GS850G rear brakes

[Guest]

I have done the search thing and cannot find a specific answer. I have listened to everyone on here and rebuilt my whole rear brake system. I am now trying to bleed the brakes and cannot get the brake fluid to come out to the bleeders. I don't think the fluid is even leaving the master cylinder.
I have an additional query about the little soft rubber cap that comes with the rebuild kit, but does not appear on any of the microfiches. Where does this cap go? I put the new one where I found the old one, but I have a feeling that there is something wrong. Any advise greatly appreciated as I am now totally confused and irritated.

[Poot]

That little rubber cap is for the bleeder valve.

Did you rebuild just the caliper, or the master cylinder as well?

SO, to bleed, you should start with both of the bleeder valves completely tight.

You hook up a little hose to one of them, to drain the fluid somewhere, and start pumping the brake. Once its been pumped a few times, loosen the bleeder valve-nut a bit, and keep pumping. You shouldn't have to loosen the nut much.

If the fluid doesn't start going through, and you didn't touch the master cylinder assembly, then you could have seated the brake piston+seals wrong so that there is no seal. Also, just think whether you put the banjo bolts in properly with the right washers. I don't think it would be that, but think about it.


Just my guess. Someone here will post shortly that knows more, but let us know what you rebuilt.



Poot

[Nessism]

Sometimes it helps to prime the master cylinder by drawing a vacuum on one of the brake caliper bleeder nipples. Once you get a little fluid moving it often starts pumping. Of course, this assumes you put everything together properly. Not sure what you mean by the rubber cap; if by chance you are referring to the piston cup, the service manual shows the assembly order.

[ardbeglily]

thanks

I rebuilt the caliper and the master cylinder. The service manual is the same picture as Bike Bandit etc and none show where the rubber cap goes. The rebuild kit comes with 2 seals, 2 dust covers, 1 piston, 1 spring , 1 piston cap (fits into the bottom of the spring and on top of the piston) and 1 rubber cap??, that when I took the system apart was on top of the spring and therefore in the top of the piston. I will try the vacuum trick. I also replaced the line with a s/s line. When I did the search yesterday someone had the same question back in 2008 but there was no definitive answer. I can also call Z1 on Monday and see if their guys know. Thanks again guys for all the help.

[Nessism]

Just in case there may be a misunderstanding...there are three main parts to the rear master kit: spring, rubber cup, and main piston. The spring goes in first with the tapered end, or the end opposite the check valve, going in last. Next the rubber cup goes in; put this in with the bottom going in last. Lastly you install the main piston.

Try drawing a vacuum on the system to get the master primed. That usually does it.

Good luck.

[ardbeglily]

photo of parts

I hope I have attached a pic of the parts. The rubber cap I am referring to has the arrow pointing to it. Hopefully this will clarify my question. Thanks again

[Baatfam]

I hope I have attached a pic of the parts. The rubber cap I am referring to has the arrow pointing to it. Hopefully this will clarify my question. Thanks again

That's just a cap for the bleeder nipple...something to keep crud off the end of it.
It has nothing to do with your issue...

[Nessism]

Assemble in the order shown below...

[ardbeglily]

Thank you Nessism

To say that a picture is worth a thousand words belittles the relief I felt when I saw your post. Thank you so much. There should be a GS for Dummies section or this picture should be added to the garage section with a similar one of the front master cylinder, which I will tackle next.