Brake Pressure Gauge, Diagnostic

[GCroyle]

Guys,



Do any of you own brake pressure gages that read the system hydraulic pressure? Not the type that reads the pressure exerted by the caliper against the brake pads. I have seen a few on the web so far that tap into where the bleed screw goes.



If you own or have used one, have you been able to use it to visually diagnose air in the system? Does air show a different ramp up pressure, kinda like if you see this on a vacuum gauge on a gas engine, it means this... .



Thoughts and comments appreciated.

 

[seafish]

Gary, I have the BrakeSmart trailer brake controller on my 2005. It has a small pressure transducer that taps into one of the brake master cylinder lines and gives an accurate reading of brake line pressure from 60 to >1500 psi. It does this whether the engione is on or off. Simply lightly touching the brake pedal activates the controller and the readings come onto the led screen.

When I first installed the transducer, I did not correctly bleed the brake line per their simple instructions, and I FELT the brake pedal be spongier then before the install. I then bled out all the lines and restored pedal pressure. At no thime did I notice a diffrence in pressure readings, though to be fair I was NOT looking ofr it yet.

I am sure that if air could be sensed in the system it would be by the "ramp up" time to achieve full brake lin epressure, and not in that actual pressure value, as the air also compresses to full pressure, but at a different rate (thus the spongy feeling). I am sure that it would take a well trained eye to SEE the difference in brake pressure ramp up due to trapped air, or perhaps some sort of computer graph read out, and I have NO idea whether that tool actually exists.

So all that being said, why not just bleed the entire system and be done with the problem??

 

[HBarlow]

Gary,

I also have a BrakeSmart brake controller that reads hydraulic line pressure but have never had air in the system and have never had reason to use the brake controller to diagnose or repair.

 

[GCroyle]

Oops,



I see now that I should have included the rest of the story.



My truck has the MaxBrake and I have ZERO issues with the brakes on my 2005 Ram.



The tool does exist, I have found examples of it on various sites. But I have not found a tutorial on how the tool works, what the readings might tell us etc.



The vehicle is a TT with twin Dexter axles and 4 piston per rotor hydraulic disc brakes. with an electric actuator made by Carlisle. The number of "things" that I have done and worked on regarding these brakes is too long of a list. But bleeding a total of 8 caliper "halves" with 16 total pistons, is a chore and I was wondering if the pressure gage might be a worthwhile diagnostic. Getting to the bleed screws which are on the outside caliper half thru the wheel spokes is not a real possibility, plus then you might wind up getting DOT 3 all over your brake pads. So each time that I have had to bleed this rig, up in the air and all tires come off just to get to the calipers.



Trust me guys, it is a VERY long story, actually involving OE design issues and an actual error when built plus refinements plus mfgr's product failures but I am hoping to write the final chapter real soon and then enjoy it for a long time.



Thanks for looking.

 

[HBarlow]

Gary,

I'm still in the dark on your problem and details of your goal for diagnosing it but I'm assuming you have a braking issue and suspect air in the system.

I bought a new Goldwing in January, a year ago. When I took delivery and rode it home from a dealer near OKC it had soft and ineffective brakes. I took it to the nearest dealer and complained. This began a series of return visits and new attempts.

The GW has linked front and rear brakes meaning multiple calipers on each wheel alternatedly shared with the rear brake pedal and the front brake lever. It also has a front wheel anti-dive on braking feature that uses brake line pressure for activation.

The tech is a good and experienced one. He bled the brake system during each visit and once replaced the rear wheel master cylinder under warranty. After each attempt soft braking remained or returned. Ultimately he corrected the problem using a non-standard, non-approved procedure he described as pressure bleeding. With brake pressure applied he bled each caliper in sequence. The aggravating and unsafe problem was finally corrected when he released a small manufacturing assembly air bubble on one of the front brake calipers. Now I have great brakes.

Perhaps pressure bleeding could help your problem.

 

[GCroyle]

Harvey,



I used to own a GL1200 and although I never had a brake problem with it I did flush and bleed on a regular basis. My tool of choice for that job was vacuum bleeding at the cylinder.



This TT using an electric actuator can supply an almost continuous fluid flow as long as you keep feeding it brake fluid. The issue that I would like to overcome is the guess work, IS IT BLED? I even reconfigured the inboard caliper connection (all std brake line components) to allow cracking the connection to bleed the inboard independant of and in addition to the outboard bleed screw.



I have to tear it completely apart, down to the piston seals (16) possibly to affect my hopeful final cure and that means bleeding it AGAIN. When I do this, I have an opportunity to install an inline trailer T fitting at the actuator discharge port and this would give me a tap connection to the system for pressure tap for maintance and inspection purposes.



From my work with clutch release systems I am painfully aware of the detrimental effect an air bubble can have. With your Wing the feedback is in your hand or foot, with a TT you have to hook up and test drive to check for delayed braking.

 

[HBarlow]

Harvey,

I used to own a GL1200 and although I never had a brake problem with it I did flush and bleed on a regular basis. My tool of choice for that job was vacuum bleeding at the cylinder.

This TT using an electric actuator can supply an almost continuous fluid flow as long as you keep feeding it brake fluid. The issue that I would like to overcome is the guess work, IS IT BLED? I even reconfigured the inboard caliper connection (all std brake line components) to allow cracking the connection to bleed the inboard independant of and in addition to the outboard bleed screw.

I have to tear it completely apart, down to the piston seals (16) possibly to affect my hopeful final cure and that means bleeding it AGAIN. When I do this, I have an opportunity to install an inline trailer T fitting at the actuator discharge port and this would give me a tap connection to the system for pressure tap for maintance and inspection purposes.

From my work with clutch release systems I am painfully aware of the detrimental effect an air bubble can have. With your Wing the feedback is in your hand or foot, with a TT you have to hook up and test drive to check for delayed braking.

I understand. It's much more challenging to avoid or ensure there are no air bubbles in your TT system.

 

[GCroyle]

I understand. It's much more challenging to avoid or ensure there are no air bubbles in your TT system.

Harvey,



That's a bingo. My hands get kinda tired of the nasty feel of brake fluid, want to get it done right and overwith, got better things to do.



Also, I looking into this deeply as a pobbible diagnostic tool for other owners on another forum.



So, any brake pressure gauge owners with hands on feedback about their gauge?



Gary