View Full Version : removing brake relay valve

12-19-2018, 10:55 PM
Valve on LH rear leaking out the bottom. Want to remove. I am assuming the numerous air hoses should have swivel fittings so you can remove at the valve. Any tricks?

Joe Camper
12-20-2018, 06:30 AM
Can you take a picture of it. Or can you see it from looking in from the side? If you can see it from looking in from the side it's not a brake relay valve it's a brake anti lock valve.

If it is the brake anti lock valve that I think is leaking out the exhaust port on the bottom it's not actually the anti-lock valve that you can see that's bad. It is in fact the brake relay valve that's feeding it that's the culprit and you cannot see that just looking in cuz it's way up in there.

You have 4 brake relays back there 2 R-12, 1 R-12DC, 1 R-14. If 1 has failed the rest aren't far behind.

They're installed at the factory loaded up with half the fittings that are pushins and also all the rubber brake hoses feeding the chambers originate out the bottom of them and it's a good time to replace those while your in there.

I would not suggest fleetpride for those relays get them from Prevo the lids r different and what prevo calls an R14 is not exactly the same as how the trucking industry configures an R14. The delivery ports can be bottom or side and port size could be 3/8 or 1/2 in in the trucking world. Prevo will get it right.

Fleetpride or similar supplier get about 50 each Prevo gets around 70 IMHO money well spent.

If you're absolutely sure you know the correct way to support the bus you can put it on stands and from the shop floor and by taking off just the tag Tire and rim on that side a guy can shimmy up in there to get to that brake relay. that's how I do them

01-22-2019, 04:07 PM
154001540115402The brake relay shown on lh side feeding the tee shown in the next picture. Goes to the tag brake. this relay is forward of the pair near the airbags. You can see part of the roll bar - valve mounted on a large square beam. My question is one, what is the correct name of this brake part and two, are all the hose connections to the valve supposed to swivel- if not how in the world would you remove all the hoses?

01-22-2019, 04:09 PM
The other picture was the surprise when I got under the bus, big puddle of oil from the inside of the wheel.

Joe Camper
01-23-2019, 07:04 AM
The relay is either an r12 an r12dc or an R14 and unless I see the top the bottom housings r all the same and won't be able to say from that photo. Prevo Elgin may be able to tell u based on location IE left front left rear right front right rear. There r 4. 2 r12, 1 r12dc and 1 r14.

If u look at the last photo that end is a swivel for the hose.

That's a drive axle inner hub seal and there is an accompanying flange gasket that goes with that. U will also be pulling the axle and need it's flange gasket too.

If u have a trip or a more than short drive to a service center check the oil level in the rear end to be safe.

The rear end can loose as much as a gallon before becoming detrimental, it holds 5 gal aprox, verses the tag and steer hubs that only hold 1 pint.

If u r doing it yourself there's I've composed many threads that covers that or I'll be happy to go through it again for u if u need .

01-23-2019, 12:28 PM
Thanks Joe- I will be doing all myself and will look for the past posts.

02-03-2019, 10:50 AM
went to remove the r-14 valve- none of the air lines would budge- soaked in PB blaster- Considering rebuilding under the bus or cutting the lines and have to replace them. Ideas?

Joe Camper
02-03-2019, 05:30 PM
I would not hesitate to cut the flexible rubber lines if i was putting new but under no circumstances would I cut those plastic lines.

First its always easier to remove an an air line or component with 0 pressure. It's got 2 rubber brake hoses out the bottom ports take those loose at the other end of the hose leave them attatched to the relay till u get it out. The top fitting is a 1/4 many times a push in reach up there and feel for it collapse the lock ring and pull it out and if it's a good style old fashioned Parker fitting it's a 9/16 wrench get a little stubby and reach up there you can do it blind you can feel for it. Once you pull the quarter inch line off the top next go to the compression fittings that accept all the plastic lines and take the nuts loose on all of them and slide them back. Or if they r push in claps the lock ring and pull them out. Prevo does a really good job of clamping down all the hoses and making sure there's not a bunch of extra flapping and you have to be aware of it when you're taking stuff apart you got to do it a little differently or it'll be a real pain in the ass. So once you've taken all the compression fittings loose for the plastic lines then take a 9/16 either on a 3/8 drive ratchet a short socket 9/16 or get a little stubby ratchet wrench 9/16 and do it by Feel Again reach onto the top and two of the four bolts that hold the top on r going through its bracket. Loosen up the two bolts that have it attached to its bracket and take them off completely remove them. At that point now you the only thing holding up the relay are those plastic compression lines and you can pull on the relay while holding them lines and you can get all that stuff separated that way don't try to remove the fittings from the relay just loosen the nut and pull the nut and the airline away you're leaving the bracket on the bus and you're going to pull the relay down with the rubber brake hoses still attached to it and all the fittings still in it you're just going to leave the nuts and compression rings and the plastic lines in place. Now that you got the relay in your hand you can stick it in a vice and really easily do whatever you want to do with the rubber brake hoses and switch your fittings over if they're good fittings or replace all the pushins with the good Parker stuff while you've got it out. I'd replace those brake hoses those are Parker and in my opinion they suck.

Here is what I carry and use. The older Prevo had really nice Arrowquip 2 piece reusable fittings on a lot of the chassis but they don't do that no more and probably because aeroquip has got really really proud of their stuff they want $75 for 1/2 inch by 1/2 inch 2 piece reusable non swivel end. All your bus rubber brake hoses are going to be half inch and FleetPride is going to have mostly 3/8 that's what's on trucks. You should go to FleetPride and get half inch by half inch velvac two-piece reusable air brake hose ends with springs attached and get what u need. Some of the outer ends of that brake hose where the current swivel is it'll be 1/2 inch air brake to 3/8 pipe .some of its 3/8 pipe some of it's 1/2 inch pipe the stuff that comes out of the bottom of the relay is half inch pipe thread some of the other ends or 3/8. If you use these velvac ends you can put the hoses on and tighten them down without the need of a swivel and without twisting them doing it. You also end up with brake hose assemblies that are much easily repaired in the event of an emergency say you take one out driving over something or blowing a tire with a Parker air hose you're stuck.

Good luck. Once you do it a few times it's a cinch

If your schedule permits im going to be as close as Texas, Oklahoma, Arkansas in as soon as 8 weeks and I'll be in that region of the country for at least 6 weeks maybe 2 months. I could help u. U also have that leaky hub seal who knows what else on a recent purchase of a 20yr old bus. We could remove all its rims and tires. Let the doctor put a stethoscope on it and have it cough a few times get a better idea of exactly what it does and does not need. Do it correctly, completely and painlessly.