front brake master cyl priming/bleeding issues (bit long)

davesta · Post by **davesta** » Thu Dec 13, 2007 12:34 pm

Hey all, i've just bought a set of hel braided lines for my trx (with r1 calipers and r6 master cylinder). I've fitted them up and i am having a problem with priming the master cylinder. Basically i have gotten to the stage where the lines and calipers are filled with fluid, but the MC just doesnt wanna prime. I can pump the lever and basically have no feedback at all. When i pull the banjo off at the MC there is hardly any fluid inside the MC, its like the port that is connected to the reservoir is blocked (its not, i dissembled the MC and cleaned with brake cleaner). I can prime the mc by squeezing the brake lever (with hoses unplugged) then putting my thumb over the outlet as i release the lever. This fills the mc up fine but as soon as i connect the hoses again i'm back to square one. At one point i had half of what my lever should be (and bleeding the fluid at the calipers revealed no bubbles) but it still felt like there was a huge air bubble somewhere and it was taking a lot of pumps after each bleed just to get any feel back into the system at all. Sorry this is so long, do any of you guys/gals have any ideas/hints to help me?? Feel free to take a shot at me if i havent been clear enough and i'll try and explain myself better, looking forward to your help

(oh the mc is not new to the bike, i have had it a while and it primed fine when i originally put it on with the original hoses about 6 months ago)
cheers all

Killerwhale · Post by **Killerwhale** » Thu Dec 13, 2007 1:14 pm

Sound kinda like what happened to me when changing from stock to R1 mc and braided lines.
....pumped for a LONG time before looking at an online manual, it suggested air in mc and that it was a biatch to get out.
I followed the advice and after 15-20 min i had full pressure.

Remedy...pump the mc like crazy with the reservoir open, if this is same problem you will be amazed by the amount of air coming out of the mc!

!!!!! Reservoir MUST be open!

youngy · Post by **youngy** » Thu Dec 13, 2007 1:58 pm

What he said^^^^^^

You've still got air in the system, and the fluid is still filling the hoses.

Stop taking the banjo off the master cylinder and keep on pumping!

dirty trix · Post by **dirty trix** » Fri Dec 14, 2007 2:57 pm

Try rather than pumping lightly tapping the lever very fast instead. Also try doing this with the handlebars at full lock in both directions.

I too spent ages trying to bleed my brakes... or I'd be dithing the braideds and going back to rubber.

cheesie · Post by **cheesie** » Fri Dec 14, 2007 8:06 pm

I tipped the bike from one side and pumped the lever then to the other side which worked in the end

kookimonsta · Post by **kookimonsta** » Fri Dec 14, 2007 8:31 pm

ive always found taking the caliper banjo off and pintching it between your thumb and finger, pull the leaver and let the air/ fluid come out. do it a couple of times and bolt them back onto the caliper.

yea you will let air into it but it will be in the hose not the M/C and will be alot easier to get out.

the other method ive been told is a big length of pipe on the bleed nipples and bring it back up to the M/C, cable tie the lever to the bar and open the bleed nipples. the fluid and air will naturally realease and self bleed as such. just make sure the M/C is topped up!

tom

Shifty · Post by **Shifty** » Sun Dec 16, 2007 1:49 pm

I filled her up from the calipers to the mc using the bleedingsrews.
So from down to up.
Worked like a charm.

twolfe · Post by **twolfe** » Mon Dec 17, 2007 3:47 am

Just a big shot in the dark here. I am guessing that you are using the TRX lever.? If so, change to an R1/R6 lever and your problem will dissappear. Although the TRX lever will fit, it is not compatable.The plunger is too long and will not let the M/C return to fill. If you are already using the R1/R6 lever, all this is no point so don't bother reading it.

Triton · Post by **Triton** » Mon Dec 17, 2007 8:11 am

Another easy tip... leave the top off the MC, fill it up and pump 'til empty. Tighten the bleed nipples. Refill the MC, pump a few times and cable tie the lever to the bars then go and have a beer or three. After waking up on the couch with the dog licking your face go back to the shed. THEN start the pump/refill/pump like crazy process explained elsewhere. Worked for me - standard TRX MC and lever, R6 Bluespots and Goodridge braided lines. One finger braking is the result BUT bugger all feel.

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front brake master cyl priming/bleeding issues (bit long)

front brake master cyl priming/bleeding issues (bit long)

Re: front brake master cyl priming/bleeding issues (bit long