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Silicone Brake Fluid , What are the Pros and Cons???????????

  • Terry Cockerell
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31 Aug 2021 09:41 #43824 by Terry Cockerell
Conducting a bit more research on what type of brake fluid I should be using I spoke at length with Peter Maher the owner and developer of an Australian company called Liquid Intelligence Pty Ltd which is based in Sydney.
Peter certainly knows his field which supplies a variety of products that are designed for use in antique and classic cars.
Peter has a military grade brake fluid designated 318 that is ideally suited to classic cars that are driven intermittently rather than as a daily driver. 318 will not damage the rubber components and prevents corrosion of the metal parts and will not damage a brake pressure switch. It is not cheap however he guarantees his products.
Peter explained that it is a new generation DOT 3.

T cockerell
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  • Terry Cockerell
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26 Aug 2021 23:16 - 26 Aug 2021 23:18 #43806 by Terry Cockerell
Mike that was an interesting scientific experiment you conducted.
DOT 3 is what I will be using. It pays to get other people's opinions before making a decision.
I should have done that before ordering pistons from EGGE.

T cockerell
Last edit: 26 Aug 2021 23:18 by Terry Cockerell. Reason: Spelling error
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  • mikespeed35
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26 Aug 2021 20:53 #43805 by mikespeed35
You made the right decision Terry. By that I mean you sought opinions on the subject, and made your own decision from the comments. As a aside, I did a test some years ago about the Dot 5 swelling wheel cyl. cups, verses Dot3. I took wheel cylinder cups from the same box and immersed them in one jar of Dot5 and one in Dot3. I left them sit for several weeks. Upon examination after that time they both had swelled. Couldn't' tell the difference between them. Just my unscientific observation.
CORDiallyMike

Mike Huffman
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  • mikekone
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26 Aug 2021 15:56 #43802 by mikekone
I'm a newbie and just an ACD car wannabe for now.

Might the humidity the car is kept in be a decider here? Very dry climates from my experience (I live in Colorado) in non-ACD cars are less needy when it comes to brake bleeds. In contrast, when I lived in humid New England annual brake/clutch bleeds were best. I'd think this would factor into the cost/benefit analysis of which to choose.

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  • George van Nostrand
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26 Aug 2021 14:33 #43801 by George van Nostrand
Replied by George van Nostrand on topic Silicone Brake Fluid , What are the Pros and Cons???????????
Terry Stay with the original DOT brake fluid.

Restoring 1936 Cord Westchester sedan.2023 A

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  • Thomas Wilcock
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26 Aug 2021 11:50 #43799 by Thomas Wilcock
My take on the silicone brake fluid is that because it does not absorb water, any moisture simply accumulates in the lowest area of the system. The system should be flushed regularly to get rid of it.
Tom

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  • Terry Cockerell
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26 Aug 2021 04:15 - 26 Aug 2021 07:05 #43797 by Terry Cockerell
Jim the points you listed are significant. Parts supply is a real problem here in Australia. Some of the wheel cylinder rubbers come from Spain. I had trouble getting 1 - 3/8" cups. Consequently checking compatibility becomes more of a problem. My Buick mate also mentioned brake light pressure switch failures which would mean bleeding the brakes again after finding a suitable switch. The original question was based on what was best for the car in the long run. I have had it 14 years now and have never stopped working on it so routine maintenance in the future is not an issue. Let's face it you have to be a masochist to restore and maintain a Cord unless you have deep pockets. So I think the decision is to stick with the tried and proven fluid. At least know I am going to have some reliability rather than continued expensive experimentation.
Thanks for all of your comments they will help others too.

T cockerell
Last edit: 26 Aug 2021 07:05 by Terry Cockerell. Reason: Revising text

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  • mikespeed35
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26 Aug 2021 04:01 #43796 by mikespeed35
I use Dot 5 in every thing also. Most "brake experts" have differing opinions on this controversy. They have been discussing this issue for 35 or 40 years with no agreement.
CORDiallyMike

Mike Huffman

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  • wynlaidig
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26 Aug 2021 02:02 #43795 by wynlaidig
I have used DOT 5 in all my restored cars, and never had any problems

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  • JIM.OBRIEN
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26 Aug 2021 01:06 #43794 by JIM.OBRIEN
HI Terry,

The original brake fluid was DOT 3. The down side to DOT 3 is it absorbs moisture out of the air. As a result it should be flushed out every 2 or 3 year (not that many people do this). THe water will accumulate and rust out the master cylinder and wheel cylinders (no problem with the copper lines). If you get soome water in the wrong location and it gets hot it will turn to steam and give you problems whgich will leave you scratching your head trying to figure it out.

THe DOT 5 or silicone brake fluid will not absorb moisture out of the air. THe three problems with DOT 5 is the system needs to be clean before you put it in since it is not compatible with the DOT 3 fluid - not a problem for you unless you assembled the master cylinder and wheel cylinders with DOT 3 fluid. The second issue is the DOT 5 will hold air bubbles so you have to be very careful filling the system. If you shake a can of it you need to let it sit for about 24 hours to let the air bubbles work themselves out. It can be a real task getting the brakes bleed. The third issue is a lot of the rubber will swell with the DOT 5.Make sure all the rubber parts (cups, stop light switch, etc) are compatable with the DOT 5.

The good part of the DOT 5 is you don't have to change the fluid every couple of years and it has a higher boiler point then the DOT 3.

You can choose which one to use. When I restored my sedan I put the DOT 5 in and ran it for 20 years. The only problem i had was getting a stop light switch that worked with the DOT 5.
JIm

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  • Mike Brady
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26 Aug 2021 00:39 #43793 by Mike Brady
Terry,

You have made it clear that your plan is to keep the car. So I would be honest with yourself and ask how likely you and the next generation will be flushing the system every two years,

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  • uconn_1965
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25 Aug 2021 23:29 #43791 by uconn_1965
I’ll throw in my 2 cents……. stick with The original dot brake fluid.

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  • Terry Cockerell
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25 Aug 2021 21:46 #43790 by Terry Cockerell
I am just about ready to finish the brake assembly and add the fluid which was going to be the silicone variety however talking with a brake "specialist " yesterday he advised me not to use silicone but just the normal DOT4.
A friend who has a small collection of pre and post WW2 Buicks has been using silicone for many years and recommends it.
My Cord has all new copper nickel lines, new wheel cylinder rubbers as well as in the master cylinder. The system is clean and ready for fluid. I would appreciate any comments or recommendations on using silicone.

T cockerell

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