How much is yours out by?

[pbrettle]

Just been running my PDA satnav system in the battle bus today and noticed that the speedo is out against the GPS speed - Ok so the sample on the GPS is every 2 seconds and is an average of that - but it seems to be out by as much as 5-7 MPH....

Anyone else out by this much? More than that? I guess this is normal, but how common is it to have an inaccurate speedo? Just wondering cos I am bored.

Cheers,

Paul

[Yertis]

You're not as bored as me...

[mel]

When i pulled my speedo out after the odometer stuck again I found a little TVR style paper sticker for calibration saying 5% and a set of initials.

Anyway I recalibrated against GPS and its now spot on.

[pbrettle]

Yertis said: You're not as bored as me...

Dont bank on it - want to go to bed but its just TOO EARLY.

[littlegearl]

i know my mates Suzuki SJ can be out by 15mph after he put bigger tyres on...

[minimax]

my mini is out by lots - indicated 25 mph = 32, indicated 50mph = 60, indicated 90mph = 111 - eek! all due to new dials & aftermarket wheels & tyres.

[robp]

I often find that when driving at 70mph my speedo reads as high as 110mph, honest officer.........!

[DanH]

Mines absolutely spot on (stack instrumentation I guess). They are meant to be about 5% under so its not so great being dead on or over. Sometimes I think I underead by about 4mph which isn't good with factory standard tyres etc.

Why would anyone put wheels that were the wrong diameter on a car? That has to screw with the handling... Also means your mileage clock is totally under-reading, hmm note to self, don't buy your car

Someone on the lotus board said that the amount of tread left has a measurable affect too. Dunno as I haven't done the maths.

[minimax]

DanH said:


Why would anyone put wheels that were the wrong diameter on a car? That has to screw with the handling... Also means your mileage clock is totally under-reading, hmm note to self, don't buy your car

It's a mini. you just have to. first mod if you're going to rally it (I am)

[robp]

DanH said:
Why would anyone put wheels that were the wrong diameter on a car? That has to screw with the handling... Also means your mileage clock is totally under-reading, hmm note to self, don't buy your car

Would not totally agree with this.
Obviously if the car was well engineered in the first place you have a very valid point
but
if the car in question handled like a bag of poo in the first place the correct upgrading of the suspension and tyres can improve things.

[kevinday]

DanH said:
Someone on the lotus board said that the amount of tread left has a measurable affect too. Dunno as I haven't done the maths.

Measurable, yes, if you lose about 4mm in tread depth it is around 1% difference, not enough to worry about though.

[raceboy]

Pah, I've not had a a reliable speedo for months, hooked up to a Origin Blue to give GPS speed data at a GPS 136mph (on private land) the speedo reads 70mph,
hopefully Joolz can sort it at the next service

[Tony Hall]

Think my Chimaera speedo is over-reading, now does that mean the odometer is over-reading to?
Bit like the old joke I suppose, My car's overheatin',...why have you left it in Heaton?

[pdv6]

minimax said: my mini is out by lots - indicated 25 mph = 32, indicated 50mph = 60, indicated 90mph = 111 - eek! all due to new dials & aftermarket wheels & tyres.

Pretty sure its not road legal to have an under-reading speedo...

[DanH]

I compared my Elise against the blue i, and I'm a bit suspcious as it says the speedo underreads by a few mph around 70ish.

Thing is the 2 second lag makes it very hard to use effectively.

[Byff]

littlegearl said: i know my mates Suzuki SJ can be out by 15mph after he put bigger tyres on...

I'm most upset.

I built a SJ with a 2.9iV6 and 33" tyres. I spent three years building it with a full photo history and wanted to put a little piccie on here to show the difference between standard and mine.

Can I find one single photo of it? Can I bo11ocks!

Sold it now and i've no idea where it is!

[minimax]

pdv6 said:

minimax said: my mini is out by lots - indicated 25 mph = 32, indicated 50mph = 60, indicated 90mph = 111 - eek! all due to new dials & aftermarket wheels & tyres.

Pretty sure its not road legal to have an under-reading speedo...

probably right, but it requires changing something complex in the gearbox and that requires taking the engine out etc, £350 before you start. Besides, they're only 12" minilites, possibly the most popular mod to mini wheels, so 100's (1,000's?) must have the same problem as me (although I know that just coz lots of people do it it doesn't make it right)

[srider]

Just been running my PDA satnav system in the battle bus today and noticed that the speedo is out against the GPS speed - Ok so the sample on the GPS is every 2 seconds and is an average of that - but it seems to be out by as much as 5-7 MPH....

Anyone else out by this much? More than that? I guess this is normal, but how common is it to have an inaccurate speedo? Just wondering cos I am bored.

Cheers,

Paul

According to my GPS, the speedo in my :dontlaugh: Transit over reads by 8%. Most are between 5-10%.