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Silicone Brake Fluid-DOT 5
Posted By: LYNCHROAD69.5
Silicone Brake Fluid-DOT 5 - 03/03/09 01:33 AM
Getting ready to put fluid in my new master brake cylinder, lines and wheel cylinders....auto parts store told me that I should not use DOT5 silicone brake fluid because it would blow all my seals out (not for vintage cars). My brake system is brand new..never seen any fluid. Anyone have an opinion or experience with this?
Posted By: Mastershake340
Re: Silicone Brake Fluid-DOT 5 - 03/03/09 01:45 AM
Other than some late model ABS systems, DOT 5 is just fine to use in a brake system.
Posted By: Lee446
Re: Silicone Brake Fluid-DOT 5 - 03/03/09 01:56 AM
I have used it for many years with zero problems. Since you have not put any other fluid in previous to your overhaul, it will work just fine!
Posted By: Big_John
Re: Silicone Brake Fluid-DOT 5 - 03/03/09 02:20 AM
Dot 5 has the advantage of not damaging your paint but it has a couple disadvantages. First and foremost, it does not absorb water like glycol based fluids do. Any moisture will tend to collect in the lowest part of the system and yes.. moisture does get into your braking system.
It also areates easily.. in fact, Harley Davidson says to let a new bottle sit for an hour before pouring it in the system. It compresses slightly more then glycol based fluids too.
It shouldn't harm your seals, but if you do use it, at least change it once in a while.
Posted By: LYNCHROAD69.5
Re: Silicone Brake Fluid-DOT 5 - 03/03/09 02:45 AM
Big John, I just read a similar article discussing some of the pros and cons of silicone. Some have also reported slightly spoongier feel in the pedal because silicone compresses slightly more.
Posted By: Big_John
Re: Silicone Brake Fluid-DOT 5 - 03/03/09 03:09 AM
Quote:
Big John, I just read a similar article discussing some of the pros and cons of silicone. Some have also reported slightly spoongier feel in the pedal because silicone compresses slightly more.
Yea, there's a lot of stuff written about it.
Some good info here: Brake Fluid
Posted By: 469runner
Re: Silicone Brake Fluid-DOT 5 - 03/03/09 03:09 AM
I'm no rocket scientist, but how does a liquid compress?
Posted By: Big_John
Re: Silicone Brake Fluid-DOT 5 - 03/03/09 03:22 AM
Quote:
I'm no rocket scientist, but how does a liquid compress?
As I understand it, the space between the molecules changes. I don't know if the DOT 5 fluid really compresses enough to notice, but if it areates easily (mixes with air) the bubbles would compress pretty easily.
Posted By: Anonymous
Re: Silicone Brake Fluid-DOT 5 - 03/03/09 12:26 PM
Might have a problem sealing. DOT 5 tends to find its way out a bit easier than DOT 3. But again, it won't eat paint.
Posted By: Mr T2U
Re: Silicone Brake Fluid-DOT 5 - 03/03/09 01:11 PM
the reason some people have a spongy petal when using DOT 5 fluid is because DOT 5 retains air like DOT 3 does moisture.
when installing DOT 5 place the OPEN container in direct sunlight for about 1 hour before using. this will release the air trapped in the fluid during shipping, this is why most DOT 5 fluid is shipped in black containers.
i have used DOT 5 fluid for around 10 years without any problems.
Posted By: Silver70
Re: Silicone Brake Fluid-DOT 5 - 03/03/09 03:01 PM
After putting hundereds of hours in paint on a restored car, I wouldn't use anything but dot 5. Especially considering the latest one had a leak and had I used dot 3, I'd be repainting the inner fender, frame rail, etc...
I have used it in 2 cars, both manual disc cars and I didn't notice a soft pedal or have any issues. It's not cheap, got the small bottle, they sell quarts also and it was 13 bucks, quarters are 25 or so. But small price to pay over repainting!
Posted By: RoadRunner
Re: Silicone Brake Fluid-DOT 5 - 03/03/09 03:23 PM
Yes, moisture will collect. I had to change a dust seal I put in wrong on a caliper, and when I took it apart, there was a little bit of water in the piston area. I had them sleeved with stailess, so no damage, but I gave both sides a good flush anyway. My system was all new also.
A trick I was taught was to place the container of DOT 5 fluid in a pan of boiling water. Makes the small suspended air bubles expand and rise to the top. The fact that it doesn't eat paint away is the biggest reason I use it.
Posted By: DPelletier
Re: Silicone Brake Fluid-DOT 5 - 03/03/09 05:31 PM
Quote:
After putting hundereds of hours in paint on a restored car, I wouldn't use anything but dot 5.
ditto.
Dave
Posted By: burdar
Re: Silicone Brake Fluid-DOT 5 - 03/03/09 06:13 PM
Great info guys. You sold me on the stuff. How much fluid does the average E-body hold? Are the bleeding procedures the same?
Posted By: Silver70
Re: Silicone Brake Fluid-DOT 5 - 03/04/09 01:05 AM
After bleeding the ones on the front disc/rear drum with power, I used a quart... in a 70 challenger.
Posted By: Troy
Re: Silicone Brake Fluid-DOT 5 - 03/04/09 04:16 AM
I have DOT 5 in my T/A and I must say that it does feel a little spongy compared to other cars that I have done.
just my
Posted By: CrAzYMoPaRGuY
Re: Silicone Brake Fluid-DOT 5 - 03/05/09 03:38 AM
I've used DOT5 in dozens of cars, never had a problem, no pedal difference, nothing.
Posted By: Silver70
Re: Silicone Brake Fluid-DOT 5 - 03/05/09 04:01 AM
I'd guess the people who thing the pedal feels spongey still have air in the system.
Posted By: LimeliteAero
Re: Silicone Brake Fluid-DOT 5 - 03/07/09 11:26 PM
whats the best way to flush some of my parts I will be re-using during my resto? The master and wheel cylinders have less than 2000 miles on them. also if I remember the calipers are pretty fresh.
Posted By: HPMike
Re: Silicone Brake Fluid-DOT 5 - 03/08/09 12:25 AM
Quote:
whats the best way to flush some of my parts I will be re-using during my resto? The master and wheel cylinders have less than 2000 miles on them. also if I remember the calipers are pretty fresh.
Flush them out with alcohol. You can also use some DOT5 to flush it out as well.
In response to the original inquiry, you would have to be just plain silly to use anything but silicone in a freshly restored car. I can show you countless photos of beautiful cars that had the paint destroyed by the DOT3. All of the so called maladies?? well, 25 years of using the stuff, never had a single issue. Spongy pedal?? Unless there was trapped air, frankly it's impossible. It will create tiny bubbles if you shake the bottle or really agitate the fluid while bleeding, but normally they will make their way to the top of the master and not cause any issues.
MB
Posted By: gtx6970
Re: Silicone Brake Fluid-DOT 5 - 03/08/09 12:36 AM
when I did my challenger 340 i used the dot 5 in it with no problems of poor or spongy pedal at all. I'll use it in my next one as well
Posted By: Mastershake340
Re: Silicone Brake Fluid-DOT 5 - 03/08/09 01:35 AM
Quote:
Quote:
whats the best way to flush some of my parts I will be re-using during my resto? The master and wheel cylinders have less than 2000 miles on them. also if I remember the calipers are pretty fresh.
Flush them out with alcohol. You can also use some DOT5 to flush it out as well.
In response to the original inquiry, you would have to be just plain silly to use anything but silicone in a freshly restored car. I can show you countless photos of beautiful cars that had the paint destroyed by the DOT3. All of the so called maladies?? well, 25 years of using the stuff, never had a single issue. Spongy pedal?? Unless there was trapped air, frankly it's impossible. It will create tiny bubbles if you shake the bottle or really agitate the fluid while bleeding, but normally they will make their way to the top of the master and not cause any issues.
MB
I'd recommend against using alcohol, it can damage seals, I'd just use some DOT 5 to flush but don't get carried away, even if there is still some traces of regular DOT3/4 in your system it won't cause any problems.
Posted By: Mr T2U
Re: Silicone Brake Fluid-DOT 5 - 03/08/09 04:17 AM
DON'T USE ALCHOL to flush your brake system.
all you have to do is remove as much of the old brake fluid in your master with something like a turkey baster or a syringe, i use a syringe meant for cows that a bought at farm and fleet.
then pour in DOT 5 in the master them bleed your brakes until you see the DOT 5 bleed out, easy to see because DOT 5 is purple in color. then to be safe bleed the brakes again. if there is some old fluid it will not hurt the DOT 5 fluid. it will make the DOT 5 of poorer quality.
when i convert a car over to DOT 5 i usually use 1 quart of the DOT 5 to make sure the old fluid is completely out.
This place is great.....
Thanks for the info guys!
Posted By: Steve340
Re: Silicone Brake Fluid-DOT 5 - 03/08/09 07:06 PM
I have found that the main reason for a spongy pedal is when you install new brake shoes. Until the brake shows "arc" to the same radius as the drum inner surface, your brakes will feel spongy. It usually takes about 5000 miles to get a hard brake pedal. They used to arc the brake shows to the freshly turned drums years ago just for this reason but the EPA made them stop doing it because lot required a machine that would grind of brake shoe material or asbestos into the air.
Maybe this is why when a person rebuilds the entire brake system, it feels spongy and they think its the DOT 5 brake fluid that is causing it.