Guest Infinity Performance Posted May 1, 2014 Share Posted May 1, 2014 A little background: Last spring I purchased a 54 Eldorado that has been in the family since 1960. Having said that, the car hadn't been on the road since 1967. During that 45 years it had been in various states of storage; some good, some not so good. In the end was a true survivor. The car was nearly completely original and 100% complete. Nothing was touched on the car since 67, and it wears its mostly original paint. Although it was a very good, solid car; it had also seen significant neglect. Honestly, the car isn't even a restoration candidate as far as I am concerned. It was too complete and original, and in too good of shape to do anything but bring it back to life. Thankfully the paint and trim turned out beyond expectation with enough work bringing it back and all the systems came back on line well after being gone through and sorting out the normal issues for a car like this. The exhaust was nearly rotted away and the brakes system was completely non-functional. In fact, all the brake fluid essentially became a solid, white powder. The entire brake system was removed while the mechanical items like the wheel cylinders, master cylinder, and power brake booster were disassembled, cleaned, repaired as needed, and reassembled with new wear items. The drums were turned, new pads installed on the shoes, new brake hardware, brake lines, hoses, etc.Now the problem:The brakes have yet to work properly. The system bled fine and originally developed a week pedal. I adjusted the drum to shoe clearance and found that the pedal had good feel. However, this only lasted for a short while. Recently I tuned the drum to shoe clearance again. It's tighter than I would like, but I wanted to rule out the possibility that I just wasn't moving enough fluid to engage the brakes. What I do know is there is no air in the system and there are no external leaks anywhere. Having said that, there are only 2 ways to get a good pedal; 1) engage the parking brake and pump the pedal a couple times. 2) Spike the brake pedal very quickly. If you apply the brake slowly, as in normal driving conditions, it drifts all the way to the floor. I'm left scratching my head. Originally I began thinking that maybe the system had an internal leak, but when you do get a good pedal it will hold fine. Plenty of stopping power, no pulling, no drifting of the pedal, etc.Hopefully someone here has had similar experience and can shed some light on this or point out something I may be missing. It's that last mechanical hold up to enjoying the car.For what it's worth, my next move is to put a pressure gauge on the master cylinder in an attempt to begin ruling things out.Below are a couple of photo's just so you can see where it started and where it ended up. The first photo is the night I brought it home last march, and the other is probably late summer 2013.Thanks, Link to comment Share on other sites More sharing options...
Pete O Posted May 1, 2014 Share Posted May 1, 2014 Sure sounds like the master cylinder needs attention. Link to comment Share on other sites More sharing options...
Larry Schramm Posted May 2, 2014 Share Posted May 2, 2014 I also agree on master cylinder.Nice looking ride though. Link to comment Share on other sites More sharing options...
c49er Posted May 2, 2014 Share Posted May 2, 2014 Master cylinder by-passing fluid. Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted May 2, 2014 Share Posted May 2, 2014 The master cylinder is down on the frame; the booster assembly is at a different location in the front of the engine compartment. I doubt that the master cylinder is the cause of the problem; to me, the booster is probably at fault; they are rather difficult to rebuilt correctly.By the way, the wheel covers are for a '56 Cad; I believe wire wheels were standard on '54 Eldorados. Link to comment Share on other sites More sharing options...
Graham Man Posted May 2, 2014 Share Posted May 2, 2014 If you can pump the pedal several time and get good feel the only way that can happen is if the fluid is getting past the master cylinder. I would have it sleeved with a stainless steel liner, it gets the master cylinder to work better than new. You can test the booster by depressing the brake pedal and starting up the car, the pedal should slowly depress a 1/2 inch or so then hold firm.Good luck beautiful car, my Grandfather had one just like it but pink! Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted May 2, 2014 Share Posted May 2, 2014 If the fluid is getting past the master cylinder, there would be a loss of fluid. The master cylinder is connected to the booster by a long brake line. Link to comment Share on other sites More sharing options...
Graham Man Posted May 2, 2014 Share Posted May 2, 2014 There is a seal between the pressure side and the reservoir side. If the seal leaks the fluid returns to the reservoir (no fluid loss) this causes the loss of pressure to the brake shoes, when you pump the brake pedal the pressure builds up on the brake shoe side. That is why I recommend a sleeve for the master cylinder, a lot of times it is not the seal but the condition of the cylinder wall, it can even be the cylinder has been honed too much/large causing the same problem. Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted May 2, 2014 Share Posted May 2, 2014 Explained that way, I agree that's a possibility. Further, as the master cylinder is at the lowest point, if there was once water in the system (due to the hygroscopic nature of the brake fluid), the master cylinder is getting its share. Link to comment Share on other sites More sharing options...
Graham Man Posted May 2, 2014 Share Posted May 2, 2014 Did you have the master cylinder rebuilt? they should have checked the bore inside diameter. The best way is to press in a stainless steel sleeve, most good brake shops should be able to do this. I use the Brake & Equipment Warehouse in Minneapolis MN USA. http://srv4.sitealiveauto.com/be/portal.jsp#top Link to comment Share on other sites More sharing options...
TexasJohn55 Posted May 2, 2014 Share Posted May 2, 2014 Jamming the pedal quickly flares the cup seal against the MC wall and seals it. When pressed slowly, the cup seal doesn't flare enough to seal. Either the cup seal is bad or the bore is damaged or oversized. IT IS THE MASTER CYLINDER. Link to comment Share on other sites More sharing options...
Guest Commodore Posted May 4, 2014 Share Posted May 4, 2014 We know the Master Cylinder is bad. Ask Felix the Cat. Link to comment Share on other sites More sharing options...
Guest Infinity Performance Posted May 28, 2014 Share Posted May 28, 2014 Thanks for all the feedback and support. It's greatly appreciated.Roger, The caps are from a 56. At some point in time my grandfather put steel wheels and caps on it. I have the original wires, but they are in sad, sad shape. That will be taken care of some day down the road, but unfortunately, it's not time financially.As for the master cylinder; I agree with all that was said, and concur that leaking past the piston generally does not create a fluid loss. Since this post I pulled the master cylinder, disassembled it, and sent it out to be sleeved. It didn't look bad, but I did do a light hone when I rebuilt it the first time and figured it good money spent. Upon return, I did assembled it with the same "new" rebuild parts from the first go round. Unfortunately, the problem persists. The system moves fluid well when the bleeder screws are open and bleeds fine, but can't build pressure normally at the wheels with everything closed up. For S&G's I'm going to pick up new internal parts to rule out the possibility of just getting some bad parts.For what it's worth, the booster is not hooked up. I didn't want to be trouble shooting 2 systems at once, so I started out with the booster bypassed. For now, that's definitely not a factor.The only other thing is that I'm using DOT 5 synthetic brake fluid since its non-corrosive and non-hydroscopic. I've had success before in vehicles where the system was completely disassembled, cleaned, and started fresh with synthetic. Have you guys ever had a problem with synthetic fluid in a clean rebuilt system?Thanks,Jason Link to comment Share on other sites More sharing options...
MikeC5 Posted June 1, 2014 Share Posted June 1, 2014 I haven't used Dot 5 but have read that it can be extremely difficult to bleed properly. Maybe worth trying Dot 4 as a san Link to comment Share on other sites More sharing options...
MikeC5 Posted June 1, 2014 Share Posted June 1, 2014 Sanity check... Link to comment Share on other sites More sharing options...
GLong Posted June 4, 2014 Share Posted June 4, 2014 I'd replace the cup in the master cylinder. TexasJohn55 stated it right. I've had the identical situation several times. The rubber cup is hard from being old, in a box, on a shelf for too long. Find a new cup that is softer, and has a sharp edge on the outer edge. On many old single cup master cylinders, can be 'made' to bypass fluid past the cup. Just VERY gently push on the brake pedal, if the cup is the least bit hardened, or the edge of the cup where it contacts the wall of the cylinder is rounded and not sharp, fluid will bypass the cup. A rapid 'jab' at the pedal forces the edge of the cup against the cylinder wall. So, even though you had the cylinder sleeved, you reinstalled the culprit: the cup from the previous rebuild kit.. replace it, I'm sure you will have normal acting brakes again. GLong Link to comment Share on other sites More sharing options...
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