Brake fluid

Regarding Howard's recent suggestion to Hankster to change brake fluid --for any number of reasons, including that brake fluid is ascorbic and will draw in moisture from the atmosphere and thus contaminate the fluid, brought to mind that

Several years ago I changed my brake fluid from DOT4 to DOT5 because DOT5 is synthetic. And because DOT5 is synthetic it is non-ascorbic. I experienced no ill effects using the DOT5 fluid and probably put on 20+ thousand miles with that fluid before the scoot became Humpty Dumpty in a non brake-related accident.

I also intend to switch to DOT5 on my "new" '09 SW when the spirit moves me. 

Tim

DOT 4 and DOT 5.1 are both glycol-based brake fluids and are used widely in the automotive and cycle industry. They are controlled by standards set out by the Department of Transportation (DOT) - hence the name.

The main difference between these two brake fluids is in their boiling points. Part of the standards that need to be met by the manufacturers of DOT fluids are the minimum dry and wet boiling points. These are the minimum temperatures that the brake fluid must perform at before the brake fluid starts to boil, which can lead to complete brake failure.

Let's take a look at the minimum boiling temperatures of DOT brake fluid as specified by the Department of Transportation.

Various boiling temperatures for DOT brake fluid
Remember, these are only the minimum standards. Brake fluid manufacturers can and often do improve on these figures and it is possible to find DOT 4 brake fluid with a higher boiling point than some DOT 5.1 fluids on the market.

Since DOT 4 and 5.1 are both glycol-based brake fluids they are compatible with each other, which means they can be readily mixed without harming your brake system. It is important never to mistake DOT 5.1 (glycol-based) with DOT 5 which is silicone-based and should never be mixed with any other DOT fluid.

So just which brake fluids can you mix without causing harm to your brake system? Let's take a look at the chart below ????? the chart didn't come along with the C&P

Thanks OWG. I'm looking forward to a broader discussion. However, I did use DOT5, (not 5.1) after bleeding the entire brake system.

Tim

It's almost getting to be like anti freeze types 3-4-5, 5.1 brake fluids, anti freeze IAT- OAT- HOAT, find the best for ones use and stick with it is the EZ way.

Cosmic_Jumper wrote:

Regarding Howard's recent suggestion to Hankster to change brake fluid --for any number of reasons, including that brake fluid is ascorbic and will draw in moisture from the atmosphere and thus contaminate the fluid, brought to mind that

Several years ago I changed my brake fluid from DOT4 to DOT5 because DOT5 is synthetic. And because DOT5 is synthetic it is non-ascorbic. I experienced no ill effects using the DOT5 fluid and probably put on 20+ thousand miles with that fluid before the scoot became Humpty Dumpty in a non brake-related accident.

I also intend to switch to DOT5 on my "new" '09 SW when the spirit moves me. 




Tim

Can I chip in here,  the recommended brake fluid for a Silver Wing is Honda DOT 4 Brake Fluid or any brake fluid of equal quality or performance. Since DOT 4 brake fluid is widely available why would you want to use anything else?

I changed my DOT 4 brake fluid earlier this year, it was a straightforward job and the 'old' brake fluid that had been in the system for over 4 years looked no different from the fresh DOT brake fluid I added. So what exactly is wrong with putting the recommended grade back in?

You're also sagely telling the forum that DOT 4 brake fluid is ascorbic which is incorrect, DOT 4 brake fluid is hygroscopic.

Thank you for that correction, Meldrew. Who knew?...Sage advise from the brain-impaired. 

There is nothing wrong with using DOT4 brake fluid. I chose to switch from DOT4 to DOT5 because it is synthetic and is non hygroscopic. It is also readily available. Similiarily, I also chose to use full synthetic oil rather than petroleum oil in the scoot. Personal decisions which have served me well. YMMV

Tim