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Brake Fluid question. DOT 5? #2759992
04/04/20 03:09 PM
04/04/20 03:09 PM
Joined: Oct 2007
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Wisconsin
wkroncke17 Offline OP
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wkroncke17  Offline OP
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All,
Installing a whole new braking system on my Demon.
Wilwood m/c, ‘73& up front disc, and right stuff rear disc setup (‘85 Caddy) caliper.
I’ve heard DOT 5 won’t harm paint but isn’t recommended for daily street use?
Anyone have experience with this?
Thanks all!

Wally.

Re: Brake Fluid question. DOT 5? [Re: wkroncke17] #2760036
04/04/20 03:39 PM
04/04/20 03:39 PM
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West Plains, MO
DrCharles Offline
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It's working fine in my '72 Dart. Good firm pedal (nonpower front disc conversion) for years now. Tried it in the hydraulic clutch too but the Howe pull slave cylinder leaked it, so had to go back to conventional fluid there. Any recently manufactured brake components should have compatible seals.

DOT 5 silicone fluid does not absorb water like DOT 3/4/5.1 glycol does, so any water in the system will collect at a low point, usually wheel cylinder or caliper.
This can cause localized corrosion (as opposed to the wet glycol which rusts everywhere just a little bit).
On the other hand, silicone won't attract water out of the air in the first place. shruggy

And it will not turn into a goo or explode if inadvertently mixed with glycol. It just won't combine, and the purple dye will eventually migrate from the silicone to the glycol.
There is a large amount of misinformation and phobias on the Internet, but you have to do your own research to find out what's real and what's not.

The only disadvantage I know of is that it has to be bled slowly and carefully, because air bubbles entrained in the fluid take FOREVER to settle out. Same caution with shaking the container or pouring it into the master too fast. twocents
popcorn

Re: Brake Fluid question. DOT 5? [Re: DrCharles] #2760038
04/04/20 03:53 PM
04/04/20 03:53 PM
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Minnesota
Hemi_Joel Offline
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I have been using DOT 5 in my cars since 1981. It is the very best thing out there. I put it in my '67 442 in 81, drove it till 87, parked it till 2010, dug it out of storage, and the brakes still worked perfectly with zero issues, so I drove it on Power Tour 2011, Drag Week 2014, and Cars 'n Cones Road Trip 2016 with no issues. And I live in damp, humid MInnesota. How can you beat that? I rebuilt the brakes in my 65 F100 in 1990. Let a friend drive it for 6 months, then parked it till 2019. Drug it out of storage from my neighbors barn. The brakes are still working.
I put in my 67 GTX in 2002 when I put the wilwood discs on the front. Wilwood said do't use DOT 5 but I did it anyway. Never had an issue. Race cars, street cars, cars that get stored, DOT 5 always works.
Just do it!

Edit: I agree on the bleeding. I usually allow a week or so for that. Pour it slow and careful to avoid bubbles. I bleed the master, install it, do an initial bleed using a slow downward pump of the pedal with the screw open, and a slow release with the screw closed. I do all 4 and don't have to get it perfect. Then let it sit for a few days for the air to collect. Then I jiggle the pedal just a tiny bit while watching the master for little bubble to rise. I pause for a few minutes, then jiggle till the bubbles stop. Then repeat daily till no more bubbles. Usually the pedal is rock solid by then. If not, repeat the bleed thru the screws.

Last edited by Hemi_Joel; 04/04/20 04:01 PM.

[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"
Re: Brake Fluid question. DOT 5? [Re: Hemi_Joel] #2760046
04/04/20 04:23 PM
04/04/20 04:23 PM
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New York, USA
Chargerfan68 Offline
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I have read that due to the air entraining characteristic with Dot 5, the reason newer cars cannot use it is because they have anti-lock brakes. And the anti-lock solenoid pulses which would aggravate that issue. That is what i’ve always believed. I use it in my 68 b body with manual disc brakes and it works great for 10+ years.


1.50 60Ft. , 10.75@ 127MPH Hauling 3900 LBS.
Re: Brake Fluid question. DOT 5? [Re: Chargerfan68] #2760049
04/04/20 04:30 PM
04/04/20 04:30 PM
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Minnesota
Hemi_Joel Offline
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There is no reason on earth why the OEM's would use DOT 5. Dot 3 is cheaper, faster to bleed, and will outlast the warranty, yet foil the brake system when the car is old, prompting new car sales. DOT 5 is for cars like ours.


[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"
Re: Brake Fluid question. DOT 5? [Re: Hemi_Joel] #2760102
04/04/20 06:35 PM
04/04/20 06:35 PM
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Fulton County, PA
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CMcAllister Offline
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You should be OK using it IF the system is all new or is completely rebuilt before installing it. I don't think I would use it on a system that previously had regular fluid in it. Strange recommends against it in their stuff for reasons stated - absorbs water, slightly compressible possibly causing a soft pedal, etc.

Last edited by CMcAllister; 04/04/20 06:36 PM.

If the results don't match the theory, change the theory.
Re: Brake Fluid question. DOT 5? [Re: Hemi_Joel] #2760103
04/04/20 06:35 PM
04/04/20 06:35 PM
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MI, usa
dvw Offline
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I agree I've used DOT 5 since the 80's. Never had a corrosion problem, leak, or any other issue. Use it in the drag car as well.
Doug

Re: Brake Fluid question. DOT 5? [Re: dvw] #2760110
04/04/20 06:51 PM
04/04/20 06:51 PM
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lewtot184 Offline
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dot 5 in both my street cars for decades. never an issue.

Re: Brake Fluid question. DOT 5? [Re: lewtot184] #2760116
04/04/20 07:02 PM
04/04/20 07:02 PM
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Pattison Texas
CSK Offline
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Use it in my street car


1968 Charger COLD A/C Hilborn EFI
512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim
2020 T/A 392 Stock 11.79 @ 114.5

Re: Brake Fluid question. DOT 5? [Re: lewtot184] #2760121
04/04/20 07:15 PM
04/04/20 07:15 PM
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Benton, IL.
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DaveRS23 Offline
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Originally Posted by lewtot184
dot 5 in both my street cars for decades. never an issue.


Me, too.


Master, again and still
Re: Brake Fluid question. DOT 5? [Re: DaveRS23] #2760175
04/04/20 09:32 PM
04/04/20 09:32 PM
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Bend,OR USA
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Cab_Burge Offline
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Originally Posted by DaveRS23
Originally Posted by lewtot184
dot 5 in both my street cars for decades. never an issue.


Me, too.
I don't, Dot 4 only now due to the brake makers like Wilwood saying to not use Dot 5 in their parts work


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Brake Fluid question. DOT 5? [Re: Cab_Burge] #2760184
04/04/20 09:57 PM
04/04/20 09:57 PM
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West Plains, MO
DrCharles Offline
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Originally Posted by Cab_Burge
I don't, Dot 4 only now due to the brake makers like Wilwood saying to not use Dot 5 in their parts work


I asked Wilwood if I could use Dot 5 in their clutch slave cylinder and they said I could, but still recommend Dot 3 or 4. shruggy

Re: Brake Fluid question. DOT 5? [Re: DrCharles] #2760186
04/04/20 10:05 PM
04/04/20 10:05 PM
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Minnesota
Hemi_Joel Offline
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After many years of telling us not to use DOT 5 in their stuff, Wilwood has now flip-flopped and says it's OK, and now they even sell it. up

Wilwood-DOT-5-silicone-brake-fluid-768x768.jpg

[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"
Re: Brake Fluid question. DOT 5? [Re: wkroncke17] #2760282
04/05/20 09:15 AM
04/05/20 09:15 AM
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NC
440Jim Offline
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I haven't used DOT 5.
When I put new master cylinders in my racing Daytona with Wilwood system, I used this Jeg's product, DOT 4.
https://www.jegs.com/i/JEGS/555/28073/10002/-1

DOT4_Jegs.JPG

1993 Daytona, 5.50 at 130mph (1/8) 1.19 sixty ft (PG). Link to 572 B1 - Part 1
Re: Brake Fluid question. DOT 5? [Re: 440Jim] #2760346
04/05/20 11:57 AM
04/05/20 11:57 AM
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Benton, IL.
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DaveRS23 Offline
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Cool! 479* Racing brake fluid. Is that made by the same company that made the 200mph Racing tape?


Master, again and still
Re: Brake Fluid question. DOT 5? [Re: DaveRS23] #2760570
04/05/20 10:20 PM
04/05/20 10:20 PM
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back in Georgia
dthemi Offline
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5.1 for me in a drag, or street car

Re: Brake Fluid question. DOT 5? [Re: dthemi] #2760899
04/06/20 09:12 PM
04/06/20 09:12 PM
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Wisconsin
wkroncke17 Offline OP
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Originally Posted by dthemi
5.1 for me in a drag, or street car


What is the difference between DOT 5 and 5.1?

Re: Brake Fluid question. DOT 5? [Re: wkroncke17] #2760919
04/06/20 10:05 PM
04/06/20 10:05 PM
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West Plains, MO
DrCharles Offline
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DOT 5 is silicone
DOT 5.1 is glycol.

Re: Brake Fluid question. DOT 5? [Re: DrCharles] #2761327
04/08/20 12:15 AM
04/08/20 12:15 AM
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Wisconsin
wkroncke17 Offline OP
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Originally Posted by DrCharles
DOT 5 is silicone
DOT 5.1 is glycol.


Thank you very much!
All advice given here was great and much appreciated!,

DOT 5 it is.

Wally.

Re: Brake Fluid question. DOT 5? [Re: wkroncke17] #2761495
04/08/20 01:50 PM
04/08/20 01:50 PM
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Fulton County, PA
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CMcAllister Offline
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DOT 5 has disadvantages. DOT 4 has a higher boiling point than DOT 3 and is what I use.

Moisture will get into the system from the atmosphere. DOT 3 & 4 will absorb it and take it along with it when you do an occasional bleed and flush. DOT 5 will allow it to settle out and rust/corrode parts.

DOT 3 & 4 will hurt the paint. Don't spill it, don't be a slob when bleeding and don't have any leaks. That's my plan.


If the results don't match the theory, change the theory.
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