General Brake System Question

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jondearmond
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Joined: Fri Nov 09, 2012 7:27 am
Location: Virginia Beach, VA

General Brake System Question

Post by jondearmond » Mon Dec 03, 2012 11:10 am

I am a month into my first Packard/any car prior to 1965 project. I have a 1950 Packard with manual hydraulic brakes. The brakes work so I haven't checked them yet beyond shoe thickness, but I want to. What kind of fluid do I need to put in the master cylinder? Will there be a full mark in there, or is full a distance from the top? How often should the rubber brake lines be replaced? Mine look about 20 years old.

Dave Czirr
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Re: General Brake System Question

Post by Dave Czirr » Mon Dec 03, 2012 1:33 pm

I'd recomend you change your brake hoses immediately. You should also consider checking the condition of wheel cylinders if you haven't already done so. Just peel back the rubber dust boot and look for any signs of crud or brake fluid seepage and if present, replace or rebuild the cylinders also. Your brake system originally used DOT 3 brake fluid which is still available at any auto parts store, fill to about 1/2 inch below the bottom of the filler port. DOT4 fluid is also compatible with DOT3 but if someone converted your brake system to silicone fluid, it is incompatible with conventional brake fluids!! Unfortunately many owners who convert to silicone fluid don't tag or mark the filler cap and leave future owners uninformed of the change. If you can't determine what type of fluid you have, best bet it to completely drain the system and replace the wheel cylinders & hoses, flush, rinse with alcohol and blow-dry the steel lines and then fill with the fluid of your choice.

Though silicone brake fluid is often colored purple, I don't know that that is a standard; perhaps someone else can tell you how to tell which type of brake fluid you currently have. The "feel" when you rub it between your fingers is different but that's hard to describe in words.

Anyone have a good and conclusive method to differentiate regular from silicone brake fluid?

jondearmond
Posts: 96
Joined: Fri Nov 09, 2012 7:27 am
Location: Virginia Beach, VA

Re: General Brake System Question

Post by jondearmond » Tue Dec 04, 2012 12:02 pm

Thanks. That gave me a reference point with which to do a little research. Dot 3 and dot 4 at least according to about 5 online sources are mixable whether they are conventional or synthetic (did not specify whether this was 100% kosher, just possible). Dot 5 fluid is the silicone and cannot be mixed with anything else. I just wanted to be sure the brake fluid reservoir actually took brake fluid and not hydraulic oil, ATF, or 30W.

Everything on this car needs a little something so I'll just add flushing the brake system and changing the lines to the list.

Adam
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Location: lincolnshire, uk

Re: General Brake System Question

Post by Adam » Thu Dec 06, 2012 3:44 am

you have got it. Dot 3 or Dot 4. Please don`t use hydraulic oil, engine oil or ATF !!!!! :shock:

Good luck with it all.

Adam..
"Do not underestimate the English cousin.....they are not as stupid as they look!" - Signor Altabani in The Italian Job.

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