Soft front Brakes

[pdrangula]

Rebuilt the front brakes off of my 79 GS850G. But it takes 2 pumps to stiffen them. I bleed the brakes but still soft. Any tips or suggestions? I am still using the OEM perportioner block and lines.

 

[bobthebiker88]

are your rotors straight? if not they can compress the caliper causing it to do what you're describing.

 

[cowboyup3371]

Did you rebuild the master cylinder as well? You might need to take the MC off, find a screwdriver or something to push in the piston and bleed that first. Do a search for it; I think someone said it in one of my posts as well.

 

[BassCliff]

Hi,

I concur, there may still be some air in the master cylinder. Did you replace the 30 year old rubber lines with some nice, new braided stainless steel lines? That will help.


Thank you for your indulgence,

BassCliff

 

[pdrangula]

New Lines

New Lines

Ya you can rebuild everything but not replace the lines! That may be the issue. I am going to try that first. But has ayone removed the perportioner block and ran straight lines from the master cylinder down?

 

[SVSooke]

Ya you can rebuild everything but not replace the lines! That may be the issue. I am going to try that first. But has ayone removed the perportioner block and ran straight lines from the master cylinder down?

That is an often used way of doing lines.

 

[nufnuf]

discs can go a bit concave
Braided lines are a big improvement also
I use a suringe to help bleed the brakes, i find it works really well
One of my bikes has straight through lines with no splitter block
Just needed a double banjo bolt at the master
It works very well but is illegal according to our local laws

 

[Nessism]

discs can go a bit concave
Braided lines are a big improvement also
I use a suringe to help bleed the brakes, i find it works really well
One of my bikes has straight through lines with no splitter block
Just needed a double banjo bolt at the master
It works very well but is illegal according to our local laws

This is the first time I've heard about changing brake line routing could be illegal. Where do you live?

Regarding the problem, sounds like either air or the pistons are not coming out of the calipers like they should. Pulling the front brake lever as hard as you can and then tying it in place with a bungee or similar over night sometimes help the pistons creep out of the caliper bore where they should be. Of course, this assumes you removed the caliper pistons and cleaned out all the gunk inside. Doing the lines is mandatory as well, and cleaning the master should be done too. Brakes are nothing to short cut.

Good luck.

 

[nufnuf]

This is the first time I've heard about changing brake line routing could be illegal. Where do you live?

In Australia (Victoria)
Where the roadworthy requirements dont neccesarily make sense and you dont argue with police because they have guns
Braided lines are legal as long as they meet certain requirements
the straight through lines on my track bike dont meet the requirements

 

[nufnuf]

Rebuilt the front brakes off of my 79 GS850G. But it takes 2 pumps to stiffen them. I bleed the brakes but still soft. Any tips or suggestions? I am still using the OEM perportioner block and lines.

That the brakes pump up indicate air still in the system somewhere
I use a large suringe with some clear fuel hose attatched
Slip one end of the hose over the nipple you want to bleed
Suck the fluid out gently holding the suringe upright to let air bubbles rise.
Be careful if you are plunging down on the suringe as it will force fluid back up to the master cylinder which may overflow
This method gives you good control over the brake fluid and assuming all the fluid is clean and moisture free you can suck and squeeze to your hearts content and get those pesky bubbles out fast
Air bubbles may appear when you suck on the nipple (with suringe)from between the thread of the nipple and the brake body. As long as you hold the suringe upright so the bubbles rise and dont pump them back into the system you should be fine
Whenever i reuse the little brass washers in the brake system I anneal them first. (heat them to not quite cherry on the stove then let them cool)
This softens them and they seal better
Rinse any spilt brake fluid with lots of soapy water after youve finished
or better still dont spill any

 

[GabrielGoes]

discs can go a bit concave
Braided lines are a big improvement also
I use a suringe to help bleed the brakes, i find it works really well
One of my bikes has straight through lines with no splitter block
Just needed a double banjo bolt at the master
It works very well but is illegal according to our local laws

ill believe that its illegal but why? whats wrong with strong brakes?

 

[nufnuf]

I dont make the laws I just obey some of them