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Dot 5 fluid

Started by edison1970, November 11, 2020, 06:24:22 PM

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edison1970

Does anyone know if there is a compatibility issue with using Dot 5 in our older brake systems?  I had to put another master cylinder on my car because the seal on the back where the rod goes was leaking . This is the second one.

cudaize

I have DOT 5 silicone fluid in (2) of my 71 Cudas and my 70 Challenger and have not had any problems.  I did these when I replaced all brake components as the DOT 5 does not mix with the DOT 3.  If your system has fluid in it you can bleed it out.

The only problem that I have seen is that the silicone fluid ruins the brake switches that are actuated by fluid.  My father goes through about one every year or two on his 58 Fury.  The switches on E-bodies are mechanical so not an issue.

71340RT

I have run Dot 5 brake fluid in my 71 Challenger RT for at least 20 years with no problems and it won't damage paint.
1971 Challenger RT 340 auto 1 of 731
1973 Challenger Rallye 392 Hemi A41 4 speed automatic
2016 Dodge Challenger Scat Pack 392 Hemi auto


750-h2

On a restoration Dot 5 brake fluid is the only way to go. If you have a leak or spill it will NOT harm the paint. :clapping:

Jay Bee

My car's had DOT 5 SILICONE in it since 2011 with absolutely no problems or issues. The master, all the lines and wheel cylinder were replaced first.

anlauto

Dot 5 in all my restorations  :twothumbsup:
I've taught you everything you know....but I haven't taught you everything I know....
Check out my web site ....  Alan Gallant Automotive Restoration

floorit426

Can you change from DOT 3, to DOT 5, without dismantling your brake system?


edison1970

Sounds like the answers I was hoping for.  All of the brake components are new on my car. Maybe just poor master cylinders. 

mopar jack

Quote from: edison1970 on November 11, 2020, 06:24:22 PM
Does anyone know if there is a compatibility issue with using Dot 5 in our older brake systems?  I had to put another master cylinder on my car because the seal on the back where the rod goes was leaking . This is the second one.
No leaks at the back but have had a couple disc brake master cylinders leak internally where the front wheel reservoir(the large one) level would go low and the rear wheel reservoir would go high and start to spill out the top.

MoparLeo

Personal/professional recommendation. Never use a rebuilt master cylinder, always a high quality, new unit only. Rebuilt M/C's  regularly fail at a much faster rate than new. It only has to fail once....
moparleo@hotmail.com  For professionally rebuilt door hinges...

dodj

Quote from: floorit426 on November 12, 2020, 07:03:48 AM
Can you change from DOT 3, to DOT 5, without dismantling your brake system?
You need to flush it thoroughly first.
"There is nothing your government can give you that it hasn't already taken from you in the first place" -Winston Churchill


FSHTAIL

Quote from: 750-h2 on November 12, 2020, 06:20:37 AM
On a restoration Dot 5 brake fluid is the only way to go. If you have a leak or spill it will NOT harm the paint. :clapping:

That's what the body shop recommended as well just because of the paint.. 
1973 BS23H Cuda' 340/TKX 5 speed (70 AAR clone-ish)

GoodysGotaCuda

Quote from: dodj on November 12, 2020, 12:32:58 PM
Quote from: floorit426 on November 12, 2020, 07:03:48 AM
Can you change from DOT 3, to DOT 5, without dismantling your brake system?
You need to flush it thoroughly first.

I have read "no, you cannot change."

Something to do with how the seals respond to one of the fluids that they need to be new.

I've not tried it.


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1972 Barracuda - 5.7L Hemi/T56 Magnum
2020 RAM 1500 - 5.7L

My Wheel and Tire Specs

Rich G.

I just got my master cylinder back from White Post Restoration's with a installation sheet and a lifetime guarantee but void if using dot 5 brake fluid. So many different opinions on this . The only plus I see is that it won't hurt the paint if you have a leak.

rocketresto

Make sure the master is compatible with Dot 5.  Have had several fail here with the "correct" repo drum brake master cylinder.  Know Dot 3 can kill paint but seems like every time we run Dot 5 is either leaks or the master fails.  Only run Dot 3 now.
Rocket Restorations
Olympia, Washington