Silicone or Dot 3 Brake fluid

[Jim D.]

Re: Silicone or Dot 3 Brake fluid

I use it in every Corvette I restore. It's been in my 60 since 1984 and I've never had an issue with it.

Jim

[John H.]

Re: Silicone or Dot 3 Brake fluid

BTW: New Corvettes use DOT 3 for the brakes and DOT 4 for the clutch. The clutch is exposed to more heat than the brakes (unless you track the car) thus the DOT4 there. And that specification is all bout cost.

Correcto. Could never understand that level of cost-consciousness on a $60,000 performance car.

After I took over as the Viper plant manager and launched the new plant, I had a round-table discussion with a group of Viper owners (who care about nothing except going, turning, and stopping), and they asked why I didn't factory-fill them with DOT4 instead of DOT3, which gave them a little higher boiling point for track days instead of flushing/filling with premium fluids like Motul 600.

I talked to my Brake engineer, and the answer was that DOT3 was the corporate standard for all products. We met the next day with Dow Chemical (fluid supplier), and two days later we were factory-filling with DOT4. The cost penalty was about 23 cents per car over DOT3, and Dow agreed to eat it in return for a Dow sticker on our GTS-R factory race cars.

[Terry M.]

Re: Silicone or Dot 3 Brake fluid

Correcto. Could never understand that level of cost-consciousness on a $60,000 performance car.

After I took over as the Viper plant manager and launched the new plant, I had a round-table discussion with a group of Viper owners (who care about nothing except going, turning, and stopping), and they asked why I didn't factory-fill them with DOT4 instead of DOT3, which gave them a little higher boiling point for track days instead of flushing/filling with premium fluids like Motul 600.

I talked to my Brake engineer, and the answer was that DOT3 was the corporate standard for all products. We met the next day with Dow Chemical (fluid supplier), and two days later we were factory-filling with DOT4. The cost penalty was about 23 cents per car over DOT3, and Dow agreed to eat it in return for a Dow sticker on our GTS-R factory race cars.

I wish Corvette would learn that lesson -- even though I have no intention of tracking my car. It is about due for a fluid change anyway and it will get DOT4.

Not to play the cynic too much, John but what would that sticker have cost Dow if they wanted to buy the space? I'm guessing they came out ahead on that deal.

[Joseph K.]

Re: Silicone or Dot 3 Brake fluid

I have had 5 in my car for only two years after a complete rebuild and no problems. It not as long as others but I have heard of problems with leaking cylinders only after a year.

[Duke W.]

Re: Silicone or Dot 3 Brake fluid

I Think leave the dot 5 to the euro.cars ( BMW Mercedes)

Mercedes specifies DOT 4 and probably most of the other European manufacturers. Mercedes also recommends a brake fluid change every two years and every year on some models.

The only way I have ever converted to DOT 5, and what I highly recommend to others, is to only do it if you start from the ground up with everything spotless, dry, and not one even one remaining molecule of DOT 3 or 4.

Then assemble the wheel cylinders/calipers and master cylinder with DOT 5. Assemble the system and then fill/bleed with DOT 5.

Otherwise, use DOT 4 and flush it on a schedule that's suitable for your driving environment and climate understanding that the biggest problem with DOT 3 and 4 is moisture absorption, which will lead to internal corrosion of the hydraulic components.

Duke

[Dennis O.]

Re: Silicone or Dot 3 Brake fluid

I put DOT5 in my '68 when I did the brakes about 15 years ago. I have had no problems since. I do remember a couple of things however. First, the instructions on the container said to heat the fluid on the stove to whatever temperature they specified to drive the air out of the fluid, which I did (I bought a cheap teakettle to do this). Second, it seemed like an awful chore to get them bled. As I remember, I had to have my girlfriend push the pedal down once, when I would open the bleeder screw, and then close it before she let up. It took a long time to bleed them, but we finally got them done. After that experience, I've gone back to DOT4. Whenever I've got one of my vehicles in the shop, if I think of it, I gravity bleed one of the circuits. It's easy to do, and if you watch what you're doing, you can do it between other little tasks. I just finished doing this to my '99 F150 (gasp), and I was amazed at how discolored the fluid that came out was. I just let it run until new fluid came out, closed the bleeders, and topped off the master cylinder. This works real well in a vehicle where the master cylinder is a bit higher than the wheel cylinders. I still need the girlfriend to pump the brakes on my stock '51 Ford with the master cylinder under the floor, though.

[Jeff P.]

Re: Silicone or Dot 3 Brake fluid

Thank you all. I guess Dot 5 it is. I had another post reguarding the rear brake line that goes around the caliper. One has the circular ribs at the bend,and the other has nothing. Any 68 owners know which one is correct? Thanks again for your help. Jeff

[Carl B.]

Re: Silicone or Dot 3 Brake fluid

been using silicone 9 years on my 62 Impala and 4 years on my 66 vett. no problems one note when checking disassembled wheel cylinders you would not believe the amount of rust that built up inside the cylinder also when assembling brake parts (cylinders /calipers fill with fluid before mounting on car even though some will run out enough will remain to help bleeding brakes never had a problem bleeding brakes

[Ronald L.]

Re: Silicone or Dot 3 Brake fluid

Dennis, don't gasp on those F-150's! That with trailer tow (or a F350) is the only way to trailer a car.

The Alcohol based Dot 3/4 will still pick up water and discolor (age oxidize corrode) in time, and not that long. No more than 4 years to avoid surprises and I would think you still want to keep the resivor as full as possible and pump brakes as described so as to keep pressure on the fluid in the line. Keep pumping until fluid is clear and cut off the valve when fluid is squirting out, if not you run the risk of air getting back in the system.


The other important thing is you start with the furthest away, RR the LR followed by RF then LF.

[Duke W.]

Re: Silicone or Dot 3 Brake fluid

Dot 3 and 4 brake fluids are formulated from a chemical family known as polyglycol ethers, not alcohol.

Duke

[Edward J.]

Re: Silicone or Dot 3 Brake fluid

Guys, I thought I would pass this web site along to you all so you can read, Its very interesting and as it compares all the different types of dot fluids used, all the pros and cons. (www.motorcycleproject.com) go to information then click on dot3vs dot5

[Terry M.]

Re: Silicone or Dot 3 Brake fluid

Guys, I thought I would pass this web site along to you all so you can read, Its very interesting and as it compares all the different types of dot fluids used, all the pros and cons. (www.motorcycleproject.com) go to information then click on dot3vs dot5

I am reluctant to disagree with you Ed, but there is a substantial amount of misinformation in that article. I won't bother with ALL of it, but the assertion that DOT 5 requires frequent changes, requires special seals and lacks lubricity is the start of the misinformation, and it is downhill from there.

As you can see from the testimony of many of us here, frequent flushing of DOT 5 is NOT necessary in normal use, nor is the use of special seals. My understanding is that most racers do not use DOT 5 precisely because they flush fresh glycol fluid through their system frequently -- often before each race. The permanence of DOT 5 is counter to their regimen.

[Edward C.]

Re: Silicone or Dot 3 Brake fluid

I have had SS Sleeves and Silicone Fluid in my 71 for 27 years and no problems at all. Ed

[Jim L.]

Re: Silicone or Dot 3 Brake fluid

My understanding is that most racers do not use DOT 5 precisely because they flush fresh glycol fluid through their system frequently -- often before each race. The permanence of DOT 5 is counter to their regimen.

Most racers don't use DOT5, but with two track cars to support, and basically being lazy, I do use it so I don't have to repeatedly bleed the brakes.

In fact the interval between brake bleeding sessions on either car is measurable in terms of years. Even then, it tends to happen only when there has been a compelling reason to open up the system..... new master cylinder, new flex hoses.... that sort of thing.

Never a problem and I'd never go back to DOT3/4 fluid.

Jim

[Paul C.]

Re: Silicone or Dot 3 Brake fluid

I rebuilt the brake system on my 71 and refilled with DOT 5. Can't tell any difference--works great and I don't have to worry about the water in the fluid. Cost is not an object here when you consider how much money we have invested in these cars.