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Discussion Starter #1
One of my cutting brakes is not releasing preasure. It is not from using the cutting brake. It is just durring normal driving the right rear will lock up and not unlock till I release preasure from the bleeder or any of the fittings up to the cutting brake. There is no real preasure before the cutting brake and the left one does not do it so that should eliminate the residual preasure valve and master cylinder. They are the 2 in 2 out style CNCs from Polly Performance and I have 2 for individual wheel control.

Any thoughts?

wayne
 

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I have seen this problem before in Tracy Jordans matrix and in Dean bullocks buggy at koh. Take the pins out of the handles and try it. On the ones i have seen there was some bad machining and the handles werent allowing the pistons to come all the way out and the would just hold pressure. Every time they hit the brakes they would hold more and more pressure till the buggys would barely move.
 

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My cutting brake has also locked up on more then one occasion. What do you mean by take the handles out and try it? Just remove the handles and drive to see if it still drags. My problem seems to be related to using the cutting brakes and to release the pressure you must make violent motions through the range of the cutter and it will suddenly release the pressure. I haven't ever noticed that it starts developing drag when I haven't just used the cutter. Allmost as though it is sticking
 

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I just talked to tracy. What the problem is the holes arent machined right in the bore and wont allow the pressure to bleed off and return to the master cylinder. You dont have to use the cutting brakes to have this happen being all the brake pressure travels thru the cutting brakes. He had 2 bad ones and cnc gave him new ones to replace them.
 

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Discussion Starter #6
I just talked to tracy. What the problem is the holes arent machined right in the bore and wont allow the pressure to bleed off and return to the master cylinder. You dont have to use the cutting brakes to have this happen being all the brake pressure travels thru the cutting brakes. He had 2 bad ones and cnc gave him new ones to replace them.
Mine worked fine for a few months then @ Perris a rock broke the right rear caliper which caused us to loose all the fluid in the rear brakes. I have been chasing it since. Did Traci have this poblem from the start or did it develop over time.

wayne
 

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For a quick on-course fix...rapid and strong SHORT STROKES, hit and release the regular brake pedal while at the same time, doignt he same with the cutting brake handle...it only takes a second to get it to release. We only have this happen once every few months, but it was a pain in the ass until we figured out it was simple to overcome. Ours is simply from the angle the cutting brake is mounted at and the weight of the handles is enough to hold the cylinder in the lockout position for using the cutting brake. If it happens more than once or twice randmly, then you should talk to CNC...it may just be a fluke with the handle position when you hit the brake.
 

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Discussion Starter #8
For a quick on-course fix...rapid and strong SHORT STROKES, hit and release the regular brake pedal while at the same time, doignt he same with the cutting brake handle...it only takes a second to get it to release. We only have this happen once every few months, but it was a pain in the ass until we figured out it was simple to overcome. Ours is simply from the angle the cutting brake is mounted at and the weight of the handles is enough to hold the cylinder in the lockout position for using the cutting brake. If it happens more than once or twice randmly, then you should talk to CNC...it may just be a fluke with the handle position when you hit the brake.
That works some times but not very often. I have an Idea from the above post though so thanks all for the help.

wayne
 

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I know this is waaaayyyy out there, but I had something similar happen on a dirtbike once.

I dont know how it happened, but I got water into my front brakes. As the brake system heated up the water pressurized and locked the brakes. I had no idea why I had crashed in every corner on the last lap (other than I was tired and not that good of a rider anyway!!) until I returned to the pits and put the bike on a moto-stand. Upon inspection the front brakes were locked. I drained and flushed the system and never had that problem again.

This might be out there, but I will never forget that experience or the cause of it!!!

Dane
 

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Discussion Starter #11
The rod has backed out of the clevis that attaches to the handle making the whole assembly too long. I looked at it at lunch but no time to fix it. I will get to it tonight and report back.

wayne
 

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Discussion Starter #12
Just to put this to bed. Crewchief mentioned pistons not returning and bad machining which got me thinking that the piston is not returning for some reason. I then remembered that when you press the brake pedal the right cutting handle moves back just a bit due to preasure in the front brake lines. The only relation ship I could see here was that the lower (back) actuating rod was too long and the front cutting brake was applying preasure to the rear through the handle and actuating rods. I took the whole thing apart tonight and the lower (rear) Rod had backed out of the clevis almost 1/4". the whole thing made sence and I matched the length of both rods and put it back together, works great and no loading up at least in the shop. Cedar city will be the real test. See you there.

Wayne
 

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For a quick on-course fix...rapid and strong SHORT STROKES, hit and release the regular brake pedal while at the same time, doignt he same with the cutting brake handle...it only takes a second to get it to release. We only have this happen once every few months, but it was a pain in the ass until we figured out it was simple to overcome. Ours is simply from the angle the cutting brake is mounted at and the weight of the handles is enough to hold the cylinder in the lockout position for using the cutting brake. If it happens more than once or twice randmly, then you should talk to CNC...it may just be a fluke with the handle position when you hit the brake.
Maybe I should get in touch with CNC, ours did this from the start and the short strong strokes don't always free it up right away. It has definitly taken over a minute to free it up before.
 

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I put a rear cutting brake on my new rig with a rear ARB. its the 1 in 2 out one. I will drive this on the street, so this concerns me. I thought about putting bypass valves around the cutting brake, so this wouldnt happen on the street. Anyone see anything wrong with doing that?
 
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