Jump to content

Rear Brake Master cylinder rebuild issue

Recommended Posts

Hello all,

Yesterday, I installed an all balls rear brake master cylinder item, but I am having a really hard time getting to work after it has been reassembled.  

after I reinstalled all the items and put brake fluid back in, it seems that there is no connection between the master cylinder and the brake system.  When you press on the rear brake lever, there is not pressure put on the system, thus not squeezing the pads in the back.  

What could be wrong?  What can I check?

Thanks in advance.

Share this post


Link to post
Share on other sites

Crack the bleeder bolt and pour brake fluid in the master cylinder and allow it to flow through the system. Keep adding fluid and don't let it run dry. It will take a few minutes for the fluid to begin flowing but once it does it will start flowing quickly. A good 15 minutes of this will ensure no air is in the system and then you can begin with the standard pump the brake and crack the bleeder process to build up pressure. Assuming the master cylinder was installed correctly this is the best way to bleed a rebuilt system

  • Like 1

Share this post


Link to post
Share on other sites

Gravity doesn't help much on the rear brake because of the layout.  My suggestion is this:

Fill the master

  • Open the bleeder and depress the pedal smoothly and slowly through one full stroke to the bottom (it should take one full second at least), HOLD it there, close the bleeder, then release the pedal
  • Repeat this until you get bubble free fluid coming from the bleeder. Be sure the master does not run low on fluid.

At this point, you will still most likely not have a solid feel, so next you finish the job.  The banjo fitting where the line connects holds a large enough volume to hold a pretty big bubble and allow fluid to flow under or around the bubble while you bleed the line. It also happens to be the high point of the system, so air naturally flows up to there.  To get rid of it:

  • Depress the pedal smoothly and slowly through one full stroke to the bottom, or close to it, then instead of opening the bleeder, loosen the banjo fitting
  • Repeat

That usually does the job.

  • Like 2

Share this post


Link to post
Share on other sites

Thank you Gray!  That makes sense.  I will try that when I get back home.  The second part totally makes sense.  When you mention the banjo bolt, you are referring to the one that connects to the Master cylinder correct?

 

 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:


×