Bleeding CNC cutting brakes.

[alexcliffo]

Does anybody have any special techniques to bleed CNC cutting brakes when plumbed inline between master cylinder and rear brakes?

Or has anybody had issues with rear brake pressure using the footbrake when they have a cutting brake plumbed in?

They are obviously a high point in the brake system.

I am having issues getting rear brakes when using the foot pedal, and have tried different plumbing and bled the system (including both cutting brake cylinders) a few times pretty well. The rear wheels brake well when stopped individually from the cutting brake though.

[turbo gu]

Can you clamp the rear brake line and try and see if the pedal improves?
That should eliminate the cutting brakes if they are good. If no improvement there could be air still in them.
the other thing is the master cylinder could be the wrong size for your patrol brakes

[alexcliffo]

Will try that.

Apparently the RR master is good for GU Patrol brakes, as others have setups similar with good results.

Cheers

[mud guts]

If the master(CNC) has balance bar front and rear need to be cracked together. If just cutting, pump up and crack rear bleed, pull on cut lever(hold), close bleed and pump pedal filling cutting master, lever will start to move back to start, so let it move slowly whilst still holding it. after its been done few times, about 3 pumps will get lever back to start. Works for me.

[alexcliffo]

cheers mud guts.

[evanstaniland]

CNC instructions say pump up pedal, crack nipple while pushing pedal as normal once pedal hits floor then pull handle then lock nipple. And repeat lots!
Also been told to try pushing fluid up from caliper

[V.W.Dave]

The can be a right royal C^^T of a thing I have spend a few days bleeding them before. Best way I found was force feeing from the calliper. I have also had one that it simply needed to be driven a ew times and bleed after each trip and it eventually came good. I have had mates uses a vacuum pump with mixed success as well.

[sloshy]

Just bleed your brakes like normal, theres no need to touch the cutting brakes forget they are even there, it will take more time than usual just keep at it.

[was a 75]

sorry to hi jack your thread but does anyone know a good mobile brake mechanic in the ipswich area that can plumb in a hydraulic handbrake?

cheers

[evanstaniland]

It's not a hard job to do yourself and the tooling required is cheap

[mud guts]

Just bleed your brakes like normal, theres no need to touch the cutting brakes forget they are even there, it will take more time than usual just keep at it.

Of coarse, it will take an unusual amount of time if you do it the normal way. Doing as i previously described will manually force the air pocket out and replacing with fluid. Its for the very same reason you dont lift your foot off the pedal until your mate closes the bleed, if you let the cut lever go before the cylinder is full you just suck the air back up into it.