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Sensors
Manual Page |
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Before
fitting any type of sensor to a vehicle
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Connect
it up to the Brantz meter and check its' correct operation by
rotating the inner of speedometer cable types, or repeated touching
of wheel types to a metal object. Use a low calibration figure
on the meter, and watch the readouts increment. If the readouts
do not increment there is a problem which should be investigated.
Make absolutely sure that sensors are correctly connected before
turning on the meter as they will be destroyed by reverse current.
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Wheel
Sensor Installation
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Before
fitting the sensor to the vehicle, connect it up to the tripmeter
and test its' functionality by touching the sensing end many
times with a screwdriver, and note that the tripmeter increments.
A bracket to mount the sensor to the suspension strut should
be made rigid enough to prevent flexing. Bolt heads (a minimum
of four for accuracy) should pass squarely across the face of
the sensor all at a distance of 1mm (IMPORTANT). Socket head
bolts cannot be used as they cause problems. Correct fitting
of the sensor can be checked by monitoring the voltage across
the sensor with a voltmeter. When connected to the tripmeter
and the sensor is next to a bolthead the voltage should be about
2 volts. When the sensor is clear of the bolt head the voltage
should be about 4.2 volts. Check that all (four?) bolts give
similar results. If the tripmeter is put onto calibration figure
0001 then all four bolts should cause the tripmeter to increment.
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Gearbox
(Japanese/Ford)
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Most
Japanese manufacturers have standardised their gearbox outputs
to accept a M22 x 1.5 threaded sensor which has a round peg
drive with a 'lug' pinched onto the side. Unscrew the original
speedometer cable from the gearbox, screw in the Brantz Jap
sensor with the drive pin in place, and screw the original speedometer
cable into the sensor. Wiring is to the Brantz GREY cable as
follows: Green to Green, Blue to Blue, Brown to Brown. Some
Jap sensors have a different colour code and are wired as follows:
Green to Black or Silver, Brown to Red, Blue to White. Many
Ford/GMfVauxhall FiatIVW/Skoda/Lada gearbox outputs are similar
in that they have a square drive and a Ml8 x 1.5 screw thread.
The Brantz Ford/GM sensor will fit many of these vehicles but
will require some degree of filing/cutting/drilling before they
are an acceptable engineering fit. Select this sensor only if
you have the skills to do this. Wiring is the same as for the
Jap sensor above.
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Japanese
Gearbox
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Ford/GM
Gearbox Sensor
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Universal
Speedometer Cable
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This
plastic unit fits in the length of almost any speedometer cable,
though some old cables require holes to be slightly enlarged
due to 'chunky' cable dimensions, and some modern speedometer
cables need ingenuity to dismantle them as manufacturers seem
to want to prevent customers from separating the inner from
the outer. Generally with the so-called 'sealed' cables, a section
of sheath from the centre of the cable should be removed first
to obviate the fixing system used on the ends of the inner.
Replacement lengths of sheath can always be put back in after
the cable has been separated. Heat-shrink sleeve, particularly
the type which is adhesive-lined makes easy repairs to segmented
sheaths. To assist with fitting, a cross-section of the universal
sensor is shown. Note that the rotor floats in air and puts
no additional strain on the speedometer drive, but this construction
demands that the sensor should not be subjected to 'end thrust'
which could be produced by a worn cable, or being fitted on
a bend in the cable. Modern sensors can be stripped to help
with fitting in difficult cases. Connections are Brown to Brown,
Blue to Blue; Green to Green.
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Universal
speedometer cable installation
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Directions
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1.
Remove inner core. Cut through the outer sheath at the location
of the sensor with a fine toothed hacksaw. 32 teeth/inch recommended.
2.
Make a second cut through sheath to shorten the sheath by 1/2
inch (13mm).
3.
Remove any burrs with a fine file.
4.
Wipe off any excess grease and any metal debris from the inner
and the outer, and re-insert the inner which has an enlarged
end through its' section of sheath.
5.
Place clamps (Jubilee clips or preferably screw type petrol
hose clips) on to both ends of the plastic sensor.
6.
Insert the loose end of the speedometers cable inner into one
end of the sensor and push very firmly through the sensor's
internal friction bushing until the sheath section is fully
seated in the sensor. If your speedometer cable sheath is of
a smaller diameter than can be easily clamped by the sensor
then build up the diameter of the sheath with adhesive aluminium
tape. Tighten the clamps moderately.
7.
Feed the loose end of the inner through the last piece of sheath
until it is fully inside the sensor. Tighten the clamps moderately.
If you do not wish to use clamps, they could be replaced with
adhesive lined heat-shrink sleeve.
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Trouble
Shooting
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If
it is suspected that either a wheel or speedometer sensor has
been damaged in service (ie tripmeter does not increment on
the road) then the output from the sensor can be tested with
a voltmeter (voltage varies as wheel or sensor is rotated 2
volts to 4 volts). Alternatively the tripmeter itself can be
proven to be OK by the following test which must be carried
out strictly in the order described, a) Switch off the meter.
b) Pull off the three push-on connectors from the grey cable
to the sensor. c) Ease back the insulating sleeves from the
Blue and Green wires of the grey cable described in b). Keep
these away from contact with anything else. d) Select calibration
001 on the tripmeter. e) Switch on the tripmeter. f) Press all
the zeroing buttons. g) Tap the above Blue and Green wire connectors
together electrically many times. The tripmeter should increment.
If it does, and there is no increment during normal use on the
road with the sensor connected, then the sensor has indeed been
damaged and the tripmeter itself is still functional. The other
type of misoperation from which a tripmeter can suffer is self-stepping
whilst the vehicle's engine is running, or self zeroing, or
readouts going on and off by themselves. Assuming the power
supply is reliable (try powering the meter directly from a separate
battery placed temporarily in the passenger area) then suspect
powerful radio interference from home-made H.T. sparkplug leads.
This is particularly common with historic vehicles. Replace
them with standard proprietary parts from an accessory shop.
Testing for interference is easily demonstrated using a portable
radio on the AM band (important). Tune away from the stations
into a quiet frequency, turn up the volume, then start up the
engine. Listen for loud clicks. That's interference which should
be cured, as it is far too powerful to defend against with screening
etc. Vehicles with interference will normally fail pre-event
scrutineering.
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Pre-Scaler
Interface
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This
interface is intended to safely drive Brantz meters from digital
pulse supplies found on vehicles fitted with digitally pulsed
electronic speedometers or tachographs and as such, substitute
for other types of motion sensors. Some types of ABS sensors
are suitable as inputs to the interface, though some ABS systems
do not generate a speedometer pulse until they reach a certain
speed and so are not capable of accurate work Check with your
car supplier. The three push-on connectors on the right of the
device are colour coded to match the wires inside the GREY cable
coming from the Brantz meter. The single push-on connector on
the left of the interface will respond to digital ground pulses
coming from the vehicle. Confirm suitability with a voltmeter
before connecting the interface to the vehicle's pulse wire:
Low signal = less than one volt, high signal is greater than
4 volts positive with respect to ground. Analogue sources are
not suitable. Check that the signal occurs at very low speeds
as well as at normal.
The rotary switch on the interface sets the prescale ratio and
should be greater than zero. The lower the prescale ratio is,
the greater the meter accuracy will be, but this facility is
provided to compensate for very high pulse rates which would
take the Brantz meter out of its normal calibration range of
up to 999. If the meter calibration is out of range, rotate
the prescale ratio above the normal setting of ONE. Prescalers
version 6 also have a SENSITIVITY control under the Prescale
Switch. This control adjustment should normally be placed about
centrally in its' range, but rotated anticlockwise it allows
desensitization of the input threshold which could be useful
in hostie environments, and in its' clockwise direction, the
interface is sensitized to lower voltages which can permit some
types of ABS-derived speed pulses to be detected a little more
reliably than would otherwise be possible. Technical information:
Drain on the vehicle's sensor is less than 0.5mA, TTL Compatible.
Interface current consumption is less than lOmA. Input is 'dioded'
to prevent interaction of the interface and the vehicle if the
meter is switched off. Divide ratio = figure on the rotary switch
(1 to 15) zero is not valid. Power source from meter is 5 volts,
interface is not protected from reverse connection. Output is
open collector.
Hall Effect :
Special sensor for generic detection of rotating shafts to provide
distance sensing for the Brantz range of odometers.
This sensor type is a fall-back fitment to be utilised when
the more easily implemented standard types are unuseable and
requires some level of interpretation for each individual situation.
Select this sensor option only if you are able to provide some
amount of engineering expertise and originality. The detector
section of the standard universal speedometer cable sensor is
wired as normal to the Brantz odometer's sensor wires (usually
in the grey cable) green to green, blue to blue, brown to brown.
BEFORE fitting to the vehicle is attempted, demonstrate the
functionality of the components IN THE HAND by wiring to the
Brantz odometer (on a low calibration figure) and pass the white
end of the magnet across the white dot of the sensor. See the
odometer increment. Do not proceed to the fitting stage without
this test.
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The
sensor has a detection spot which has been highlighted with
a white dot. The actual package appearance of the sensor may
differ from the picture above. The supplied magnet has a painted
white dot on one end which must pass the sensor dot at about
5mm distance. The magnet must be attached to the rotating shaft
so that the white end is pointing radially out from the shaft.
A non-magnetic band (such as aluminium) could be fabricated
to wrap around the shaft and magnet, and a holding compound
such as sanitary silicone sealant could be used to prevent looseness.
Two or more magnets could be used to increase vehicle accuracy.
The black sensor should be provided with a mounting bracket
which moves around at the same time as the axis of the rotating
shaft so that gaps are not varying unduly. If a metal rod is
used as a mounting, the rod can be pushed into the tubular section
of one of the sensor types and can be clamped in place with
a jubilee clip or similar. Check the output on the blue wire
with a voltmeter when everything is connected up to show that
a voltage change occurs (0volts to 5volts and back etc) as the
magnet passes the sensor. Wiring colour codes to the Brantz
GREY CABLE for the sensor are: Green to Green (or Green/Yellow),
Blue to Blue, Brown to Brown (or to Red). Information regarding
the use of Brantz odometers is available on www.brantz.co.uk
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Wheel
Sensor Installation
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Before
fitting the sensor to the vehicle, connect it up to the tripmeter
and test its' functionality by touching the sensing end many
times with a screwdriver, and note that the tripmeter increments.
A bracket to mount the sensor to the suspension strut should
be made rigid enough to prevent flexing. Bolt heads (a minimum
of four for accuracy) should pass squarely across the face of
the sensor all at a distance of 1mm (IMPORTANT). Socket head
bolts cannot be used as they cause problems. Correct fitting
of the sensor can be checked by monitoring the voltage across
the sensor with a voltmeter. When connected to the tripmeter
and the sensor is next to a bolthead the voltage should be about
2 volts. When the sensor is clear of the bolt head the voltage
should be about 4.2 volts. Check that all (four?) bolts give
similar results. If the tripmeter is put onto calibration figure
0001 then all four bolts should cause the tripmeter to increment.
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