Xantia speedo

louis1 · Post by **louis1** » 22 Oct 2003, 07:06

Hi I have a 1998 Xantia V6 auto, and the speedo goes off the clock [:D]when driving fast and hits the tripometre button at the bottem of the clock. The revs carry on going up but the speedo can't, so does anyone know how i can work out my speed e.g speed per 1000 revs in top gear.

fastred · Post by **fastred** » 22 Oct 2003, 16:59

Call it 30 mph per 1000rpm. This is near enough right and makes it easy to do the mental arithmetic.
Fastred (2000 V6 Exclusive)

KevMayer · Post by **KevMayer** » 23 Oct 2003, 01:14

How fast is it going when it goes off the clock ? It sounds wicked !

AndersDK · Post by **AndersDK** » 23 Oct 2003, 01:47

Sounds like a transducer problem - check the plug/cable on the speedo transducer at the diff.

louis1 · Post by **louis1** » 23 Oct 2003, 19:08

This is my problem
http://home.iae.nl/users/havens/xantia.htm
Scroll down to speedo picture.

Homer · Post by **Homer** » 24 Oct 2003, 02:07

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">This picture is taken on the German Autobahn.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Thanks for that, you had me a bit worried.
It looks like fastred's calculation is a bit 'out' at those kind of speeds. Probably works well at British (snail's pace) motorway speeds. His calculation would give you 180mph at those revs, which is above the possible performance of the V6 Xantia.
240kph works out at around 150mph, which is only a fraction over the supposed top speed which I think is around the 140 mark, so I would guess it is simply the usual error margin built into all speedometers (0 to +10%).
I think your best bet would be to get hold of a GPS system to obtain an accurate speed reading. Because at those speeds, errors due to tyre pressure/wear/size would affect any calculation based on RPM. Or time it over a measured distance.
A bit of a jump from the BX16 I imagine?
[added]
I suppose for a rough estimate you could take the revs at a known speed (say 200kph) and use that to do the calculations.
So if you are doing 5000RPM at 200kph then that gives you 40kph for each 1000RPM. If so then the 6250RPM indicated in your picture would equate to 250kph (152mph, which is within 140 + 10%)

Homer · Post by **Homer** » 24 Oct 2003, 02:33

Oh and by the way, I am jealous.
Xantia V6, with Activa suspension is something we don't even have the option of in the UK. You'll be telling me it's a manual transmission next.[:(!]

fastred · Post by **fastred** » 24 Oct 2003, 14:42

You did not say at first that your car is an Activa - my figures were from my V6 Exclusive. The gearing on a car not sold in the Uk may be different.
Fastred