Hi Guys,

Been pondering this as an option - switching over to Silicone brake fluid. Primary reason to keep corrosive brake fluid off paint and other things. Apparently there are some draw backs, especially with cars equipped with ABS but we don't have that problem. Lots of info out there on why DOT 3,4 and 5.1 doesn't mix with DOT 5, but not a whole lot on compatibility with rubber parts made for a 3rd Gen. Or how hard it is to actually bleed a silicone system, w/o introducing air into the lines.

Anyone ever do this?

 

Don't really see the point of it. DOT 3 works just fine...

 

Been done lots of times to lots of cars of all sorts for DECADES. There's nothing unique or specific to our cars in this area.

FYI, Vettes started coming from the factory with it, at some time at or before 1985.

As stated it doesn't mix well with the usual stuff; and, it doesn't take much at all of the other, to make the fluid still be hygroscopic. Best to do ONLY when replacing EVERY component of the system that can't be TOTALLY and ABSOLUTELY flushed and cleaned; which pretty much means, the only thing you get to leave intact is the steel lines, and those must be THOROUGHLY flushed with solvent and blown dry. So, as long as you're replacing your MC, PV, all calipers, and all rubber hoses, it can work out just fine.

Other than its lack of hygroscopic properties, and higher boiling point, there's no particular advantage to it.

Bleeding is exactly the same as with any other fluid.

 

Thanks Sofa. I'm reading accounts of it creating air bubbles more easily. i.e you gotta be careful when you pour it and also when bleeding the system - as if maybe you don't want to pump the brakes too fast. (which seems like a good idea anyway regardless of type used).

 

Maybe it's different now, but the last car I had a hand in converting, about 30 or 35 years ago, I don't recall having that kind of trouble. The fluid is a noticeably bit thicker (or was back then anyway) but it wasn't so much as to be a problem.

If you're doing one of those COMPLETE brake jobs, I don't see any reason not to switch to it; gives those few advantages, not least of which is, eliminating the whole moisture (corrosion) thing that goes on with brakes; might add $2 or something to your $500 or whatever project; but short of that, it's a whole lot of maze to run, with very little cheeeeeeeeze at the end.

 

I've never used Dot5, but I've read a few articles on them, yeah they say it doesn't absorb fluid the same way as previous specs, but water still gets into the system, so you still have to flush it out.

Honestly, I just run a quality DOT4. Though in the last few years, since I had it on my RS, I switched all my cars to Castrol SRF. Its expensive to convert yeah, but not so bad once you are just maintaining it with a once a year maintenance. I suck the old fluid out of the reservoir, fill with new fluid, then bleed the system.

I LOVE the way the pedal stays firm no matter how hard I am on the car. Whether that's back roads hooning, or dedicated track time. I love the smell of a car at the track, all those cancer causing VOCs burning off lol. The smell of hot brakes and a engine warm enough that it starts out-gassing the grease/oil on the outside.

SRF is expensive, but worth it to me. Love knowing I can tear up the track for 20-30 minutes a session, and still drive home.

 

The ONLY reason I'd want to do it is to eliminate toxicness. when I'm bleeding. period. don't want it on my hands or my paint. Especially since these cars can't be pressure bled - that I'm aware of anyway. the gizmos I've seen don't look reliable. I plan to research switching my other cars from DOT 4 to DOT 5.1, they do get driven hard. But still no need for racing fluid.

 

Give it time and I think this mid-life brake fluid crisis will pass.

 

Knowing how hot the header primaries get on the driver side, and how close the brake lines are? All that ambient heat can cook the fluid over time.

I'm glad I've got the SRF in there just for that alone.

 

I've done it on few cars with all new calipers/cylinders with no issues- what can be a problem is having one car on a lift with another with good paint below on my 69 bird I did brakes with silicone and the clutch dot 3 what I forget when bleeding a T56 is that it runs inside bellhousing UGH I had shower curtain and several towels on car below till that stopped dripping- hindsight is 20/20

 

Doing this now. Pm me if you want. Its a very slow process.Speedi bleed makes a nice pressure bleeder. Basically you will need to flush the whole system. And or replace rebuild calipers. You can flush the system with denatured alcohol. Its takes along time. Dot 5 doesn't mix well with anything else. You can't pump these to bleed. Best way to get started is gravity bleed once the dot 5 is in the system. Then the pressure bleeder is used. The main concerns is once system is flushed you def need to bench bleed the master cylinder. Which takes awhile. Slow and steady because this stuff makes microscopic bubbles when poured. Vacume bleeder is good to get it started but if you have bypass at the bleeder you will never know of its the fluid bubbles or air getting sucked passed the bleeder. The ingenuity of the speedi bleeder is it has it own container to continuously add through the system eliminating the need to keep refilling the master. Its a pretty big undertaking. Patience is the key. But a godsend because if it splashes, and it has its just a quick wipe down no issues.

 

Thanks for the update, and keep us posted on how it goes. Happen to have a link to the Speedi blend bleeder? I have always been afraid to use a pressure bleeder on these cars, getting a seal on the master cyl seems impossible. Give us some photos too while your at it!