electronic speedometers

[mr impact]

Hi guys, since my P6 has been modified with a 3.9 V8, an SD1 manual gearbox, a 2000 diff and bigger wheels, the original speedometer (circular one) was way out and has now stopped working all together, Im looking for an electronic replacement. But Im a little lost as to which are best and they are all expencive so Im wondering if there is a cheaper option.

Ive found an electronic speedometer from a TD5 Landrover defender that is just an indivdual dial and not a cluster like most modern cars. Does anyone know if that would work with an elcectronic sender cable like this one?

http://www.ebay.co.uk/itm/141167243165? ... 1423.l2649

Or would I need a speedometer dial like this:

http://www.ebay.co.uk/itm/370669068548? ... 1423.l2649

Any help would be great as using the revcounter for speed isnt ideal!

 

[PeterZRH]

Without the matching sender and everything else being equal without custom electronics you're back to the same problem you have with a fixed cable. An electonic speedo is identical to a tachometer.

Fortunately for you there might be an easy option. There are "digital speedo correctors" which on the face of it are designed to change speedo readouts from mph to kph and vice versa. It seems some of these are configurable and might just be what you are looking for providing they happen to fit in the right sort of range.

For example: http://www.autospeed.co.nz/cms/article. ... r&A=108415

I'm guessing the method used is simply a pulse train in proportion to vehicle speed. It certainly wouldn't be too complicated to make something like this using op amps and timer circuits. May cars, certainly my old Audi had a thing called a GAL signal built in which could be used with accessories like a trip computer of GPS.

Another option is keep the analogue one and buy one of the black boxes the guy who converted to the ZF autobox use.

 

[harveyp6]

my P6 has been modified with a 3.9 V8, an SD1 manual gearbox, a 2000 diff and bigger wheels,

the original speedometer (circular one) was way out and has now stopped working all together,

Im looking for an electronic replacement. But Im a little lost as to which are best and they are all expencive so Im wondering if there is a cheaper option.

There are lots of P6's fitted with LT77's, so as the speedo was working, and electronic ones are expensive, why not find out why it's stopped working, fix that, and then get the head recalibrated.

 

[mr impact]

How do you get them re-calebrated then? I think the sender cable has come off when we was last underneath it as I was driving home from the workshop when the speedo just fell back to 0. I havent been underneath since and have just used a satnav to see what speeds Im doing at what revs and driving by that. But Its getting annoying now so really need to fix it! If I can use the mechanical sender and original dial but have it calebrated right that would be ideal. Whats involved in re-calebrating?

 

[harveyp6]

How do you get them re-calebrated then?

Send it here:

http://www.speedycables.com/

Whats involved in re-calebrating?

They will send you a formula that involves measuring from the centre of the driven wheel to the ground, pushing the car forwards six turns of the wheel, and counting the number of times the speedo inner cable turns. (IIRC). Send them that info along with the clock, and they do the rest.

 

[mr impact]

Cool, cheers. Yeah that sounds a good plan to me!

 

[vaultsman]

I have an LT77 fitted in my V8, together with non-standard wheels & tyres, so my speedo was under-reading by a good margin.

I used these people....

http://www.speedograph-richfield.com/

...not, I hasten to add, because I think they're any better than Speedy - just that they were local to me. Did a good job.

When you're counting the inner cable turns, something like this on stiff card helps.



Good luck,

Stan

 

[mr impact]

Cheers for the help guys, thats the next job to do then!