Post by anon on Feb 1, 2007 21:37:36 GMT
From: kintheuk Sent: 6/6/2004
I have bled the front brake on my 600N and there is no sign of any air in the expelled fluid. My problem is that the brake lever when fully pulled back to the bar does come very close even with the preset turned up to its highest. The lever still has some movement and seems slightly spongy, if this is the right term for waht I am feeling, what could the problem be? Am I just being paranoid?
Also can someone tell me the spanner size I need for the brake bleed nipple?
I used and adjustable fine on the front but the back is proving very difficult.
Cheers in advance
Keith
From: Padster-1- Sent: 6/6/2004
The bleed nipple should need an 8mm spanner. If it is spongy then there is likely to be air trapped in it still if it wasn't spongy before. You can set up a pipe from the bleed nipple to the reservoir and keep pumping the fluid round until it has cleared and the lever movement has firmed up. One of the automatic bleed kits helps if you are doing the job on your own (@£5 from Halfords). If you know anyone in the trade they have some great kit now for doing the job and should only take them a couple of minutes.
Paddy
From: Speck- Sent: 6/6/2004
It could be the rubber hose gone weak and flexing under the pressure of the brake fluid. A new hose should cure the problem, steel braided is best.
From: Biff Sent: 6/6/2004
Hi Keith,
Just done my front brakes on my 600S, replaced the brake pads etc and had the spongy feeling you're talking about.
First, definatley a 8mm spanner for the bleed nipple.
Second, used a automatic brake bleed kit (£3.50), to rid the system of air. I would get someone to help as there is only a very small reservior which runs low fast and if it empties more air just gets in. Just keep pumping the fluid through until the air is dispelled.
I also think the spongy feeling can only be caused by trapped air. The weakening of the rubber hoses would be felt more with 'brake fade' after the pressure is kept on for a while. Saying that braided hoses are definately better....
HTH
Biff
From: m40man Sent: 6/6/2004
Hi Keith,
Your problems mirrored my first attempt at bleeding, front brakes.
I can't help but feel more persistence is needed. Also, in between gently squeezing the lever, alternate the handlebar position from right to left a fair few times. This helps dislodge bubbles caught at the top, where the hose reaches the res. (Hard turn to the left appeared to offer best final bleeding of them darned micro-bubbles in my case, once the lever has started to offer fair resistance.)
Letting the system rest for a while also brings surprising amount of bubbles to the top when you start again.
I don't think your hoses are to blame here - not until further persistent bleeding leaves no alternative anyway.
Good luck,
Martin.
From: Popsflynn1 Sent: 6/6/2004
Had the same problem a few weeks back. Didnt have one of them self bleed kits so sort of made one and then back bled the system. Got an oil can, the type with a thumb trigger and make sure it is clean. Filled that with brake fluid. Attach a small bore bit of pipe between the end of oil can to bleed nipple and pump the fluid back up to the resevoir. you can see all the bubbles rise in the res. Worked a treat.
Good luck
Keith (Pops)
From: GhostlyBlankStare Sent: 6/6/2004
Question: have you just changed your pads and pushed the pistons fully back into the caliper?
If you have then the exciting 'all the way back to the bars' feeling could be because the pistons have yet to settle down in their seals again and are presently withdrawing too far into the caliper when you release the lever.
Try pumping the lever a couple of times to build up pressure and then really squeezing it hard. Do this 10 or 20 times and you may well settle the pistons in the seals further out from the caliper, so requiring less pull on the lever in future to fully contact the pads on the disk.
If after that you find the brake still doesn't have the bite you'd expect, try going on a 17 mile stop-start charity ride-out with 6,500 bikes to bed the pads in. It worked for me - at the end of the 2 hour ride (I did say it was stop-start there were so many bikes on the road) I had better braking power with normal pads than I had previously with HH pads that hadn't ever been bedded in properly.
From: Ian31110 Sent: 6/7/2004
One trick I learnt whilst restoring old bikes and suffering the same problem you have.
solution...tie the brake lever back as far as it will go and leave it overnight....youll be surprised how much better it will be in the morning for no effort whatsoever
Ian
From: kintheuk Sent: 6/7/2004
As always guys some great ideas, I will try them over the next couple of days and let you know if it all works out.
Thanks to all
Keith
From: gurninman Sent: 6/7/2004
Ian's right - leave the brakes overnight for the fluid to stabilise, and it should be a lot easier.Unfortunately, divvy front brakes are notorious for being B***ers to bleed, last time I did mine it took me about 4 hours constantly pumping to get them right.
I would have left them overnight, but I had to get the bike to the MOT garage that afternoon for the free re-test......
From: GhostlyBlankStare Sent: 6/7/2004
It's just a matter of practice and application. Last time I did it, it took me just 15 minutes to bleed them - even though I'd removed both pistons to clean them and re-seated the seals.
From: Peepo Sent: 6/7/2004
I've bled the brakes a few times on my 600N....the secret, don't pump like mad, take the lid of the reservoir and just pull lightly on the lever until it clicks, keeping doing this...SLOWLY. Bubbles will continue to pop up from the tiny hole and the lever will get tighter and tighter.
Hope this helps.
Patience!
Peepo.
