So after an evening of wheeling I noticed a problem thats been bugging me. After a couple of hours in on the trail I started getting some pretty significant brake fade. Enough that before I attempt an obstacle I tap the pedal to pump it up. I just checked for leaks and all. Found nothing. On the road its not an issue just in the woods. Master Cylinder fluid is a little brown but not horrible. Could this be an issue of just needing to change the fluid? I searched around and found that a number of other people have upgraded their MC. Not sure if thats even an option on the Disco w/o serious fab work for a new pedal assembly. Any thoughts. I am going to flush the system tomorrow and see of that helps.

If our pads are thick enough to not be a culprit, bleed the system. If that doesnt fix it you have a problem. Brake bleeding is Pirate 4x4 worthy tech!

Hi,

I wouldn´t think that off roading is a cause for brake-fading. Coming down PikesPeaks or sth. would put a lot of heat into the rotors. On the trial you are going slowly so there´s not so much kinetic energy to be transformed and, furthermore, the rotors have good time to cool down.
In any case the brake fluid is recommended to be changed everey 2 years. It degrades by collection water (strongly hydrophil) which then reduced the boiling point. Err .. changing just the fluid in the master reservoir is not going to help a lot, though being easier - that´s why I remember someone doing so :( .
A very useful tool I think is this one:
http://www.hawg-shop.de/xtcshop/images/product_images/popup_images/MCE300.jpg
(made by Lucas, Model MCE300). It transforms compressed air into a vacuum by which the fluid is drawn through the lines when connected to the bleed screws. Very comfortable and clean. With it you see many bubbles in the line, but they´re air being drawn through the thread of the bleed screw. If one closes the screw once new fluid is seen and the pedal is firm, all is fine in the end. I do prefer this system over pressure brake bleeding.



As the brakes faded while wheeling:
Are you sure it´s not just water / wet brake pads which temporarily have much reduced friction ?

After a couple of hours in on the trail I started getting some pretty significant brake fade. Enough that before I attempt an obstacle I tap the pedal to pump it up

I would put money on this being a problem with loose wheel bearings.
if they have a slight amount of play in them, as you go over big bumps it causes the disks to push the pads and therefore push the pistons back into the callipers.

when you next go to press the pedal - its half way to the floor, as the first press is just pushing the pistons back out of the callipers and pushing the pads back against the disks. the second press of the pedal will then start putting stopping pressure onto the disks.
Mud pushing its way between the pads and disks will also do the same thing - to an extent...

When I go to Brake the pedal is very low. 1 pump then back up and good brakes. Great idea Nick. This occured to me but I didnt really think it would be an issue with a solid axle. The truck was purchased used so this very well could use a repacking and tightening. I will jack it up and give it a shake. Still going to flush the barkes fluid. I may go get one of those bleaders. Very nice. Thanks Landy. My Dad has one of these in his shop but I moved to WV from CA and its not too convenient to drive to CA to flush my brakes. I often mourn not having access to a lift, mill/lathe, etc. Mostly the Lift and a high roof. The disco doesnt fit in the garage with the roof rack on.

The disco doesnt fit in the garage with the roof rack on.

Not to worry. Hang around here long enough and you'll be getting rid of that silly rack AND the roof that's holding it up. :flipoff2:

Nick's prolly right about the brakes.

All above, and the fact that you are in low gear on the trail. You don´t exactly have the gearing nor power to drive through the brakes, but there is a noticeable difference from hi gear.

The disco doesnt fit in the garage with the roof rack on.

:rainbow:

Sonoma, CA not San Francisco

I would put money on this being a problem with loose wheel bearings.
if they have a slight amount of play in them, as you go over big bumps it causes the disks to push the pads and therefore push the pistons back into the callipers.

when you next go to press the pedal - its half way to the floor, as the first press is just pushing the pistons back out of the callipers and pushing the pads back against the disks. the second press of the pedal will then start putting stopping pressure onto the disks.
Mud pushing its way between the pads and disks will also do the same thing - to an extent...

My dodge Dakota did the same thing a few years ago. That truck needed new wheel bearings every 30,000kms!