Dot 5 brake fluid help

[1969 beep beep]

i am currently restoring my 69 b body. I am reusing all my brake components. Lines, mc, wheel cylinders, front calipers. All components where only a couple years old. I drained all the lines, painted the calipers, mc and rear wheel cylinders. I tried to remove as much dot 3 fluid as possible. There might be very light amounts stuck in the wheel cylinders, maybe internal to the master and in the brake caliper cavity’s.

I was thinking of switching to dot 5. In order to protect the paint. The car has manual brakes.

Will this be ok to add dot 5 to this system? I have read they shouldn’t mix.

I also replaced the proportioning valve from inline tube. I have read to not use dot 5 with there valves because of leaks??

Any recommendations?

 

[MoparMitch]

I use Dot 5 in every car I restore, And I use it to flush out the old Dot 3. Never a problem. Have a car that has has Dot 5 in it for 30 years....LOL

 

[65RoadRacer]

Careful: There's a HUGE difference between DOT 5 and DOT 5.1! Do not mix DOT 5 with ANY other brake fluid: it is silicon based while DOT 4 and DOT 5.1 are glycol based. DOT 5 will not mix with DOT 3 or DOT 4. DOT 5.1 is fine, but to use DOT 5 you will need to completely flush all lines with denatured alcohol and remove all old DOT 3 or DOT 4 fluid.

 

[PurpleBeeper]

Yep, what 65 said.... denatured alcohol sounds like a good flush. Flush, flush, flush again, then keep flushing....then repeat flushing with DOT5.

 

[moparnation74]

The rule was what you use is what you have to stay with.....it is hard to absolutely know if you flushed it all out.....

When you think you flushed enough, flush again.....

 

[1969 beep beep]

What worries me is that all my brake items are used. I only let the dot3 drip out of all components. So there is definitely residue within all parts.

 

[1967coronet440]

What worries me is that all my brake items are used. I only let the dot3 drip out of all components. So there is definitely residue within all parts.

Why not just use the dot 3 again?

 

[1969 beep beep]

That would be the easiest but I would hate to have something leak and ruin the paint on my car.

 

[ir3333]

save a few bucks,dot 3 or 4 is more than adequate.If there were no original leaks you will be fine.
Keep a wet rag handy for dot 3 or 4

 

[moparnation74]

That would be the easiest but I would hate to have something leak and ruin the paint on my car.

Which is cheaper?...a paint job or replacing the brake components.....

The difference here is the guys chiming in dont know what you have vested into your car....I do....

 

[1967coronet440]

if you have that much invested into it and you’re worried about paint getting ruined why wouldn’t you just replace all the lines and cylinders etc the run whatever fluid you want.

 

[moparnation74]

if you have that much invested into it and you’re worried about paint getting ruined why wouldn’t you just replace all the lines and cylinders etc the run whatever fluid you want.

Probably, because you want to see if you can save it versus throwing more money into the pit....

 

[1967coronet440]

Probably, because you want to see if you can save it versus throwing more money into the pit....

I get it, but is it worth risking another trip to the paint shop, which is cheaper? You know the answer to that one lol

 

[moparnation74]

I get it, but is it worth risking another trip to the paint shop, which is cheaper? You know the answer to that one lol

That was my point Bo....Your just restating my point earlier....

Mine has DOT 5....it is a no brainer

 

[Dipstick]

DOT 5 will not mix with DOT 3 or DOT 4.

It's true they won't "mix" but that doesn't mean they can't be in the same system.

In order to receive DOT certification all brake fluids must be able to coexist in the same system with no harm. Some makers prohibit it because of their own prejudice, not because of any harm to the system.

 

[1967coronet440]

That was my point Bo....Your just restating my point earlier....

Mine has DOT 5....it is a no brainer

Duhhhh lol read right over it, didn’t even notice you said it.

 

[moparnation74]

Duhhhh lol read right over it, didn’t even notice you said it.

Your not the only one my friend....I do that all the time..

 

[65RoadRacer]

It's true they won't "mix" but that doesn't mean they can't be in the same system.

In order to receive DOT certification all brake fluids must be able to coexist in the same system with no harm. Some makers prohibit it because of their own prejudice, not because of any harm to the system.

I disagree with that... they can work in the same system, but not together at the same time. DOT 3 & 4 (even synthetic) and DOT 5.1 are glycol based, DOT 5 is silicon based and the two will not work together in the same system. It's not about 'harm' to the system, it's about poor brake performance and bad pedal feel because the two fluids are not compatible.

I used to work at a high end performance shop and I sold DOT 5 and DOT 4 brake fluids to racers all over the US. The one constant - even back in the 1980s - was that to go from, for instance, ATE DOT 4 brake fluid to Castrol DOT 5 the recommended procedure was to clean out the calipers, masters, slaves, and all lines with denatured alcohol and flush all components completely. Just because they're DOT certified it does not mean they are compatible.

 

[1969 beep beep]

Yes that pit is very deep. Lol

Can I not just add dot 5 and keep bleeding the brakes, or should I dissembled the calipers and wash everything with denatured alcohol? Can I add the alcohol to the master and flush that within the system?

 

[moparnation74]

Yes that pit is very deep. Lol

Can I not just add dot 5 and keep bleeding the brakes, or should I dissembled the calipers and wash everything with denatured alcohol? Can I add the alcohol to the master and flush that within the system?

The whole system.......