RoadMaster Even Brake Repair



To safely tow our 2006 Jeep Wrangler Unlimited behind our Class A motorhome, it needed a few modifications and accessories.  One being a supplemental braking system on the towed vehicle.  I've been using RoadMaster products since 2004, and have been very pleased with the quality and performance of their products.  While shopping for Even Brake 9400 system, I found one on eBay.  It was well used, working, and I bought it for $450 + $47 shipping.  I used it for a year with no issues, then it had a failure.  The onboard compressor would never shut off during the test phase it performs each time it is installed.  Wouldn't build up pressure, and I could hear air rushing from a leak inside.


When I bought it, the outside of the case was very dirty.  Once I removed the cover, it was way worse inside.  Looks like it lived in a barn for years.

I plugged it into a 12V source so I could locate the source of the leak.  It was coming from a valve at the base of the piston.

The 1/4" line is easily removed by sliding the black locking collar towards the body of the fitting, then gently pulling the line free.  The vavle was then simply unscrewed from the piston.

This is a quick release valve.  It dumps air after braking is applied to release the brake pedal quickly.  This is the logo and model number of the valve.

I took the valve apart carefully in case it had a spring inside, but it only has a diaphram.

The rubber diaphram had ripped apart, and this was the cause of the air leak.

There are a number of places that sell this repair kit.  Just Google "Humphrey SRKSQE".  I suspect lots of equipment have these valves.  I paid less than $10, and purchased mine here.

Just make sure to put the diaphram in the correct way.  Not sure it could be put in backwards, but don't test my theory.

Came with a new diaphram and o-ring.  I put a little silicon grease on these parts before installing.

A little teflon tape on the piston threads before threading on the valve.

I cleaned up much of the visible dirt, and thoroughly inspected all the moving parts, and the circuit board located in the top of the cover.

Another bench test before re-assembly.  The valve now holds air.  Time to button it up, and test it in the Jeep.

Rewiring The Transmitter

While I was in repair mode, I took the transmitter apart as well.  Didn't like the factory wiring.

A pic so I could document how the stock wiring was before rewiring it.

I made the cable longer, used high quality wire, and added insulated sleeve to protect the wiring.  The end that's usually hardwired to the vehicle, I used Anderson PowerPole connectors so the entire thing can be quickly removed.

These are very high quality connectors.  This same housing can accept 15A, 30A, or 45A conductors, based on the size wire being using.  The pins can be soldered onto the wires, but I have a crimper, which makes for a fast/secure installation method.  FWIW, I used these for almost 30 years onboard helicopters on the communication systems.  Zero failures even in that high vibration environment.

This is where the transmitter was initially installed.  The signal would occasionally drop out on the receiver in the motorhome.  With the (now) longer cord, I could put the transmitter on the dash during towing, and had no further issues.

The Even Brake systems sits on the floor of the driver's side, and the piston clamps onto the brake pedal.  When the supplemental braking system detects the motorhome is slowing, it automatically applies the brake to the towed vehicle - proportionally to the slowing of the RV.  The braking signal is simultaneously transmitted to the receiver in the motorhome, so the driver is aware of the situation.

When the Even Brake system is setup each time, it starts its compressor, then applies the brakes 3 times, and detects if there was suffiient air without running the air compressor again, and that the brake lights illuminated each time.  If all goes well, this is the message displayed on the receiver.

All hitched up, and ready for another adventure!  The system has worked flawlessly since repairing the valve and extending the transmitter cables.

Conclusion:  Buying a used supplemental braking system on eBay does have some risks.  It did work when I first got it, but needed repair after a year.  Fortunately, the part was inexpensive, and readily available.  This type of work is simple to me, but I have a diverse work background.  Ultimately, it was a minor repair, and I save about $1000 over the cost of a new unit.  And to ready test the system properly, I hitched the Jeep to the back of my truck, put a GoPro in the Jeep, and took it for a drive.  Did a bunch of light braking, mixed with some aggressive braking.  I now feel confident everything works as designed when towing it behind the motorhome.

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Last updated 01/24/22    All rights reserved.