NEW BRAKES....DOT 5?

-
CFD244

CFD244

"I LOST MY ID IN A FLOOD"
FABO Gold Member
Joined
Sep 7, 2017
Messages
4,136
Reaction score
5,817
Location
Northern Ontario, Canada
Hi Folks

I've been mulling over the Dot 5 posts. Here are the details.........

1971 Demon with original K/H brakes on the front and 10 inch drums on the back. I will be re-building my ORIGINAL master, proportioning valve, calipers, and wheel cylinders. All brand new lines and hoses. Not a drop of original brake fluid anywhere.

Question.....Will all of the original equipment work as designed if I use Dot 5?

Thanks
 
No issues with my Bee so far... no reason that there should be if everything is clear of old DOT 3. Just never make a mistake of topping with DOT 3 some year down the road....
superbirdcleanup20182019 587.JPG
 
Yup. No problems here either. I'll add that the brakes feel the same before the fluid was changed. I was reading where it would stop differently. Not true, at least for me.
 
Rebuilt a lil red express with my dad years ago. All new system. We went with DOT5 silicone based. Truck stopped just fine. We added a placard to the master cylinder that said use DOT5 silicone based fluid only.
 
DOT-5 was supposed to feel more spongy but it was probably the DOT-3 seals contamination. All new DOT-5 is a great upgrade. No more rusty M/C and no more paint corrosion.
 
Used dot 5 in our 67 factory kh setup. Had dot 3 in prior, so there was residual in there and zero issues. That was 2012.
Matt had a good idea with "DOT 5 ONLY" sign.
 
Go for it. <rolls eyes>
 
Dot 5 Is not recommended for street use. Only show cars and Military purposes.
As it is true that DOT 5 does not damage paint . It does not absorb moisture which is good and bad. The ability to absorb moisture means a gradual dilution of the fluid as the water mixes with the fluid. DOT 5 does not absorb moisture but separates it. Like oil and water. Unfortunately water is more dense than the fluid and so it settles at the lowest points of the brake system. This leads to corrosion just where you don't want it. Wheel cylinders and brake calipers.
Also very expensive.
Just a little logic here. If it is such a great fluid, why is it still not used for the millions of passenger vehicles made each year ? Its cost would go down with more being used so price is not it.
Read up on the different fluids before you commit to some type and see if it fits your personal use.

What is The Difference between DOT 3, DOT 4 and DOT 5 Brake Fluids | Rx Mechanic
 
Last edited:
Ummm no. DOT is used in street going motorcycles. It's probably to help protect the paint, as well as preventing corrosion from moisture entering the system.
 
moparmat2000 said:
Ummm no. DOT is used in street going motorcycles. It's probably to help protect the paint, as well as preventing corrosion from moisture entering the system.
Click to expand...

It does not protect against moisture. That's a common misconception. DOT5 cannot be contaminated with moisture. In other words, it will not ABSORB moisture. Moisture will still be present in the system. It simply does not mix into the fluid.
 
From what I understand, Glycol based fluid picks up it's moisture from the air. If Silicone based fluids don't absorb moisture, there shouldn't be any in the system? It's not like water is leaking in. Is my logic sound?
 
CFD244 said:
From what I understand, Glycol based fluid picks up it's moisture from the air. If Silicone based fluids don't absorb moisture, there shouldn't be any in the system? It's not like water is leaking in. Is my logic sound?
Click to expand...

No, because there will always be condensation. The braking system is also not sealed as it has a vent in the cap. But even if it didn't, there would be condensation on the inside of the system, especially in the cast iron master cylinder and cast iron calipers and wheel cylinders.
 
My 1994 Chevy 1500 pickup is dot 3 and has been that way since i bought it new. Every 2 years I use my mityvac and power bleed the system until the fluid comes out clean. Only things I ever replaced besides pads and rotors in the 160K miles I put on it in 27 years were rear wheel cylinders, master cylinder, and I added Russell braded brake hoses, just because I wanted something better than OEM. Flushing the system periodically keeps contaminates out of the lines weather you use Dot3 or Dot5
 
The production of condensation is air reaching it's dew point....Warm moist air on a cold surface. There shouldn't be any air inside the calipers or wheel cylinders. I do see how that is possible in the iron master cylinder if the level is allowed to drop though.
 
When I pull the cuda out this year(hopefully), I will check the fluid. I have checked periodically with zero issues. We switched to 5 after the master cyl puked 3 and peeled paint.
F**k that!
 
On these old mopars I think(for the most part) that we are wrenching on them all the time one way or another. If you are leaving any fluid in there long enough to cause serious rust, then you're neglecting it.
deviledchin said:
Yeah that's why I switched. I'll take the chance with condensation as I, and I'm sure most of you, do your own maintenance to keep up on it.
Click to expand...
 
RustyRatRod said:
The braking system is also not sealed as it has a vent in the cap
Click to expand...
Rusty I have to disagree with you.:(

The vent/s in the cap allows the gasket to expand and contract. The system is sealed by the MC gasket. There are bellows of sorts and as the pads / shoes wear, the fluid level goes down and the bellows gets sucked into the top of the MC a bit.

Ever notice that sometimes you have to push the bellows back into the cap when you take the cap off.

The vents vent above the gasket, and the gasket has no holes in it.

16168809964617788348188296413118.jpg
16168813855182000798500833367823.jpg
 
Dana67Dart said:
Rusty I have to disagree with you.:(

The vent/s in the cap allows the gasket to expand and contract. The system is sealed by the MC gasket. There are bellows of sorts and as the pads / shoes wear, the fluid level goes down and the bellows gets sucked into the top of the MC a bit.

Ever notice that sometimes you have to push the bellows back into the cap when you take the cap off.

The vents vent above the gasket, and the gasket has no holes in it.

View attachment 1715714591 View attachment 1715714592
Click to expand...

Disagree. That's fine. The system is still not moisture proof.
 
CFD244 said:
The production of condensation is air reaching it's dew point....Warm moist air on a cold surface. There shouldn't be any air inside the calipers or wheel cylinders. I do see how that is possible in the iron master cylinder if the level is allowed to drop though.
Click to expand...

How many calipers have you torn down? Not many if you think that.

Look guys, I'm not arguing the point. Just telling yall what I've seen from experience. Yall run whatever you want. DOT5 is a good fluid. I'm not arguing that.
 
Then what are you arguing Meester Eye roller??:poke:
DOT 5 works just fine and doesnt peel paint. As I said 9 years since I've converted and ZERO issues. Zip zilch nada, AND if I remember correctly, Dad n I drained the DOT 3 down and out the bleeders until the MC was empty, then added DOT 5 directly ON TOP of the 3. Bled the piss outta them till DOT 5 came out the bleeders. :steering:
RustyRatRod said:
How many calipers have you torn down? Not many if you think that.

Look guys, I'm not arguing the point. Just telling yall what I've seen from experience. Yall run whatever you want. DOT5 is a good fluid. I'm not arguing that.
Click to expand...
 
4spdragtop said:
Then what are you arguing Meester Eye roller??:poke:
DOT 5 works just fine and doesnt peel paint. As I said 9 years since I've converted and ZERO issues. Zip zilch nada, AND if I remember correctly, Dad n I drained the DOT 3 down and out the bleeders until the MC was empty, then added DOT 5 directly ON TOP of the 3. Bled the piss outta them till DOT 5 came out the bleeders. :steering:
Click to expand...

Well, I'm not really arguing anything, really. Just giving an opinion. That's still allowed, as of now. There's no NEED for DOT5 in our cars. That cannot be argued. All they NEED is DOT3.

I'm not a slob, so I don't get brake fluid everywhere and if an accident does happen, it's water soluble, so it hoses right off.

Never made any comments about getting DOT3 and 5 mixed. Only that DOT5 does not absorb moisture AND that there is always "some moisture" in the system. Those points are true.

So, what is your argument?
 
RustyRatRod said:
How many calipers have you torn down? Not many if you think that.

Look guys, I'm not arguing the point. Just telling yall what I've seen from experience. Yall run whatever you want. DOT5 is a good fluid. I'm not arguing that.
Click to expand...
Torn down many calipers in my day Rusty, no Dot 5, all Dot 3. That's my point. Dot 3 absorbs moisture from the atmosphere when you check the master and the open bottle. Just trying to wrap my head around things.
 
You must log in or register to reply here.
-

Back
Top