Completely finished a new brake system with all new components .I was told now is the time to put in Dot 5 rather than the traditional Dot 3,another person stated that dot 5 is prone to swelling or damaging the rubber seals,that it is not compatable with many brake systems?? Our cars here in Mn sit for long periods of time due to our long winters. That Dot 3 draws moisture and will eventially rust the walls of the wheel cyls. and start a leak ? Gene in Mn
Right on the can, DOT3 says use what you need and throw the rest of the can away. Thats how ****py DOT3 is. Harley Davidson and the military use DOT5. Any other questions? I used to find wheel cylinders full of muddy **** and corrosion but I've used DOT5 for more than 30 years and I never find **** in my cylinders
Dot 5 is the best. It will not swell your seals or harm your system in any way. And it will not draw moisture into the system. I have been using it for over 35 years. 11 years ago Wilwood told me no way could I use it in their brake system, I did it anyway. It is still in there with never an issue. I put it in my olds in 1981, drove it till 87, stored it till 2010, took it out of storage and drove it on power tour without touching the brake system. Try that with dot 3.
You decide, The search engine is your best friend. https://jimsgarage.wordpress.com/2007/01/09/dot-3-dot-4-and-dot-5/ https://www.jalopyjournal.com/forum/threads/dot-3-vs-dot-5.675492/
Eleven years and counting with dot 5 and no problem except brake light switches. Changed to a Harley switch and cured the problem. I also heard wives tales of troubles with dot 5 silicone fluids but I wouldn't hesitate to do my next car and us it again.
I built my 3W in the early '80s, so it's been on the road for over 35 years. I have had Dot 5 in the brake system since built and never any problem. No way would I use Dot 3.
I'm a DOT 4 guy. DOT 5 is best for cars that sit a lot because it doesn't attract moisture, but it is no good for motor sports applications (I had DOT 5 boil up on me after a short track stint). But DOT 5 should be fine for regular street use.
Totally rebuilt our 49 Ford brake system. Whatever was in there before had turned to slushy Ovaltine looking crud. Only guessing what was in there drew moisture? Car had been on the bare ground for several years under a tin shed roof. We went with all new cylinders, lines, etc. and use DOT 5.
Earlier brake fluids are "hygroscopic" and absorb moisture, but that's a feature, not a bug. Since it's not a sealed system the water would otherwise pool in low areas over time and potentially freeze solid in cold weather. It's supposed to be changed periodically, though hardly anybody does this.
The one fact that interests me is that no automobile manufacturer that I know of uses Dot-5 as OEM fluid. Does anyone know why this is? If it is so much better, I don't think cost would be a factor for high-end performance cars. I put Dot-5 in my '68 Corvette, but it was a ***** to get bled correctly. Once in, it works fine and lasts a long time. Since the advent of "Speed-Bleeders" that making flushing the system a relatively easy one-person task, I have gone back to Dot-4.
Auto Manufacturers want their cars to last 5 years/100000 miles. After that they want them to generate large repair bills at the dealers. So the dealers profit, then the owner gets sick of that an buys a new car. DOT 5 fluid does not fit that formula.
Read all the stuff above when I was trying to figure out what fluid to use. I picked the DOT 5 because I have a lot of panted parts the brake system was close to and didn't want paint work spoiled if I had a leak. I installed all new lines and components. DOT 5 does tend to aerate a little easier but, don't pump the **** out of the pedal. I did however use a vacuum bleeder to initially fill the system THEN pump bled each wheel cylinder, slowly one pump crack the screw.....and so on, till I had a firm pedal. It did save me because I did have a small leak down an exposed painted frame rail. Oh yea, the car stops great with a nice firm pedal.
Technically 3 and 4 are "synthetic", some kind of glycol. Some brands tout this on the label, as if there is a distinction between theirs and the other stuff. Sort of like the jar of peanut ****er has a blurb "No Preservatives or Artificial Flavors!" (Neither does anybody elses)
I run 5 in my pick up, it's good for street driving and for cars that sit long periods. Make sure you don't aerate the fluid when you pour it into the master, and don't pump the master when bleeding, as this will also aerate the fluid making it very difficult to get all of the air out. Just crack the bleeder, SLOWLY push the pedal down once, close the bleeder, SLOWLY let up on the pedal and repeat until you get a firm pedal. To answer the question as to why modern cars don't use 5 is because of the anti lock brake systems, when they pulse the solenoids cycle rapidly on and off which causes the fluid to become foamy and develop air pockets in the lines = no more brake pressure.
It would also boil already at 100 degrees, instead of around or above 200 degrees as when mixed with the glycol based DOT 1-4 and 5.1 brake fluid. (Celsius ofcourse.)
What model ford? And who's brake parts? I ask because I'm building a 49 F1 Sent from my SM-G920V using The H.A.M.B. mobile app
1929 Model A Coupe with Corvette Master Cyl with booster bought through Summit with disk in the front and drum in the back
I use DOT 4 in my Harley, the new bikes say DOT 5 but mine came with DOT 4. I personally have never had a problem with DOT 3, I have even brought field cars home got them running topped them off and drove them. That said, unless you have a something that recommends a specific brake fluid use whatever makes you happy. If I was setting up a new system I would use silicone brake fluid, I have used it before and like it real well. But that starts a whole new discussion doesn't it.
I like what Hemi Joel said: Auto Manufacturers want their cars to last 5 years/100000 miles. After that they want them to generate large repair bills at the dealers. So the dealers profit, then the owner gets sick of that an buys a new car. DOT 5 fluid does not fit that formula.
The wife's '05 Silverado say right on the master cylinder cap ( as well as the owners manual) DOT 5 only. The truck has about 200K on it and the only major repair so far was last week I needed to replace the blower motor. It probably didn't have much to do with the brake fluid. I did replace the front brake pads @ about 139K that may have been fluid related.
One reason was/is cost. Another is incompatibility with most/all ABS systems. Has nothing to do with 5 year/100,000 mile warrantys. DOT 5 is not a high performance fluid, and has one real advantage, not attacking paint. The wet and dry boiling temps of some DOT 3/4/5.1 equal or surp*** DOT 5. DOT 3, 4 and 5.1 are glycol based.
I also think new car manufacturers do not use Silicone brake fluid because people are stupid. If you add Dot 3 or 4 to your Dot 5 they react, turn into a gelatin mess. I have Dot 5 in my '92 GMC that has a early ABS on the rear wheels. 25 years later and I never fail to stop. My uncle did the conversion and took all the new wheel cylinders and master apart and cleaned them, then lubricated them with Dot 5. My '70 Dodge I flushed the system and put in Dot 5 with no issues. I have a Master Power Brake conversion for a non-HAMB friendly and the kit says to not use Dot 5. When I have inquired why they don't have a good answer.
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