When was the last time you bled your brakes?

[Trevor Jessie]

I try to bleed mine every 2-3 years.

Why?

1. If you are using regular glycol based brake fluid it absorbs water and can cause cylinder walls to rust ... and that leads to brake failure. There can also be a build up of rubber debris from seals and rubber hoses... and that can lead to brake failure.

2. If you are using silicone fluid, then water can condense in the system and work its way into the cylinders and again cause rust...and that leads to brake failure. The bigger problem with the silicone fluid is that it doesn't lubricate as well and the rubber seals in the cylinders degrade and collect and clog lines...and that can lead to brake failure.

Of course you should also visually inspect your brake hoses every year as well. Replace any that show signs of damage or are older than 10 years old.

I'm working on a bugeye that has silicone brake fluid, teflon brake hoses, and disk brakes in the front. The attached picture shows what was flushed out of the brake/clutch system. To my knowledge, the brakes have not been bled in at least two years.

 

[Trevor Jessie]

Let's add one other issue. With silicone brake fluid, there is anecdotal evidence the the brake light switch does not last as long. The switch still works on the Bugeye that I am currently working on, but it takes significant pressure to activate (am not sure if that is due to the silicone or the age of the switch). On my Bugeye I have a pedal activated switch. I like for people to know the second I tap my brakes.

 

[glemon]

I agree about the possible water issues, I had a 7 year old master cylinder fail in my Triumph, silicone fluid, was assuming I could rebuild, was a line of corrosion down the bottom of the cylinder, as if the water pooled down there.

I don't agree about silicone being a worse lubricant, I have about 20 years of driving LBCs with Castrol LMA, and the next 20 with DOT 5. Replacement of master and slave cylinders was a common occurrence, every year or two something would go out, often a rear slave cylinder, but other parts as well. The last 20 years after using silicone the above mentioned master cylinder is the only one I can recall.

I wouldn't call this scientific research by any means, and the first twenty years there was much more daily driver activity, the last 20 more sheltered life and lower miles, but nevertheless, the stuff does not seem to wear out components faster to me.

But once again, do agree totally about flushing the fluid.

 

[Trevor Jessie]

I guess I shouldn't claim that the lack of lubricity causes premature wear. But I think I could prove that silicone fluid does do not lubricate as well as DOT 4.

 

[twas_brillig]

A quick commercial for the best possible LBC upgade: LED tail/brake/signal lights. Also for any other classic motor vehicle. Doug