You might have air in the line.
I would recommend (because it's easy and doesn't take a lot of fluid)
to flush out the old fluid and put in new.
This will cure that ill real quick.

skatnbnc wrote on 04/22/08 at 08:48:40:


A sign that you have air in the line is if the brakes work better after you "pump" the brakes.  On a bike that is pulling the lever several times quickly, and if it stiffens up you most likely got air in the line.  

Is that what is happening?????

Quote:

I assume you drained your brake fluid off before refilling. If so, did you drain off into a jar via a plastc/rubber hose emersed in brake fluid to prevent air intake as you drain/refill?.

skatnbnc wrote on 04/22/08 at 08:48:40:

Normally, pushing the brake cylinder back to put new pads on will refill the master.  If you had to refill it, why?

verslagen1 wrote on 04/22/08 at 11:16:36:


I did not refill the entire thing, just topped off the resevoir and replaced the lid. But could that have squished some air into the line?

skatnbnc wrote on 04/22/08 at 13:43:47:

I don't think that would have pushed any air into the line.
Check the tightness of all the fittings and bleeder.
I'd replace the fluid, it's easy enough to do.
You can do it single handed if you want, but if your first time  
It's much easier to do it with a friend.

have a friend squeeze the lever and keep squeezing it till it's about to hit the bar.  Then your assistant should warn you that it's about to stop.
You break open the bleeder, close it before it stops.  Then tell your assistant to release the lever and squeeze again. Remember squeeze, open, close, and release.  Repeat as neccessary.

Be sure to have a cup and tube on the end keeps it from squirting all over the place.  Tube is not absolutely neccessary, but hold it in the non wrenching hand to bring it as close as posible the the tip.  Keep a little pressure on the fluid to keep air out of the line.  

I'd let the reservour go dry the first time then refill with good fluid.  When the air bubble gets to the other side you're just about done.  2 or 3 more times should be good.

A small can (pt.) should be fine, should only take 4 to 6 oz.

Justin, she still had fluid in the slave cylinder and the lines, she wasn't really totally dry.  Totally dry is a pain in the ass, yep it is.  Baggie time.  To be avoided, yep.

To pump out a bike master cylinder I put a yard of quarter inch clear vinyl hose on the nipple, just crack the nipple enough to let fluid out under pressure and the yard of clear tubing takes the place of somebody opening and closing the valve manually.  

This method is easy and it allows one person to pay full attention to keeping the reservoir full of brake fluid while very gently pumping the lever.  You just glance down to floor level to check the clear hose for fluid color shift and any bubbles moving up the clear hose.

This method avoids opening and closing the bleed valve manually.  Only trick is you just barely break the bleeder valve to the point fluid can escape under some lever pressure, you should feel the lever move slowly against some back pressure.

More "open" than this on the bleeder valve might mean some air could enter the system on the return stroke of the lever.  No air will enter if you are needing lever pressure to make the fluid exit the bleeder valve.

If you want to be paranoid, you can do a final stroke with manual bleeder valve open & close, but it really isn't necessary if you have the bleeder valve set right.  

Proof of this is in the 1/4" clear tubing -- if air entered using this system on the return you would see tiny bubbles show up in the vinyl hose on the next full push stroke.  No tiny bubbles, no air leak.


Oldfeller