Zero front brakes; halp

garrett · Post by **garrett** » Sat Dec 08, 2012 11:35 pm

I can't get anything out of the front brakes though. Bike was sitting for ~6 years in a barn in Maine. Calipers were froze. Bought good calipers. Master wasn't making pressure. Bought known good master. Still got zero brake feel. Any ideas?

garrett · Post by **garrett** » Sun Dec 09, 2012 12:08 am

Here is a quick vid I made

You can see the caliper slighly move

Stig · Post by **Stig** » Sun Dec 09, 2012 1:12 pm

try back bleeding with a syringe and then pull lever, open bleed nipple, close bleed nipple, release lever....keep repeating and make sure res is topped up.
Its just a matter of patience and perseverance

HybridSport600 · Post by **HybridSport600** » Sun Dec 09, 2012 10:01 pm

If master and caliper are good, the you would have air trapped in system, or the master cylinder pump seal is so worn, will pump and spray fluid with lines off, but when under pressure they just seep air into system and will barely move pistons. I would remove the line from the master cylinder and place finger over hole while pulling lever. The result should force your finger off and spray fluid, if there is no pressure forcing your finger off the hole, then you will need to get a master cylinder rebuild kit. Good luck!

Stig · Post by **Stig** » Mon Dec 10, 2012 3:10 pm

HybridSport600 wrote:you will need to get a master cylinder rebuild kit. Good luck!

OP stated that he'd got a good known master cylinder

_Will_ · Post by **_Will_** » Tue Dec 11, 2012 12:27 am

Possibly silly question since your garage history looks experienced but have you bled the MC first? Ours don't have bleeder screws but a towel wrapped around the banjo fittings should avoid the above mentioned problems and just loosen, pump, hold, and tighten. Brake fluid is nasty stuff so some gloves and eye protection aren't a bad idea.

HybridSport600 · Post by **HybridSport600** » Tue Dec 11, 2012 1:21 am

You leave the cap off while you pull handle to bleed the master cylinder (obviously Slowely) and adding fluid as it fills system. When no more fluid is being accepted and Leaving the cap off, move to the Caliper and bleed it several times.
not sure why the banjo bolt is being messed with.

The object of removing the line and using finger is to check that the pump seal will hold enough good pressure to move the fluid.

Not to bleed master! Dont use this method to bleed it, it will only allow air into the system, forcing you to start all over again.

Anyway, Garrett your symptom is pointing to either a weak master cylinder, or swolen rubber lines. Its either loosing pressure, or not producing it.

SouthendChris · Post by **SouthendChris** » Thu Dec 13, 2012 9:01 am

Try taking each caliper off and turn it upside down and around a few times (dont disconnect brake hose!). It might be there are air bubbles trapped in the nooks and crannies inside the caliper. This is always a problem when bleeding from scratch (new lines?) rather than just changing fluid. I also use a syringe to bleed and to agitate the fluid in the caliper.

Good luck with it

HybridSport600 · Post by **HybridSport600** » Mon Dec 17, 2012 6:34 pm

fizalone wrote:
HybridSport600 wrote: I would remove the line from the master cylinder and place finger over hole while pulling lever. The result should force your finger off and spray fluid,
That brake fluid will or could splatter all over your paint work, or even into your eyes

Sorry but thats the dumbest advice I've saw since RaceRD recommend putting your thumb over the plug hole to perform a compression test.

Only in America as the saying goes. Im not implying that all Americans are dumb, far from it. Dumb people live in every country but the biggest Idiots well...... as the saying goes hehe

WOW! Im not sure what words to waste first but here we go again! im sure we all know that brake fluid is dangerous and fatal if swallowed
( Please dont try it fizz) And I would assume he does not want it all over his paint either and again, Sorry I thought we all had some smarts here to know that if we are testing pressure then yes it might spray! and will need to wrap a shop towel or wrag around it to prevent this.
Sorry, Elementary Watson!! next time I will include pictures and colors for you fizz!

Good day..............

punkandbikes · Post by **punkandbikes** » Sat Jan 26, 2013 5:41 pm

When the master cylinder is pressed, should it really spray fluid out or just like trickle? I think mine is the latter camp and might be why I'm tearing my hair out trying to get it working after trying to remedy sticking front brakes.

GreyImport · Post by **GreyImport** » Sat Jan 26, 2013 8:23 pm

punkandbikes · Post by **punkandbikes** » Sun Jan 27, 2013 3:15 pm

I took the calipers and master cylinder off and cleaned them all, replacing the seals in the calipers, and now I'm trying to get the new fluid through. When I was bench bleeding the MC with my gloved thumb, I did it until fluid was just sort of trickling out and then put the banjo bolt back on with the two lines and then used a mityvac to pull the fluid through. it worked well on one side but not so well on the other, and I now think it might be due to the bleed valve being loose as I've just been to look and found fluid sitting in the wheel. I might have put too much teflon / ptfe tape in the thread. But I can't see any effect in the MC when I pull the lever, and in one of the tutorials I watched it seemed to make quite a strong flow back into the MC trough.

I've got a syringe in the post to try and back bleed the system, but I'm not very confident. Think it might just be too much for a newbie! Wonder how much a garage would cost to clean and synch my carbs?

Stig · Post by **Stig** » Mon Jan 28, 2013 12:03 pm

NO!, no tape or PTFE should be used in a brake system. All the fittings are either taper compression or copper washer gaskets. Its more than likely some of the tape has blocked a bleed hole or fluid tract

punkandbikes · Post by **punkandbikes** » Mon Jan 28, 2013 2:33 pm

No tape? Shit, that's what the mityvac manual said. Reckon I have to flush it again? I bought new bleed screws to see if they'll fit more snugly. I only had tape at the top of the thread so hopefully it will peel off without staying in the holes.

punkandbikes · Post by **punkandbikes** » Mon Jan 28, 2013 2:39 pm

Oh, and do people rate the thundercat master cylinders? Are they that different from the standard R6 swap?

http://www.ebay.co.uk/itm/YAMAHA-YZF600 ... 4d08311ac7

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