72 brakes

[Chris]

I am redoing the brakes what should I flush the lines/master with?
and can I go to dot 5?

[robertprentice55]

DO NOT use dot 5 brake fluid, unless the car is to be shown, but not driven!!!  It will eliminate most of the moisture that can cause the demise of the brake system, but it has a tendency to foam very easily, which causes a really spongy pedal, and poor stopping power!!!
Larry Cooley...rednek55
Chris wrote:

> I am redoing the brakes what should I flush the lines/master with?
> and can I go to dot 5?

[dealadayray]

I have to wade into this.
DOT, D ept.
O f
T ransportation Numbers 3, 4 and 5.  DOT3 is a moisture collecting fluid that will last for about 2 years under normal driving conditions.  Then you have to change it.  DOT 4 likewise collects moisture but for only the first year.  It too must be changed only this should be done every year.  Then there is DOT 5.  Both DOT3 and 4 are made up of fluids that will corrode the inside of your Honda 600 cylinders if left there long enough.  DOT 5 is inert, does not collect moisture, is kind to your rubber parts and will last for several years.  This fluid was produced by the Military to keep brake systems from destroying themselves while their vehicles were in storage for many years.  So what Larry said about collector vehicles is true and correct, it is used in collector cars to keep their brake systems from destroying the cylinders and pistons in them for many years.  It also will not give the same hard peddle that both DOT 3 and 4 will.  And, foaming action will occur if you pump the brake peddle
while bleeding the system .  Slow steady down and up movements to the brake and holding it while you bleed the system will get all the air out and then the brakes can be pumped to your harts content.
Now for the good parts, to change your fluid I have an article on the ANZ Yahoo group page in the files section that gives all the details and how to use it.  Two weeks ago Harry Lineback and I restored his brake system after over 10 years using DOT 5.  I replaced three O rings in the booster and the seals in the Master Cylinder, but the seals in the Power Booster were successfully used again and the Master Cylinder seals showed no wear.
 What happens is the polishing effect the metal pistons on the inside of the cylinders causes that black sooty material (you see when polishing your aluminum engine parts or wheels) in the fluid, this material scuffs the rubber seals over time causing the brake cylinder to have a leak-by and fail.   It does the same with DOT3 and 4 fluids, this is why the fluid gets almost black.  However oxidation and corrosion occurs when moisture and air as in H2O water, gets into the system, which happens simply because they heat up and cool down.  What DOT3 and 4 do that DOT 5 does not, is cut the seals when the scuffing causes leak-by and air crystallizes the DOT 3 and 4 fluids.  These crystals are the hardened crud caking up under the rubber cylinder covers at the ends of the wheel cylinders.
DOT 5, does work, and it will keep your brake system working for years.

[Steve]

I have been using Dot 5 in several of my vehicles for years. I first
used it in my 1967 Honda S800 Coupe. It worked great and had really
hard pedal. I used it in my 1965 S600 clutch but not the brakes.
I currently use it in my Ducati motorcycle in both the clutch &
brakes. Since the hydraulic clutch slave is mounted directly to the
engine casing and is not insulated - Dot 5 works especially well with
the heat. Dot 4 tended to cause a squeek in the master cylinder.
I also have it in the N600 I am building. I am dissatisfied with the
pedal pressure. I bled it just after assembly, there is pressure, the
brakes are adjusted but there is still a spongy pedal. I hope after
more bleeding the pedal will be there, otherwise it's coming out.
Dot 5 also does not eat paint like Dot 3 & 4, so when it overflows at
the reservoir, it won't eat your firewall paint.
Miles