speedometer adjustment

[Francis]

Hello guys,

Does anyone know if it is possible to adjust the speedometer in my series 2 E-Type?

My speedometer runs about 10 km/h too fast at 60 km/h and 20 km/h too fast at 120 km/h.

I think the proportionality is constant. I took it out, disassembled it, did a good cleaning job of all parts but I did not see or figure out how to adjust it, if possible.

Any suggestions?

Francis

[abowie]

Speedo calibration is a combined effect of the magnets and spring inside the instrument.

Best thing to do is send it to Speedograph Richfields in Nottingham. They will service and calibrate it for around UKP70.

[Heuer]

They will need to know your diff ratio and tyre size to calibrate. Shttp://etypeuk.com/forum/viewtopic.php?t=186&highlight=speedographee here:

[MLBS3V12]

Hi David
The link http://etypeuk.com/forum/viewtopic.php? ... edographee" you have indicared does not work.
Is there something wrong in ?
I m also interested with this topic as I plan to use a Getrag 5 with a 2.88 diff on my s3.
Regards
Michel

[MLBS3V12]

Found.
There is an "s" just before http......

[Francis]

Thanks for all the suggestions! I will probably send it out for re calibration. I did install a 5 speed Borg Wagner in it. This may be the reason for the discrepancy.

Now I also installed a 123 Ignition distributor. When I turn the ignition on, the needle shoots to the other side of the gauge. Once the engine is on, it seems to go back to normal. Last week, on the highway, in 5th gear (yes, it is being used!) I was traveling at 120 kms (about 70 mph) and the revs indicated was 1800... It seems to me to be a bit low. How can I check the accuracy of the tachometer and, or how can I get rid of the slam at first contact?

[Heuer]

You can use this calculator to work out what your speed should be for a given rpm: http://wahiduddin.net/calc/calc_speed_rpm.htm Great little tool!

Changing to a 5 speed gearbox should not affect your speedo calibration, which is dependant on the final drive ratio. Could be your speedo has been swapped for another or your diff ratio has been changed. You can use this table to check your speedomter reference number: http://etypeuk.com/forum/viewtopic.php? ... ter+number

To give you an idea our OTS is fitted with a 5 speed box and 2.88 diff with 185 tyres. 3,000 rpm in 5th is 100mph measured with a SatNav. In your car 1800rpm = 70mph which means at 5,000 rpm the car should be capable of 194mph! I think your tachometer is under-reading but first you need to check your speedo with a SatNav, or a Police radar trap

No personal experience of using a 123 in an S2 so maybe someone else can chip in or post the question on the 123 Forum.

[christopher storey]

The tachometer in an S2 is an electronic one of the early RVI design I think, which is generally speaking incompatible with electronic ignition. It works by counting the pulses in the ignition system , and did this by an inductive double loop of the white ignition supply wire being attached to a sensor on the back of the instrument. The sensor circuitry, and the needle itself is powered by a green wire from the fuse box . There is a potentiometer incorporated in the circuitry which fine tunes the system to the ignition system and this is usually hidden under a rubber bung in the back of the instrument . Whether you can get it to work properly with 123 is rather a matter of chance, and the full scale deflection on switching on is probably a function of the 123 circuitry rather than a defect in the tacho itself . There are susbtitute circuit boards available for RVI type tachos which convert them to the later RVC type, but whether these work with 123 I do not know

[Heuer]

Found this information for you:

"My ignition was also equipped with a ballast resistor. I removed the ballast resistor and purchased a good quality 3 ohm coil. I ran a separate and fused line directly from a separate switched 12 volt source to the 123 distributor (in other words, there is no positive connection between the coil and the 123 distributor). "

"This is a common problem with Smiths RVI tachs. To fix it remove the 123 power supply wire from the coil and connect it to a different switched ign wire. The electronics mess with the triggering of the tach."

[Francis]

Thanks Guys.

I chose to send my tach and speedo to a shop called JDO Instruments in England.

This guy says he will calibrate my speedo and change the electronics of the tach to make it compatible with the 123 ignition distributor.

I was required to do a driving test of 10 miles.

Using my Garmin GPS I drove 10 miles and my speedo counter reading showed 9.7...

Francis