Is this a Brake Fluid issue?

[Rock Doctor]

Not sure where to post this one, but it's Argo related, so I'll try it here.

At room temp I have my brakes set up so I have a little slack before they engage. All good.

When I take it out, everything is fine untill the brake system heats up, then one brake tightens up untill there is no slack, and the brake is actually partially engaged. Then I have to stop and loosen that brake off.

Once I get home, and park the Argo, it cools off, and when I get in for the next ride, THAT brake is so slack that it it drops away from the dash 4-5 times as far as the other brake before it will engage.

So, is this a fluid problem, or an O-ring problem, or........?


RD

[Slimpickin]

I'd try honing the master cylinder and replacing the components. Bleed the system to get rid of the old fluid.

Slim

[6X6]

Not sure on this one, but my first thought would be water in the system. Brake fluid will absorb water, and the water would expand with heat, boil and put pressure on the system, when the brakes start dragging it only compounds the issue. My first thought anyways.

[jerseybigfoot]

The piston in the master cylinder has to return past the filling port (small hole from the reservoir to the piston cavity), When the master cylinder adjusters are over tightened you are closing off the fill port. The fill port also allows the fluid to expand into the reservoir when the fluid heats up. You will have to back off the adjusters. Getting the slack out of the Argo controls usually requires replacing the brake pads or rebuilding the master cylinders.

[AussieMax]

I agree with Jersey. Hydraulic brakes should self adjust. The only way you would have problems is if the piston in the master cylinder is adjusted so it can't return fully allowing the fill port to open and equalise the pressure when the brakes are released. If they are adjusted correctly and dont have any air in them and still give trouble, then it may be time to rekit the master cylinders.

[mike bar]

I had the same problem with mine RD. I'd adjust it then it would tighten, so i'd loosen, give up for a while, try again and so on. Must have done something right because it's been good lately.

[dgh110]

sounds like time for new brake fluid(using a higher dot# means better with heat and water) and spend some time bleeding to make sure that there is possitivly no air in the system. next is to make adjustments. hope this helps out.

Darin

[plott hound]

theres more to brake fade then meets the eye.
Drum brake - Wikipedia, the free encyclopedia
Brake fade - Wikipedia, the free encyclopedia
and you can add a heat sink
Fade Stop Brake Cooler

[Rock Doctor]

How high do the DOT rating's go? ODG is pretty specific, they say DOT5 is the one.

[Rock Doctor]

I guess I never mentioned how this started.
Everything was fine with the brakes, fluid levels were good, pads ware fine(almost new),fluid itself looked good, disks looked fine as well. Then I noticed that the sprocket was screwed on one disk. I pulled both brakes off, and replaced both brake rotors, then the brakes went back on. Everything went very smoothly, but now the one is acting up a bit.
Still have not had much of a chance to tear into it, but I will do just that as soon as I can. Until then I will just live with the slack brake (it only lasts about 15 min, until it heats up)

Thanks for the replies, if I discover anything "earth shattering" I'll let you know.

RD

[number1cas]

sounds like time for new brake fluid(using a higher dot# means better with heat and water) Darin

Please be careful, you can't use a higher DOT than the system was designed for as I understand it. My parts dealer told me that I cannot just put in any DOT, when I was buying for my motorcycle, he said that it may react with the rubber and other items in the system, I assumed I shouldn't use 4 instead of 5, but he said 5 instead of 4 is bad too. Just my 2 cents of course, but now I think I will research this a bit more to find out why, unless anyone here knows ???

******************Correction**********************
It appears that DOT5 is a silicone fluid and IS NOT compatible with DOT3 and 4, so if you had 3 or 4 in the system you would have to evacuate ALL of it first, and then it may still have absorbed into the rubber. Apparently using a higher DOT than the system is designed for can cause the whole brake system to fail instead of fade as a DOT3 system is not designed to run at the temps that DOT4 fluid will allow, etc...
DOT2 was for brake drum systems and is now obsolete.
MAN, it pays to read !
Check this out for the nitty gritty on brake fluids http://www.motorcycleproject.com/mot...rakefluid.html WOW! Who knew there was that much to it?

[ememechanic]

DOT 5 is a silicone based brake fluid that can't be mixed with other types of brake fluid. Dot 3 and 4 are not silicone based. Mixing the two can melt seals and O-rings and bring about grief. My old Argo says to use Dot 5, so I went to Argo and got two rebuild kits,two new cover seals and all new pads. Flushed the system, rebuilt it and have had no issues with the brakes since I did them last spring.

[vader8x8]

I had the same issue last summer blah blah blah RD Have you seen bigfoot up there yet?

[Toynut]

How high do the DOT rating's go? ODG is pretty specific, they say DOT5 is the one.

Don't use silicone based fluid (DOT5.0) in anything other than racing purposed track vehicles, particularly those exposed to water. Silicone based brake fluid is not hydroscopic (water loving)
and will not absorb/mix with water (part of the function of brake fluid) leading to potential water traps in lower portions of the brake circuits or at the bottom of cylinder bores, promoting rust or potential plugged circuits in freezing weather. Silicone fluid is also slight compressible, which may yield a slightly mushy application of the brakes (can't use it in ABS applications). It does have a higher boiling point than DOT 3.0 or 4.0 but the real world tradeoffs are not worth using it in most vehicles.

The highest boiling point that you can use would be DOT 5.1, should you need the extra margin (I use it on my sport bikes), although, most vehicle brake systems run just fine on DOT 3.0 or 4.0 as long as service life or exposure to moisture is not exceeded. Your brake circuit might be vented to atmospheric air and if subject to moisture in a 6X6 that regularly runs in water or muddy environment might have to be completely flushed every season or two.

[Toynut]

OOPS!
Looks like the silicone fluid was addressed on the 2nd page of the thread....didn't read it through before answering....., my bad.

Almost looks like a DOT 5.0 dog pile!