Grover Horns

[wfire32]

We've got a new engine with Grover Stuttertones mounted in the bumper. From delivery, they sounded like crap. We had the manufacturer try to tune them and they came back still sounding like crap.

Yesterday I went under to investigate and found that the bracket that holds the horns was too short so you couldn't turn the bell in enough to tighten it to get a decent sound. I adjusted the bracket and now have full adjustibility, but I still can't get a clean crisp sound out of them. They still have a horn sound instead of a blast and its pretty weak if you ask me. They look to be plumbed right except for the line coming to the tee could be only a 1/4" which could be a problem.

Anyone know how to tune these things?

[lvwrench]

horny

The Grover air horns have been on our units for decades with the only problems being twofold. First they are sensitive to being adjusted exactly right for the best sound. The main problem comes from the gasket at the bell to trumpet. The gasket tends to dry out and shrink up and not provide a good seal. Try some new gaskets and soak them in a little WD40 first. Also make sure that the diaphragm is good before reassembly. The 1/4" air line should be sufficient as long as there is at least 90 psi or better.

[lvwrench]

more

I would not necessarily say that a 1/4 turn but a 1/2 to full turn. The distance from the vibrating disc to trumpet end is the key. No real way to measure that but by feel. Guess I have been doing it for so long it is second nature to me. The reason for my "expertise" is that when the guys wash to rigs and wipe them they tend to lossen the trumpet from the bell end and then can't figure out why the horn won't blow.

[wfire32]

Who's horny?

Thanks lvwrench So by saying that they are sensitive, are you talking within a quarter turn or more/less? They are brand new horns so I'm not thinking that the gaskets are a problem, but if it comes to it I will check them. One thing I need to check is the distance that the valve is from the horns. Sounds like that could be a problem if it is too far. I'm going to go screw around with them tonight. They're not even usable right now.

[metrobob]

Size matters !!

wfire32

Just curious, are these trumpets the 24" versions? Our engine has smaller trumpets (12" or 16") and they have sounded awful from delivery. We have adjusted them continously to no avail.

Good luck!

[Chauffeur6]

Oh boy, this brings back bad memories. I had to remove the bumper face off one of our engines a few years back, and it took me HOURS to get those damn horns to sound right again. Good luck brother!

[wfire32]

any hints?

Sounds like I have my work cut out for me. Is it best to disconnect one and do one at a time? Any other suggestions to expedite the process? I'm not going to get to them tonight probably tomorrow. Thanks for the help guys.

[Chauffeur6]

It might help to try one at a time if there's a valve to shut one at a time off (or you can disconnect and plug the line also). Honestly what I wound up doing was wearing foam earplugs AND isolation headsets, climbing under the truck and adjusting them slowly while someone sat in the cab giving short bursts on them. Still took a while, but it sure was better than having to get and down up a million times.

[MichaelD77]

We had the manufacturer try to tune them and they came back still sounding like crap.

That's what happens when you buy from a company that shares its name with a Sesame Street character.

[MG3610]

The sound of the horns has alot to do with the air flow through them which is a function of the size air lines and type of valve. We have the same issues with one of our rigs. We replaced the sound units and gaskets and tuned them, with little improvment. I'm going to replace the valve next.

Looking at another rig we have, it has a large (possibly 3/8 or 1/2) supply line coming in and teeing off to two grover brand solenoid valves so each trumpet has its own valve. These horns have a super loud blast to them. The sound they emit is very much like what seems standard on many pierce rigs. the clip below is what Im talking about.

http://www.youtube.com/watch?v=--oulIB78k0

Sharper sound horns in this next clip

http://www.youtube.com/watch?v=PSEILoJORfw

[wfire32]

New Quest

It sounds like this project is going to turn in to a quest for the "sound". We'll see what I can get out of them tonight.

Does anyone know how they plumb those things on Pierce's and Spartan rigs? I know I've heard those and they sound good.

Should you have to have two valves? Grover's website doesn't say anything about that.

MichaelD77 nice addition to the thread. It has nothing to do with the horn manufactuerer, its the truck manufacturer that took them apart to put them through the bumper.

[MG3610]

http://www.midcoast.com/~library/town/fire/engine2/50444.pdf

[Rescue101]

32,Couple things.First there is a little disc in the back of the trumpet that can get dislodged if you turn 'em too far.Secondly I've gotten so pi**ed at ours on occasion,I now remove them, tune them in the shop(vise)and put 'em back on when they're right.Just use a blow gun with a rubber end in place of your nylon feed line.Much easier to do incremental adjustments in the shop setting than trying to adjust under the rig.At least alone which is generally where I am when the damn things need adjusting.And yes,they are VERY sensitive.A 1/16 of a turn will make them sound lousy. T.C.

[Fire304]

101 you beat me too it. With a blow gun you get a lot less air so its not as loud and you control it. You can also stuff a rag into one trumpet (hold it with masking tape) and tune the other.

That damned little rubber washer between the the diaphram housing and the base keeps falling out if you back them off too far. A little dab of grease will help keep it in place if that happens to you.

Also, if it's just not getting better, the diaphram may be damaged. They are relatively thin and fragile, can be torn or dimpled.

[Chauffeur6]

Trouble is, most trucks today have the horns in the bumper with the flared bell end bigger than the cutout in the bumper facing. There's no way to tune them off the truck, because you have to remove the trumpet from the sound unit to remove/install them.