1985 Code 3 XL - Belt Tension too High, Seizes Motor - HELP!

BartMaster1234

New Member
Jun 9, 2019
11
San Francisco, CA
Hello.

I was bored in Las Vegas a few weeks ago so I visited the local junkyard. I found a mid-1980's ambulance that was used as a mobile billboard for a literal ambulance chaser law firm. Was a time capsule walking into the back of it, everything was beige, brown, or woodgrain.

Anyway, I took the light bar it had on the roof. According to the date code on the motor, it was manufactured on October 17th, 1985. It's a Code 3 XL. I took it home and only one bank of lights would rotate, while the other was seized. It's an old belt driven design with a worm gear motor driving a pulley which were connected via belt to two light rotators.

I noticed if I kept it on for longer than 30 seconds, the belt tension would become so high that it seizes the motor and prevents it from spinning anymore. If I give it a nudge with my hand, it releases the tension and it starts spinning again. I tested with two different types of power delivery, 14v directly from the battery harness on my Tacoma holding 3,000 RPM, as well as a normal independent car battery on a test bench at 12v. Same result.

What is causing the motors to seize the the high belt tension. I tested the motors with no load (belt and rotators) and it spun fine, no issue. I tried messing with the belt tensioner, but it did nothing. I took the rotators apart, lubricated the shafts, and all moving parts - but it was no help.

Any ideas on how I can fix the belt seizing issue? I just want them to spin freely as you can imagine. Video below.


4R34RRRR.jpg34R34R.jpg
 
Dec 17, 2018
85
TX, USA
Man, that would be awesome to find at my local boneyard. I'd really enjoy going through a few of them.

Didn't know they took ambulance chaser so literal.
 

Pete L.

Member
May 21, 2010
2,575
Virginia (south/central)
It's been awhile since screwed with the SD/XL belt drive bars. I seem to remember that there
was a tensioning screw on that transmission attached to the motor. Worth checking it out
 

BartMaster1234

New Member
Jun 9, 2019
11
San Francisco, CA
It's been awhile since screwed with the SD/XL belt drive bars. I seem to remember that there
was a tensioning screw on that transmission attached to the motor. Worth checking it out

So you're saying I can adjust tension on the motor itself? I tried adjusting the actual belt tensioner but it didn't do anything.

I ordered some newer Code 3 rotators that are direct drive so I can get this thing working, but it isn't as cool as the belt driven one.

Man, that would be awesome to find at my local boneyard. I'd really enjoy going through a few of them.

Didn't know they took ambulance chaser so literal.

I travel to junkyards for a living and I've only ever seen two ambulances. The first one was pretty stripped, nothing left although it was a modern 2000+ one. This one was a 1985 era model and it was almost untouched. People were only interested in the engine parts, everything else was like a time capsule. There were still things inside the glass cabinets inside the cab area of it.
 
May 21, 2010
1,256
Minnesota
My first guess is that the belt is a bit stretched and lost its flexability. I did see the belt jump a little indicating the teeth are not lining up.

If you loosened the tensioner and nothing, it may not be functional. Did you take the motor off and check the underside of the tensioner for movement or the guide wheels under it too?

Old grease on moving parts can actually become sticky. It woukd be good to throughly remove it all before using a new, light lubricant.
 

BartMaster1234

New Member
Jun 9, 2019
11
San Francisco, CA
My first guess is that the belt is a bit stretched and lost its flexability. I did see the belt jump a little indicating the teeth are not lining up.

If you loosened the tensioner and nothing, it may not be functional. Did you take the motor off and check the underside of the tensioner for movement or the guide wheels under it too?

I did take the motor off and checked for play in the driven gear, but it was fine.

The tensioner seems very simple, it's just that plastic gear on a swinging arm. It didn't seem like it had excessive play. I even removed the tensioner completely from the equation and it made no difference.
 
May 21, 2010
1,256
Minnesota
Removed the tensioner and it still rotated? The belt makes kindof an S under the motor (around the motor then around the tensioner wheel). How did you run it without that? I must be missing something here.

You could try and run the motor with no belt, use your fingers to lightly pinch the drive gear while it spins if it stopps then the issue is within the motor (in other words, putting a little load on the motor while removing all other potential problem points). I doubt that both are bad, that and those belts are making a lot of noise indicating high tension and or misalignment.
 

BartMaster1234

New Member
Jun 9, 2019
11
San Francisco, CA
Removed the tensioner and it still rotated? The belt makes kindof an S under the motor (around the motor then around the tensioner wheel). How did you run it without that? I must be missing something here.

You could try and run the motor with no belt, use your fingers to lightly pinch the drive gear while it spins if it stopps then the issue is within the motor (in other words, putting a little load on the motor while removing all other potential problem points). I doubt that both are bad, that and those belts are making a lot of noise indicating high tension and or misalignment.

I just unscrewed the set screw for the tensioner wheel and set it to the side so that it applied no tension to the drive belt. Removing the wheel or adjusting it makes no difference.

I did try the motor without a belt, it will spin forever no issue. I even put the belt on let it spin on my finger, no issue either. The issue is that when connected, it builds up so much tension after X amount of revolutions it just seizes the motor from the sheer amount of tension. If I release the tension by nudging the rotator, it works again. However it'll only spin for maybe 30 seconds before the issue repeats.
 
May 21, 2010
1,256
Minnesota
With the video you posted and your last post I suspect the belt has shrunk and the teeth are trying to jump gears. With it being so tight they can't jump because there's not enough room for them to walk from one the next. When you move it by hand you can see it looks like it makes a good jump and then continues to rotate until the tension builds up again. That along with being able to see the belt shake between the two lightheads and the noise it makes. If it were me I would get new belts as that would likely solve that issue.

Another post says these are the belts for it.
 

BartMaster1234

New Member
Jun 9, 2019
11
San Francisco, CA
What the video you posted and your last post I suspect the belt has shrunk and the teeth are trying to jump gears. With it being so tight they can't jump because there's not enough room for them to walk from one the next. When you move it by hand you can see it looks like it makes a good jump and then continues to rotate until the tension builds up again. If it were me I would get new belts as that would likely solve that issue.

Another post says these are the belts for it.

Wow! They still sell the drive belt for it?

Is that the exact one I need? I don't know if all the Code 3 XL models are the same.
 
May 21, 2010
1,256
Minnesota
I found that belt by searching through the postings here quite a while back. Although I have not purchased it, I was told that's the one that fits my bar. The lightheads are opposite and not offset on mine. Dont think they changed the drive gear size for those but I have seen stranger things.
 

BartMaster1234

New Member
Jun 9, 2019
11
San Francisco, CA
I found that belt by searching through the postings here quite a while back. Although I have not purchased it, I was told that's the one that fits my bar. The lightheads are opposite and not offset on mine.

Thanks for the help, I'll go order some new belts. I figured this this was so old and only meant to be used on a fleet for such a short amount of time aftermarket support is non existent. I already bought some modern Code 3 direct driver rotators, I just don't like them as much.


Looks like Gates makes that belt on Amazon, I ordered two I'll see if it solves my issue.


Dont think they changed the drive gear size for those but I have seen stranger things.

Oh yeah, the newest season is great!
 
May 21, 2010
1,256
Minnesota
Please update us when you get that belt installed, I'd love to know how it works out. As for those rotators you bought, those are just standard MX rotators. Unfortunately people list those for other bars like the lp6000 also. They are so under sized for your bar and others. I guess at the end of the day they'd be better than nothing at all but I don't think I would put them in yours or some other bars.
 

BartMaster1234

New Member
Jun 9, 2019
11
San Francisco, CA
Please update us when you get that belt installed, I'd love to know how it works out. As for those rotators you bought, those are just standard MX rotators. Unfortunately people list those for other bars like the lp6000 also. They are so under sized for your bar and others. I guess at the end of the day they'd be better than nothing at all but I don't think I would put them in yours or some other bars.

I haven't actually seen them yet, they're coming in a few days. Figured I'd put one in the siren cage since it's empty on my bar. I have some Whelen Blue/Red strobe pods I figured I'd throw in there too.

I really want to find a Blue Code 3 XL lens so I can make it a police spec'd bar. Just looks cooler than solid red. They're so hard to find though.

This is just a stupid thing I'm going to hang on my wall in the garage and rig it up to a button.
 
Jun 18, 2013
3,709
PA
300XL025 is the correct belt for the XL 9000 series bars.

The issue your having is 1 of 2 things.. the belt is installed improperly, or the belt is shot and needs to be replaced. Make sure that everything spins freely, and apply lubrication if needed on the guide wheel and rotators.

There are a few guides out here on elb.. I have created at least 1 dealing with belt installation issues.
 

BartMaster1234

New Member
Jun 9, 2019
11
San Francisco, CA
Please update us when you get that belt installed, I'd love to know how it works out. As for those rotators you bought, those are just standard MX rotators. Unfortunately people list those for other bars like the lp6000 also. They are so under sized for your bar and others. I guess at the end of the day they'd be better than nothing at all but I don't think I would put them in yours or some other bars.
300XL025 is the correct belt for the XL 9000 series bars.

The issue your having is 1 of 2 things.. the belt is installed improperly, or the belt is shot and needs to be replaced. Make sure that everything spins freely, and apply lubrication if needed on the guide wheel and rotators.

There are a few guides out here on elb.. I have created at least 1 dealing with belt installation issues.

It was indeed the belts. I bought 2x Gates 300XL025 PowerGrip Timing Belt off Amazon, about $20 for two and it solved my issue. As far as I could tell, I had the original drive belts from October 17th, 1985 on the lightbar. They shrunk from sitting in the hot Las Vegas sun for 34 years after I found it in the junkyard and drove it back to San Francisco.

Thanks for the help everyone. Happy to have it working now. I'm curious how people are getting a high amperage 12v power supply to power it at home, right now I'm using a car battery on a charger. I threw my Fluke ampmeter on it and it draws 23.6 Amps, or 300-ish watts. It drained that damn battery in 10 minutes.

Was thinking of hacking open an ATX computer power supply and using the 12v rail. I looked at landscaping light power supplies too (Fun Fact: the bulbs on this vintage of a lightbar are used as landscaping lights) but they're damn pricey.
 

shues

Lifetime VIP Donor
May 21, 2010
10,276
NW Indiana
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stansdds

Member
May 25, 2010
3,533
U.S.A., Virginia
Those PSE Code 3 bars were pretty brutal on vehicle alternators and batteries too.
Glad you got the hesitation issue fixed. These are neat light, a bit complex and, as you have found, real power hogs.
 

BartMaster1234

New Member
Jun 9, 2019
11
San Francisco, CA
Those PSE Code 3 bars were pretty brutal on vehicle alternators and batteries too.
Glad you got the hesitation issue fixed. These are neat light, a bit complex and, as you have found, real power hogs.

Kind of amazing how much power this bar draws. It got my really thick gauge jumper cables almost burning hot after being on for a few minutes,
 

stansdds

Member
May 25, 2010
3,533
U.S.A., Virginia
In new condition, that bar would draw a solid 24 amps while running. As the motor wears, dirt gets into the drive system, the belts get old and hard, the amperage goes up.
 

BartMaster1234

New Member
Jun 9, 2019
11
San Francisco, CA
In new condition, that bar would draw a solid 24 amps while running. As the motor wears, dirt gets into the drive system, the belts get old and hard, the amperage goes up.

I installed some rotators and a siren unit too so I guess that accounts for the extra few amps. I’m in the process of combining all the wires on the 12v rail of a computer power supply to power this bar. It outputs about 76 Amps.
 

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