Answered Bleeding headscratcher

[RustyMTB]

I'm having a bit of trouble getting a brake bleed to finish well. It's a Hope E4 rear caliper, persistent spongy lever.

I've bled it repeatedly with Dot 5.1 from the top per Hope instructions, I've advanced the pistons in the caliper & pushed them back in with the bleed port open, doing both sides separately to purge any air in the bores. I've bled from the caliper bleed nipple I.e. from bottom to top and tried rotating the lever 90 degrees & flicking it repeatedly which is another Hope tip to purge air. I've also tried opening the master cylinder cap & flicking the lever repeatedly to purge any air in the lines.

I'm no stranger to bleeding brakes & feel I've tried most of the tricks to get to a solid lever but I'm asking here to see if I've missed anything useful. I guess next stop is to go over the unions but I don't see any wet at the lever or the banjo.

 

[Pigin]

You could try this.

With a sealed up unit.
Put the bike so it’s as upright as possible, standing just on the back wheel would be ideal.
Pump the brake lever until it’s really firm.
With the pressure still applied cable tie the brake lever to keep the pressure on.
Leave it over night.

Good luck

 

[steve_sordy]

I would do what @Pigin suggests. I was about to recommend it, but he beat me to it.

I would only add a small improvement (IMO).

Ensure that the rear brake hose is positioned so that it only has an upwards path for any air bubbles.

Tying down the brake lever (firmly) has two benefits that I can see. There may be more (or less!).
1. It puts the brake on and therefore helps to keep the bike upright in its precariously balanced position.
2. Compression makes any air bubbles smaller and more likely to flow upwards to the reservoir.

 

[Ripping g]

Back bleed with a sringe ??

 

[RustyMTB]

Right lads, I'll try hanging it by it's neck & cable tie the lever. See? There's always something new to learn

 

[RustyMTB]

Interestingly, I just wandered out to the garage to zip tie the brake & the lever is noticeably better than when I posted last night, so I reckon you lads have it right & I'm going to say this is sorted. I've cable tied it anyway & will leave it for a day & see how we go but almost certainly, bubbles have worked their way out overnight.