Dot5 silicone brake fluid

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08-16-2006, 08:22 PM

NJ-LE

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Dot5 silicone brake fluid

I seem to recall that GM shipped mid and late 90's Corvettes with Dot5 silcone brake fluid from the factory. Can anyone verify that?
Also, does anyone discount the UMI Camaro to C5 Vette brake kits or is UMI the sole source?

08-16-2006, 10:49 PM

n2ceptor

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Re: Dot5 silicone brake fluid

I doubt it, because DOT 5 is not used in ABS systems..... And just looking around the web, all I saw was DOT 3 or upgrade DOT 4 for C5 vette.....

Unless there was a special edition somewhere....

As far as the second question, no idea....

08-17-2006, 08:51 AM

NJ-LE

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Re: Dot5 silicone brake fluid

I'm asking because I've probably seen the same opinion pieces that you have that claim silicone fluids won't work properly in ABS systems. Unless there is a major viscosity difference, I don't see why they wouldn't. The other reason that water would collect in low spots I think is bogus because silicone fluids aren't hydroscopic like the high molecular weight glycol-ethers are so silicone won't attract moisture the moisture to begin with.
Maybe my recollection of Vettes using silicone is wrong or it was an "off-road" option or they had bad experiences with it. I don't know. Possibly some racers don't because it takes longer and more care to bleed systems properly. I've always used s.s.-teflon hoses and silicone fluids on motorcycles and been happy and maintenance free other than pads.
I plan on doing the UMI C5 front brake upgrade soon and figured Vettes and Camaros probably shared many of the same ABS components so if they used silicone I could too.

08-21-2006, 06:49 PM

Severous01

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Re: Dot5 silicone brake fluid

it's not just the silicone additive that's making up the difference. there are other things in that may eat away the seals/gaskets or even the lines. do your research. you can't use anything but dot4 in hondas because anything else destroys the aluminum lines. dot3 is for steel lines...dot5 may be capable for both...not sure.

it's like adding the red stuff to the green stuff in the coolant...some have problems and i know they dont mix because i've disassembled a block that had 3 gallons of sluge in it from mixing them.

use it at your own risk and tell us how it turns out for you

08-24-2006, 05:54 AM

Norm Peterson

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Re: Dot5 silicone brake fluid

Here's some tech (boldface mine)

Quote:

DOT 5: This brake fluid is based upon silicone. Its dry boiling point (ERBP) is 260°C minimum and wet boiling point is (Wet ERBP) 180°C. It is used in applications, like for weekend, antique, collector cars that sit for long periods and for some military vehicles. Some car manufacturers are also used in their road driven vehicles. This brake fluid does not mix with DOT 3, DOT 4 or DOT 5.1. It will not absorb water and will not damage the paint on a vehicle. It is also compatible with most rubber formulations. It absorbs more air and giving poor pedal feeling. It is unsuitable for racing due to more compressibility under high temperatures. If as little as one drop of water enters the fluid, severe localized corrosion, freezing or gassing may occur. This can happen because water is heavier and not mixable with silicone fluids thus it is unsuitable for ABS.

DOT 5 fluid is highly compressible due to aeration and foaming under normal braking conditions, providing a spongy brake feel. Poly glycol type fluids are 2 times less compressible than silicone type fluids, even when heated.

DOT 5.1 is a different animal

Quote:

DOT 5.1: This brake fluid is also based upon poly glycol. Its dry boiling point (ERBP) is 260°C minimum and wet boiling point (Wet ERBP) is 180°C minimum. It is used in severe-duty vehicles such as fleets and delivery trucks; towing vehicles, and racecars. It can be mixed with DOT 3 or DOT 4 without damage to the system. It maintains higher boiling point than DOT 3 or DOT 4 fluids. It is excellent for severe duty applications particularly for racing of car. It also absorbs moisture out of the atmosphere and thus reduces its boiling point. It can also damage the paint on a vehicle.

Link

Norm

Last edited by Norm Peterson; 08-24-2006 at 05:59 AM.

08-24-2006, 05:04 PM

NJ-LE

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Re: Dot5 silicone brake fluid

Thanks for the post Norm. Though I've got a 95 it has <30K miles so I suppose it qualifies as a weekend car. I may try some autocross events which is my :-) justification for the C5 brake upgrade! My bike experience with dot 5 silicone has been all positive including rock hard lever pressures. I could also vacuum degas the fluid during the fill process but haven't in the past. I'll probably mentally flip a coin when when I do the C5 install whether to use 5.0 or 5.1.