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Re: Talk me out of DOT 5 brake fluid? [Re: GoodysGotaCuda] #2417455
12/12/17 05:26 PM
12/12/17 05:26 PM
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MoparCar Offline
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Originally Posted By GoodysGotaCuda
For what it's worth, for street use I haven't had any issues with the DOT5, but it's also only been 1,500 miles.

....the Wildwood pad knockback, however, is a different story.



Goody,
Is that knock back on fronts, rears or both?

Thanks, Wes

Re: Talk me out of DOT 5 brake fluid? [Re: MoparCar] #2417672
12/12/17 11:32 PM
12/12/17 11:32 PM
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Posts: 24,639
Texas
GoodysGotaCuda Offline OP
5.7L Hemi, 6spd
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Originally Posted By MoparCar
Originally Posted By GoodysGotaCuda
For what it's worth, for street use I haven't had any issues with the DOT5, but it's also only been 1,500 miles.

....the Wildwood pad knockback, however, is a different story.



Goody,
Is that knock back on fronts, rears or both?

Thanks, Wes


Haven't quite determined that just yet.


1972 Barracuda - 5.7L Hemi, T56 Magnum 6spd - https://www.facebook.com/GoodysGotaHemi
1976 Dodge Warlock - "Her Truck" - 360/727 2wd
2016 Subaru WRX - E30 Tune ~320whp
[img]https://i.imgur.com/v9yezP9.jpg[/img]
Re: Talk me out of DOT 5 brake fluid? [Re: GoodysGotaCuda] #2417676
12/12/17 11:42 PM
12/12/17 11:42 PM
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Lake Orion, MI
goldduster318 Offline
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Originally Posted By John_Kunkel
Originally Posted By goldduster318
. I am not aware of any OEM vehicle that comes with DOT5.


Avanti, Harley Davidson, probably some exotics.


If there is any ABS/ESC on these vehicles (which is required on USA sold cars since 2011), I can pretty much assure you they aren't using DOT5 silicone brake fluid as I'm not aware of any supplier that allows it. I worked at 2 of the 6 major companies that sell these systems. DOT5.1, they allow but I don't consider that to be very different than DOT4.

Originally Posted By Supercuda
Dot 5 or Dot 5.1?

Dot 5 isn't compatible with ABS systems so I doubt any OEM is using it.

5.1 is NOT silicone based.


Thank you, I believe you are correct.

Originally Posted By GoodysGotaCuda
For what it's worth, for street use I haven't had any issues with the DOT5, but it's also only been 1,500 miles.

....the Wilwood pad knockback, however, is a different story.


What's your rotor runout? If they are the two piece hub type, perhaps you can re-clock the rotor on the hub to help it. IMO over 40 micron is too much on anything near a new condition.

also from wilwood's own site:
http://www.wilwood.com/TechTip/TechBrakeFluidTip.aspx

Quote:
Wilwood does not recommend using DOT 5 fluid in any racing applications. DOT 5 fluid is not hygroscopic, so as moisture enters the system, it is not absorbed by the fluid, and results in beads of moisture moving through the brake line, collecting in the calipers. It is not uncommon to have caliper temperatures exceed 200 degrees F, and at 212 degrees F, this collected moisture will boil causing vapor lock and system failure. Additionally, DOT 5 fluid is highly compressible due to aeration and foaming under normal braking conditions, providing a spongy brake feel.


'70 Duster 470hp 340/T56 Magnum/8 3/4 3.23 Sure-Grip
Re: Talk me out of DOT 5 brake fluid? [Re: GoodysGotaCuda] #2418206
12/13/17 11:04 PM
12/13/17 11:04 PM
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Minn
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SportF Offline
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Gosh, I just love this topic. And I always did.

Re: Talk me out of DOT 5 brake fluid? [Re: goldduster318] #2418377
12/14/17 10:28 AM
12/14/17 10:28 AM
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Posts: 24,639
Texas
GoodysGotaCuda Offline OP
5.7L Hemi, 6spd
GoodysGotaCuda  Offline OP
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Originally Posted By goldduster318


What's your rotor runout? If they are the two piece hub type, perhaps you can re-clock the rotor on the hub to help it. IMO over 40 micron is too much on anything near a new condition.


Haven't bothered measuring runout as it only appears after a decent turn. I suspect it's more of a dynamic problem. I will be investigating a residual valve, which has been recommended across a few resources I have come across.

Quote:

also from wilwood's own site:
http://www.wilwood.com/TechTip/TechBrakeFluidTip.aspx

[quote]Wilwood does not recommend using DOT 5 fluid in any racing applications. DOT 5 fluid is not hygroscopic, so as moisture enters the system, it is not absorbed by the fluid, and results in beads of moisture moving through the brake line, collecting in the calipers. It is not uncommon to have caliper temperatures exceed 200 degrees F, and at 212 degrees F, this collected moisture will boil causing vapor lock and system failure. Additionally, DOT 5 fluid is highly compressible due to aeration and foaming under normal braking conditions, providing a spongy brake feel.


Understood. When I consider racing the car, I will flush out the DOT5. Until then, I have had no issues with as aggressive of street braking as I can get.


1972 Barracuda - 5.7L Hemi, T56 Magnum 6spd - https://www.facebook.com/GoodysGotaHemi
1976 Dodge Warlock - "Her Truck" - 360/727 2wd
2016 Subaru WRX - E30 Tune ~320whp
[img]https://i.imgur.com/v9yezP9.jpg[/img]
Re: Talk me out of DOT 5 brake fluid? [Re: GoodysGotaCuda] #2451097
02/13/18 08:37 AM
02/13/18 08:37 AM
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Dilbert Offline
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pad knock back is typically from loose wheel bearings...how did you set up the wheel bearings?
...and dot 5 in a track type street car is amusing...

Last edited by Dilbert; 02/13/18 08:38 AM.
Re: Talk me out of DOT 5 brake fluid? [Re: Dilbert] #2452400
02/16/18 01:07 AM
02/16/18 01:07 AM
Joined: Nov 2004
Posts: 24,639
Texas
GoodysGotaCuda Offline OP
5.7L Hemi, 6spd
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Texas
Originally Posted By Dilbert
pad knock back is typically from loose wheel bearings...how did you set up the wheel bearings?
...and dot 5 in a track type street car is amusing...


Wheel bearings were setup to factory spec, actually tightened slightly, no improvement. Rears are green bearings, as required with the Wilwoods.


1972 Barracuda - 5.7L Hemi, T56 Magnum 6spd - https://www.facebook.com/GoodysGotaHemi
1976 Dodge Warlock - "Her Truck" - 360/727 2wd
2016 Subaru WRX - E30 Tune ~320whp
[img]https://i.imgur.com/v9yezP9.jpg[/img]
Re: Talk me out of DOT 5 brake fluid? [Re: GoodysGotaCuda] #2453751
02/19/18 01:38 AM
02/19/18 01:38 AM
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North Carolina
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469runner Offline
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My friend in the Army that is a heavy vehicle mechanic says all the vehicles they service run DOT 5 fluid.

Re: Talk me out of DOT 5 brake fluid? [Re: 469runner] #2453791
02/19/18 04:15 AM
02/19/18 04:15 AM
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Phila. Pa.
Mattax Offline
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Originally Posted By 469runner
My friend in the Army that is a heavy vehicle mechanic says all the vehicles they service run DOT 5 fluid.
That would correspond with the Army Report I cited (and linked) on the previous page.

All of these fluids have an application.

Some people assume that posts in this subforum are oriented toward racing, and on the other side, there are a few who don't have clue that some people are here because they are very interested in high performance driving and racing. Otherwise the pros and cons seem to be outlined pretty well. Both silicon and non-silicone have their place.

Whichever you choose, it will depend on the intended uses and priorities.


Last edited by Mattax; 02/19/18 04:19 AM.
Re: Talk me out of DOT 5 brake fluid? [Re: Mattax] #2470230
03/22/18 05:38 AM
03/22/18 05:38 AM
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so cal
alltime Offline
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Good write up Matt.

Also I remember reading about problems back when GM Started using Silicone . Something about it causing the rubber components swelling up to some degree and causing problems.

From my brief experince with road racing, If you are having a problem boiling DOT 3 then you can find problems elsewhere in your brake system, ie, Old Caliper piston seals that without elasticity cause the pads to drag and generate more heat, inefficient calipers such as floater type or a weak design that flexes with increased temp, not enough air flow. Pads installed without enough clearance on backing plates to move freely, etc, etc

Last edited by alltime; 03/22/18 05:39 AM.
Re: Talk me out of DOT 5 brake fluid? [Re: Mattax] #2478450
04/06/18 07:05 PM
04/06/18 07:05 PM
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Marlboro, NY, USA
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Rick_Ehrenberg Offline
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I've been using DOT 5 silicone since the mid-'70s. Confirmation came when the Army spec'd it in the 1978 (?) military Dodge pickups.

Never a stuck caliper piston. Never any paint damage. Never any boiling, even stops from 163 MPH using stock cop brakes.

Miscible (by law) with any other DOT fluid.

Stuff I have used recently is all Dow-Corning military surplus. I think virtually all sold in the USA, regardless of name on can, is D-C supplied.

Yes, a bit heavier viscosity - maybe. Would not recommend it with ABS systems.

BTW, Chrysler, in IMSA / GTU racing, used off-the-shelf Mopar DOT3.

Rick

Re: Talk me out of DOT 5 brake fluid? [Re: GoodysGotaCuda] #2478547
04/06/18 11:11 PM
04/06/18 11:11 PM
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Mattax Offline
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The brake fluid compatibility standard, S5.1.10, of 49CFR571.116 exempts DOT5 from the requirement not to stratify.
"(2) Fluids, except DOT 5 SBBF, shall show no stratification."

Further the manufacturers themselves discouraging mixing.
eg https://www.penriteoil.com.au/assets/pdf/tech/Nov2015/Brake_Fluids.pdf

Anyone switching should flush the glycol based fluids out thoroughly. Good paper referencing SAE papers and standards as well as the usually suspects from Carol Smith to various manufacturers and retailers. http://www.niagarabritishcarclub.org/index_htm_files/Brake%20Fluid.pdf

I stand by what I wrote before. Its a case by case personal decision. I personally wouldn't use SBBF in my car as I want everything in my favor on road course type use. For someone with a restored car with all new or cleaned hydraulics, its a rational choice. For road racing, of course there may not be a choice - follow the rules of the sanctioning body and host track.

Re: Talk me out of DOT 5 brake fluid? [Re: GoodysGotaCuda] #2478579
04/06/18 11:57 PM
04/06/18 11:57 PM
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I find this discussion very interesting. One thing I would caution is something that has not been brought up as of yet. Any silicone based product is a nightmare to deal with if you every have to repaint any portion of your car.

In other words if any of the silicone gets on a painted surface it is almost impossible to remove fully and will cause fish eyes in future paint application.


XP29H8B198192
Re: Talk me out of DOT 5 brake fluid? [Re: Mattax] #2479195
04/08/18 01:21 AM
04/08/18 01:21 AM
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Marlboro, NY, USA
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The Dow-Corning documents I read in the '80s said, basically, just dump it in, no flushing required. Which is exactly what I have been doing since the '70s. Back then, DOT5 was "it", there was no 5.1, and the DOT / FMVSS numbers were solely related to boiling point, and 5 was max.

I am sure it doesn't stratify with the glycol-based stuff, but is that a problem? It sure hasn't caused me any, and this is on circle tracks, superspeedways, road courses, pro rallies, and drags over the course of damn near a lifetime. Not to mention untold millions of street miles!

I guess you pays you money and you takes your choice.

Repro of Dodge pickup (military) sticker:



Rick

Re: Talk me out of DOT 5 brake fluid? [Re: GoodysGotaCuda] #2479290
04/08/18 10:59 AM
04/08/18 10:59 AM
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Phila. Pa.
Mattax Offline
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That sticker would suggest that they don't want you to mix it.
LOL

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