Brake Buddy

[Geechee]

I have been very happy with my Brake Buddy until recently. The last few trips I have encounter a problem with the air cylinder retracting the piston instead of extending it when the test button is pressed. It did not do it all the time and may only start doing so after the second or third time the button is pressed to dump the vacuum in the CR-V's brake booster. My calls to BB have been less than helpful. The first tech I spoke to said that it had to be a problem with the electrical connection and if it happened again I should try in plugged into the coach 12v system. His reasoning was that the BB would function correctly or not function at all. So the next time I did just that. Install the BB, went through the CR-V's prescribed 3 minute cycle for lubricating the transmission and then shutoff the engine. Pressed the test button and the cylinder as expected extended to press the brake pedal. Released the button and the piston retracted as normal. Pressed it again and the cylinder tried to retract as if air was being applied to the wrong side of the piston. Pressed again and the same thing occurred. Disconnected the piston from the brake pedal and uninstalled the BB. Took the unit into the MH and connected it to the 12v plug. Again pressed the test button and the piston again attempted to retract instead of extending. Call Brake Buddy tech support and was told that what I was describing was impossible and it had to be a power problem. I measured the voltage at both lighter sockets and they were 13.8 and 13.4 volts. The BB plug appears to be in working order and as I said before the problem had been intermittent. However, since the last failure the BB has not returned to normal operation. Does anyone have any ideas?

[Geechee]

I have been very happy with my Brake Buddy until recently. The last few trips I have encounter a problem with the air cylinder retracting the piston instead of extending it when the test button is pressed. It did not do it all the time and may only start doing so after the second or third time the button is pressed to dump the vacuum in the CR-V's brake booster. My calls to BB have been less than helpful. The first tech I spoke to said that it had to be a problem with the electrical connection and if it happened again I should try in plugged into the coach 12v system. His reasoning was that the BB would function correctly or not function at all. So the next time I did just that. Install the BB, went through the CR-V's prescribed 3 minute cycle for lubricating the transmission and then shutoff the engine. Pressed the test button and the cylinder as expected extended to press the brake pedal. Released the button and the piston retracted as normal. Pressed it again and the cylinder tried to retract as if air was being applied to the wrong side of the piston. Pressed again and the same thing occurred. Disconnected the piston from the brake pedal and uninstalled the BB. Took the unit into the MH and connected it to the 12v plug. Again pressed the test button and the piston again attempted to retract instead of extending. Call Brake Buddy tech support and was told that what I was describing was impossible and it had to be a power problem. I measured the voltage at both lighter sockets and they were 13.8 and 13.4 volts. The BB plug appears to be in working order and as I said before the problem had been intermittent. However, since the last failure the BB has not returned to normal operation. Does anyone have any ideas?

[RetiredSKP]

Geeche

This is a simple hydraulic or pneumatic problem. I am surprised that Brake Buddy cannot help you. Here is what is happening. There is a leak in the seal that seals the piston to the piston body. Air pressure is getting to the opposite side of the piston as well as the correct side. Now, why does it go the wrong way? Imagine that the "push out"� side of the piston has 2 square inches of surface. Now fifty pounds of air would push out with 25 pounds per square inch. (50 pps / 2 sq in = 25 pps pushing force) Now looking at the "rod side"� of the piston, the rod pushes on the brake pedal. Let's say that the rod takes up ½ square inches of surface area on that side of the piston where it is fastened to the piston. That leaves 1 ½ square inches of surface to push back toward the brake buddy. If the amount of air is the same "pressure"� on both sides then the rod side of the piston pushes with 33.3 pounds per square inch and it wins. (50 pps / 1 ½ sq in = 33.3 pps pushing force. The rod goes back toward the brake buddy.

Call Brake Buddy back and tell them that you need a seal kit.

RetiredSKP

[Geechee]

RetiredSKP,

Thanks for the feedback. Your explanation seem totaly plausible to me. I will try BB one more time, but as I said in my post, the tech did not accept that the condition I described could occur.

Thanks again,

Geechee

[Dsouthw524]

The tech was probably thinking that something was running the air pump in reverse and pulling rather than pushing. Now that you have done the test as you described, he will undoubtedly arrive at the problem being a repair.

Hope they help you out quickly.