disco speedo

DEFENDER90-DAZ · Sep 16, 2011

Hi noticed yesterday that my speedo is reading 10mph high (40 mph @ 30 mph on satnav) its a 1997 discovery 300tdi jap import.

I'm using 205/80/16 tyres on 16x7 modular wheels.

Has anyone seen this before??
How can i sort it out so that it reads accuratelyish??

Cheers
Daz

jyhelle · Sep 16, 2011

I had this on my bike when I changed the tyre size, since the perimeter of the wheel was changed ... do you have the correct tyre size ?

DEFENDER90-DAZ · Sep 16, 2011

I've just edited the first post with the wheel/tyre sizes.

Daz

DEFENDER90-DAZ · Sep 16, 2011

Just had a thought: are the speedo senders different for km and mph???

If they are i might have to get 1 that does mph???

Daz

Dr_evil · Sep 16, 2011

Get the speedo calibrated, your rolling circumference will be out like mine is on the 109 (tyres are too small)

DEFENDER90-DAZ · Sep 16, 2011

I have checked the "which tyres for my disco" thread on here and 205/80/16 is the standard fit which gives 0% change to the speedo readings??

If i do need it calibrating is it a main stealer job??

Daz

jyhelle · Sep 16, 2011

DISCOVERY1-DAZ said:
If i do need it calibrating is it a main stealer job??

no idea how it's done, but speedos are usually security-locked so one can't modify the total distance for the vehicle (no problem to open it, but might become one if you want to resell the car later)

Dr_evil · Sep 16, 2011

If you've converted from KPH to MPH I guess thats what you meant by your post, the speedo may just be one of those stick over jobbies in which case it could be out a bit

However if its had smaller or larger tyres on before you got it and the speedo was calibrated for that by the previous owner that might account for it and it just needs changing back. Shouldn't be a big job and most places can do it, the wheel shop where I was getting my new ones from offered to do it as its a quickie.

Now if your speedo is consistently reading 10mph under through the entire range you could just drive 10mph faster and live with it if it's not a huge issue to you, I'd opt for that method and leave it until it goes in for its next service or pre MOT service then get it done at the same time

DEFENDER90-DAZ · Sep 16, 2011

I've sent the main stealer an enquiry via their website so i'll wait and see what they say.
Thanks a lot for the info guys!!!

Just remembered that the car did come with 255/65/16 tyres - so that might be it!!!!

Cheers
Daz

jyhelle · Sep 16, 2011

205/80/16 gives an outer circonference of 230.72 cm (sorry my program gives metric answers...)

255/65/16 gives 231.82 cm, not much different

zen · Sep 17, 2011

might have different ransferbox fitted in past..lower gearing?

you can get different speedo drives (transferbox fitting,very easy)

or..if all is standard,and prehaps your speedo is just ****ed,then..

disco instrument clusters go for not alot..buy one..easy fit..

jamesmartin · Sep 17, 2011

zen said:
might have different ransferbox fitted in past..lower gearing?

you can get different speedo drives (transferbox fitting,very easy)

or..if all is standard,and prehaps your speedo is just ****ed,then..

disco instrument clusters go for not alot..buy one..easy fit..

you cant change speedo drive for different colour ratio in 300 tdis as only black one fits transducer speedos

disco speedo

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