Brakes fading

[muskwa]

have a 1997 argo conquest and have been recently having trouble with the brakes. everything starts off fine but after a while the machine starts dragging the left brake and then will lose that sides brake all together. have been reading on the site about brake fade and have changed the fluid in both resevoirs thinking maybe it was shot, but nothing has changed. wondering if anyone has any ideas as to what this may be and ways of fixing. im not really in the mood to track down the problem and was thinking instead of getting the rebuild kit for the masters i myswell just put brand new into it. think im jumping into this too soon. thank you guys in advance.

[ANDY]

Check to see if your left brake is adjusted properly. Brake fade is caused by over heating. And also Argos need to have dot 5 brake fluid to prevent boiling due to extreme heat. I had dot 3 brake fluid and my brakes were not workin properly.

[Rock Doctor]

DOT 5
Dry Boiling point 500degF
Wet boiling point 356DegF

DOT 5 is silicone brake fluid. Silicone brake fluid (DOT 5) is not compatible with regular brake fluid, it is hard to pour without introducing bubbles and thus results in soft brake feel, and moisture still gets into your system and will pool in low areas like your calipers and encourage rapid corrosion.
The amount of moisture in brake fluid definitely affects its performance. The big problem is it is absorbs moisture quickly. Over a relatively short period of time brake fluid will absorb moisture from the air.
As water content in brake fluid increases over time, the boiling point decreases. Fluid with a reduced boiling point (or high water content) can create vapor by boiling in the caliper.
The end result is even though DOT 5 fluid is "rated" at greater than 500oF, in the typical 3 to 4 year old machine with 3 to 4% moisture content, it could boil under 350oF. And if it has got more than 4% moisture, you may as well be running straight water!

Changing the fluid in the resevoirs is not enough, you probably have a bit of moisture in the lines to the calipers as well, they should be purged too.
I think what's happening is that the moisture is heating up, and trying to expand into a gas, this is when you get the brake drag happening. Then, when some moisture does flash into a vapor, you get the "spongy" brake (or NO brake) feel.

It's been recomended to me to change brake fluid every 2 yrs, for this reason (I don't actually do that, but will change the fluid when the brakes start acting up, like you describe)
Just my thoughts, but hope it helps


RD

[muskwa]

thank you both for your replies. i have already tried backing the left brake right off to where you have to pull the lateral about 3 inches from the dash to get the plunger engaging, to no avail. and have already put a reservoir full of fresh fluid through the lines to the calipers to try and flush them out. will this have helped or should a guy take the calipers off and flush them? this machine did sit for 5-6 years before i bought it so maybe the water in the system when put away has started cooroding internal parts causing them to stick? dont know what to think at this point. thought i had tried everything i could. maybe engine compartment is to hot also. rock doctor what does your machine run at say on a 25 degree day? mine peaks at just about 200 then drops off to 170 or so and continues this process. the top body on the exhaust side of the machine gets very hot when running in these temps and if i were to push on the plastic it will deform. am i missing something? should i try and run this machine with lower temp thermostat? thanks

[Rock Doctor]

Damn, thought I had that one pegged

Calipers might have to come apart. I don't have one in front of me, but it seems to me that if you bleed the calipers off, you only really bleed off one side (don't remember for sure though). Water being heavier than brake fluid, it would get into the lowest points.

Another possibility that I've come across is that the rubbers in the Master Cylinders are getting hard. When the Plunger Cylinder heats up and expands, the rubbers on the Plunger might not be sealing as good. Changing out the seals is pretty easy, you could give that a try.

As for the temp on my machine..............Hmmmmmm. You'll probably think I'm crazy, but my temp guage has not worked ever since I bought the machine. Then I upgraded to a 27hp engine, and it came with a ON/OFF type temp switch that is not compatable with the guage on the dash. So, in a nutshell...........I have no idea what temp I run at, but either way, both engines have the same high temp symptems. First thing I notice, usually, is that my feet start getting hotter than normal. Then , I will start to get brake fade, if I let it go on, I start noticing a little bit of a lack in HP and sputtery idle (gas boiling in carb). Once it gets to that point, I will take my Hood off the machine. If I really let my "Stupid" show, I will carry on untill I can smell Coolant (Glycol), at this point, it's a good idea to stop for a bit and let the engine idle with the hood off. Just removing the hood when the brakes start to fade will usually take care of the heat issue. If I think it's going to be a hot ride, I take the hood off before I even start. Good thing is that it doesn't get that hot outside around here too often (30degC) is a hot day around here

I've never really spent to much time driving my other Conquest, but I THINK it runs in the 170-180 range. Don't normally load that one up too much though. If I take the second one with me someplace, it usually has a lesser experienced driver operating it.

One last thing, stupid question, I know. Have you cleaned the trash screen just in front of your Rad? (NOT the "Punchplate" Upper Body Screen). It doesn't take much fluf, grass, spider webs and dust to start choking off your cold air intake.

TIP, You can cover/block the Warm Air Intake into your Air Filter Box (Duct Tape works fine), this helps keep the carb a little cooler on hot days.

RD

[muskwa]

i will have to take a closer look at this i think. i have tried running with the hood off and the brakes still fade so i guess we can write off the engine compartment temp?? when i did empty the reservoirs this time i did notice alot of water in the fluid and like you said all in the bottom. im wondering if maybe the caliper is sticking closed, not realeasing all brake tension and boiling the fluid? problem has me kinda screwed for taking it on the moose hunt this year i think. would really not be any good trying to get the meat back to a cooler and having to stop every 10 mins to let the fluid cool off for 10-15 mins. i have not checked the 'trash screen' yet. honestly i havent even looked into it to see if their was anything in there. will have to check on that tomorow. anyone out there have any pictures of under the hood showing the tin shrouds around the muffler and exhaust? i think this machine may be missing a peice or two maybe adding to the heat problem in the compartment(heat around exhaust is not guided out of body) anyways you guys have been helpfull so far and im sure sooner or later we'll(more you'll)get this problem figured. sorry andy guess i should have asked you as well what your machine runs at for a temp? anyways thanks for the support

[akpride]

I just did a brake overhaul (caliper reseal and master cylinder reseal, new fluid, bleed). I can tell you it fixed my spongy feel I was having. It wasn't that hard but there was a bit of corrosion in the calipers. I recommend doing it the dang dot 5 fluid is expensive. If you have questions about it let me know I do have some pics. I was going to post a thread on it but the pics are kind of crappy. If I don't answer for a week it's because I am moose hunting.

[yellowknife argo]

Check to see if your plunger is out of line and getting push to one side when you are operation your machine.That may be putting pressure on the plunger.

[muskwa]

i will check the plungers again but when i looked last time(when adjusted) they looked both normal to me. if i do end up getting into the masters insted of replacing i will hit you up for those pics. or if you post them on here im sure they will be useful to more than just myself. thanks you guys. still have to get out to the garage to check but will let you know what i find.

[Rock Doctor]

You don't HAVE to remove the Masters, just the steering handles and the Plunger adjusters. If the plungers in the Master Cylinders are relatively loose, they will stick out just a bit, and can be grabbed and pulled out (Carefully) with Needle Nose Plyers. If they are a little tight, and don't protrude a bit to get a hold of them, give em a sharp push in with the Needle Nose Plyers and quickly release. This will allow the return spring to shove the plungers out at you a bit, usually just enough to enable you to grab the end of them . Once you have them out, it's just a matter of changing the rubbers (Make sure you install the new ones the right way)

Note, doing this will drain all the brake fluid out of the masters.


RD