We agree on that much. You need everything squeeky clean before you convert to DOT5 and not many are going to go to that trouble. Simply adding DOT5 and thinking you can push all the DOT3 out is a BAD mistake.

I'm glad yoiu have had good luck with DOT5. I'm just telling you what i've learned about the pooling after spending several years on the internet doing research... Road course guys hate the stuff and that says a lot to me.

 

Silicone fluid in mine since 2000 without any issues....

 

"Road course guys hate the stuff and that says a lot to me. "

Yeh... I'm not a "road course guy", just a former autocrosser and a seasoned mechanic. I used to own & operate a 7 bay Machine Shop & Repair facility (Lake Machine in Budd Lake NJ on Rt 46) and I've done thousands of brake jobs. I still do brake work for fellow forum members in Raleigh and the surrounding area. When you do this kind of work professionally, you have to do it right.... the liability is too high. Last weekend I did a Toyota and a Nissan. This weekend it's a Mustang heater core.

"I'm just telling you what i've learned about the pooling after spending several years on the internet doing research... "

My research consists of actually doing the work. I don't put much faith in the hype I read on the internet. If you really want the answers, you have to get your hands dirty.

core.

 

My dad did a 13 year test on Dot 3.(44,000mi)
Never touched the brake sytem, brakes work fine. That's long enough for me to prove Dot 3/4 doesn't need to be flushed every year. But Kudos to the fluid salesman for making plenty of sales

 

Tom454
What is the change interval for new cars, as recommended in the owners manual? And what fluid do they use?

 

Test was done on a Vette??

I have several 15 year old cars with DOT3 in them that are all gunked up but don't leak either... but they're not Vettes with crooked rotors. The DOT 3 fluid is black.... the goop is thick... but they still work.

I agree it doesn't have to be flushed every year... depends on the "service". I've worked on schoolbuses, dumptrucks, backhoes and cars... some will last longer without a fluid change. If you live in a mild climate, then you can wait longer between changes. If you live in the "snow/salt belt", then you need to change the fluid more regularly. The brake jobs I did in Syracuse & Binghamton NY and NJ were very different than the brake jobs I do here in NC. It's all based on exposure. I spent more time replacing rusted out lines in NY than I did actually doing the pads/shoes. The fittings would corrode and "rust weld" to the calipers/wheel cylinders. The lines were very often destroyed just trying to disconnect them. Here in Raleigh, everything just comes right apart... no such issues.

C2/C3 Vettes are more subsceptible to water problems due to the caliper/rotor design. The fixed caliper & low runout requirement are the culprit.

I had runout on my C3... overhauled the brakes, drove it around the block a few times... and had to re-bleed. Had nothing to do with the type of fluid.

DOT 3 gets dirty fast because it absorbs water. Doesn't matter which car (or backhoe) it is in.

DOT 3/4 works. So does DOT 5.

 

Then why is it still used by automotive companies, water absorbing problems and all? You think they would use the best fluid, considering their azz is on the line if their cars don't stop. BTW- I do agree with you on one thing...

 

Actually, he NEVER said he was looking for "the cheapest solution"!

I have read pros and cons of Silicone but my 72 gets the synthetic DOT 4 (Valvoline maybe?) that you see in most auto parts stores. My car sits in an unheated garage for four months out of the year and I have no issues with standard fluid. I don't really have a preference but since my 72 has never had brake issues with rust I stick with DOT 4. One of the posters suggested that standard brake fluid absorbs water. True. At the same time, most manufacturers suggest regular changing of your brake fluid for just that reason. I have five cars in my family and every two years the brake fluid and antifreeze get changed.

When I inherited my mother-in-laws 25 year old Mercedes Benz, I checked her extensive collection of every repair receipt for that car. At no time did she ever have her brake system flushed and her brake fluid barely poured out of the master cylinder and was as black as a coal miners face at night. Needless to say, I completely drained and flushed that system. During the subsequent year I rebuilt all four brake calipers and only one of them had a tiny bit of rust.

This whole discussion doesn't mean that seals and such don't wear out if you use silicone. You will still need to periodically rebuild brake calipers but the good news is that those rebuild kits are cheap and rebuilds are easy.

Gary

 

u guys are all spoiled. when i was 16, i was so poor, my 1st car, a 56 ford, didn't even have a master cylinder
U haven't lived until u learn how to do hot laps with NO BRAKES

 

Its funny we don't have the time to talk about brake fluid but we have all the time in the world to talk about all the stupid Off Topic stuff such as "monkey **** house" "what does TTT mean"



This is a very important issue. Everyone needs to know that you can't just pour in DOT5 without completely cleaning the system.

Lots of good exchange of ideas going on here.

 

While we are beating the dead horse and all....I though I would add that Stainless Steel Brakes Corporation does not recomend the use of denatured alcohol to clean out the system as some of it can become trapped in the system and it will "boil" very easily when heated from hard brake use causing brake system vapor lock. They recomend using fresh DOT-3 as a flushing media to use before converting to DOT-5.

-Mark.

 

thats what i did and ended up with gobs of congealed crap in the system and a stuck brake light switch.

The only answer then is to take the system apart and clean it completely removing all old DOT3 before installing DOT5

 

1. Because it's cheap and they could care less what happens after the warranty wears off. By the way... warranties do not cover "normal wear items"... so the definition is open as to what they decide is a wear item... check the fine print.

2. Many new cars have ABS... DOT 5 is not a good choice for ABS cars.

"The only answer then is to take the system apart and clean it completely removing all old DOT3 before installing DOT5"

Yes... that's the ticket. People spend more time screwing around trying to "save some work" by finding the easy way to do things... then end up doing it 2 or 3 times over.

 

A slight tangent...

Since the BrakSystem is a simple hydraulic circuit, why do they use these exotic fluids? Why not use hydraulic fluid? It doesn't absord water, it doesn't dissolve paint, it's cheap...

Seriously, I'm curious.

 

Boiling point ?

 

That's a pretty good question. I think that Tom might have it right. I would guess that Hyraulic fluid would have a lower boiling point. Probably more significant is that there would be more volatile compounds in this fluid. Since hydraulic systems circulate fluid, unlike a brake system, the gasses comming of would collect in a sump rather than in the lines. That would be my guess anyways.

 

Thats all I use and never have a problem.do not get cheap with the brakes

 

It is very clear ... be careful mixing 3 /4 and 5.
But, I am in the same situation as the original post ...
totally fresh system, all rebuilt, new stainless lines.
I am seriously (and still) 95% sure that I will use DOT5.
My baseball cap is on straight, but my little shiny things are all freshly painted.
Also, I will not be racing - except for maybe a run or two at the drag strip.

 

Years ago, I believe it was NCRS (but it might have been NCCC) issued a warning for those driving their Vettes to a meet held in Colorado that to NOT use silicone brake fluid. Their reasoning as I remember was that the change in altitude coupled with harder brake use in the mountain roads created air bubbles which in turn made for dangerous braking.

I suspect that the "pumping" action of the rotors were a major factor in getting air into the system, but perhaps silicone is more prone to getting air bubbles making the problem worse.

I put silicone in a completely new SS brake system in my 65 and then let it sit in a garage for years and years. When I brought it out last summer, the front seals were leaking so when I rebuilt the system I found that the rear reservoir of the master cylinder was completely rusted and full of gunk. The dual master cylinder on a 65 has plastic screw-on caps so I would have thought no air/moisture would have gotten into the system. I cleaned out the master cylinder and put more silicone in it because I didn't want to completely clean the system to go to Ford's DOT 4.

My daughter and I are doing a body-off on her 72 LT-1 and I'm still contemplating what kind of fluid to use and consequently am interested in all comments and opinions I've found here.
Thanks
Ol Blue

 

in FL it is so humid, i wonder if using a vacuum pump on new lines is a good idea w/ dot5?
how else can that moisture be kept out?