My aquired Q

[JasonC]

Low power as in not enough with my alternaor. I need a high amp alternator for that q. Works good enough as I don't realy need it. The model 78 has a smaller stator and rotor. I imagine it doesn't need as much as the ten inch Q. The power required for the Q to spin up has to be more than the model 78. Smae exact motor though. My 78 had a little cover that attatched arround the comutator to keep water out. My Q didn't. It has the chrome shroud. I removed the shroud and swaped the plate to the Q so I could use the same mount. Same motor exactly!

Yea, they both did use the same motor. Your Q should run fine for short bursts, regardless of your alternator's power. You need a good battery and a large cable ran to the siren. Mine ran flawlessly from my old '88 S10 Blazer. It had a 66 amp alternator along with a small car battery and a 12 AWG cable between the two, so there definitely wasn't a beefy power system. However, my Q peaked in no time and worked great the few times I played with it. Unlike a fire truck however, if I were to go over a minute or so cycling the Q, yea, I'd overtax my electrical system and I wouldn't have enough power. But for short runs, anything will work really. Are you planning to run code with the siren?

[JasonC]

Also, you mention your 78 is missing the end piece. Are you talking about the chrome motor cover? If so, it probably came like that. Sirens that were specked out to be flush mounted with the cab or bumper, thus did not come with a chrome bullet housing. A Q siren without the chrome housing is known as a Q1A or Q1B. Mechanically the same though.

[Robert Gift]

Low power as in not enough with my alternaor. ... The model 78 has a smaller stator and rotor. ... The power required for the Q to spin up has to be more than the model 78. ...Same motor exactly!

Neither of the motors list a peak rpm, do they?
How many ports are in the Q? (Years ago I counted but have forgotten.)
You listed the ports on the 78 as 8/9. (Surprised FS doesn't call it a Model 89.)
I'd love to know the peak pitches of your two sirens, but that would be difficult to attain in town.
As a reservoir, the battery can be partiallly drained to power the Q.
During the off periods as the Q coasts, the battery is being replenished.
As Jason says, have a heavy enough conductor to the motor.
Ha! I remember in 1976, when I drove our FD ambulance (a van converted to an ambulance) to the hospital, the engine always started when we left.
Others, who were not sparing with the Q, often needed a jump to start the engine to leave the hospital. Embarrassing

[q2bman]

Ya, the motor cover and the front cap. The one that goes over the motor stator on the intake section. The siren I got is a model Q1A. It has a chrome motor "bullet" cover. I wounder if someone put t on to make a Q2A??? I assume the "b" is for brake, which mine dose not have. The thing coasts for mins! And ya, I've got the same power wire i put on for the 78. It's #6. I think #6 would work better. It winds up slowly. But sounds nice and loud! On your Blazer, did it wind up slow? I have about the same electrical supply.

No, I don't see an rpm lable anywhere. I would gues high though. It realy spins! I will have to cout the ports for you. I would guess 12. That video I made of the 78 on my Jeep comes close to peak rpm for my electrical system.

http://www.youtube.com/watch?v=pC0gLz8ov5o

I'll have to video the Q.

[Robert Gift]

Ya, the motor cover and the front cap. The one that goes over the motor stator on the intake section.

I'd remove that cover anyway to reveal their beautiful spiral rotor fins!

I assume the "b" is for brake, which mine dose not have.

Yes! I would not use one, anyway. Love the lengthy coast-down.

It winds up slowly. But sounds nice and loud! On your Blazer, did it wind up slow? I have about the same electrical supply.

With big battery and sufficent wire, it should quickly wind up. The alternator determines how many such cycles can be accomplished by how fast it can replenish the batteries.

No, I don't see an rpm lable anywhere.

Do they even rate DC motor rpm?

I would guess 12 [ports].

I think more!

That video I made of the 78 on my Jeep comes close to peak rpm for my electrical system.

It should still attain peak rpm, just more slowly.

I'll have to video the Q.

Will like to see it.

[JasonC]

I've never heard a model 70 series siren speed up instantly. Nor any older Q's for that matter. Who knows, they are just general starter motors powering the siren. I can't remember exactly, but I think the Q has 13 or 14 ports.

[q2bman]

I found the problem. The clutch assembly is the older style and is worn out. It causes the motor to rev faster than the rotor. The siren never gets to full RPM. I'll replace it with a newer style I have. My model 78 has the old style clutch which is basicly two large rough metal washers rubbing together when the screw shaft spins up. This works fine on the 78 since the rotor is much smaller and lighter. No on the beafy Q! It needs the newer style clutch.

[Robert Gift]

Congratulations! Now it will get even louder.
How is it that you happen to have the newer style clutch?
Good job!

[q2bman]

I got some old model 78 parts and the newer clutch was with them.

I have run into another issue though. The dang siren is so old I can't get the old clutch off of the shaft. The nut is fused to the shaft and there is nothing on the old Q's to hold onto with vice grips. The newer Q sirens have a shaft on the rear. This old man has nothing. I'll have to remove the rear peice.

[Robert Gift]

...The dang siren is so old I can't get the old clutch off of the shaft. The nut is fused to the shaft and there is nothing on the old Q's to hold onto with vice grips. The newer Q sirens have a shaft on the rear. This old man has nothing. I'll have to remove the rear peice.

Can you soak the shaft nut in penetrating oil and also heat and cool it a several cycles to free it?
Or is it actually welded to the shaft?
If you use vice grips, can you use wet leather between the jaws to prevent scarring the shaft.
I'd much rather have an old Q than a new one!