Hello VETTEHEADS, I know everyone is tired about questions around silicone brake fluid, but, Friday I do the deed. I will be replacing all rotors,calipers,rubber lines. I have bled the system down with air and read a ton of material on DOT3,4 verses DOT5 and my final question before I use my 2 quarts of DOT5 is.... when, not if, the slight bit of moisture gets in and the water drops to the bottom of my calipers how in the heck will I get it out without pulling the calipers off and turning them upside down to dump out the water puddle that has settled in the bottom of the caliper
and will be eating the bottom ,out?I can't bleed it out because the bleeders as we know are at the top. I really am struggling with this so any and all input, before I do something I may regret later is appreciated. Remember everything is new, so this is the best time to do it right. THANK YOU

PETER :confused: :flag


[Modified by Bond007, 11:23 PM 6/19/2002]

 

No takers???? :flag

 

When you go and bleed the system the water will rise to the top as the brake fluid is denser than water. They do not mix. The water is pushed out as you bleed. When you do bleed make sure you flush the system good to remove any comtaminites. Good luck :cheers:

 

Hi,
I'd heard that water sinks to the bottom of the system, but the above post says the opposite. I've never tried mixing silicon fluid & water to see what happens, so can't comment on it. I can say this:
I've run silicon DOT5 in my bike, which has cast iron calipers, for the last 20 years. I very rarely change the fluid (only if I pull it apart for whatever reason) or need to bleed it. The fluid resorvoir is exposed to the atmosphere by a small breather in it, which will allow water in over time. I've NEVER had a problem with internal rot while running silicon fluid. When I last took a caliper off to re-paint it I checked out the bores for rot & they were fine. The same systems on other bikes that are run on normal fluid invariably have internal rot (people rarely change the fluid). My practical experience of silicon fluid is that the system will be in better condition after using it than if it was run with non-silicon fluid.
What puzzles me is that with the bike water can get in because the reservoir is exposed to the elements. On the Vette it's in a dry place under the hood. Normal fluid is hygroscopic (sp?) so draws moisture in from the atmosphere. Silicon fluid isn't hygroscopic, so how does the water get in the system? :confused:
Paul

 

UK, It has been said by guys with much more reading and experiences with DOT5 fluids that the water problems with DOT3-4 junk are so bad it attracts water right through the hoses...sounds silly to me, but the testing seems to reveal that, more likely is rainwater passing the top seal of the master cylinder....

BTW that pin drop of water in the calipers is so small it's a forgetaboutit type thing....after 4 some odd years of east coast driving habitat...lotsa rain, constant moisture...my shark had just a pin ***** worth of water in both front cylinders....and such a minor rust spot it just didn't matter...
reason for failure was one caliper the lip seals gave out, leaked...so I rebuilt both of them with O ring pistons, leaving outthe damn springs of course...works fine....

GENE

 

Gene,
I swapped to silicon fluid because after 1 year of use my DOT3 had soaked up so much of our British weather that the master cylinder was already rusting. Since swapping I've not had a problem & it is truly fit&forget. I've heard a lot of horror stories about silicon fluid, but even if it's true that water sinks to the bottom, the damage to the system will be far less than if DOT3 was used for the same period of time.
I remember when CDI ignitions came on the market at affordable prices. Horror stories were circulating about using them, even to the extent that using one could make you sterile - so I rushed out & bought 3! :lol: ).
:cheers:

 

i only do things to my car that make it:
1. go faster
2. stop faster
3. look better
4. corner faster
when i called sellers of dot 5 they all told me i might be unable to stop coming down a long hill, or it might just get a soft down to the floor pedal :confused: The previous owner put it in my c3, who knows what he did? I don't know why the calipers leaked and had rusty water in the bottom.
Anyway they all said it was good for trailered cars not driven fast, or at all, certainly not driven hard thru the mountains.
So for me i got rid of it, but for others it might be wonderful :confused:


[Modified by drives61, 9:29 AM 6/20/2002]

 

I just don't see the advantage in using silicone fluid. If it's so great, why dosen't Porsche use it? They have the best brakes in the world.

 

The advantage for me is that I don't have to change the fluid every year because it's soaked up water. For a lazy bugger like me, that is one big advantage :D

 

BMW recomends a flush every 4 years. There is also a very easy way to bleed them (though time consuming) Just open up all of the bleeders & let gravity do it.

 

Just stick to Dot-3 and you are done. Next keep your brakes in good repair.

 

VETTEHEADS, will be doing the system with silicone this weekend, THANK ALL OF YOU, for your input. Since I was sent 2 quarts of silicone with my calipers I quess destiny dictates I go with it. Wish me luck and will get back with a report on how it went.

Peter :cheers: :seeya :flag

 

Porsche probably has ABS brakes ???

The pulsing of ABS brakes *supposedly* introduces air bubbles into DOT5.
That would be the reason they don't use it.
A guess on my part. DOT 5 is not recommended for cars with ABS.

I just put a small amount of DOT 5 in a teaspoon, and added a few drops of water. At first, the DOT 5 floated on top. Then I agitated it a little, and it sank to the bottom. It seems that the specific gravity of DOT 5 and (my) tap water are very close to the same number.

I have been using DOT 5 for over 20 years and it has performed flawlessly.
People that bad mouth the stuff usually are speaking from others opinions, hearsay, and rumors. I used it... it works. Recently took my 66 apart and the DOT 5 fluid I put in it over 20 years ago is just as clean as the day I put it in... so I re-used it.

When a system is serviced, such as a conversion from DOT 3 to DOT 5 (or from DOT 5 to DOT 3), it is common for people not to rebuild the entire system. Normally, not a problem. But if your system has sludge in it, and seals that are marginal, the service work can disturb them and cause system failure..... which is commonly blamed on the fluid change.

My DOT 5 brakes perform flawlessly, even under hard braking, and the pedal is hard as a rock.

Just stick with DOT 5 and forget the DOT 3 rot problems.



[Modified by Tom454, 10:00 AM 6/21/2002]

 

Tom454
A little off the beaten path, but did you by any chance ever live in S Florida- Pembroke pines area???

 

Nope... never lived in Florida. But I'm considering planting myself on South Beach.

 

OK... thanks...thought you might be an ex-neighbor of mine. Maybe your twin..same car and all.

 

You cannot use DOT-5 inn A.B.S. systems because the fluid is thinner and will fool the computer that the pressure is lower than it really is. Also when there is moisture in the calipers you need to bleed as much as you can, after that just drive the car hard and heat the calipers to evaporate the moisture with heat. :cheers:

 

Tom - you are probably correct in assuming that the ABS may cause problems. I've put a great deal of thought into this, and other things that car manf's don't do.
My guess for the non use of silicone brake fluid is that once they sell the car they have little control of how the car is maintained. A lot new car owners are clueless on how to maintain a car. It also seems that the more someone pays for the car, the more daft they are.
With that said, even though silicone fluid is better, regular brake fluid has a "safety net" if you will.
The fact that it does absorb water protects the system from any rust developing after the water settles at the lowest part. Regular fluid would absorb it, and hopefully if the owner takes the car in for service, the fluid would be changed every few years.
The manfactuer has to build the car for the guy who doesn't service his car regularly. I could see it now, 60 Minutes doing a story on brake systems that "rust"
IMO

 

Absorption of water by DOT 3 does not protect the system from damage... the exact opposite occurs. Having done several hundred brake jobs as a professional mechanic, and as the owner/operator of a 7 bay facility, I can tell you without a doubt that DOT 3 systems are the nastiest to work on. Although the water is "absorbed" by DOT 3, this does not prevent it from doing damage. Extensive damage occurs in the master cylinder at the low spots, where the piston seals are at the limit of their travel. This is where you will find "pits", which tear up new seals when installed. Hence, the need for honing sets...... which you will find in an autoparts store. In fact, they used to sell oversized cups for brake system parts due to the extensive amount of "over-honing" that was typically done by mechanics in an effort to repair DOT 3 rust damaged components.

Master cylinders that are sitting on the shelf waiting to be sold are also subject to this problem. That is why I dis-assemble ALL master cylinders that I purchase for customers BEFORE I install them. Most are defective. Even the new (not just rebuilt) units fall victim to DOT 3.

The master cylinder in my 66 Vette, which was treated to DOT 5 over 20 years ago, has absolutely no rust in it. Neither do the calipers. The seals still wear out and take a "set", causing leaks, but the metal inside the system is pristine.

It was 20 years before I even opend up the system... and the fluid is like new. No rust to be found anywhere.

The DOT 3 safety net idea might work if people had their cars serviced regularly and correctly, but my experience as a mechanic says that this simply does not occur. Especially after the car goes past the magic warranty date, and gets sold down the food chain where someone may have to make the decision... "Let's see, do I want to pay to have my (functioning) brakes flushed, or do I want to feed my family for two days?"

If you properly clean and rebuild a brake system, and use DOT 5, you won't be having internal rust problems. It's when improper methods are used, and/or the mechanic does not physically disassemble and clean each and every part, that water finds its way into the system. Blowing out brake lines with compressed air that is laden with water is a typical example.

When I convert a system, I never flush it, taking the easy way out. I totally disassemble the master cylinder and all four calipers, cleaning out everything, checking for damage, and installing new seals. There is no amount of flushing that will dislodge the crud that builds up inside the system. It has to be manually removed. Voice of experience. Lots of experience. I tried flushing.... and then disassembled systems... they were still full of debris.

The statement about ABS brakes that I made is something that I was told by people who know way more than me about ABS. I just regurgitated it here for everyones amusement. But it is common knowledge that you are not supposed to use DOT 5 with ABS..... for whatever reason.

 

Thank you Tom just got through with half my brake job today with DOT5 but had a problem with my rear rotor please look at my post just down a little titled "halfway through my brake job........etc once again thank you and all who have been helping me will update tomarrow night on progress

Peter :cheers: :seeya :flag