Author Topic: Test the bleeding with GS 911  (Read 4257 times)

Bhm

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Test the bleeding with GS 911
« on: May 01, 2015, 03:22:31 PM »
Hello,

Most of you certainly know what follows but it may help some newcomers as I spent time doing wrong things and misunterprating the results.

I had to replace my brake hoses and did my best to eliminate air. However I wanted a GS 911 confirmation. After several attempts, the bar staying always in the red, and before bleeding again I went to the net and then back to the bike :

- Standing (I am 75 kg) on the brake pedal and fearing as one said it might break, in the end the bar turned to green and I received the instruction to release the brake.
- I had to take the front brake handle with my two hands to obtain the same result

So it was clean !

I misunderstood the GS 911 program advice to press smoothly which I wrongly took for softly. I suppose it only means "do not pump!" but actualy you must press very strong !
I also regret that an index is not indicated on the bar frame to indicate up to what you must press and push the bar in order to hope a "clean" result.

Alexm1

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Re: Test the bleeding with GS 911
« Reply #1 on: May 02, 2015, 12:55:27 AM »
Good advice, I had exactly the same experience when I tried the brake test.
Alex

Bhm

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Re: Test the bleeding with GS 911
« Reply #2 on: May 03, 2015, 06:14:23 PM »
Hi,

2 questions which may concern the design of the brake system rather than the testing tool :

1/ Concerning the "why" we have to push so hard to get the green bar : is an air buble a sort of "cushion" which will prevent to reach the researched highest brake oil pressure when the break handle or break pedal are pressed "madly" ?

2/ The procedure indicates (correct me if I am wrong) that at first front pad (if one begins with the front brake) is placed against the disk and then the the handle is pressed strongly. But when pressed firmly at max both front and rear pads are blocked again the disks.
So, if one gets a clean front, but not a clean rear, since both front and rear wheel circuits have been implied, does it mean that the culprit is the rear command circuit and therefore the only one to be bled again ? or the fact that the rear pad was not against the disk at the beginning of the process is against such conclusion ?