Brake Fluid for new system

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1983Pinin
Posts: 44
Joined: Mon Jun 23, 2014 2:50 pm
Your car is a: 1983 Pininfarina

Brake Fluid for new system

Postby 1983Pinin » Tue Oct 17, 2017 6:22 pm

Hello,

I have an 83 Spider and plan to redo the entire brake system, other than the rigid lines--new braided hose, booster, master cylinder, rebuilds on all calipers, vacuum line.
Should I consider a higher DOT brake fluid for this new system? I plan to leave the rear brake compensation valve in the system.

Thanks for any tips.

--Peter
--Peter

1960 something 850 Spider in 1974-1976
1970 something 124 Spider 1977-1980
Currently 1983 Spider 2000

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Odoyle
Posts: 215
Joined: Mon Dec 01, 2014 10:06 pm
Your car is a: 1983 Pinafarina Spider

Re: Brake Fluid for new system

Postby Odoyle » Wed Oct 18, 2017 4:12 am

Nothing but DOT 3 non-synthetic. NAPA sells some. Will most likely want to replace compensator valve with brand new one, will also want new bushings for linkage rod on the diff. Be careful removing brake fittings, their made of a soft alloy which can easily be stripped. PB Blaster and wire brush any visible threads is a must (in my book). 10mm flare nut wrench is handy, some vendors also use a vice grip-style nut wrench which works well.

rridge
Posts: 50
Joined: Thu Aug 10, 2006 11:59 am

Re: Brake Fluid for new system

Postby rridge » Wed Oct 18, 2017 8:07 am

All brake fluid is synthetic. The choice is between glycol and silicone bases. Each has pluses and minuses. SAE 3 glycol-based is cheap and works well if the system is bled periodically to remove moisture saturated fluid.

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Odoyle
Posts: 215
Joined: Mon Dec 01, 2014 10:06 pm
Your car is a: 1983 Pinafarina Spider

Re: Brake Fluid for new system

Postby Odoyle » Wed Oct 18, 2017 12:27 pm

Obviously DOT 3 is a man made substance, but you have to make sure it is not petroleum based, which would classify it as synthetic. DOT 5 is silicon based, which can never be mixed with anything.

maxdog
Posts: 76
Joined: Thu Jul 07, 2016 11:27 pm
Your car is a: 1979 spyder 124
Location: Montreal Quebec Canada

Re: Brake Fluid for new system

Postby maxdog » Wed Oct 18, 2017 1:18 pm

DOT 3 And DOT 4 are both "synthetic ", and petroleum based .They are synthesised from Ethylene Glycol which in turn is made from Ethylene ; itself a petroleum derivative .DOT 4 is a glycol based fluid with a higher temperature range than DOT 3
DOT 5 is a silicone based fluid which is totally incompatible with any Glycol based fluid and many of the commonly used rubber parts of systems designed for DOT 5. NEVER use DOT 5 in a system which has seen DOT 3 or 4.
Maxdog

maxdog
Posts: 76
Joined: Thu Jul 07, 2016 11:27 pm
Your car is a: 1979 spyder 124
Location: Montreal Quebec Canada

Re: Brake Fluid for new system

Postby maxdog » Wed Oct 18, 2017 1:21 pm

OOPS Major mistype in my previous post
Should have said " never use DOT 5 in a system designed for DOT 3 or 4""
Maxdog


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