Speedometer 407

[Nick Challacombe]

Late last year I had my Speedometer reconditioned by Speedograph Richfield and I replaced the cable.
Everything has seemed OK after the rebuild but with winter and lockdown I have done very little mileage. On the Layer Marney Tower Cup run last weekend the speedo packed up again, it was removed today and this time the cable is intact and the trip is OK but there is a plastic box behind the speedometer marked HUNTER , the maker perhaps, the speedo cable enters this box and then the speedo, I presume it is some sort of reduction gear inside the box. It is pretty mangled in the connecting female hole. The speedo head it tight to turn and I feel this has lead this time to the reduction HUNTER box being rendered useless. Please can anybody help with an explanation as to the function of the box and any idea about where I may obtain a replacement. Thank you in anticipation, Nick.

[Clive Foster]

Either a corrector gear to adjust the speedo calibration or a reversing gear when the drive turns the wrong way.

Lets the same speedo head be used on range of different vehicles without needing special calibration.

Speedograph Richfield have a variety on their website but don't give Bristol as an application.

[Nick Challacombe]

Thank you Clive for the reply, I googled Hunter, and came up with a 65H Hunter Speedo Transducer! This sends pulses to a sensor.
I then put 2 and two together and thought it must have something to do with the electric power steering fitted by GTC Engineering at Silverstone on Bristol's, then Brian Marrelli's, recommendation. It was works well but obviously something has gone wrong in the take off.
I have sent the Speedo back to Speedograph for a check over and asked GTC what I can do now.
It is under warranty so I expect very little trouble, it was obviously a faulty unit as they have fitted hundreds to classic cars of the era and before.
The power steering by the way is fantastic!