Type of Brake Fluid

Discussions related to braking systems.
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John 3:16
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Joined: Sat Mar 08, 2014 9:48 am

Type of Brake Fluid

Post by John 3:16 » Tue Feb 10, 2015 3:36 pm

I need brake fluid for my 1937 Packard 115c. What type of brake fluid should I use? THANKS

Dave Czirr
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Location: New Jersey

Re: Type of Brake Fluid

Post by Dave Czirr » Tue Feb 10, 2015 3:50 pm

That depends on what type of brake fluid is in it now. Originally it used DOT3 which is widely available and still the most common brake fluid. You can also use DOT4 which has a slightly higher boiling point and can be mixed in any proportion with DOT3. BUT (big BUT) many older cars have been converted to Silicone brake fluid which is totally incompatible with any other type of fluid so if you car has been converted, then you MUST stick with Silicone (DOT5 as I recall).

Unfortunately many who converted to Silicone failed to attach a tag or other notation. If you don't know what you've got, stick you finger in the master and take a good smell of it. Then clean your finger and stick it in DOT3 or DOT4 - they both smell quite strongly and Silicone fluid is essentially odorless (and sometimes has a purple dye added).

If in doubt, drain the entire system, flush all the components with alcohol and replace all the rubber hoses and internal rubber parts in the wheel and master cylinders, then fill with the fluid of your choice and bleed the system as normal.

John 3:16
Posts: 101
Joined: Sat Mar 08, 2014 9:48 am

Re: Type of Brake Fluid

Post by John 3:16 » Tue Feb 10, 2015 6:20 pm

Thanks, Dave

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