Dot 5 Fluid and CSSB Warning

[Mark E.]

Re: Dot 5 Fluid and CSSB Warning

Thanks Terry. Yes, I pointed out the "hydroscopic" typo in the post. A common misused word.

[Mark E.]

Re: Dot 5 Fluid and CSSB Warning

That is total toro poo! I've run DOT5 for 40 years in my ancient cars and NOT ONCE have I found a speck of rust in the systems.

Good Lord......


Eeeeeyeah. They also have another reputation among ethical folks.





No it's not. Anyone who has a problem with DOT5 fluid didn't properly convert their brake system to it.

My vintage racer and my bride's road racing track car both use DOT5 fluid and neither car has ever (EVER!) had a brake issue.

Jim

Thanks Jim. Your erudite input is appreciated.

[Jack J.]

[Jim L.]

Re: Dot 5 Fluid and CSSB Warning

Thanks Jim. Your erudite input is appreciated.

Mark, you may be the first person in recorded history to use my name and the word "erudite" in the same paragraph. Most use less flattering adjectives. Jim

[Patrick H.]

Re: Dot 5 Fluid and CSSB Warning

I have some old stock (Does that qualify as NOS? ) but not enough to do the job -- actually two jobs. My need will require me convincing Elrod to go against what he believes is his better judgment. Do you want to be a fly on the wall for that?

He and I discussed it several times when I was fighting with the 77.
It's yours if you need some. You know how to contact me.
I might even deliver.

[Domenic T.]

Re: Dot 5 Fluid and CSSB Warning

Here comes the monkey wrench!
There was a wind storm and a airplane was upside down leaking fuel and being blown towards others that were tied down. They came to me and asked if I would get my old fork lift there to anchor the plane that was upside down.
Always had to add dot 3 to the fork lift, but couldn't find my dot 3 bleeder so I could fill the empty master cylinder. System is simple, 1 master cylinder and all metal lines to the 2 wheels with brakes. #1, I had to rebuild the entire system any way, so I filled the master cylinder with dot 5. So what did I have to loose, I needed to do the master and both wheel brakes.
Point here was that I mixed dot 3 and dot 5 to get things done and my brakes worked good for about 4 years after the mix.
Not saying that you can mix, but I did it on something that needed a complete brake overhaul and it worked!!
Would NEVER do that to a road car, but it saved the day from getting worse, and a few planes.

Dom, and yes you can say BuBa Dom!

[Jim L.]

Re: Dot 5 Fluid and CSSB Warning

So, on the basis of this existing virgin brake system, what would be the “BEST” brake fluid recommended?? Thanks, Jack J.

"Best" anything is always context dependent. Best for what purpose?

However, if it were my car, filling the system with DOT5 would be a no-brainer. There is no down side to the stuff.

[Terry M.]

Re: Dot 5 Fluid and CSSB Warning

"Best" anything is always context dependent. Best for what purpose?

However, if it were my car, filling the system with DOT5 would be a no-brainer. There is no down side to the stuff.

Me too. If nothing else the lack of damage to paint is more than enough for me.

[Timothy B.]

Re: Dot 5 Fluid and CSSB Warning

Here comes the monkey wrench!
There was a wind storm and a airplane was upside down leaking fuel and being blown towards others that were tied down. They came to me and asked if I would get my old fork lift there to anchor the plane that was upside down.
Always had to add dot 3 to the fork lift, but couldn't find my dot 3 bleeder so I could fill the empty master cylinder. System is simple, 1 master cylinder and all metal lines to the 2 wheels with brakes. #1, I had to rebuild the entire system any way, so I filled the master cylinder with dot 5. So what did I have to loose, I needed to do the master and both wheel brakes.
Point here was that I mixed dot 3 and dot 5 to get things done and my brakes worked good for about 4 years after the mix.
Not saying that you can mix, but I did it on something that needed a complete brake overhaul and it worked!!
Would NEVER do that to a road car, but it saved the day from getting worse, and a few planes.

Dom, and yes you can say BuBa Dom!

Dom,

So what happened to the forklift after the four years with DOT 5 in the system.

The reason I asked this question is because that's exactly what I did with my 67 Corvette. After I resealed the brake calipers I filled with DOT5 and bled it through until the purple so so color was obvious. Bled just a little more just for peace of mind and have never had any issues after 25 or so years. I did have to overhaul the rear calipers again because of sitting with lip seals but the insides were clean and normal, (stainless sleeves).

[Stephen L.]

Re: Dot 5 Fluid and CSSB Warning

I've had DOT5 in my Corvette since about 1983..... no problems. Same for 4 other vintage cars. Great stuff.

[Owen L.]

Re: Dot 5 Fluid and CSSB Warning

The reason I asked this question is because that's exactly what I did with my 67 Corvette. After I resealed the brake calipers I filled with DOT5 and bled it through until the purple so so color was obvious. Bled just a little more just for peace of mind and have never had any issues after 25 or so years. I did have to overhaul the rear calipers again because of sitting with lip seals but the insides were clean and normal, (stainless sleeves).

Same with my '67. I didn't go to great pains to flush the system other than bleeding until it ran purple. Silicone is pretty selfish stuff - not a lot mixes with it very well. I believe I saw a YouTube video of a guy mixing 5 with 4 which don't mix and clearly separate. I don't know long-term but that could be interesting to combine the two and set on a shelf to see if anything happens. In a system, the 4 is still going to attract any moisture it encounters so may lead to rust-out because the user thinks the 5 is protecting the entire system. Just speculating here.

[Joe L.]

Re: Dot 5 Fluid and CSSB Warning

Dom,

So what happened to the forklift after the four years with DOT 5 in the system.

The reason I asked this question is because that's exactly what I did with my 67 Corvette. After I resealed the brake calipers I filled with DOT5 and bled it through until the purple so so color was obvious. Bled just a little more just for peace of mind and have never had any issues after 25 or so years. I did have to overhaul the rear calipers again because of sitting with lip seals but the insides were clean and normal, (stainless sleeves).

Timothy-------


The glycol and silicone-based fluids are immiscible so the notion that's been promulgated that having both fluids in the system is disastrous is nonsense (I actually believed that once-upon-a-time, too). There is only one problem that can be caused by having both fluids in the system. That is that some of the benefit of the silicone fluid can be lost. That's because any glycol fluid remaining in the system will have absorbed water and, thus, that fluid can cause corrosion in the brake system.

[Domenic T.]

Re: Dot 5 Fluid and CSSB Warning

Tim,
System eventually needed work, but lasted about 4 years. Remember, system was shot before I added the dot 5 and my guess was that there was at least 1/3rd dot 3 fluid in the system. I have not worked on the system since and when I use the fork lift which is rare, I stop it with the emgcy mechanical brake.
Also, I did the same to my 67 coupe that you did. Did mine in the mid 70's and ha no problems to the day I did the frame off about 6 years ago. I did have rust issues before switching to dot 5 and honed them out reaching the limits that can be honed.
Now since the frame off, I had SS sleeves put on all calipers, but have yet to drive the car. I did notice back in the 70's when I switched to dot 5 that my pedal was very hard (manual brakes) and there was no cushion when pushing the pedal down, felt direct and hard. I did a good bleeding when I did the switch. I always bleed from the calipers up to the master and usually have to suck the fluid out about 4 times.

Dom

[Patrick B.]

Re: Dot 5 Fluid and CSSB Warning

Timothy-------


The glycol and silicone-based fluids are immiscible so the notion that's been promulgated that having both fluids in the system is disastrous is nonsense (I actually believed that once-upon-a-time, too). There is only one problem that can be caused by having both fluids in the system. That is that some of the benefit of the silicone fluid can be lost. That's because any glycol fluid remaining in the system will have absorbed water and, thus, that fluid can cause corrosion in the brake system.

That question was what the NHTSA experiment that used my car was about. The question was what happens if silicone fluid is simply bled through a system filled with DOT-3. The result was just what Joe said. The DOT-3 fluid around the pistons did not bleed out sufficiently. That fluid still absorbed (or had already absorbed) water, so it’s boiling point and rust potential stayed the same and negated the benefits of the silicone fluid, but there were no adverse effects from the mixture. Consequently, NHTSA recommended only starting silicone fluid in systems that had been thoroughly cleaned out.

The only problem I have seen with silicone fluid is that the reproduction master cylinder that Lone Star sells would not bleed properly with silicone fluid due to it higher viscosity. The passages between the reservoir and the bore are more restrictive on these GM Licensed reproductions which look like the original castings but have inferior machining. I got an original master cylinder sleeved and it worked fine. Maybe that is one of the reasons they discourage the use of DOT-5.


on

[Jim L.]

Re: Dot 5 Fluid and CSSB Warning

The only problem I have seen with silicone fluid is that the reproduction master cylinder that Lone Star sells would not bleed properly with silicone fluid due to it higher viscosity. The passages between the reservoir and the bore are more restrictive on these GM Licensed reproductions which look like the original castings but have inferior machining. I got an original master cylinder sleeved and it worked fine. Maybe that is one of the reasons they discourage the use of DOT-5.

on

That's clearly a problem with the repro part and not with the DOT5 fluid!