PatG

I purchased Scott Cooper's Vette Brakes calipers from his parted out '69 and ordered a complete set of O-Ring pistons and seals from Vette Brakes. So, a break overhaul is in the near future for my '79. I have seen and read many articles on silicone brake fluid from "it is great" to "don't use it". Please help me decide if I should do the DOT5 conversion.

LT1driver

Stay with DOT 3/4 and change every couple years and no problems, DOT 5 is unneccessary for most and on the street.

mrvette

When I first got this vette, a '72, some 5-6 years ago, it had rust old dot3-4 fluid in it, I took the allready stainless lines calipers apart and washed out the entire system, replaced with stock pistons/rubber and reassembled as new everything....put in dot 5 fluid, and no caliper springs, worked fine for about 4 years....then calipers finally started leaking on driver's front...
SO, I ordered a complete kit of O ring pistons and seals from Vette Brakes....and proceeded to do the fronts over, never did get around to the rears even yet....and noticed ONE thing, ONE GLARING THING....NO significant sludge/rust/corrosion...NONE, only maybe 2 small drops of rust in the calipers and NONE in the master cylinder....so I installed the O ring pistons and refilled with.....dot 5 of course, pedal is a bit spongy, but for a street car, it's fine, locks them up no sweat....so to me with my own proof on actually 2 differant cars and a huge amount of success of rust prevention over some total of 10 years now....it's worth changing out to dot 5....all other tales are bullpoopie in my book....there ARE NO NEGATIVES!!

GENE

Larry B.

If you are starting fresh, definately go with DOT5. I agree with GENE 100%. No rust, crud or corrosion. I have use DOT 5 for years. No problems EVER if you gravity bleed them and don't have any rotor runout to introduce air into the system. An added bonus is the fact that DOT 5 won't "eat" paint. You can dump out the can on your hood,wipe it off and forget it. DO NOT try that with DOT 3 or 4.!!!


[Modified by silvervetteman, 5:15 AM 12/21/2001]

mrvette

Silver, if you take those silly springs out of the calipers, the pistons act like a more typical system, and so do not 'pump' air into the system with rotor runout.....been that way with BOTH the stock and O ring pistons for a total of nearly 6 years now on my car....NO problems....see my first post....
some guys refuse to be convinced about dot5 and or spring removal, I just know they both work fine....

woodworkr

You can put my vote in for the Dot 5 as well. The only thing that I did not see above was make sure if you decide to go with the 5, clean out the entire sustem completely of the old Dot 3. Denatured alcohole works real well for that. Just keep flushing it through until clean.
Just my .02
JoeB

Rowdy Rat

Pat,

I'm with Gene and the rest of the silicone fluid crowd on this one.

For a street driven only car (without ABS), especially one that isn't driven on a daily basis, the silicone fluid is the only way to go.

I don't know if I'd go as far as to say that there are no negatives in using silicone fluid, but I will agree that the issues are relatively insignificant and the benefits far exceed any disadvantage. Two points to keep in mind... First, if you have been running conventional brake fluid, make sure that you flush the system with denatured alcohol before changing over to the silicone fluid. Second, make certain to bleed the system well... For whatever reason, the silicone fluid seems to make purging all the air in the system more difficult (that's been my experience anyway).

Regards,

mrvette

Stan, I totally agree on the flushing, of course, but in fact I think taking apart every caliper, washing out with water, and re assembley should be done, only thing is, those dust shields may be damaged....so buy new rubber, be amazed at the corrosion on those aluminum pistons too...they pitt like crazy with that old damn dot 3-4 garbage in there....ME, doing it over again...just buy the O ring pistons/rubber and O'haul all 4 calipers...when I finish washing out with water, blow with air jet, and bake in overn at 250f for maybe 30 mins......let cool and do job...takes an afternoon, no biggie....
while at it, do the Master cyl too.....

GENE

ED DINAPOLI

PatG,
I have had dot5 in my 72 since 1985. I did not have all the knowledge about dot5 that is available today. I did not clean the system a thourghly as I should have back then, but who knew. But, I guess luckily, I have not had any problem with the dot5.
Ed

Tom454

I have a 1966 roadster with manual brakes. I Installed DOT5 around 1983. Last year, I had to redo the calipers because of normal wear (leaks) and I found only a trace of rust (one small speck, in only one caliper) in the entire system. This must have been moisture that I failed to remove in 1983. The fluid was so clean (after 16+ years) that I re-used it. The brakes were as hard as a rock before this work, and they are hard as a rock today. There is absolutely no discernible "sponge". If you have spongy brakes with DOT5, then you have air in the system, a bad M/C, or rotten rubber brake hoses. This car has manul brakes as well. It has a harder brake pedal than my 70 which has DOT3 and power brakes (soon to be connverted to DOT5). I have had such great success with DOT5 that I am converting my Mustang and Crown Vic to it as well. It's a "win-win" situation. I've gone through 5 sets of rear wheel cylinders on the Crown Vic... DOT3.

DOT5 will not permanently cure leaky calipoers... the rubber parts will still eventually wear & leak. But it takes a long, long time for this to happen because the level of contamination (water) is virtually none.

terryrudy

I thought that DOT5 actually increases chances for rusting as it doesn't absorb the water, so the water tends to acculuate in the lowest part of the brake system (ie: the calipers). Normal bleeding should take care of this water. This is what I've been told. I run DOT 3 on my Vette, but recently switched to DOT5.1 on my Eclipse and have been happy with that. DOT5.1 is not related to DOT5 at all. Its more like a high performance DOT3 or 4. IF you do any racing or extreme driving, you may want to consider DOT5.1, though I have had no probs with DOT3 on my Vette.
-terry

Barry's70LT1

Definately DOT5..
I converted about 12 years ago. Hard pedal, same as with DOT3.

A hint on gravity bleeding. Use a rubber hammer to do a lot of "tapping"
of the lines and calipers while bleeding. It will dislodge tiny trapped air
bubbles.

Barry

Tom454

terry- I've heard that as well...on this forum only. Based on my experience, and in my opinion, that is a "wives tale" (no flame intended). If the system is serviced properly, there will be no water in it to begin with... and thus no water settling in the calipers. In my case, I must not have removed all of the water 16 years ago. It was only a "spec"... no bigger than a pin head. After 16+ years of use, this is proof positive (in my opinion) that the stuff works as planned. Also, the spec was no where near the bores... it was adjacent to a bleeder screw hole. A 16 year test is not something to dismiss. So I'll stick with DOT5.

terryrudy

True.
Definitely impressive.
thanks,
-terry

PatG

Thanks everyone for the replies to this post. It seems that there is a certain camp of those who have done the DOT5 conversion and swear by it. I can find no equal enthusiasm for the use of DOT3. I have also seen crud build up in DOT3 systems and really do not want to see it again. Based on the replies here and articles on the internet I believe that I will do the conversion to DOT5.