| rick50 | -- 02-21-2015 @ 12:53 PM |
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I have a question regarding the brakes on my '50 Deluxe. I've replaced the linings, wheel cylinders, brake hoses and a reproduction (china) master cylinder. The brakes are properly adjusted as well as the pedal free play. After bleeding the brakes the pedal would be firm at a height even with the gas pedal. Wait a few seconds and the pedal would drop almost to the floor the next time the brakes were applied. If the pedal was held it would slowly drop completely to the floor. I'm sure there was no air in the system. This is an indication they the master cylinder was not holding pressure. I contacted the supplier of the master cylinder and they provided a replacement unit. After bleeding the replacement unit the pedal will feel firm at one inch above the gas pedal. I thought I had the problem corrected. If you wait a few seconds the pedal will get firm even with the gas pedal the next time the brakes are applied. The pedal no longer slowly drops to the floor. If the pedal is pumped two or three times the pedal will be firm at one inch above the gas pedal. The cycle will repeat itself after waiting a few seconds. I'm going to let the car sit overnight and check to see how far the pedal travels before obtaining a firm pedal. This cannot be correct. I've never experienced this problem with any other vehicle. I'm a retired ASE master mechanic. I should mention that the unit is an aftermarket reproduction. I searched for an NOS or NORS unit but every one that I looked at was extremely rusty and looked as if it was stored outside. I eventually bit the bullet and purchase a reproduction. Am I missing something? I don't think this is normal. Are the reproduction units problematic? I'm unable to road test the car because the engine is out for rebuild. After installing the replacement unit there was some improvement but it still does not feel correct to me. Any thought would be appreciated.
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| rick50 | -- 02-21-2015 @ 4:40 PM |
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I went out to the garage and applied the brakes. After sitting for four hours the pedal goes almost to the floor. It's got to be a defective master cylinder. Can anyone recommend a company to sleeve my original? I'll continue looking for a NOS unit also.
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| shogun1940 | -- 02-21-2015 @ 5:17 PM |
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master cylinders in the old days had residual check valves to keep around 7 psi in the lines.. they had a problem when they switched over to disc drum in the seventies if you got wrong m/c for an all drum system.. its worth a look
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| cliftford | -- 02-21-2015 @ 5:36 PM |
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You came up with the same solution I would have suggested. There are several companies that do cylinder resleeving that advertise in Hemmings Motor News. It sounds like you got a bum MC. Also, Mac's offers both US made and foreign made MC's
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| TomO | -- 02-23-2015 @ 8:04 AM |
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Call your local pats house and have them check around for a re-manufactured master cylinder. Wagner makes a good one. Cardone has a good reputation for brake cylinders and they do make a replacement for your car. Rear Counter shows one NOS one available at the following phone Number. (229) 686-5101 I have had the same problem with the Chinese made master cylinders. I put in 4 of them in one car before I got one that worked, and it failed a week later. I had my local parts house get me a re-manufactured one from Wagner and it is working fine. Tom This message was edited by TomO on 2-23-15 @ 8:08 AM
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| rick50 | -- 02-23-2015 @ 3:23 PM |
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I contacted the vender of the master cylinder. He stated that he has not seen a lot of problems with these units. He asked if the pedal would continue to go to the floor. The first unit did leak down to the floor. The replacement unit would not leak down. He suggested that the condition that was occurring could be caused by improper adjustment. If the pedal eventually was hard the master could not be leaking down. I rechecked the adjustment and found that the LF secondary shoe had excessive travel. After inspecting the shoes and not finding a problem I readjusted that wheel. The pedal height was now correct. I'm not sure what the problem was. I readjusted all four wheels using the feeler gauge per the manual and the pedal action is correct. The vender was correct. I was too focused on the master cylinder because of the problems with the first unit. I'm will continue to look for an NOS or remanufactured unit just in case. Thanks for all of the useful information regarding this issue.
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