Help! No brake pressure after pad change.

[VladTepes]

Help!
I changed my front brake pads  obviously had to push pistons back into calipers to do so. Buttoned everything up and went to bleed them but couldn't get much lever pressure. Managed to bleed enough to establish no air in lines but still can't build up pressure so bugger all brakes!
Ride planned for tomorrow so I'd appreciate any and all advice please!

[grog]

Vlad, theres still air in there.

[Del]

Try bleeding them from the master cylinder as the air will have travelled up the lines

[VladTepes]

I've tried bleeding 40 minutes per side can't see any air. Also can't get pressure to pu h too much fluid out either. Sigh

[VladTepes]

Try bleeding them from the master cylinder as the air will have travelled up the lines

No bleed nipple there though mate eh.

[grog]

Vlad, what lines you have? Master cylinder, bleed at banjo connection. Lots of rags, towells to protect. Squeeze lever in, undo banjo, re tighten. Air is trapped somewhere.

[Snapey]

As Grog said but also cable tie the brake lever to the handlebar and leave sitting overnight.

[Mick_J]

Over the years I have learnt a few things which have helped me to get good brakes without having any bleeding problems.

I clean my brakes every year and what I do is once the callipers are off and the pads removed I pump the brakes to push the pistons out to get to clean part of the piston and give the whole lot a dam good clean. Then I crack the bleed nipple open and push the pistons back in as far as they go before tightening up the nipple (make sure you have an hose and old bits of rag around the calliper to catch the fluid as it shoots out if not). once they are back on the bike with pads I just top up the reservoir and give the callipers a very short bleed to remove any air that got in. I have been doing this for many years and never have to completely change fluid as it's done incrementally over time. This way ensures I don't push dirty contaminated fluid (or air) back up the system and fluid only ever flows down the lines, not up.

[Hooli]

Vacuum bleed them or fill the system from the bleed nipples with a syringe.

It's normal for 14 brakes when dry to be an utter twat to bleed the traditional way.

[grog]

Hooli, Vlads shouldnt have been dry, just changing pads. One reason i like rubber hoses, just clamp them off before calipers.

[VladTepes]

I wish I had a syringe or vacuum bleeder.

[SA14]

Vlad, obviously I'm no expert but I just bled an entirely dry system which has got to be more difficult than what you're doing. I'm going to make a few suggestions in case it helps.

I suggest starting from scratch and use the gravity bleed method. Remove the pads and undo the banjos and bleed nipples and push all the pistons all the way in until they stop. That will eliminate the air cushion which might be trapped behind your pistons.

Then with the banjos loose or even off the caliper and bleeding nipples also loose start by topping up the master cylinder until fluid starts to leak out of the banjos then install them back onto the calipers but leave the bleed nipples loose still. Keep topping up the master cylinder until fluid starts coming out of them then do them up. It'll only take a few seconds before fluid starts pissing out of the nipples. I know this because I left mine undone by mistake and fluid started pissing out everywhere.

Now you've got full fluid in the lines and the calipers. Then attach your clear hose to the nipples and make sure the other end is submerged in a cup or bottle with fluid in it. I'm not sure why or how this helps but I was advised to do it and it worked for me.

Now it should be a normal process of bleeding out the remaining little air bubbles in the system and your lever should return. Make sure you don't shake up the brake fluid bottle because that will "champagne" the fluid and you'll get a lot of small microscopic bubbles still in the system. Also don't re-use flushed fluid for the same reason. It's already aerated and useless until it calms down which may take days so use fresh still fluid for the bleed.

This has to work because it worked on my totally dry system. I used several videos to get advice plus advice from a local member and mine are now hard and solid.

[Tally]

@VladTepes , as sa14 says that's how I did mine cos my lines are a lower case h configuration where the secondary line loops over the mudguard from right leg to left,it was a pig to bleed. I got perfectly fine brakes after that

[mlivkovich]

I made vacuum brake bleeder from old fridge compressor, jar, aquarium valve, rubber hose and some silicone. One of the best tools I made for bike maintenance! It took me literally 10 mins to bleed front brakes on gsxr600 and it was complete dry as I had to replace damaged brake pad pins.

[VladTepes]

Well handle tied back to bar overnight. Nothing.
Just tried bleeding again and it's not getting much liquid through though what is coming out has no bubbles. Oh did I mention I did the crack the banjo at the master cylinder thing too?

There's no apparent blow by so seals are presumably OK.

One of the few things I can think of is failure of pump valve thing in master cylinder assembly BUT that has already been rebuilt with a kit etc. One would hope that wouldn't happen twice in the space of a few years though.

My morning ride is screwed but I still have to get to work tomorrow somehow!!

Looks like I'll have to use your method @SA14 which I had wanted to avoid because didn't want to pull the calipers etc off again....

But I gots ta do what I gots ta do.
WIll have to head down to supercheap to get some Dot4 as my existing one is running put. It's also been there a wee while so despite having been sealed it might have absorbed somer moisture too I guess. Maybe?

Sigh.


(I did buy a vaccuum bleeder - prob take a week or so though to get here - might make future bleeds a tad easier.)