12 replies to this topic

[willava182]

Bought my Mini Rio recently at noticed the the speedo was about %20 out, when i was doing 30 its reading around 50mph.
Is this a simple fix?
It doesn't bother me to much, just would like to get it sorted.
Thanks

[Dan]

How simple it is to fix depends on why it's wrong. Is it the original speedo? Original wheels? Original gearbox?

[willava182]

At one point the engine and gearbox was replaced, so i assume its something to do with that?
And as far as i can tell its the original speedo.

Edited by willava182, 11 April 2013 - 02:50 PM.

[Tamworthbay]

You can either find and fit the original drive bits in the gearbox (cheap but difficult) or get someone like speedy cables to recalibrate the speedo (expensive but easy) OR stick numbers on the outside at the right places (cheap and easy but ugly).

[tb205gti]

... get someone like speedy cables to recalibrate the speedo (expensive but easy)

THe previous owner of my mini had to take the speedo apart in order to get the milage counter to "roll over", after this the speedo reads about 20km/h too much. Can you describe how to recalibeate it? Speedodrive is the right one in my car.

[Tamworthbay]

... get someone like speedy cables to recalibrate the speedo (expensive but easy)

THe previous owner of my mini had to take the speedo apart in order to get the milage counter to "roll over", after this the speedo reads about 20km/h too much. Can you describe how to recalibeate it? Speedodrive is the right one in my car.

I don't know how they do it. They ask for wheel diameter, circumference and a couple of other measurements if I recall correctly. Best bet is to give them a ring. For my import Suzuki Katana it was £70 but that was few years ago and included an MPH dial face.

[Dan]

You can't calibrate a speedo head at home. If you ask Speedy, they will tell you the technical process they carry out is to 'bung a bit more magnet in'. Speedo heads, at least old fashioned ones like ours, work by magnetic drag, eddy currents and induction.

[matt615]

Willava, you need to change the speedo drive gears in the gearbox. You can use guessworks calculator to work out which gears you need

http://www.guess-wor.../Tech/ratio.htm

Or the other way to do it is test your speedo against a sat nav, and work out how wrong it is. Eg it may only read 80% of the correct speed. Then check what drive gears you have fitted, work out the ratio between the two gears, and then you can work out what ratio of gears need to be fitted to make the speedo read 100% of what it should.

Some people will tell you that changing speedo drives gears is a nightmare and can only be done by taking the engine engine. In reality it's not that hard to do with the engine in, and is quite straight forward if you are used to working on minis.

[willava182]

Willava, you need to change the speedo drive gears in the gearbox. You can use guessworks calculator to work out which gears you need

http://www.guess-wor.../Tech/ratio.htm

Or the other way to do it is test your speedo against a sat nav, and work out how wrong it is. Eg it may only read 80% of the correct speed. Then check what drive gears you have fitted, work out the ratio between the two gears, and then you can work out what ratio of gears need to be fitted to make the speedo read 100% of what it should.

Some people will tell you that changing speedo drives gears is a nightmare and can only be done by taking the engine engine. In reality it's not that hard to do with the engine in, and is quite straight forward if you are used to working on minis.

Thanks mate! and to all others that helped.
Are the gear parts cheap? and wheres best to get them?

Also if this changes anything, i dont think the fuel gauge is working properly.

[KernowCooper]

They are coloured coded in accordance with the final drive ratio and vary between £15-£40 and some are obslete so only s/h units available, before you buy anything see what final drive ratio you have and current drive colour you have. If the speedo head is out of calibration changing the drive would be hit or miss, and its a job for speedy cables.

Prices of drives are here http://www.minispare...eedo drive.aspx

[Guess-Works.com]

Speedo drives are reputed to be colour coded, but different manufacturers used different coloured plastics for the pinions and the paint/dye on the worms comes off in hot oil so is next to useless...

So don't rely on colour... count the teeth...

Your first issue will be to find out the final drive in the gearbox, and approximate 'guess' can be made by the RPM in 4th @ 60mph ( real speed not speedo speed ). At 60 the RPM will be approximately 1000 times the final drive ratio.

Then using the tmp of your speed ( if original to the rio speedo this will be 1242 as it should be a 90mph twin Nippon clock )

and finally your tyre size....

then go here.... http://www.guess-wor.../Tech/ratio.htm

[tiger99]

If you need to change both gear and pinion, the worst scenario, the radiator and engine mount have to come off, and the gearbox extension housing, but that is far, far quicker and easier than lifting the engine. You need a couple of fresh gaskets afterwards, but no major problems should be experienced. Some of the bolts for the extension housing are hidden behind tha alloy adaptor block that the radiator/engine mount bracket bolts to, but it will all be obvious once you get started.

[willava182]

There is a mini specialist garage just down the road from me in kingsteignton, so before i do ANYTHING, ill see what they say, they are meant to be very trustworthy and good.
Also just to give it a check round.