View Full Version : Brake Fluid
TxMike64
10-05-2023, 12:38 PM
What fluid are yall using? DOT 3 / DOT 4 conventional polyethylene-glycol or DOT 5 silicone based? I think I'll use DOT 5 because it's safer for paint and other finished, even if it might need to be flushed more often. It's not that humid here so I'm not too worried about moisture.
Thoughts? Tips?
Jeff Kleiner
10-05-2023, 02:43 PM
It’s been a few years since I delivered this lecture so guess it’s time to do it again...trust me on this---DO NOT USE DOT5. In a nutshell it is a silicone fluid and retains millions of tiny air bubbles making it compressible meaning you will never get a firm pedal. Additionally it is non-hygroscopic (does not mix with water) so any moisture will stay separated and since H2O is heavier than the silicone it will settle in the low points; i.e. calipers. Get the brakes hot, the water boils and you have no brakes! Stick with glycol based DOT3, 4 or 5.1 fluid.
Jeff
Mastertech5
10-05-2023, 10:10 PM
I double down on what Jeff says! The rubber in your system may not be compatible either.
OSU Cowboy
10-06-2023, 10:45 AM
Unfortunate ... for me. Build School recommended DOT-5 and that's what I did.
Nearly 21K miles on the car across 4 years of being on the road. I don't drive it really hard, so rarely aggressive on the brakes.
RoadRacer
10-06-2023, 11:24 AM
Clutch dot 3, brake dot 4 here.
(The clutch specifically says no dot 4)
Jeff Kleiner
10-06-2023, 11:51 AM
Unfortunate ... for me. Build School recommended DOT-5 and that's what I did.
Nearly 21K miles on the car across 4 years of being on the road. I don't drive it really hard, so rarely aggressive on the brakes.
You sure that they didn’t recommend DOT 5.1?
Jeff
egchewy79
10-06-2023, 01:19 PM
just curious, when is dot 5 supposed to be used? based on it's high temp profile, I'm guessing race cars and bikes, but would require frequent flushing to prevent water from fouling the system?
TxMike64
10-09-2023, 10:07 AM
I understand the disadvantages to DOT5. But It's hard to get past the fact that it won't eat my finishes! I'll probably go DOT3/4 just for availability.
egchewy79
10-09-2023, 02:23 PM
just think of it this way...your daily driver and most cars use DOT 3/4 with no issues. Just make sure you don't have any leaks and you should be fine.
I did have a leaky rear caliper but was able to quickly find the source as the brake fluid and eaten away the paint I had sprayed on the stock calipers.