So I rebuilt the front calipers on my f4i. Right now the master cylinder is still full of old liquid. I have the cables unattached from the calipers still. The problem that I am running into is that when I pull on the front brake lever the liquid is not being pushed through the lines coming out of the ends of the lines. It is like the master cylinder is not pushing the liquid through. It is not building up any pressure. I opened up the resevoir and took a look inside and everything looks to be working but it just won't push it through no matter how fast or slow you pump the lever. The brakes were working FINE before I took them apart. Does anyone have any ideas on what I am doing wrong trying to get the liquid completely out and ready for new????

 

 

I am no expert, but I believe the issue is because you have no leading pressure. You will probably need a mityvac to bleed the brakes as they have no pressure.

 

I've had that happen to me twice and it was fairly easy to solve.

Try to hook the brake lines and pump the lever a good amount of times to see if any kind of resistance builds up. If it does, your all good, just start the normal procedure for bleeding. If not...

Check all your banjo bolts to see if any of them is clogged with something, it does happen...

Happen once each situation.

 

I did however cover both ends of the brake lines with my hands and pumped the lever. I DID feel pressure but it did not build up. In theory, it should have pressurized and moved my hand off the opening. Any ideas on that? (The master cylinder cap was off on this experiment and then I also tried it when it was screwed down and it made no diff)

 

If you assembled everything the right way (?) you should be good to go.

Check your bleeding nipples, they might not be closing/seating properly. Try to put a bit of teflon around them, my back nipple was leaking and is wrapped for 2 years...

 

Ya I am going to completely assemble it and try to flush the lines. I just wanted to get the majority of the old oil out of the main reservoir before I put the new stuff in. So your saying just assemble it like your gonna ride it and try it that way?

 

You could always just use a turkey baster to remove the old fluid from the master. Or shove some paper towel in there to soak it up.

 

Yep, just don't cover the master cylinder. Don"t forget to check bleeding nipples for leaks

On a side note I'm going to rebuild my own, what part nr. did you order?
Cuz in ronayers parts fiche, they have 2 different nr. and prices for the same seals in the schematics.

I'm guessing the different nrs. refer to individual seals and both seals ?

 

My seals were good still so I didn't order any.