Brake bleeding

[Roymondo]

Is there any special trick or technique involved in bleeding the front brake hydraulics on these bikes? Mine is a 2011 ABS-equipped GSA and while I had the wheels out for tyre replacement purposes I decided to renew the front brake pads (not quite worn out, but getting a bit thin) and refresh the brake fluid (which I should have done at the 24k mile service but didn't get a round tuit). Pad replacement no problem at all, but try as I may I cannot get a good, firm feel at the brake lever (Oo-err..). I'm doing it the same way I've done various other bikes over the years - i.e. tubing on bleed nipple, squeeze the lever, then briefly open the nipple and close it again before releasing the lever, and I'm working fluid all the way through (with no bubbles visible in the tubing). On the road, the brakes are working fine for normal slowing down and stopping but at a standstill the lever still feels mushy and can, with a really hard squeeze, be brought back to the handlebar. All the caliper pistons appear to move freely.

 

[Paul Everton]

I believe you have to activate the abs pump to bleed the air out of it..... The diagnostic tool gs 911 will open this for you so you can bleed all the air out ..... I'm sure another member will come along just to add to this and verify ...

 

[Steptoe]

New pads need to bed in with the wear pattern on the discs. Hence the spongy feeling when pulling the lever at standstill, but working fine when stopping.

 

[Roymondo]

ABS pump? I thought only the earlier, servo-braked 1200s had a pumped system?

 

[Roymondo]

I'm going to take the pads out again tomorrow and fettle things to ensure totally free movement.

 

[Paul Everton]

The Abs unit needs to be bled .... If your doing a full brake fluid replacement ....

 

[Bendy toy]

If the hydraulics were fine before new pads and we're not touched they should be fine after.
If disc a wear ridge the pads will sit on the high ridges and flex. As Steppers says.


Sent from my phone with mangled spelling

 

[Roymondo]

The Abs unit needs to be bled .... If your doing a full brake fluid replacement ....

How do you do that?

 

[Paul C]

Hi Roy, I did a standard with a tube bleed. Then used the GS911 to cycle the ABS. No air came afterwards. But I guess you'd be best using the GS911 to be sure.

 

[Roymondo]

Thanks Paul - I think purchase of a GS911 has to be on the cards.

Meanwhile I shall pop the pads out again and double-check for free movement etc.

 

[MWH]

Lots of threads about bleeding ABS bikes. Keep getting pointed at one, some page called wisdom or something.

They go through a long procedure of bleeding the abs pump with funnels etc.

The GS911 advice is just to do a normal bleed, then bleed test with their software, then bleed normally again and repeat until all air is out.

Quite a difference, which one is right? With GS911's advice you dont even have to take the tank off!

There are wheel circuits and control circuits I gather. Is the fluid in these circuits independent from each other? I mean do you pull the brake lever, this pushes a plunger affair in the ABS module which then puts pressure into the caliper circuit?

It appears there is no definitive answer. Have had issues with my local dealer who want over £100 to change the fluid but to be honest after past experiences there I'd be a bit sceptical if they actually did it.

 

[Steptoe]

They go through a long procedure of bleeding the abs pump with funnels etc.

The GS911 advice is just to do a normal bleed, then bleed test with their software, then bleed normally again and repeat until all air is out.

Quite a difference, which one is right? With GS911's advice you dont even have to take the tank off!

There are wheel circuits and control circuits I gather. Is the fluid in these circuits independent from each other? I mean do you pull the brake lever, this pushes a plunger affair in the ABS module which then puts pressure into the caliper circuit?

It appears there is no definitive answer.

There is no definitive answer because there are different types of abs depending on year. For the 1200 bikes from 2004 up until 2007 you have to remove the tank to bleed the abs/servo modulator, which contains the front and rear wheel circuits. You only need a funnel if you're type that can't control your own saliva or your lips move when you read, or you're american.

The later 2007 + abs can be bled in the usual/standard way without removing the fuel tank.

 

[MWH]

You only need a funnel if you're type that can't control your own saliva or your lips move when you read, or you're american..

That made me laugh. Thanks for the reply. The most informative comment I've seen so far regarding brake bleeding!

 

[Bendy toy]

That's good to know my 2008 needs a fluid change. I can now get on with it and know its all done.

 

[Roymondo]

As a postscript, it appears my issues may well have been a result of new pads not bedded in. I didn't do anything else to the brakes before I was rudely unseated just a week or so later, resulting in an enforced lay-off from riding for a couple of months, and the bike being away for a while getting mangled bits replaced. Anyway, while they were at it I got the dealer to do an MoT and the brakes were fine (just an advisory for slightly worn rear disc).

 

[Pukmeister]

My old Yamaha sumitomo calipers were a classic for bleeding/lever travel issues until shown why by a trusted bike mechanic. One pad would contact the disk long before the other and flex it sideways on its bobbins until it eventually clamped between both pads at maximum lever travel. By jamming a screwdriver in the gap of closest pad and squeezing the lever, the more distant pad could be hydraulically brought into contact with the disk. Once both pads were squeezed onto the disc equally without first flexing it sideways, powerful braking with little lever travel was restored.