If you are struggling to decide which sensor best suits your vehicle, please find following some tips on selecting the correct sensor.

Brantz Rally Tripmeters require a sensor to send travel information up to the instrument so that it can calculate and display just how far the vehicle has travelled.


The most suitable sensor is chosen from a few key factors pertaining to the vehicle that the tripmeter is being installed into.

The criteria are:


  1. Positioning – You don't want the sensor knocked off by flying debris on a rough course

  2. Accuracy - Different bits of the vehicle travel different distances when rallying

  3. Ease of Fitting – Do you prefer mechanical or electrical

  4. Cost Considerations - Remember the cost includes fitting time and servicing time.


The first choice is the screw-on gearbox sensor which is the fastest and easiest to fit. It has great reliability as it is not near high heat sources or in the path of flying under-car debris.


The two most common types are:


  • BR3: Japanese Gearbox Sensor: This sensor fits many Japanese cars which have the M22x1.5 gearbox threaded speedo output fitting (the rotating drive pin is round with a single ‘lug’ pinched onto one side.

  • BR4: European Gearbox Sensor: This sensor fits many European cars and also a significant number of Ford vehicles which have a M18x1.5mm thread. The drive pin is a square section and is also reversible to accommodate different drive pin length requirements.


If you have a different variation of gearbox thread than our 2 standard fittings above, please feel free to contact us with the thread, pitch and drive pin shape of your speedo-cable feed as we do stock quantities of alternative sizes.

If the vehicle has a mechanically driven speedometer but is not suitable a gearbox sensor if space is limited or on older British cars with imperial gearbox thread, then choose the BR1: Universal Speedometer Cable Sensor which fits somewhere in the length of the existing speedometer cable. This choice will require the removal of the speedo cable and cutting of the speedo cable sleeving, which is a little more effort, but is an excellent and common choice.


The first generation of cars which had an electronically driven speedometer (i.e. there was no mechanical cable) generated pulses from a device screwed onto the gearbox where the old cable once went, or from a dedicated sender built into the transmission chain somewhere. They are three-wire devices; one wire being ground, one wire being +12v power when the ignition key is ON, and the one wire we are interested in, which has a digital signal on it. The voltage on this wire if viewed by a voltmeter will go up to 12volts and down to ground a few times per revolution of the transmission. For these vehicles the part required would be a BR5: Electronic Speedo Interface. Connect this wire to the single terminal end of our BR5 interface. The other end of the interface goes to the tripmeter. The BR5 will prevent the car and the tripmeter from damaging each other. The additional feature of the BR5 (such as for some Astra cars) allows a very high pulse rate source to be divided down to a reasonable pulse rate so that our tripmeters can calibrate in the normal range. Very quick and easy to fit.


Rally cars competing on loose surfaces use a lot of wheel spin at the driven wheels. This scenario dictates that an accurate tripmeter will need to pick up from a non-driven wheel using the BR2A: Wheel Sensor. There is an expectation that this type of sensor will not have a long life due to heat from brakes and flying debris damage. For hot climates and runs with increased amounts of braking we would recommend a BR2A-HT: High Temperature Wheel Sensor which will cope with temperatures up to 120°C. Both these sensors have a 1mm sensing distance, minimising the likelihood of debris becoming lodged between the sensor and its pick-up. For situations where there is likely to be movement between the sensor and pick-ups, such as at the extremities of the wheel, we would recommend our BR2A-4mm: Wheel Sensor, which has a slightly larger sensing distance of 4mm.


An alternative positioning for our BR2A range of sensors is to pick up on flying tabs (minimum of 2 positioned 180° apart) fasted on the bolt heads of the prop shaft’s Universal Joint.


Customers may wish to fit a backup sensor (possibly of a different type, or maybe the same type fitted onto a different wheel) to cover for damage. In order to connect your 2 sensors up to the one tripmeter we recommend our BR49: Dual Sensor Switch which allows you to quickly and easily switch to your back up sensor without having to get out of your vehicle.


Vehicles which cannot use any of the above sensors such as; modern vehicles with ABS systems which only generate pulses above 7kph for their own speedometers, 4wd type vehicles and also Pre-War vehicles whose speedometer cable is particularly large or sealed to the outer sleeving. In these cases we would recommend the BRH2: Drive/Prop Shaft Sensor. These are straightforward to fit, but care should be taken to fit them in a location which does not suffer from flying debris or moves out of alignment with the suspension etc.


Another alternative if you are using a modern car; or are doing a race reccy in your everyday car is the BR57-58: CANBUS Interface. These plug directly into your diagnostic OBDII socket (usually located in the drivers foot-well) it is extremely easy to fit and remove without any mechanical or electrical effort. Simply Plug & Go. This is really only for vehicles newer than 2005. There are 2 different types of Plug & Go Inerfaces for different vehicle configurations. Please refer to our CANBUS Compatibility guide - but please note - this is not a definitive list – there may be additional vehicles we have not tested and there will always be exceptions to the rule, particularly with crossover years of manufacture. Please
consult your vehicle manufacturer for more information


Some of the modern vehicles that have the CANBUS system unavailable at the OBDII socket, in this instance we do a version that wires directly in the CAN HI & CAN LO wires BR56: CANBUS Interface, either directly or via our BRCCR: Contactless CAN Reader

N.B. Please check before purchasing that your vehicles speed pulse is fed into the CANBUS system.


If the information is not available at the vehicles OBDII Socket an alternative Plug & Go system is our BRGPS: Satellite Seeker. This is again great for rally reccy's in your modern vehicle or hire car and 4wd drive events where there is likely to be a lot of wheel spin on all wheels.


Too Few Pulses:

If your sensor set up results in a particularly low calibration figure – under 499; we would advise fitting a BR52: Pulse Doubler in between the sensor and the tripmeter to raise the calibration figure which in turn increases the tripmeter accuracy.


Too Many Pulses:

If your sensor set up results in a too high a calibration figure to enter on your tripmeter – over 999; you will need to fit a BR5-2A: Pulse Reducer between your BR2A: Brantz Wheel Sensor and the tripmeter.

If you are getting too many pulses from a sensor other than the Wheel Sensor, you would need to use the BR5 as a Pulse Reducer.


The Official Brantz brand of Rally Equipment


Tel: 0044 (0) 1625 669366

Email: sales@brantz.co.uk

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