Brake fluid - all the same or should I be more selective? | Page 2 | GTAMotorcycle.com

Brake fluid - all the same or should I be more selective?

If one piston went cockeyed it probably came out far enough to let air into the calliper through the piston seal. It only takes a tiny bubble to hose up a brake system.

The simple thing to try at this point is to bleed it using the procedure I posted above.
 
PrivatePilot said:
If one piston went cockeyed it probably came out far enough to let air into the calliper through the piston seal. It only takes a tiny bubble to hose up a brake system.

The simple thing to try at this point is to bleed it using the procedure I posted above.
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I think you are confirming my fear of what may have happened. Ugh.
I will give it a shot.

Might go back and re clean the caliper. Any idea on how the lub the piston?
 
sburns said:
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The pedal goes way down much more then before. If I pump it a bit, the pressure stays, but then looses it.
I think one of the pistons isn't working right, sticking? Can I grease it somehow.

As far as I can tell no air got into the system the fluid wasn't very low, and it did go back up to normal.
Ideas? Thx
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Air in the system will compress and that results in pressure issues. Fluid does not compress, if the brake system is 100% full of fluid it will hydraulic, meaning almost nothing can stop it from coming up solid. Pistons might stick and not retract because that would require suction or forces in the opposite direction, pistons don't stick in the off position because there is simply far too much hydraulic purchase available at the lever, something will move, leak or burst.
The calliper pistons do not rely on lubrication, but they do need to be spotless clean and free of physical damage such as rust, think gun bore more then gear box.
 
Trials said:
Air in the system will compress and that results in pressure issues. Fluid does not compress, if the brake system is 100% full of fluid it will hydraulic, meaning almost nothing can stop it from coming up solid. Pistons might stick and not retract because that would require suction or forces in the opposite direction, pistons don't stick in the off position because there is simply far too much hydraulic purchase available at the lever, something will move, leak or burst.
The calliper pistons do not rely on lubrication, but they do need to be spotless clean and free of physical damage such as rust, think gun bore more then gear box.
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Thx, I will try to bleed the line. But knowing my luck and with it being ABS I will have to take it in to be done.
 
Theres little chance that air would have worked its way back to the ABS module - a bubble at the calliper itself probably stayed in the calliper. Just do an aggressive bleed flushing 50-100ML through the lines and calliper and see if you can get it out - that's what the bleeder valve is designed to do. ;)
 
;) the only given is it's all collecting in a high spot, bleed the high spots.
If the piston came out far enough to go cockeyed it absolutely introduced air at that point.
I'd be concerned about the cockeyed piston thing, if the piston is in the hole it can only move in straight lines, if it goes crooked it came all the way out and now you could have potentially introduced dirt into the fluid :/ I would do a complete brake job at that point, but I don't have ABS so it is a bone simple job ymmv. You know better then the rest of us because you were there, do you think you got any dirt in there? or did you clean it all up good before that even happened?
 
Ok --- success -- I think!

Took the caliper off to take a look. It seems like all the pistons are working ok as all 4 were engaged against the pads and at equal distance. +1
I gave them a blast of cleaner just in case.
Put it back on, time to do the bleed.
I didn't have one of those vacuum tools so I just attached a hose to the plug and pumped the brake, slowly.
I exchanged the reservoir a few times just to be sure.
Tightened the plug, topped the fluid, tightener up. Pumped brake -- pressure!! +1
Did a quick test run around a few blocks, stop and go, slow speed turn, cornering... pressure +1

2 things, I used the Brake Fluid I opened yesterday. Not sure if being 1 day open on the shelf will matter much.
I may have topped it up too much as there is less travel then before.

Otherwise am I good?
 
Sure sounds good.

pop a wheelie! No wait, I'm not allowed to say that don't pop a wheelie.
 
sburns said:
I may have topped it up too much as there is less travel."

There is less travel because there is more pad and fresh fluid with no air or water in the system.

Sent from my SM-A530W using Tapatalk
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