How do I rewind a speedo...

[rockthebus]

Hi all
I've just got hold of a replacement speedo and need the mileage going back from 275000kms to 127000kms to match the correct mileage.
What options so I have?
Thanks in advance.


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[R0B]

I'm sure that is illegal to do.

[keytouch]

Screwdriver bit in a cordless drill in the hole in the back for the cable

Would possibly be the way to do it.

Technically you're not changing the mileage on the vehicle.

You're setting a spare part to match the vehicle before its ever been fitted

[R0B]

Thinking about it,if it can be done who's to know.Not sure if you can run it backwards though without damaging it.

[rockthebus]

Thinking about it,if it can be done who's to know.Not sure if you can run it backwards though without damaging it.

When we drive in reverse the cable is still attached so I would guess it will be ok.

If I find a tiny square drive I wonder how many hours it will take...

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[R0B]

Good point about the cable.Thing is the mileage does not go down when you reverse,so i don't think turning it back will be possible.Maybe forwards is the only way to do it.

[ajsimmo]

With speedo on the bench, you can drive out the centre "axle" then set the numbers to what you want and refit the axle shaft. Prepare to drop them, not be able to get them to line up, swear a lot at how fiddly it all is, then achieve it and think it wasn't so tricky after all.

[rockthebus]

With speedo on the bench, you can drive out the centre "axle" then set the numbers to what you want and refit the axle shaft. Prepare to drop them, not be able to get them to line up, swear a lot at how fiddly it all is, then achieve it and think it wasn't so tricky after all.

My previous speedo shaft was lose on the drive gear so mileage didn't work. I'm worried that driving it out will cause this to happen again. How much 'force' should it take?

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[tforturton]

Have you never watched "Matilda"? Danny DeVito does the old drill in reverse trick. But Ferris Bueller's efforts came to nothing.

[ajsimmo]

Hard to describe, but I know "some" isn't all that helpful!
It takes more force than is comfortable the first time you knock one out, but it'll come. After fiddling about with your digits, just nip the end of the shaft with some pliers and put a drop of araldite on it. This should bruise it out of round enough to ensure the end doesn't slip, and the glue will lube it for re-entry then go hard to ensure a good tight fit.

[gary1998]

use the drill on end of speedo cable don't run it backwards go forward
and right away round


in Ireland it's not illegal .. but it is illegal to knownly mislead a buyer if your selling
but you can just state mileage not correct .... but in your case it will be correct ( mot certs will confirm will it not )

[captain Byrne]

Tried the electric drill trick on an old Morris Marina many years ago. I set it up on a bench all secured & left the drill running for about an hour, checked the mileage & it had gone back by about ten miles. Figured it would have taken a couple of weeks with the drill running for it to have any noticeable effect.

[MagicWagon]

On my stag I had to put the mileage forward when I replaced my speedo. Did it by opening it up, then was able to separate each digit barrel enough to turn each independently. That was a smiths speedo. Don't know if the same would work on a T25, but if you still have the old one you could practice on that.

[ghost123uk]

With speedo on the bench, you can drive out the centre "axle" then set the numbers to what you want and refit the axle shaft.

Is how I did it. One thing I do know is be careful with the tiny delicate hair spring that "zeros" the needle. After successfully setting my mileage to the correct level, I went to test that it was still clocking up the miles correctly by using an electric drill and the end of an artists paintbrush. During this test I briefly ran it backwards by mistake, with no needle attached, and doing that wrecked that tiny spring I then had to source another speedo and do it all again

Also note, when removing the needle, there is a tiny dot, just on the "wrong side" of the needle stop pin. This is where you "set" the needle when re-fitting it, then you carefully lift it over the top of that stop pin so that it has a slight pre-tension. If you don't do this, the speedo will read quite a long way out.

[pirate-pete]

Good ideas above.

Esp the one about the araldite - I made the mistake of using superglue which dripped on to the trip meter cogs and took ages to clean up so the gears would mesh properly.

For smaller corrections in mileage you could easily disconnect the long gear on the side which goes from the cable area to drive the shaft with the numbered dials on. Then you can spin that shaft with your finger and it will clock up the miles quite quickly while you sit there watching TV whatever.