Brake Fluid

[Ian Crombie UK]

Hi guys ..

Done my search,read the threads and posts on what brake fluids to use and now i'm more baffled than before...duhh!!

I'm using Dot.4 and after a long spell sitting parked up in the garage,i had to shift it...popped the front cylinder seal which it does regularly after sitting a while.

Someone says that Dot.3 absorbs moisture and if i'm right looking at the rust around the cylinder wall so does Dot.4

If i was to use Dot.5 after replacing all new cylinders and flex pipes,how do i flush out the brake tubes without dismanteling from the vehicle or does one think i should stick to the Dot.4 ??

Someone help me sleep tonight please

[Jim Saraceno]

I've never done it but from what I understand, the issue is rubber. So even though you're talking about replacing the cylinders and flexible tubes, you would have to get new rubber for the main cylinder.

I would think the best thing to do would be to flush out the system before you replace anything, that way you'll have the new fluid in place. Then you could replace the wheel cylinders, flex tube and replace the rubber in the main cylinder.

Then you would have to bleed the system.

[Ian Crombie UK]

Thanks Jim...I have all new rubbers to replace as well but i did this the last time it popped out on the front cylinder when again it was showing rust deposits in the chamber ...just wondered if it was the Dot.4 that might be the problem??

Can i mix the Dot.4 with Dot .5 or is that a no go area as mentioned before with dot3 and dot5 ??

Can i use airpressure to clean the tubes out from the master cylinder via the wheel cylinders or am i talkin' balonies??

Ian UK

[1950 Special Deluxe]

I did mine last winter. I was told not to mix Dot 5 with either 3 or 4. I installed new wheel cylinders and the hoses. Rebuilt the master cylinder, flushed the hard lines with alcohol and then blew them out with compressed air before reassembling the hoses and cylinders. no issues yet. As the car sits all winter, I try to pump the pedal every couple of weeks to keep the fluid moving a bit.

[Ian Crombie UK]

Thanks for that but what Dot did ya use in the end and if your suggesting to a Scotman to use good Alcohol to flush the hard pipes out ??mmmm!!!

If i do i'll be at the other end waiting for the next refil.

No wonder u've had no problems all winter wi good ole Whisky in the pipes..lol

Ian

[1950 Special Deluxe]

I went with Dot 5.

[thrashingcows]

I've used Dot 5 before with no problems, but a clean, new system is best if converting to it. I just never liked the added cost over the Dot3/4.

I use Dot 3/4 in all my stuff, and just flush the system every year, two at the most. It only takes me 30 minutes to flush the system by myself, and then you get rid of any fluid that might have absorbed moisture. Part of my regular maintenance.

[louie the fly]

Ian, have a look here. http://rdabrakes.com.au/index.php/technical/74-brake-fluid-information.html

They explain it all in fairly simple terms. DOT5 is what is commonly referred as silicon brake fluid. DOT3 & DOT4 are both glycol ether based and both absorb moisture whereas DOT5 traps air when pouring because it is more viscous. I think you should stick to DOT4 because it's easier to use, but that's just my opinion. One thing a brakes guy told me once was don't mix brands, like coolant, because each manufacturer has a slightly different formulation.

Louie

[55 Fargo]

Using DOT5, happy with it, but all lines. hoses MC rebuilt, and cyls new and clean, prior to introducing Silicone based Dot 5 brake fluid. I think for long term storage it is good stuff.

If I lived where I drove my car most of the year, maybe would not use it, but so far so good....

[55 Fargo]

Thanks Jim...I have all new rubbers to replace as well but i did this the last time it popped out on the front cylinder when again it was showing rust deposits in the chamber ...just wondered if it was the Dot.4 that might be the problem??

Can i mix the Dot.4 with Dot .5 or is that a no go area as mentioned before with dot3 and dot5 ??

Can i use airpressure to clean the tubes out from the master cylinder via the wheel cylinders or am i talkin' balonies??

Ian UK

Absolutely do not mix Dot4 and Silicone based Dot 5, they are not even remotely compatible, this goes for mixing DOT3 and DOT 5 too.

Get all your hard lines cleaned and flushed thoroughly, new and clean wheel cyls with no DOT3 or 4 left inside of them, new hoses, new rubber and clean out MC. Flush out lines , make sure all old residual DOT 3 or 4 is out, assemble the entire brake system, nice and clean and tidy within entire system, now you can safely introduce DOT 5 silicone brake fluid. Bleed system, adjust brake shoes and test.....

[Ian Crombie UK]

Thanks guys for the info's and Thanks for the web site Louie.