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RTR Upgrade
Part No:
Price Ex VAT @ 20%

AVAILABLE This part is available to order

Image 1

Proximity Sensor for electronic Speedometer. For those wishing to personalise their installation we supply RTR8558-2 proximity sensor which when mounted on a bracket will count the passing of something metal, usually a bolt head such as a prop or disc attachment bolt.

Whilst the use of a bolt head might provide an adequate signal, the prop bolts in particular are arranges in a rectangular pattern, This sensor requires a square pattern such as the disc attachment bolts. The best option when using the prop-shaft is to use some angle steel to produce two tabs on diagonal corners of the flange to produce the equal spacing required. this is important as the speedometer may not work or work erratically whilst the trip counter will work normally leading to an erroneous assumption that the instrument is faulty. when a rectangular pattern is used the speedometer pointer will vibrate at lower speeds and wander around, sometimes dropping to zero and speed increases, whist the trip and odometer still clocked correctly. The cause is unequal bolt spacing on the prop flange (bolts in a rectangular pattern) What happens is that the speedo gets a short and then long pulse and so on, confusing the instrument. The total number of pulses remains the same though so clocks the Kilometers (miles) correctly. The fix as mentioned above is to fit some tabs to the diagonal corners of the flange so that he instrument reads two bolts per revolution. 

This unit RTR8558-2  provides an output to drive the speedometer in the same way as RTR8558-1.

We do not provide a mounting bracket with this part as it can be mounted in many locations to suit customers preference. 


our direct fitting counting sensor RTR8558-1 which screws into the speedometer cable output drive of the gearbox or overdrive is available too for those who prefer a ready fit option

Our electronic speedometers come with manufacturers fitting instructions however additions helpful notes specific to a TR installation are to be found in Information sheet IS0061, downloadable by pressing the 'Further Reading' tab above.

 More advanced technical information

The maximum gap for reliable use is around 4 mm  the minimum is 0 mm. Due to these units being micro metal detectors as opposed to reluctance sensors they are very forgiving regarding spacing.
There is also a maximum sensor frequency of around 2500Hz, or 2500 pulses/second. Depending on setup the speed of the signal will vary, but it would have to be an odd setup to find the limit. With 4 or 8 pulses on the prop there will never be an issue. with 4 bolts and 3:1 diff and average small wheels the frequency is only 166Hz at 60 MPH.

Electrical systems, Instruments etc.

No catalogue plates are available