did not install, and as I said to no avail would thye come up and give me a pedal, I actually vacuum bled the master cylinder on the bench and in fact when I pushed on the piston it blew off the hose to the cup and squited brake fluid over the bench, not tomention on to my parked expedition which I then had to wash, good thing there was lots of salt cover on it. Based on that and then vacuum bleedin gat all the wheels I would have thought I would have had a pedal and as I said to no avail. Maybe I just didn't get all the air out which to me is strange becaue I have been rebuilding brakes and bleeding for years and never ran into one this difficult. Again Thanks for all your info and you are right its not a rocket science system either,

[thomas11]

Hey Bossman,

It sounds to me that it has to be either a mechanical issue between the pushrod and MC or you still have alot of air in your lines. If you segregated your front/rear circuits and didnt isolate the issue, then I'd think it was your pushrod is not adjusted right. Is your MC a correct KH unit? Tbirds used a 7/8 diameter MC while the Galaxies had a 1 inch. I would think that wouldnt matter though as far as getting a pedal.

I'm assuming that your car will roll around such that the calipers are not stuck. The calipers are rather large and displace alot of fluid.

If you remove the MC cover and push the brake, do you see evidence of fluid displacement (like a slight lift in the fluid above the feed hole about 2/3 towards the rear of the bowl)?

[bossman2696]

Thanks again Thomas, As Ia said to Vince, I think the Brake Fairy came on saturday night because thye worked on Sunday, I have finally driven slowly enough outside to see that the brakes will slow the car to a stop for now. To answer your inquiry it is a bendix 1" master cylinder and it appears to be the same as on my other 7 litre. I beleive at this point that there was air in the lines still preventing it from a complete bleed maybe? I can't tell you how much brake fliud I pushed through it but it was way more than any other car I normally did. for now it will get the car out of my way until spring and I will go from there. If I decide to road drive it the car would need a complete brake redo anyway. Thanks for all your help. If i get a break at work I will get it registered and pictures before it goes outside. Bossman