Talk me out of DOT 5 brake fluid?
#2312692
05/29/17 12:19 AM
05/29/17 12:19 AM
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Joined: Nov 2004
Posts: 25,050 Texas
GoodysGotaCuda
OP
5.7L Hemi, 6spd
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OP
5.7L Hemi, 6spd
Joined: Nov 2004
Posts: 25,050
Texas
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I am working on hydraulics these days and am looking to pick a brake fluid to go with. As my car is freshly painted, I am naturally not too thrilled about conventional DOT 3/4 brake fluids being near my car, if I can help it.
For now, my car will be a primarily street car, some spirited driving and the occasional autocross event. I do not have plans for heavy, high-speed/repeated , braking at this time [road course].
I would like to use DOT5 in my hydraulic clutch and brake system and am curious to hear your experiences.
Wilwoods DOT5 has a 500°F boiling point. Their best DOT4 is about 600°F.
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Re: Talk me out of DOT 5 brake fluid?
[Re: GoodysGotaCuda]
#2312802
05/29/17 09:13 AM
05/29/17 09:13 AM
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Joined: Jan 2003
Posts: 1,376 NORTHERN CA
HUSTLESTUFF
pro stock
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pro stock
Joined: Jan 2003
Posts: 1,376
NORTHERN CA
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I wouldn't talk you out of it. On a new build with all new lines and fresh paint, pour it in. If you have a leak no peeling paint while you tighten up the fittings. If you later decide to go balls out on a road course, once you know there are no leaks, swap it out for some race stuff.
"Were in it to win it. Anything less will end up being..... A whole lot of fun doing!!" UNLAWFL RIP UN
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Re: Talk me out of DOT 5 brake fluid?
[Re: GoodysGotaCuda]
#2313047
05/29/17 04:02 PM
05/29/17 04:02 PM
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Joined: Aug 2005
Posts: 1,385 Az
69hemibeep
pro stock
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pro stock
Joined: Aug 2005
Posts: 1,385
Az
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I have put DOT 5 in 2 new builds and I will use it in the next one. Of course they had all new parts.
1969 Hemi Roadrunner 2nd owner
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Re: Talk me out of DOT 5 brake fluid?
[Re: GoodysGotaCuda]
#2313654
05/30/17 04:56 PM
05/30/17 04:56 PM
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Joined: Feb 2011
Posts: 4,302 Nebraska
72Swinger
master
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master
Joined: Feb 2011
Posts: 4,302
Nebraska
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Motul, just be careful and rinse it off quick if you spill.
Mopar to the bone!!!
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Re: Talk me out of DOT 5 brake fluid?
[Re: GoodysGotaCuda]
#2313720
05/30/17 06:43 PM
05/30/17 06:43 PM
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Joined: Jun 2003
Posts: 7,660 SK. Canada
Not_A_Duster
master
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master
Joined: Jun 2003
Posts: 7,660
SK. Canada
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Demon got all new cylinders, lines, prop valve and master cylinder when I had it apart. Been using Kleen Flo DOT 5 since then (2007) with not a single issue.
Car of course brakes much better after changing out the tiny drums it came with, so I can't speak to any potential performance differences between the fluids.
....evil is winning....
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Re: Talk me out of DOT 5 brake fluid?
[Re: GoodysGotaCuda]
#2315800
06/04/17 02:18 AM
06/04/17 02:18 AM
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Joined: Jan 2003
Posts: 7,490 Minnesota
Hemi_Joel
master
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master
Joined: Jan 2003
Posts: 7,490
Minnesota
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I first used dot 5 in 1981, and it is so awesome, I always use it in any thing that matters ever since. I put it in my 442 in 81, drove it untill the end of 1987, stored it for 23 years, then drove it on power tour Without changing fluid or touching the brake system. Try that with dot 3!
[img]http://i.imgur.com/boeexFms.jpg[/img]31 Plymouth Coupe, 392 Hemi, T56 magnum RS23J71 RS27J77 RP23J71 RO23J71 WM21J8A I don't regret the things I've done. I only regret the things I didn't do. "Wise men talk because they have something to say; fools because they have to say something. ~ Plato"
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Re: Talk me out of DOT 5 brake fluid?
[Re: Hemi_Joel]
#2315835
06/04/17 07:57 AM
06/04/17 07:57 AM
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Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
About to go away
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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I first used dot 5 in 1981, and it is so awesome, I always use it in any thing that matters ever since. I put it in my 442 in 81, drove it untill the end of 1987, stored it for 23 years, then drove it on power tour Without changing fluid or touching the brake system. Try that with dot 3! Pretty sure I wouldn't try that with anything.
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
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Re: Talk me out of DOT 5 brake fluid?
[Re: GoodysGotaCuda]
#2315840
06/04/17 09:03 AM
06/04/17 09:03 AM
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Joined: Oct 2003
Posts: 21,345 Marysville, O-H-I-O
70Cuda383
Too Many Posts
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Too Many Posts
Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
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I had heard that moisture in the system will turn dot 5 to hard solid silicone. No truth to that? All brake systems pick up moisture over time, which is why they rust from the inside too, and fluid turns dark brown or black without regular maintenance.
**Photobucket sucks**
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Re: Talk me out of DOT 5 brake fluid?
[Re: 70Cuda383]
#2315911
06/04/17 12:56 PM
06/04/17 12:56 PM
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Joined: Feb 2010
Posts: 1,645 Phila. Pa.
Mattax
top fuel
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top fuel
Joined: Feb 2010
Posts: 1,645
Phila. Pa.
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See if you can find anything in print (including internet) that supports that claim.
If you want my guess, it sounds like something posted in sarcasm that was then repeated as fact. First of all, the DOT designations are part of the FMVSS - Federal Motor Vehicle Safety Standards. They're there to protect us (and the manufacturers) on critical items. So a fluid that turned solid making the brake system completely useless would never have made it into the standard except as a major F-up. Second, silicone based (primarily dimethyl polysiloxane fluid) was created in large part because it is not hygroscopic. For that reason FMVSS 116 (Brake Fluid standards) test procedures for DOT 5 relating to water absorbtion are different than for DOT 3 and DOT 4.
FWIW, SAE J1704 is where the composition of the different brake fluids is described. That's an industry standard rather than a Federal standard. The Feds only care if it works, not how it works.
As a result, DOT 4 usually has esters as well as glycol. It mixes with DOT 3 and has similar viscosity. Both absorb moisture over time. Both should be changed as needed; If racing, the moisture lowers boiling point and increases compressiblity. If just regular or weekend driving; the corrosion inhibitors get used up and rust can become a problem.
DOT 5 silicone based has several characteristics that make it unsuitable for certain uses. The viscosity doesn't work well with some ABS. In some environments, moisture that does get in the system could (theoreticly?) collect in low points. (I suspect if this was a real issue, we'ld hear and read anecdotal stories about it). Finally it is more compressible than the glycol and ester fluids. This compressibility goes up with temperature.
Road racing requires every bit of pedal feel and braking performance possible. Road courses also require repeated braking that can elevate brake fluid temperatures far higher than seen on most public roads or other competition venues. A pedal that gets spongier and travels further during a race is at best disconcerting!
One public road situation where brake fluid can get pretty hot is long and repeated downhills with heavy braking loads. So yea if you're driving your classic in places where the brakes get hot enough you can smell 'em, DOT 5 may not be the best choice there either.
So to the original question by the OP, for many situations DOT 5 is fine. Yours seems like it would good for what you want and plan to do.
Last edited by Mattax; 06/04/17 01:12 PM.
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Re: Talk me out of DOT 5 brake fluid?
[Re: GoodysGotaCuda]
#2316086
06/04/17 06:05 PM
06/04/17 06:05 PM
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Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
About to go away
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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I dunno what's with the Aussie brake fluids being linked, how about y'all kink a North American source?
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
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Re: Talk me out of DOT 5 brake fluid?
[Re: Supercuda]
#2316171
06/04/17 08:29 PM
06/04/17 08:29 PM
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Joined: Jun 2007
Posts: 2,432 NorCal
RylisPro
top fuel
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top fuel
Joined: Jun 2007
Posts: 2,432
NorCal
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Aussies seem to do motorsports better than us Yanks, burnouts too! One can easily get Castrol SRF or Motul from Summit, Amazon, major race tracks, etc. The good stuff doesn't come cheap though!
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Re: Talk me out of DOT 5 brake fluid?
[Re: Mattax]
#2316249
06/04/17 10:06 PM
06/04/17 10:06 PM
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Joined: Dec 2003
Posts: 22,696 Bitopia
jcc
If you can't dazzle em with diamonds..
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If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 22,696
Bitopia
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Finally it is more compressible than the glycol and ester fluids. This compressibility goes up with temperature.
I concur with most of your other points, but I have "read" the compressibility issue with DOT5 is, it traps/entrains air when pouring, and first impressions just after installing, leads to the compressibility observations, unfairly, if confirmable. The rising temp issue leading to increased compressibility, is the first I have heard of that condition.
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
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Re: Talk me out of DOT 5 brake fluid?
[Re: GoodysGotaCuda]
#2316331
06/04/17 11:57 PM
06/04/17 11:57 PM
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Joined: Jan 2003
Posts: 7,490 Minnesota
Hemi_Joel
master
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master
Joined: Jan 2003
Posts: 7,490
Minnesota
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Any car with DOT 3 that I have left sit for more than a couple years has no pedal when I get it out of storage. The fluid has absorbed moisture and rusted up the cylinders. Minnesota is damp. My experience related in the post above positively demonstrates that DOT does not attract moisture and ruin the brake system. For those of us who store our cars over the winter or longer, this is vitally important. We don't want to rebuild the hydraulic system of the brakes every other year. All of the internet hype about the drawbacks of DOT 5 is irrelevant to 95% of users, including me and the OP. In 2002 I bought a set of Wilwood front disc brakes for my race car. They had a tag warning not to use DOT 5. I called them and asked why. They said DOT 5 is not hygroscopic, so moisture will collect in the brake system and it will fail. I called bs on that and put in DOT 5. 14 years later I still have those brakes and they have not yet failed or had any issues. Wilwood has since changed their tune, and now they sell DOT 5 with their own name on it, they still say don't put it in a race car. I suppose in another 14 years they will sell race car DOT 5.
[img]http://i.imgur.com/boeexFms.jpg[/img]31 Plymouth Coupe, 392 Hemi, T56 magnum RS23J71 RS27J77 RP23J71 RO23J71 WM21J8A I don't regret the things I've done. I only regret the things I didn't do. "Wise men talk because they have something to say; fools because they have to say something. ~ Plato"
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Re: Talk me out of DOT 5 brake fluid?
[Re: GoodysGotaCuda]
#2316402
06/05/17 01:55 AM
06/05/17 01:55 AM
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Joined: Jan 2003
Posts: 15,976 Chilliwack B.C. Canada
RUNCHARGER
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 15,976
Chilliwack B.C. Canada
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I use DOT5 in my stuff too with no problems. It's nice not worrying about it when it gets on the backing plates and painted calipers when bleeding too.
Sheldon
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