Rear brakes locking up on the buggy.

onanysunday

onanysunday

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So this is the second full season after I put the Jamar pro x micro stub kit on my car. I have not looked at the brake pads but can't imagine they are worn way down making the pucks go out a long way. Still need to check it though. This trip twice my brakes completely locked up basically bringing the car sliding to a stop. Bizarre to say the least. One time I was yelling on the radio since I had just gone over a steep lip and didn't want another buggy up my butt. With the original gray area hubs which I believe is what came on the Gen 4 Funcos I never had any kind of issue like this. Each time when it was locked up the turning brake was locked solid. Couldn't move it forward or backward. Push back and forth and pushed on the brake pedal and it freed up each time. Pretty unnerving though. Anyone ever have anything like this happen? I have at least one more trip and would like to know if there's something I'm not thinking of. Only thing I can think is those pucks are hanging up. Or maybe the pads are worn way down and I don't realize it.

 
I have a similar issue. When I hit the brake pedal it locks up the rears. If I hit the turning brake in either direction it frees them. I haven't had a chance to try and figure out if it's locking up both rears or just one. Some friends suggested the Master is scored, but if it was the master wouldn't all 4 lock up?

 
You running a single lever turn brake? If so, the bumps will start putting a little pressure on a rear brake from the handle vibrating, then heat and then total lock up. 
Loosen up the top rod and problem will go away. Had it happen a few times to me until I was told the above advice. 
I also added a pressure switch on both of the rear brakes and put a little red light on my dash just to be safe, brakes on, light on. 
Using the turn brake every once in awhile will help. 

 
Rampage42 said:
You running a single lever turn brake? If so, the bumps will start putting a little pressure on a rear brake from the handle vibrating, then heat and then total lock up. 
Loosen up the top rod and problem will go away. Had it happen a few times to me until I was told the above advice. 
I also added a pressure switch on both of the rear brakes and put a little red light on my dash just to be safe, brakes on, light on. 
Using the turn brake every once in awhile will help. 
Click to expand...
So you are saying loosen up the top only?

20180617_144545.jpg

 
There are a few things. First you only have one master for front and rear brakes as I see in your picture. If your rears lock up and not the front then you are wasting your time on the residual valve. If all brakes lock up then yes first start with it. If all brakes lock up it could also be a master that is not retracting the plunger all the way. When this happens fluid can not return to reservoir so brakes can lock up when fluid expands. This could even be a too tight of a pedal. Or debris below the arm. 
now if only the rears lock up then the turning brake is the issue and most likely an adjustment. Lots of people try to get a tighter turning brake by adjusting to two piston preloads. But doing it wrong can also net the rear brakes locking up once fluid is heated

 
There is no reason to only do the top adjustment other than it does slightly change the handle position. Both should be adjusted equally (same amount of threads showing) until issue goes away

 
Not sure if was just the rears or all 4. It did it twice. Both times after the car came to a stop I pushed in and out on the brake pedal and the turning brake. Turning brake was solid and did not move. Broke free pretty easy both times. But the first time I was going off a steep lip right when it locked up. If not for getting on the radio instantly it was close to having a car on top of me. Unnerving to say the least. 

 
so the CNC turning brake IMHO was not designed well.  the pistons have no retaining clip to keep them in.  this causes an issue in trying to adjust them correctly.  the pistons must come out (at rest) far enough so that each return hole is open. this allows brake fluid to go back to the master and to not "apply" the brakes during heat expansion too.  the typical enthusiast wanting a "better" turning brake feels like they can just adjust the plungers tighter (lengthening the rods) but by doing so, can close off the return port and resulting in the rear brakes locking up.  but shortening the rods so that the returns are open by too much can result in a poor Turing brake (lots of travel).  you will also notice another characteristic of this poor design is that when the main brake pedal is applied, the turning brake lever gets stiff--why? because the pistons are trying to leave their bores which in turns tightens the handle with zero freeplay.  There is no positive piston stop

the wilwood turning brake has C clips right inside the bores so the pistons have a positive stop (while main brake pedal is being depressed).  and at that moment it is easy to set up and adjust a little bit of freeplay with the rods for optimum turning brake experience

 
John@Outfront said:
so the CNC turning brake IMHO was not designed well.  the pistons have no retaining clip to keep them in.  this causes an issue in trying to adjust them correctly.  the pistons must come out (at rest) far enough so that each return hole is open. this allows brake fluid to go back to the master and to not "apply" the brakes during heat expansion too.  the typical enthusiast wanting a "better" turning brake feels like they can just adjust the plungers tighter (lengthening the rods) but by doing so, can close off the return port and resulting in the rear brakes locking up.  but shortening the rods so that the returns are open by too much can result in a poor Turing brake (lots of travel).  you will also notice another characteristic of this poor design is that when the main brake pedal is applied, the turning brake lever gets stiff--why? because the pistons are trying to leave their bores which in turns tightens the handle with zero freeplay.  There is no positive piston stop

the wilwood turning brake has C clips right inside the bores so the pistons have a positive stop (while main brake pedal is being depressed).  and at that moment it is easy to set up and adjust a little bit of freeplay with the rods for optimum turning brake experience
Click to expand...
So worth buying a Wilwood unit and replacing?

 
So it ends up the nuts on the upper and lower came loose. Let each rod vibrate forward and didn't have enough play as mentioned in this thread. Screw them out by hand and tighten them up. Good to go.

 
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