Re: [A/S] 77 Excella with Vac brakes + Break away cable

["Andrew Rogozinski" <andyrogozinski@xxxxxxxxx>]

> Ok.  Thanks for the replies.  That explains it.  All seems to be 
> working well, except via the controller, I can't get the trailer brakes 
> to lock up, which is a good thing I guess.  They are nice and steady, 
> and not 'grabby' like all-electric.

The disc brakes that you have, should lock up.

Unfortunately, in time, the sync valve starts to leak. When that 
happens, it will not delivery enough power to the booster, which in 
turn applies power to the master cylinder, which provides power to the 
calipers.

The sync valves can be rebuilt, but you must have the proper test 
equipment to make sure it performs as intended.

A quick check you can make on the sync valve, is as follows.

Have the trailer plugged into the tow vehicle. Take the top off the 
booster cover. With the engine running, which is providing the vacuum 
to the trailer, place your ear as close as you can to the small round 
air filter. It's about 4 inches in diameter. If you hear "ANY" hissing 
sound from that filter, then the sync valve is leaking. If you do not 
hear any soumd then the sync valve is OK, and you have another problem.
 
You could possibly have some air, in the hydraulic system.

If the sync valve is leaking, it "must" be overhauled.

DO NOT ATTEMPT TO TAKE IT APART. To do so could cause a serious problem 
which could render the sync valve useless.

Everyone that had repair parts for the sync valves, are history, except 
us. We do have the proper test equipment and parts for it.

Please call us if you have any other questions regarding your disc 
brakes. 

They are, an absolute safety system and must function correctly.

Hunter does not permit a commercial company to promote themselves on 
this site. We appreciate that, however, in your case, you have a safety 
issue, that should be addressed before you make another trip.

Andy
Inland RV Center, Inc.
AirstreamCentral.com