Front Brake Buggeration!!

[Mav617]

Hi all,

Needing further help before reaching for the shotgun....

I cannot get any pressure at the front lever. Replaced the hoses, calipers refurbed by Jonesey, new ss bleed nipples and tried two different bleed kits off of eBay and still can only seem to pump new fluid through. No air seems to be coming through, but there is zero pressure at the lever. I can only assume air is getting in, replaced top banjo and crush washers, still no joy. Does it sound like the m/c might be toast, even though all was fine before I replaced the hoses and had the calipers refurbed?

My head is shedded....

[tony.mon]

That happens.
CAREFULLY (don't spill fluid on paint etc) fill the caliper, then fit the lower banjo onto the caliper. Now fill the lines and connect the top banjo. Then fill the reservoir, and start bleeding.

[mattycoops43]

Have you tried reverse bleeding with a syringe?

Have you done anything at all to the MC? Was it left dry for a long time? Could the seals be dry?

[budd]

just done mine today and it was a complete PITA, tried for an hour or so with only a ting amount of fluid coming through but no pressure. Then noticed a very slight (and I mean very slight) weep on the MC bango not a leak as such just damp. This is a double length bango with a braided hose to each ca;iper, I had to drain the whole thing, replace the copper washes and try again. This time it bled up no trouble, so even the smallest problem with a the copper washes sealing incorrectly can cause issues when trying to bleed the brakes, my suggestion would be to double check all the unions for any sign of leaks.

[lanny]

Used a little ptfe on new bleed nipple and hardly opened it when pulling leaver, closed off before reaching bar.
worked for me on the clutch.

[MacV2]

+1 on the syringe method...

http://www.ebay.co.uk/itm/390646423557? ... 1423.l2648

Push the fluid in from the bleed nipple.

As recommended by Jonesey himself...

[Mav617]

Thanks all, heartbreaker this is as otherwise she's ready to roll.

[VTRDark]

You can get air bubbles get trapped behind the pistons so filling first as Tony suggested is a good idea as well as reverse bleeding. There's many way to bleed brakes. You could also have air trapped in the master cylinder so this should be bled off too. You can do this by loosening the banjo a little and squeezing the lever.

How are you doing the bleeding process Mav? Just want to double check your doing things right. The best bleeder I have come across is the colostomy bag. Though bleeder kits are not totally necessary and sometimes the old fashioned way of a finger over the bleed nipple works best. Messy but works well, especially if you have a helping hand to pull the lever in and out and keep an eye on reservoir levels.

Good link on bleeding brakes here.

(:-})

[AMCQ46]

You can also try bleeding the system off the bike, that way you can crack open all the banjos to remove any air there without fear of getting brake fluid on your bike.

If you remove the brake lever and the horn you can easily drop the master cyl down through the fairing and take the full system off as one.
Then put an old handlebar in a vice or workmate and put an Allen key or similar spacer between the pads and get bleeding. You can also push each piston in fully to push back any air out the bleed nipple.

Remember that the same process applies when bleeding from the banjos, only open when there is pressure on the lever and close before the pressure drops or you release te lever.

[VTRDark]

Bleeding brakes AMQ style.





(:-})

[Mav617]

You can get air bubbles get trapped behind the pistons so filling first as Tony suggested is a good idea as well as reverse bleeding. There's many way to bleed brakes. You could also have air trapped in the master cylinder so this should be bled off too. You can do this by loosening the banjo a little and squeezing the lever.

How are you doing the bleeding process Mav? Just want to double check your doing things right. The best bleeder I have come across is the colostomy bag. Though bleeder kits are not totally necessary and sometimes the old fashioned way of a finger over the bleed nipple works best. Messy but works well, especially if you have a helping hand to pull the lever in and out and keep an eye on reservoir levels.

Good link on bleeding brakes here.

(:-})

Thanks Carl, the second one was the bag, bought off your posted link.

[sirch345]

You can also try bleeding the system off the bike,

That's what I would suggest (well the master cylinder not the calipers), so that the double banjo bolt is not stuck up above the master cylinder as it is when fitted to the bike, assuming you have the standard clip-on handle bars fitted.

Chris.

[VTRDark]

Thanks Carl, the second one was the bag, bought off your posted link.

Oh I'm sorry to hear that. Are locking the bleed nipple on and off? You could also try giving the callipers, MC and lines a tap with the back of a ratchet handle of soft mallet to dislodge any trapped bubbles.

Open nipple, squeeze lever in, lock off nipple, release lever, open nipple, squeeze lever in, lock off nipple,release lever, open nipple and so on..... Start with the longest line furthest away from the MC so left calliper. I know the instructions say to just pump away and it's done but I found this only got half way there so unlocking, squeezing, locking and releasing is the way to go. It is possible to do this oneself with no extra hands with the bleed bag still attached. I also put PTFE around the bleed nipple threads and you should only have to open and close the nipple 1/2 - 3/4 turn.

(:-})

[Mav617]

I'm thinking of taking it in to have someone look at it - not sure riding 2 miles with only a back brake is a good idea??

[VTRDark]

Persevere with it mate, if you not getting any pressure at all then there must be something seriously wrong like dodgy MS seal, missing washer or washers in wrong place, Basically air getting back in the system somehow.

Drain the system and start again. Push the brake pistons right back in and re-fill and start the bleeding process over again. It may even be worth disconnecting the lines at the MC and re-annealing the copper washers (heat them up with blowtorch) then once cooled down put them back on which should give you a good seal as if new washers. Don't tighten the MC banjo bolt up fully just yet as you will still need to bleed the MC off. Tighten fully once this is done.

Use plenty of rags under your MS when bleeding so you don't get fluid on your paintwork. It's handy keeping a watering can of water nearby for any spillages. I take it your using fresh fluid?

I got one of the following to help bleeding the MC in future.
http://www.ebay.co.uk/itm/Venhill-dome- ... 20e2636822

(:-})