| Author |
Message |
SkyeW (65.140.74.5)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 31, 2004 - 11:28 am: | |
I have tracked down an air leak (when brake pedal depressed/held)on my 53' 4104. The leak is in the Brake Application Valve. Have tested according to DA BOOK. Indicates a bad diaphram or exhaust valve inside the B A V. The question is; Does anyone know if there were more than one type of BAV used on early 4104's? The picture in DA BOOK is similar in plumbing (inlet and outlet) layout, but the exhaust port on mine is facing the front not down.
All your input is appreciated.
Thanks
Skye Watson 4104-324 |
Luke Bonagura (Lukeatuscoach) (12.75.168.131)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 31, 2004 - 9:16 pm: | |
Hi Skye:
The early 4104's were built with a D-1 brake application valve which is now obsolete. I had assumed, until recently, that most 4104's would have had the brake application valve changed to a newer style by now, but to my suprise I have spoken with 2 customers within the last 30 days who still have the original valves that needed replacing!!!
Skye give me a call tomorrow toll free at: 1-888-262-2434, and I will try to help you. Or if you can take a digital photo and E-mail it to me at: uscoach@att.net, I can look at it before we talk and hopefully get you back up and running!!!
I Hope this HELPS!!!
Happy & Safe Bussin' to ALl!!!
LUKE at US COACH |
guy bouchard (161.184.192.43)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 31, 2004 - 9:19 pm: | |
Skye:
You might want to check a few things out about your brake valve before you get drastic, most of those old GM air valves can be repaired quite easily by dissmantling and adding new O-rings and lubricating with Sil-Glide. I've done most of mine and it works like a darn. Cheap too.
Guy 4905 |
FAST FRED (65.154.177.121)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, April 01, 2004 - 5:27 am: | |
IF you cant rebuild it you will have a choice between styles of new valves.
One type is similar to yours , in that it will limit the air pressure a bit , assuring smooth stops .
The other style gives up to full tank pressure , and MAY be able to lock the wheels in a panic stop.
I don't know if you will be able to stop faster , but you sure could ruin $2000 worth of tires quickly.
Do it YOUR WAY,
FAST FRED |
Jim-Bob (12.46.52.74)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, April 01, 2004 - 8:41 am: | |
My 4104 has a later coach type valve that limits full application pressure. I hate it. With the brakes perfectly adjusted it is impossible to lock up the brakes. When they're a little loose (manual adjusters) it's worse. I drive defensively & leave a lot of following space (which just encourages cars to get in front of me). There are times in today's traffic when you need every bit of braking. My 4104 could stop WAY faster if needed if it were possible to lock the wheels. (Mostly that last 30 feet at the stop light.)
I believe that the non locking valve was installed in a large part for passenger comfort and those 40 people aren't on board. Just me & mom watching the back of that &$%@$# four-wheeler (that just jumped in front of us & slowed down) get closer! Put the truck valve in & learn where the lockup point is where there's no traffic.
BTW, Fred, millions of trucks have the truck valve & don't ruin their tires. The ability to lock the wheels is not for everyday use, but, like a fire extinguisher just for emergencies.
Just MY way.
Jim-Bob |
TWO DOGS (4.226.105.176)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, April 01, 2004 - 2:20 pm: | |
"I" suggest you call LUKE....it's toll free & he will not bullshit you...if he says it's raining green outside ...it is... |
Skye Watson (Skyew) (65.140.75.91)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, April 02, 2004 - 12:47 am: | |
Thanks all. I apparently have a full pressure valve. I can lock em up without really trying. The pedal has always been extremely sensitive. So sensitive that it's not fun to drive in traffic.
Thanks again.
Skye Watson |
Phil Dumpster (24.16.243.37)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, April 02, 2004 - 4:18 am: | |
Overly sensitive brakes are almost as dangerous as badly adjusted brakes.
When you depress the brake pedal with the air system charged, you should notice that there is a pressure which pushes back against your foot to provide feedback on the application pressure. I've driven fleet vehicles before where this didn't work, and the brakes were very touchy as a result.
On my bus, when the air system is discharged the brake pedal can be depressed easily with only the spring in the assembly returning the pedal to the raised position. With the air system charged, there is feedback pressure, and to lock up the wheels you have to depress the pedal to the floor through this pressure. About half pedal is sufficient to hold the coach when in drive.
You should have your brake pedal assembly checked out. Without feedback you're going to have a difficult time coming to a controlled stop, especially on a slick surface. |
Buswarrior (Buswarrior) (64.229.212.164)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, April 03, 2004 - 10:15 pm: | |
Hello.
"Feedback" might not be the best word to use when describing what one thinks one feels under one's foot using an air brake pedal.
We are easily fooled by the rest of the vehicle dynamics into "feeling" things that are not present, and there is the variable of multiple vehicles in various unknown conditions and configurations thrown into the mix to further complicate one's observations.
You won't get any indication as to what is going on beyond your foot with an air brake system. Air won't transmit vibrations the way hydraulic brake fluid will in your car. And there isn't a direct connection between the air brake pedal and the rear brakes anyway!
If you have concerns about your brakes, sensative, gliding, or whatever, then besides an inspection of the wheel-end components, you should get the valving on your bus checked. And not just the brake pedal. The relay valve is also a culprit when braking is not as expected.
With a pressure gauge plumbed into the valve in question, see how the pressure progresses in relation to pedal travel. Progressive, late, early, high cracking pressures, lack of modulation, sticking - both while increasing and decreasing pressures, insufficient delivery of pressure.
Brake valves can fail both ways, too little as well as too much air, and at the wrong time during pedal travel.
happy coaching!
buswarrior |
Skye Watson (Skyew) (65.141.77.223)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 05, 2004 - 3:01 pm: | |
Thanks for the input guys. I've had the bus a year and the pedal has always felt too sensitive. The leak (while holding the pedal down) has gradually increased although the pedal feel has stayed the same. I really don't know what a good pedal should feel like when all is working properly.
Luke, I'll get you a digital picture when I go back up to the bus (it's 30 miles away).
Thanks,
Skye Watson 4104-324 |