speedo drive

[raz1966]

i have a strange problem with my car, the speedo moves when the car is in neutral, also it is very erratic and the needle moves all over the place. i have tried another speedo but it is still the same, the cable looks ok. is there a problem with the speedo drive? how easy is it to change?

[HFStuart]

Speedo moving when the car is in neutral is very odd - I have no idea on that.

The erratic speedo though it almost certainly the cable even if it looks OK from the outside it can be well crudded up inside, you could try running some oil down the centre but in all likelihood you need a new one. Thankfully they're relatively easy to get hold of and simple enough to fit.

Stuart

[raz1966]

the cable looks as good as new but i did notice the end which goes into the speedo has a point on the end, should it be flat?
i have not changed the gear box oil yet, i dont know if this would matter.
if i put the clutch in when the car is in neutral the speedo stops

[HFStuart]

Square section with a slight point IIRC

Gearbox oil wouldn't make a difference.

The speedo cable is driven from the offside of the diff. So if the wheels aren't moving neither is the speedo drive - that's why it's odd unless you had one wheel in the air at the time.

As to the outer condition it's no indication of the state on the inside - if damp has got in it could be rusty as hell or it could have been kinked in the past. The other thing it could be is if the drive gear has broken, unusual but not impossible. Given that it's cheap enough I'd just replace the cable and see what happens

Stuart

[raz1966]

it has no wheels on at the moment, so i guss that explains that.
i have taken the inner cable completely out and it looks fine, but i will try a new cable
do i have to remove the gearbox to renew the speedo drive?

[HFStuart]

Not 100% certain but I think so.

[HFStuart]

BTW Brand new Speedo drive gear on eBay now for only £7.

[WestonE]

Raz

The speedo drive is held in place in the Diff by 1 small Allen bolt black anodized. You remove that first then with a speedo cable outer part screwed on use an open ended spanner and a screwdriver to lever the drive out. You will find a metal outer long cylinder with and O Ring seal with a nylon drive gear that just sits inside it. Be aware the diameter and tooth pitch varies from model to model and year to year so if you replace it check this as it has to match the drive gear on the differential.

Eric   

[lukasdeopalenica]

I know the thread is very old but as my question is closely related I decided not to start a new one.
My speedo shows lower values by about 10-15%. I have standard size tires and a brand new speedo cable. I have also checked a spare instrument cluster, definitely from i.e. version. Looks the same and has the same markings at the back. No difference in operation.
I need to mention that I bought the car with no working speedo. The blocked cable probably caused the speedo nylon driven gear to broke. I replaced it with a spare one coming from ie version. It looked exactly the same as the broken one. The only element in the system that is still not checked so far is the driving gear that sits inside the differential unit. Do they vary in betas? Maybe someone in the past had installed a transmission from other version, e.g. 1.6?
However, the broken gear has some wear on its teeth, that can suggest operation with not matched properly driving gear. Are the driving and driven gears paired? Is it any rule to mach the gears?
thanks
 

[WestonE]

Yes the driving gears are paired to the gear on the crown wheel and they vary from model to model. Wear on yours suggests it does not match the drive on the Crown wheel.

Eric

[lukasdeopalenica]

thanks, Eric.
So I need to change the whole transmission box, because I do not think there is a way to replace the differential unit in situ...

[lukasdeopalenica]

If you have a chance could you please check what speed do you have at 5th gear and at 3000RPM?(preferably both at the speedo and GPS) I assume you use standard size wheels. Mine GPS shows 90kph, whereas my speedo indicates just about 70. I suppose that for the i.e. it should be about 100kph.
I would like to know what gearbox is installed in my HPE. I am pretty sure it is not the genuine one. 
thanks a lot.

[lukasdeopalenica]

Hmm, just could you please tell me what does your speedo show at 3000rpm and 5th gear? That should help answering my doubts.
thanks.