Dot brake fluid, question

[MG_Midget_74]

A couple of years ago, I had my clutch master rebuilt, at that time, it was recommended, that no synthetic, silicone, fluid be used. This meant only DOT 3. Well, last summer, some spilled around the brake box and now I have peeling paint, so I was thinking about using DOT 4 or 5 and wondered what others where using and how it was going?

 

[Sarastro]

You might want to do a search through old threads--this topic has been discussed quite a bit, but without any great consensus that I can see.

As for me, I'm sticking with DOT3. Yes, I lost a little paint around the pedal box once, but it's easy to touch up.

 

[MG_Midget_74]

You might want to do a search through old threads--this topic has been discussed quite a bit, but without any great consensus that I can see.

As for me, I'm sticking with DOT3. Yes, I lost a little paint around the pedal box once, but it's easy to touch up.

Mine is damaged behind the fender all the way down to just above the rocker, fortunately time is plentiful as winters are long and cold here.

 

[dklawson]

As mentioned by Sarastro, brake fluid threads run frequently on the board. The search feature will give you a lot to read through.

There is one point I always feel obligated to make regarding brake fluid threads on LBC forums. Prior to the mid-1970s when the brake rubber formulation was changed, the ONLY fluid you were supposed to use was DOT-4, specifically Castrol DOT-4 LMA. Adding DOT-3 to one of these older systems resulted in seal damage. Unless you have replaced 100% of your old LBC's brake rubber (including flex hoses, brake servo parts where fitted, etc.) you may want to stick with DOT-4. If you know all the rubber is new, it should be compatible with DOT-4 and DOT-3. Neither DOT-3 or DOT-4 will be kind to your paint.

I run DOT-5 in my LBCs and apart from it being responsible for killing my hydraulic brake light pressure switch I've had no ill effects. The other threads will detail the pros and cons of DOT-5.

 

[Branson]

im using DOT-5. it kills paint too /bcforum/images/%%GRAEMLIN_URL%%/smile.gif

 

[dklawson]

im using DOT-5. it kills paint too /bcforum/images/%%GRAEMLIN_URL%%/smile.gif

DOT-5 that eats paint? Perhaps you mean DOT-5.1 which <span style='font-size: 14pt'>will</span> eat paint and is not silicone based.

 

[Trevor Jessie]

But... DOT-5 is aggravating to remove so that you can paint/repaint.

 

[dklawson]

FWIW, silicone products can be removed using "gasoline". Obviously be careful when using it, but wiping a surface down with gas followed by a product like Simple Green and a water rinse will remove most of the silicone. Repeating the gas and degreaser applications a few times will get all of it.

 

[Trevor Jessie]

I used a strong sodium hydroxide wash, followed by some rinsing, then dilute phosphoric acid, and then wiped with paint prep/degreaser.

The problem ... you never really know if you have it removed until your primer cures.

 

[dklawson]

The strong base you used will work, but the bulk of the silicone is easier to remove with gasoline. This ability of gasoline to attack silicone is the reason you don't use RTV on fuel systems.

I suppose the ultimate cleaner would be to mix a small portion of gasoline in with a degreaser like Simple Green so you can lift the silicone and then wash it away. Strong sodium hydroxide is dangerous enough by itself without adding gasoline to the equation.

 

[Trevor Jessie]

I'll try your method next time.