Ok then why is some break fluid alot thinner than others, and if you cant compress fluid how does a high pressure washer work, it compresses the water. And how can you have presure in the brake lines if you dont have any fluid. There is something going on there because if the brake fluid didnt make pressure, why dont the air in your brake lines compress because air compresses too. If we need no fluid in the brake lines why dont we just use air. And if you have no fluid there is no pressure in the lines. And you dont have to buy a vacuum pump to bleed brake lines it only take about 5 minutes to bleed them regularlly.

 

[ They could leak or not let the piston return when letting off the pedal, but either way could easily be fixed by diassembling the caliper and replacing the seals. No need to buy a caliper from ebay.[/quote]

No offense or anything but me and one of my buddys were looking at the seals and calipers on the internet and the seals alone allmost cost as much as a whole new caliper. So if you have to buy the seals why not pay about $10 more bucks and get a brand new caliper. That way you know everything is ok.[img]i/expressions/face-icon-small-wink.gif[/img]

 

89exrider, your post is very hard to understand and still makes no sense. Please look it up you cannot compress a liquid. You ask how an air compressor works ? What does that have to do with this at all? And have you ever noticed how long it takes to build high PSI numbers with an air compressor...air brakes would make about as much sense as your post on an atv...you ask why don't we use air look at trucks...big trucks that is they all use air brakes. You ask why doesn't the air in the brake lines compress ? Well it does but the brake system is not suppose to run on air, it runs on fluid which you cannot compress thus making your brakes useless or possibly spongy. You really should look this stuff up your truly making yourself look foolish...you can't compress a fluid....I think that's 5th or 6th grade science.

BTW please show me where I say you NEED to buy a vacuum pump ? I simply said it's a useful tool.


Oh look at this neat little tid bit

"Brake Fluid: Brake fluid is the liquid that transmits the force through pressure for the brake pedal to the brake lines. Basically the brake fluid does not compress so it transmits this force (pressure) without lost.
One of the worse enemy of brake fluid is heat. If the brake fluid boils or there is a leak in your system there will be a lost of this incompressibility and your pedal travel will increase. Not all brake fluids are the same. Most brake fluid has ethylene glycol as it main ingredient. Ethylene glycol has lubricating capability for the rubber parts and has a high boiling point. Moisture is another enemy of brake fluids. All bake fluids will absorb moisture form the atmosphere, this moisture lowers the boiling point of the fluid drastically. This moisture also can effect the balance of the system casing corrosion. A perfect example of moisture getting your system is the early Corvette brakes where it was common to change the calipers or a regular basis due to contamination and corrosion.

Silicone brake fluid has a higher boiling point (around 700 degrees F.) than the ethylene glycol base fluids, but the major disadvantages is not "hygroscopic". Hygroscopic? "Altered by the absorption of moisture" What this means is since it is not a glycol based, when moisture enters the system it is not absorbed by the fluid. This results in beads of moisture moving through the brake line, collecting in the calipers. Since it is not uncommon to have temperatures in excess of 212 degrees F. (the boiling point of water), this collection of moisture will boil causing steam and vapor lock, this in turn will cause system failure. Silicone (DOT 5) is also highly compressible due to aeration and foaming under normal braking conditions.

If you are changing from a glycol base fluid to silicone or the other way around. The two types do not mix so your system should be completely purged, disassembled and dried out. When the two fluids are mixed you will get a gummy substance and it will really mess up your system.

We recommend using a good DOT 3 fluid. Wilwood makes a hi-temp fluid with a minimum dry-boiling point of 570 degrees F Dry-boiling point is measure in its virgin non-contaminated state. Wet-boiling point is the temperature a brake fluid will boil after it is fully saturated with moisture. DOT 3 fluids have a minimum wet boiling point of 284 degrees F.

Brake fluid should be changed periodically due to contamination. Never mix different DOT brake fluids. Under racing condition you would change these fluids like changing your oil."

 

No offense or anything but me and one of my buddys were looking at the seals and calipers on the internet and the seals alone allmost cost as much as a whole new caliper. So if you have to buy the seals why not pay about $10 more bucks and get a brand new caliper. That way you know everything is ok.[img]i/expressions/face-icon-small-wink.gif[/img][/quote]

All the seals and o-rings cost about $10. A new bare caliper w/ no seals, piston, o-rings, nothing in it costs $40. A complete caliper assy w/ all new parts is $300.

There should be no need to replace anything but the seals and o-rings when rebuilding a caliper. The ONLY time I have had to order a new caliper for a customer is when the pins holding the pads in were completely seized and nothing would get them out. This is the only time in the hundreds of caliper rebuilds I have done (mostly on streetbikes) that the original caliper couldn't be re-used.