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Losing Rear Break Pressure

2K views 16 replies 8 participants last post by  bennice 
#1 ·
Hey Guys, I posted my issue recently on a new user thread wasn't receiving much information on in back. so i decided to Post it separate.

Recently i lowered my bike on lowering links, By myself the rear breaks are fine.
with a passenger i lose rear break pressure. I have to sink the break pedal all the way down and it doesn't feel like its gripping the rotor.

I did not have this issue when i was at my original height.

- Ive checked my break lines looked for any leaks, bubbled hoses and binding against the frame.

- I've replaced and bled my break fluid

still the same results. any one else have any ideas? or has experienced this?
Should i replace my break lines? relocate my reservoir?

Reminder, This only happens with a passenger, I weight about 254 and passenger is about 160


Thanks in advance
 
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#2 ·
Fresh fluid, Be sure you got all the air out of the system.
Thats about all I can add, you said you checked for leeks.

May just be the added weight????
 
#4 ·
yea i did that, when im by myself i dont have the issue, im thinking the weight would just take me a little longer to break or even just a little tougher but not lose all pressure.

i used to ride like that at stock height and did'nt have an issue, i don't want to go back to stock height because I'm on my toes at that point
 
#3 ·
The rear caliper rides on a carrier that is kept in place my groves on the swing arm (I think), make sure everything slotted up correctly.
 
#6 ·
Well I use the front for most of my stopping power, the rear when coming to a complete stop, & sometimes to adjust my line through a corner.

But if you use the rear to much it will heat up & even over heat & loose power & feel like its loosing pressure.
 
#9 ·
My bet is on the increased weight. I hate the performance of my rear brake for stopping with just me on it and at stock height. Takes wayyy too long using rear only.

Think about it. Two people weighing 410 combined? That's twice the weight of the motorcycle stopping on one little caliper and one little rotor.

Use the front and gain more pistons and larger braking surface and two of them. No brainer.
 
#11 ·
Reviving this thread from the dead...


I've got a similar issue on my '07 w/5500 miles that I bought somewhat recently. I have already replaced the MC and reservoir, but the back brakes seem to lose ALL pressure after a few weeks. I have bled the shit out of them numerous times to where they were nice and firm and responsive. After about a week they're noticeably weaker and less responsive. In 2 weeks there's nothing.

The bike has not been lowered and no modifications done to ride height or anything of that sort. I don't ride with passengers, so that's not an issue for me. I DO use my rear brakes (you need trail braking to ride the twisties correctly, and in-town low speed maneuvers need rear brakes too).

All that's left is the line from the MC to the caliper and the caliper itself. Anybody else have this problem? What did you do to fix it? I'm fine with new lines and/or a new caliper if that's what it takes, but I'd rather know which component is the problem before going hog wild on replacing more stuff. I see all kinds of posts all over the place where people have similar issues, but very few that I've found actually have an answer.

Thanks!
 
#12 ·
The crush washers used on the brake hose both at the master and the caliper can really only be used once. If you ever loosed the banjo bolts or remove the brake line entirely you need to swap in a fresh set of crush washers.

If you dont do this, even if you dont have any leaking fluid, many times you will not be able to properly bleed the sysem and you will lose pressure.
 
#13 ·
Cool...thanks for the reply. That's something I didn't think about. I don't know if the guy who owned it before me did anything to the brakes, but I have only touched the reservoir end of the system and did NOT get new washers for those. I have not done anything to the line between caliper and MC at this point other than check to make sure they were tight.

Seems like a lot of people have this problem. Is there something particular to the setup of this bike that is problematic? I've had every generation ZX6 since 98-99 thru this 07, and also an '07 ZX10R, and none has had this particular issue (but they all have their own other issues).

Thanks again!
 
#15 ·
Could be, but man that would be some weak sauce. 6 years old, yes. But garage kept (allegedly), and only 5000 miles when I got it. The rubber looks pretty good, but I guess stranger things have happened. I think I'm gonna order a braided line just to be safe. I'm getting tired of jacking with this.

thanks for the advice.
 
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