Frequently Asked Questions

Who are CAI?

CAI is the oldest established automotive gauge maker in the world, and the UK's largest independent. We supply such prestige marquees as Aston Martin, Rolls Royce and Lotus. CAI was formerly the SMITHS Instrument Company, which was the supplier of choice for the classic British Sports cars of the 50's, 60's and 70's, such as MG, Triumph, Jaguar and the AC Cobra, our pedigree is impeccable. The products that you buy have been designed for and tested by the most discerning of customers.

What happens if I run into trouble during installation of my gauge?

Firstly, we should say that we've tried to avoid trouble for you by:-

  • Having clearly written instructions
  • Having a comprehensive range of matching sensors
  • Supplying adapters and bushings with all our senders to accommodate the most common thread types.

However, if you do get into trouble, then help is only an e-mail away at technical@caigauge.com

My car already has senders fitted, do I need to buy new to go with my gauges?

The answer here is "it just depends". Around the world there are 3 or 4 different electrical standards for gauges and senders. The standards are normally expressed in terms of their ohmic values at the low and high end of the scale shown on the gauge. So a typical European standard would be 10 ohms at empty and 180 ohms at full for a fuel gauge/sender combination. In North America you may find gauges that are 240 ohms at empty and 33 ohms at full.

CAI follow the European Standard, so if you have compatible senders, then that's fine. If you don't then you will need to buy matching senders from us, and although we've used a fuel gauge as an example, the same is true for all electrical temperture and pressure gauges.

What's the best way to pick up a speed signal from my electronic speedometer?

There are several ways of picking up a speed signal, but some are definitely better than others, our recommendation, in order of preference would be:-

  • If your engine is of recent manufacture with electronic management then you can collect a very clean, precise signal from the electronic control unit of the engine management system, and you also avoid the need to buy and fit a sensor.
  • If you engine was originally fitted with a speedometer, then you will have a mechanical take-off for the speedometer cable. Here you could fit a hall effect device, which uses the mechanical take off to generate an electronic signal, or you can use a magnetic sensor kit as described below.
  • If you engine came with neither a speedometer cable take off, nor an electronic engine management system, then you will have to use a magnetic sensor, to count the revolutions of the prop shaft or the revolutions of the road wheels. CAI offers a magnetic sensor kit which can be ordered when you purchase your speedometer.
  • we can also supply GPS devices that will provide a pulsed input into your speedometer, you will need to check whether this is an accepted method of speed measurement in your country 

Detailed fitting instructions are available for the sensor kit via LINK

What preparations do I need to make prior to installing my instruments?

The most important rule is DISCONNECT THE BATTERY, before attempting any electrical connections.

Can I get my gauges repaired and/or speedometer re-calibrated?

Yes, for all gauge repairs and speedometer re-calibration we can quote you or direct you to one of our nominated repairers

Still not got the answer you were looking for?

Don't worry, our technical team are on hand to answer any of your questions
e-mail: technical@caigauge.com