Expert Fitting Service

Bel LaserPro 904 Laser Jamming System.

Above: Control unit

The New Bel LASERPRO 904 is the first system to come out and offer both front and back jammers. In the box are three transponders, two of one type for the front of the vehicle and one of another type for the rear of the vehicle. Wiring looms, 3 port interface unit to join the heads together and 12v power and a remote display unit that can either be cut in to the dash or mounted under it. This controls the transponders and gives the warning and status. You also get a pack of screws, cable ties and level.

The operating instructions are not bad giving a clear description on how laser works and how the system works. Installation instructions come in a form of a sheet, fairly basic and giving just enough information. They give a clear warning that they recommend a professional fit the system. The only connection to the car is positive and negative (Earth) so if you are okay with this, the rest of the system is all joined together by connector's.

Bel 904 headBel 904 Head
Above: Front Unit, Mounting bracket has plenty of movement
for fitting but does make the heads bigger than they need to be

Fitting the heads is going to be the hard part, the two front heads come with brackets to allow you to mount them, There is plenty of movement for getting them horizontal however on my car it is a major operation as the heads are quite big and the smooth flow of the front of my car does not lend its self to this type of device, I would expect to have to build extra brackets. Before you spend out make sure you have a space to fit them and make sure also its in discrete position as police officers are starting to get wise to jammers. In the kit you get a small level to set them up with as they must be horizontal so when you do do the final adjustments make sure your car is loaded as you would have it and also on a level surface. The level is not that great to use and in a confined space could be next to useless.

Bel 904 rear head
Above: The single rear unit. Mounting brackets are all ready fitted,
they have no adjustment apart from bending the
metal bracket, a poor design.

The rear jammer is a little easier to fit but only if your number plate is vertical, any slope and the ready fitted bracket is going to have to be bent to shape there is no adjustment.
If you fit it where its suggested it is going to stand out on your car, if you can get it behind something looking through a gap that would much be better.

The first thought is why they only give you one rear jammer but they need two on the front. There are more areas to reflect laser back on the rear than on the front so my main concern will be if the one head will be up to the job on a UK spec vehicle which has reflector's and also a reflective number plate something the USA does not have. You can also see that the rear head has been made for USA style number plates so is not as easy to fit on UK plates without remounting the number plate.

Both the front and rear heads must be fitted in the positions suggested in the guide to give you the best protection. Failure to do so may compromise the effectiveness of the jamming heads.

All three head have a good length of cable on them and would not pose a problem on large cars. The three heads then join an interface hub, this links the heads to the control unit and also power from the car. Overall there is plenty of cable, grommet's and other parts that you should not need to buy anything else.

The parts are well made, and look tough, however the plastic cases are one piece so if you get damage to the laser face you are going to have to replace the whole case, I expect this is also something you will not be able to do yourself, its going to be a return to base.

The Jamming heads use multiple IR. diodes, (16 front, 8 in each unit, 8 rear).

On turning the system on it goes through a self test first and will tell you if there is a fault with the front or back heads, it won't tell you however which front jammer is faulty just that the front is not working. The front and rear units are both identified by red LEDS on the control panel, why they never used deferent colours I don't know.

When they are in the jamming mode they stay jamming as long as the laser gun is pointed and fired at them, there is no shut down time. Bel suggest you shut down after 5 seconds.
The way you are supposed to use the system is to check your speed when you get the alert, slow down if needed and then shut down the system to let the police get a speed reading, so remember to fit the control unit where can you see it and easily reach it. The volume of the alert is loud and clear, the lights on the display are easy to read.

The control box also has a disarm button and dark button, disarm is to kill the jammer side rather than power down the unit and the dark button controls the brightness of the display. One thing I did notice the control box is the same size as the Bel 966 control box.

So overall the kit is quite well made, but not well thought out, size of the heads may well be a problem as we have said, brackets are not that versatile and the rear unit is just not designed to be discreet or very adjustable and I would suggest that if you can go and have a look at the kit before you buy it. Remember not all mail order companies will let you return the box once its been opened so please be careful.

So did it work...... ?

We do our tests in two ways.

Part One is on a road that is quite bumpy and gives us a view of over 2000ft we do several runs on this road and we are quite strict, get a speed and the unit fails. Speeds of 30 and 60 mph are used.
Part Two is off a bridge on a major road so we can conduct tests at 60 and 80mph. Again if we get a speed it fails. The bridge also gives a harder test for the jammers. Most speedtraps you will see are on bridges. Two cars were used, one large MPV and one small car.

Given the fact that the Bel 904 has two heads front and one back we do tests in both directions for the trial.

On both tests the Front Transponders did the job, they prevented us from obtaining a speed.

However the Rear Transponder did not prevent us from getting a speed at all on our large vehicle. We re-inspected the Rear Transponder setup, just to make sure we had not fitted it incorrectly but after several more runs, we found that the Rear Transponder was not up to the job. The rear transponder was fitted to a large people carrier, further tests a few weeks later on a Porsche 911 have shown that the rear transponder will jam. We believe the jammer will work but its dependent on the size of vehicle and the type of body.

IMPORTANT NEWS: 15 Aug. 2002..... Its looking like it could be car and laser gun dependent regarding the rear transponder. We suggest you talk to the dealer for advice.


This system is also known as the "Escort Laser Shifter ZR3"

Review 12th June 2002


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