General Tech Good at troubleshooting? Have a non specific issue? Discuss general tech topics here.
Sponsored by:
Sponsored by:

help...please...brake issue!

Thread Tools
 
Search this Thread
 
  #11  
Old 12-17-2007, 03:26 PM
ffingers's Avatar
Registered Users
Thread Starter
Join Date: Jun 2007
Location: Chicago, IL (downtown)
Posts: 2,360
Likes: 0
Received 0 Likes on 0 Posts
Default RE: help...please...brake issue!

thanks...alright, i think i'll be fine once i do that and re-bleed....now that i actually have an understand of what the heck is going on...i need to get some more dot4 though as i have run through a ton of it probably priming WAY too much...lol...oh well what can you do...

you know it's just wierd to mess with the brakes...knowing how important they are...i will be very happy when they are bled an stop on a dime..plus i can't wait to see how good the ss lines feel...
 
  #12  
Old 12-18-2007, 08:36 AM
Tahoe SC's Avatar
Senior Member
Join Date: Aug 2005
Posts: 5,917
Likes: 0
Received 1 Like on 1 Post
Default RE: help...please...brake issue!

galfer actually sells a MC bolt with a bleeder screw on it!
are you leaking any fluids out of anywhere?
the stock bleeder screws have a film over them that helps it seal. loctite sells similar stuff, but i'm not sure if you can get it in autoparts store. speedbleeders has the same stuff. brake fluid actually eats up teflon tape.
 
  #13  
Old 12-18-2007, 12:10 PM
Join Date: Aug 2007
Location: Oklahoma City
Posts: 1,362
Likes: 0
Received 0 Likes on 0 Posts
Default RE: help...please...brake issue!

Just some info, (learned this from my car mechanic days, and it's hella important. Really funny if you forget, so long as you don't have to pay for damages if you hit something! haha Anyways...) You always have to "pump up" your calipers after you have compressed them. In this situation, it was for when you had them powdercoated... other times you may see this is if and when you need to replace brake pads and you compress the calipers so the new pads will fit. As your apply your brakes, the lever compresses the master cylinder piston, pushing brake fluid down to the calipers, causing them to move "out" and force the brakepads friction material to crimp down on the rotors... this friction, of course, stops your bike. However, when you let OFF the brake, only 1 (sometimes two) small forces pull the pads away from your rotors. These forces are 1. The square cut seal that goes around the piston(s), 2. Sometimes you have small metal plates or very weak metal "springs" that provide VERY minimul "out" pressure. The idea is that you only have to get the pads SLIGHTLY off the rotors to allow them to continue to spin freely. This small amount of backwards pressure to "release" your brakes assists in, as your brakepads wear down, you don't have to press more and more on the brakes. The caliper itself holds more fluid (that was originally in the master cylinder) and the piston stays further out.

Now... this all matters to you because, given that you have the pistons in the calipers compressed fully, it will take MANY (like you said) compresses of the lever to pump enough fluid (in very small amounts) to fill what's usually in the calipers. Make sure that, while you're "pumping up" your brakes, you don't let your master cylinder go dry!!!! This will pump serious air back into your lines and be very annoying.

Anyway, enough of the "this is how it works" (for anyone who was curious), here's my advice. Manually bleed the brakes. Don't rely on the vaccum pump. I'm not saying that the pump isn't a good option, but manually bleeding the brakes under pressure works when vaccum bleeders fail. (in my experience)

For those that don't know how to do a manual bleed... it can be done by one person with some good stands and good reach, but I would rec. using 2 people. --One person needs to "pump up" the brakes several times (squeeze the lever 5 or so times in a row) then HOLD the brake ON. (You don't have to mash it, just apply steady, even pressure). --Person number 2 then opens the bleeder screw. The fluid will bubble and spew out, and person one will feel the lever go all the way to the clip-on. That's good! Person one, DO NOT RELEASE the brake lever!!! --Person two, once the bubbles and the fluid stops coming out, tightens the bleeder down again. Person one now releases the lever and "pumps" the lever back up. (As the lever is "pumped" you should feel a gradual increase in pressure) ~~Repeat this as many times as you need for each caliper until you get a good firm lever feel (after pumping them back up after a 'bleed') and no bubbles when person two cracks the bleeder open with person one applying steady pressure.(I go for 2-3 "clean" bleeds to call it good)

Okay... done now. haha.
 
  #14  
Old 12-18-2007, 12:33 PM
ffingers's Avatar
Registered Users
Thread Starter
Join Date: Jun 2007
Location: Chicago, IL (downtown)
Posts: 2,360
Likes: 0
Received 0 Likes on 0 Posts
Default RE: help...please...brake issue!

thanks lrn2go...that is essentially what i figued out/knew about brakes....i didn't realize as i was doing the priming and bleeding that my caliper pistons were compressed...i just failed to remember that part....so after having bled the brakes and primed em, i was stumped of the lack of pressure...

the 'MANY' part is sooooo true....so here's an update...i went down last night and pumped the brake lever about a 1000 more times.......and sure enough they are getting firmer...to test my theory...i touched the calipe and pad as i pumped the brake lever and sure enough, i could feel the brake pads squeezing against the rotor with no leakage or anything like that...that being said, i know the brakes, M/C and everything works....the brakes now actually work when i ride the bike...granted they are still not up to snuff but they work....i think what i will do now is re-bleed the brakes with some more dot4 and finish it up with the pumping method....

the whole thing boils down to most tutorials don't address the issue where the system is dry AND the pistons are compressed...that adds an extra step of getting the pistons "un-compressed" before you can ACTUALLY prime/bleed the brakes....

now that i understand what is going on, shouldn't be an issue...the only thing that i am really pissed about through the whole process is that i wasted a good amount of dot4, i now need to get more....and because i was bleeding and priming so much, i got some fluid on my powder and it dulled it up...and i also scuffed my caliper a bit...no biggie though...a little nail polish should fix her up...

i let you know how it goes when i get them finished-finished...
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
zellster
F4i - Main Forum
13
08-19-2019 06:44 PM
markybwoi
CBR 600F4
8
04-26-2014 07:08 AM
STRETCH15
F4i - Main Forum
11
06-27-2010 05:11 AM
jam0837
F4i - Main Forum
2
04-06-2010 04:49 AM
deanot
General Tech
1
08-20-2009 10:36 PM



Quick Reply: help...please...brake issue!



All times are GMT -5. The time now is 03:44 AM.