Speedo reading accuracy?

[argas007]

Hi, how far out is the speedo allowed to read, and is it the same % error throughout the range or at specific points?

Thanks, Alan

[Justin]

Hi Alan

In the case of a modified low volume vehicle, an accurate speedometer is only a requirement where a brake performance test is required to assess the vehicles braking system. This is the relevant section, copied from the LVV Braking Systems Standard;

Other Requirements

2.3(36) Speedometers fitted to low volume vehicles must provide an
accurate indication of the vehicle’s speed, and be visible to the
driver in a normal seated position, in order to enable accurate
service brake performance testing.

There is also information covering this in the NZ Hobby Car Technical Manual;

19.2 Instrumentation & warning systems
19.2.1
A low volume vehicle must be fitted with a speedometer that:
(a) is accurate to within plus or minus 5%; and
(b) can be easily read by the driver whilst seated in a normal
driving position.

I hope this helps

Justin

[argas007]

Thanks Justin for the info.

Also if I buid a kit car using engine and g'box from the UK it would be better for me to use all the instruments with looms from the donor car (Honda S2000) not just for "looks" but because of wanting to keep all the loom and electronics standard. Is there a problem with the speedo being in mph and odo in miles?

Thanks, Alan

[Justin]

You can use whichever gauges etc you choose - but I'd say that you'd be right, and that using the complete loom would be an easier option. The speedometer can read in MPH if you choose.

Cheers, Justin

[dax]

Hi, While on the spedo subject, could you please clarify one further point Justin. Does it have to include markings in 'kph'? I have a top of the range Smiths which is only currently in 'mph' although I almost always drive on my gps indication (as my Nissan Safari reads 13% over!).

[Justin]

Hi there

Yes, your speedo can read in MPH.

It's surprising just how inaccurate some OE speedometers are!

Justin